A mes grands-parents,

A mes parents. A ma soeur A Juliette

Remerciements / Acknowledgements

Tout d'abord je remercie les membres du jury qui ont accepté de juger ce travail : Pr. Petra Rudolf et Dr. Guillaume Schull pour leur travail de rapporteur ainsi que Anna Proust et Céline Fiorini en temps qu'examinatrice. Je remercie également cette dernière pour tous les échanges que nous avons pu avoir au cours de ma thèse que ce soit pour m'expliquer le fonctionnement d'un banc d'optique ou pour me soutenir lors de mes CST.

Ce travail a été réalisé au sein de l'Institut Parisien de Chimie Moléculaire (IPCM) dans le laboratoire de Chimie des Polymères dirigé par le Dr. Laurent Bouteiller que je remercie pour son accueil, mais aussi pour les éclaircissements qu'il a su m'apporter dans le domaine des associations supramoléculaires.

Je remercie sincèrement mes « directeurs » de thèse successifs qui se sont relayés pour des raisons administratives au cours de ma thèse : David, mon premier directeur de thèse, qui m'a recruté et qui m'aura aidé jusqu'au bout, il m'a toujours donné tout le temps dont j'avais besoin quelle que soit la surcharge de son agenda et avec le sourire. Fabrice, qui récupéra le titre de directeur de thèse à quelque mois de la fin et qui a su motiver, amuser mais aussi m'enseigner notamment lors de mon séjour au Japon sous sa supervision. Et finalement Jutta qui m'a servi de directeur de transition et que je remercie pour cela. Je remercie aussi tout particulièrement Lydia ma co-directrice de thèse tout au long de ma thèse dans son cas. Lydia m'a apporté bien plus que l'on peut attendre du meilleur directeur de thèse. Par son énergie, elle est un véritable moteur de l'IPCM et a su me communiquer nombre de ses passions que ce soit pour le PowerPoint, pour la chimie des chromophores ou pour manger des gâteaux. Pour tout cela et beaucoup encore je m'estime très chanceux d'avoir pu être ton premier doctorant.

Je remercie toutes les personnes qui ont permis à ma thèse d'avancer : Claire, Regina pour leur aide avec la RMN, Gilles pour sa gentillesse pour passer des échantillons de masse dans des délais très court. Je dis un grand merci à Imad Arfaoui ainsi que Fabrice Charra qui m'ont beaucoup aidé dans mon apprentissage de la STM. Imad j'ai eu l'impression que tu étais un de mes superviseurs durant cette thèse : merci beaucoup pour toutes les connaissances et les conseils que tu as pu m'apporter. Enfin merci à tous ceux que j'ai pu croiser au LEPO qui ont contribué à ce que mes passages au CEA soit toujours un plaisir pour moi. Merci au Pr. Adachi également pour son invitation à travailler dans ses locaux à Fukuoka, ce fut un superbe séjour.

Je remercie grandement les stagiaires qui ont contribué à l'avancement de ce projet : Lucas, Lina, Allan, Hoda, Fatima, Gervaise, Quentin et Benjamin.

Ensuite je remercie tous les doctorants du groupe de chimie des matériaux pi-conjugués que j'ai côtoyés et qui on fait de ma thèse une belle aventure sociale. Ainsi merci à Dizheng, Xiao, Weiwei et Haixia qui m'ont fait découvrir la culture chinoise mais qui ont aussi acquis une vraie culture européenne au cours de leur thèse. Merci à Robin et Kevin pour les restaurants que l'on a pu découvrir ensemble et pour leur soutien à apprendre de nouvelles notions physiques.

Trop de personne au sein de l'équipe de chimie des polymères ont contribué aussi à travailler dans un environnement inégalable et je leur dis à tous et toutes merci d'animer de façon si gaie les couloirs le café et bien au-delà.

Je remercie mes 2 compères Nicolas et Laura pour l'entraide aussi bien mentale que technique et avec qui j'ai u préparer une journée de laboratoire mémorable.

Enfin je suis particulièrement reconnaissant à ma famille et mes amis : de

General introduction

Nanotechnology concerns the manipulation of matter on an atomic, molecular, and supramolecular scale for industrial purposes. It has become increasingly important because it can be applied to almost every field of science; from molecular biology and organic chemistry to semiconductor physics, device manufacturing, surface science, etc. Its main purpose lies in the potential to design and fabricate functional materials at the nanoscale (e.g. 10 -9 m), either through top-down or bottom-up methods.

Over the past decades, graphene has become a nanomaterial of interest. This material composed by an atomically flat single layer of carbon possesses remarkable properties; it is very resistant, has excellent conductive properties and is optically transparent. Researchers have been working

to exploit this inert material through its functionalization to create novel nanomaterial for over two decades. Many strategies have been explored to incorporate into graphene new functionalities and therefore be able to modulate its electron transfer, charge separation or optical properties. However, this field is still in its early stages and a lot remains to be built to access graphene-based nanodevices. Covalent-type functionalization has been employed to introduce functionalities to the graphene material, however it alters the structure of the crystalline lattice, producing defects in an un-controlled manner. On the other hand, the noncovalent (supramolecular) approach has proved to be quite successful, as it allows to keep intact graphene's structure. This type of functionalization has been investigated in the past decade; however, it has been almost exclusively limited to patterning the surface. These patterns are achieved by using self-assembling, flat molecules which are programmed to form regular lattices on the surface. However, because graphene is a conductive material, any electronic and optical properties that the adsorbed molecules might possess, will be lost due to the charge and energy transfer processes that occur on the graphene surface. So, if we want to achieve an efficient form of functionalization, the architecture of our molecules must be modified to avoid contact with the surface.

Our main goal in this PhD project was to design molecular building-blocks where we can control the formation of long range, well-ordered self-assemblies and be able to introduce a function which does not interact with the graphene surface. Two strategies of patterning are targeted: one with a porous mask on the surface to distribute the functionalities and one with pedestal functionalized to self-organize on the surface to accomplish this, we designed new supramolecular materials based on three components (Figure 1):

• A pedestal: which will enable it to stick to the surface and to control its patterning on the surface. This requires the use of a flat aromatic molecule which can be programmed to form different assemblies by modification of its molecular structure.

• An optically active functionality: to incorporate into the graphene surface and that will hopefully keep its molecular properties intact.

• A linker: to attach the pedestal to the functional part. This component should enable us to control the distance between the functionality and pedestal and as a result to the surface.

Figure 1. Description of the building-block designs and its assembly structure

These molecular building blocks are assembled by exploiting the non-covalent interactions between the components and provide a simple way to obtain a variety of supramolecular objects by a simple mix-and-match of components.

The work described in this manuscript demonstrates our approach to achieve this goal. In the first chapter, we will describe the design, synthesis and characterization of the molecular components of the new supramolecular materials we propose. The second chapter describes the methods we used to bring together these building blocks and evidence the formation and stability of these supramolecular entities. Finally, in the last Chapter we will explore how these supramolecular objects behave when deposited on a graphene or HOPG surface. This chapter also present an early investigation of the optical properties of the functionalized graphene obtained.

Chapter 1: Introduction to the synthesis and properties of the molecular components I. Introduction

I.1. Porphyrins and phthalocyanines -Historical background

Porphyrins (Ps) and phthalocyanines (Pcs) are flat, aromatic molecules. [1] Porphyrins come from the nature and due to their important presence in biological activity, they are essential in life. They can be found as the main components in the pigment chlorophyll and hemes (Figure 2) where they bear different roles due to their multiple properties. The discovery and the first experiments on porphyrins began with the study of hemoglobin in the 1840's. [2] In those primitive studies, iron hematin was turned into metal-free hematin using sulfuric acid. The ironfree hematin was isolated in a crystalline form in 1867 by L. Thudichum's and exhibited a blood-red color and also fluorescence. The term "porphyrin was first proposed by Hoppe-Seyler with his studies on haemato-and chlorophyll porphyrins in 1871 and 1879. [3] Later on, Hans

Fischer, who performed an immense work on pyrroles; reported the first syntheses of porphyrins in 1929. [4] Figure 2. From left to right: Hematin, chlorophyll a, chlorophyll b structures

The dye, conductivity and ligand properties of these molecules, have made porphyrins very interesting materials for biologists, physicists and chemists. They are used in light-harvesting and emitting materials, as chemosensory, metal-ligands for organocatalysis, supramolecules, etc. On the other hand, phthalocyanines, the synthetic analogues of porphyrins do not exist in nature and were a serendipitous discovery of Braun an Tschernak in 1907. [5] One of the most common Pcs, the copper phthalocyanine (CuPc), was obtained as an unexpected product by Diesbach and Von der Weid in 1927 [6] and once again in 1928 at the Scottish Dyes Ltd.

Company; where the phthalocyanine was obtained as an impurity. In both discoveries, they were planning to synthesize phthalonitrile from o-dibromobenzene and copper cyanide when they obtained a bright blue product in the reaction vessel, which was later identified as the copper phthalocyanine (Figure 3). The synthesis of phthalocyanines became an object of study after its structure was elucidated by Linstead et al. between 1929-1934. [7] As colorful as porphyrins, these molecules found themselves of use several years later as synthetic dyes in different materials. They have found use in the same applications as for the porphyrins; but their extended conjugated structure results in different optical and electronical properties to their natural counterparts.

Phthalocyanines and porphyrins are stable at high temperatures, presenting no degradation up to temperatures of 350 °C. Depending on the metal cation present in the cavity, this temperature can even surpass 500 °C. [8] This high temperature resilience makes their purification by sublimation an useful option. They are also chemically stable, which adds to their appeal as functional materials in various fields. [START_REF] Leznoff | Phthalocyanines : Properties and Applications[END_REF] Figure 4. Porphyrin, Phthalocyanine and their structural units

I.2. Porphyrins and phthalocyanines -Structure and chemistry

Porphyrins and phthalocyanines are aromatic macrocycles containing 18-π electrons in their conjugated ring system. (Figure 5). Their aromaticity is the basis for their thermal and chemical stability, as well as their optical and electronic properties. This aromaticity also implies that they have a completely planar structure; which leads to intermolecular π-π stacking, and explains the strong aggregation present in non-functionalized porphyrins and phthalocyanines, Pcs, having an extended π-system thanks to the four benzenoid rings attached to the core, aggregate more, which explains their lower solubility in relation to their porphyrin analogues. [START_REF] Snow | Phthalocyanine Aggregation[END_REF] Figure 5. 18-π aromatic macrocycle

Porphyrins are constituted by four pyrrole or isoindole-units for porphyrins and phthalocyanines respectively. These units are bridged by either four meso-carbons for the porphyrins and four aza-nitrogen atoms for the phthalocyanines (Figure 4). They usually have a D4h symmetry, but can also have a D3h, D5h or other more complex symmetries depending on its substituents, metal cation, and additional ligands present. In the case where only three pyrroles or isoindoles come together to form the macrocycle; these macrocycles are called subporphyrins or subphthalocyanines. In rare cases, the condensation of five isoindole units results in the formation of a superphthalocyanine (Figure 6). [11] To obtain these analogues, particular cations must be used in the synthesis: subphthalocyanines can be obtained using boron halide salts whilst superphthalocyanines result from the use of rare-earth salts like uranium chloride.

De-protonation of the indole nitrogens in phthalocyanines and the pyrroles in the case of porphyrins make these macrocycles strong Lewis bases that are capable of binding to a variety of metallic cations with a +2 oxidation number. These cations can be transition metals, metalloids, alkali metals or even lanthanides and actinides. Depending on the cation present in the macrocycle, different geometries of phthalocyanines can be observed. Additional ligands can also be coordinated to the cation inside the macrocycle's cavity; these are called axial as they are not located within the macrocycle's plane. The coordination of the central cation to the delocalized charge located on the four nitrogen atoms at the core to the leads to a square planar geometry; five or six coordination atoms can lead to a square-based pyramid, a tetrahedron or an octahedron. Lanthanides and actinides are able to have 8 coordination bonds, which leads to the formation of "sandwich-type" complexes (Figure 7). [12][13] On the other hand, when small cations like lithium [START_REF] Schöniger | [END_REF] , potassium, sodium [15] or boron [16] are coordinated, these remain within the same plane. The insertion of different cations in the core leads to a wide variety of porphyrins and phthalocyanines; with different chemical, structural and electronic properties. However, both types of macrocycles can be further functionalized in their periphery, giving us the opportunity to tune even more their properties. This huge range of possibilities on structural modification makes these molecules a great scaffold to develop molecular functional materials. Those molecular modifications are important as they have a direct impact on the material functionality and on the material's properties. In the case of porphyrins, we have four meso-carbon positions corresponding to the four bridging carbons that can be modified, as well as eight β-carbon positions on the four pyrrole units. On the other hand, phthalocyanines have a total of eight peripheral (p) and eight non-peripheral positions (np). The modification of these meso, β, p and np positions can lead to a change in the molecular symmetry, which. brings complications in the synthesis as we will see in the following section.

I.3. Porphyrins -Synthesis

While porphyrin and phthalocyanine structures look similar, their synthesis and physical properties can be really different. Thus, the synthetical pathways to obtain porphyrins and phthalocyanines will be presented separately.

The synthetic approaches to obtain porphyrins were developed with pyrrole chemistry. Two main pathways are used to obtain porphyrins: the cyclotetramerization of pyrroles with aldehydes and the 2+2 cycloaddition reaction of dipyrroles. The symmetry of the target porphyrin will determine the difficulty of the synthetic route used. The most symmetrical derivatives such as the tetrasubstituted porphyrins, like tetraphenylporphyrin (TPP) are the easiest types of porphyrins to be synthesized. This synthesis was first reported by Rothemund and then improved by Adler, Longo et al. and finally by Linstead's group. This approach is based on the cyclotetramerization of pyrrole with a benzaldehyde derivative in acidic conditions (propionic acid for Adler & Longo and a Lewis acid for Lindsey). [17] Figure 9. Typical synthesis of tetraphenylporphyrin [18] The cyclotetramerization product is not favored as the major product, ; with most pyrroles resulting in maximum reported yields of 9% with the Rothemund method [19] , 20 % for Adler's [20] and 35-40% for Lindsey's, [21] The main product of these reactions are usually a variety of pyrrole oligomers, resulting from the favored linear polymerization reaction.

Dipyrromethanes on the other hand, are used as starting materials for the 2+2 cycloaddition pathway and can be synthesized by the condensation of two pyrroles and one aldehyde. In these reactions, an excess of pyrrole is used to avoid the production of oligomers. Catalysis of the reaction is often performed using TFA, BF3 or a mixture of both. [22] In the MacDonald 2+2 cyclotetramerization, two formyl groups from one dipyrromethane will react selectively with unsubstituted pyrroles in acetic acid with catalytic amount of p-toluenesulfonic acid (Figure 10). Thus, by using differently functionalized dipyrromethanes, we can achieve the synthesis of unsymmetrical porphyrins. [23] Figure 10. Possible mixture after 2+2 synthesis of porphyrins.

As the asymmetry of the target porphyrin increases, the difficulty of the synthetic approach increases given the difficult purification of the resulting isomers that are produced. In this project, will only discuss the synthesis of symmetrical porphyrins. Metalation of porphyrins can be easily achieved by reacting a metal salt with the previously-formed porphyrin in a good solvent like THF, halogenated solvents, and also with many high boiling point solvents like chlorobenzene, DMF, or o-dichlorobenzene. The reaction is quantitative and can easily be followed by a distinct color change once the metalation has taken place.

I.4. Phthalocyanines -Synthesis

Phthalocyanines can be obtained as either metal-free or metalated macrocycles. The main pathway leading to metal-free phthalocyanines starts with a phthalonitrile which is cyclotetramerized in basic conditions with a protic, high-boiling point solvent. In the most commonly used cyclotetramerization procedure, solid lithium in pentanol reacts with phthalonitrile derivatives (Figure 11) to form a dilithium-metalated phthalocyanine. The metal cation (lithium) acts as a template for the Pc precursors to surround and thus favor the formation of a cyclic product instead of a linear oligomer. Acetic acid or other mineral acids can then be used to remove the lithium cations from the phthalocyanine cavity, leaving us with the nonmetalated phthalocyanine that can be reacted in the same way as the porphyrins to insert a different metal cation. Other precursors different to the phthalonitrile can also be used; like phthalic acid, diimidophthalimide, phthalic anhydride, or o-dibromobenzene, amongst others (Figure 12). Precursors to cyclotetramerization of phthalocyanines [24] Although the precursors used might be different, all these cyclotetramerizations share a common parameter; the cyclotetramerization reactions require heating at high temperatures, of at least 150 °C to afford the best yields. In the case where the temperature is too low, the proportion of linear oligomers produced increases (Figure 13). To synthesize metalated phthalocyanines two main pathways are used (Figure 14). The first one involves the introduction of a metal salt instead of lithium metal to provide a template for the cyclotetramerization to occur. In the second pathway, the metal salt is introduced into a, metal-free macrocycle (after removal of the lithium cations) with the aid of a high-boiling point solvent.

Figure 14. Synthesis pathway to metal phthalocyanines Unsubstituted phthalocyanines and a major part of metalated-phthalocyanines are poorly soluble in most organic solvents. At 25 °C their solubility is lower than a few milligrams per liter in the best-case scenario. The most common solvents used to solubilize non-metalated phthalocyanines are aromatic, non-polar solvents like toluene, chlorobenzene, dichlorobenzene, chloronaphthalene… In the case of some metalated phthalocyanines, the use of a coordinating solvent like THF or pyridine can increase their solubility by a factor 10 to 100. [25] Mineral acids like formic acid or trifluoracetic acid can also be a good alternative to solubilize phthalocyanines. However, with acidic solvents the heating produced during the solubilization can induce the demetallation of phthalocyanine.

I.5. Substituted Phthalocyanines -Synthesis

Functionalization of phthalocyanines can be achieved following two paths. The first one is the post functionalization of a phthalocyanine macrocycle via electrophilic aromatic substitution.

The second route, involves the cyclotetratetramerization of a previously functionalized precursor. At a first glance, the first option looks more straight-forward; however, it can be a very limited approach due to a lack of chemoselectivity on the phthalocyanine structure. A second drawback from this method comes from the very poor solubility of non-substituted phthalocyanines in organic solvents, which requires high temperature reactions. For the following discussion we will focus on the second pathway which is the precursor modification to obtain functionalized phthalocyanines. Incorporation of linear or branched alkyl or alkoxy carbon chains or similar bulky groups will increase the Pcs' solubility in organic solvents. In the other hand, the addition of sulfonate or carboxylate groups will increase their solubility in water. Substitution of non-peripheral positions by bulky groups can also induce the twisting of the phthalocyanine's plane and as a result reduce its aggregation. This however, can have a drastic effect on the Pcs' optical and electronic properties. Other ways to tune the optical and electronic properties involve the introduction of electron-withdrawing or donating groups like halides [26] , nitro [27] , ferrocene [28] , and carbazoles [29] . Like porphyrins, the synthesis of asymmetrically-substituted phthalocyanines is more complicated. For example, to obtain a specific tetra-substituted Pc derivative, no matter how the reaction is caried out, a mixture of isomers is always obtained (Figure 15) and their separation is quite complicated. We have therefore focused our research towards the synthesis of symmetrical phthalocyanines as well, specifically the case where the substituents are linear alkyl chains. Peripheral octaalkylphthalocyanine synthesis is based on the use of a 4,5-dialkylated phthalonitrile. This chemistry was developed by N. Hisao Nishi et al. in 1989 in Japan . [30] This works was mainly inspired by Michael J. Cook's and M. Hanack's works on peripheral alkyloxyphthlocyanines. [31,32] The alkylated phthalonitrile can be synthesized from several different precursors via several routes which have been developed in recent years. [33][34][35][36] These routes rely on four main strategies: a) Via o-diamides: The dehydration of o-diamides to give phthalonitriles can be done using a

Vilsmeier-Haack reagent (Figure 17, step 4, dehydration step). This reagent can be easily produced in situ with a mixture of DMF, oxalyl chloride, thionyl chloride or phosphorous oxochloride. This reaction gives good yields (75 to 90%) and can be used in presence of halides, silanes [37] , or nitro [38] substituents. The main drawback from this strategy is that the o-diamide precursor is obtained after a multistep synthesis of at least four steps, which lowers the overall synthetic yield. The diamide cannot be obtained directly from the phthalic acid precursor and so must undergo several functional group transformations from acid to anhydride (step 1), then to phthalimide (step 2) and finally to diamide (Figure 17). dihalides (Figure 18). The cuprous cyanide can be prepared in situ with a Cu(I) salt and potassium or sodium cyanide. [39] This reaction has been reported in presence alkyl, alkoxy, alkylthio, hydroxy, acyl, formyl, carboxy, ester, nitro and amine substituents; showing the versatility of this pathway. However, one major the drawback of this reaction is that it often leads to the presence of side products like a mono-nitrile product and the copper phthalocyanine. [START_REF] Sharman | Synthesis of Phthalocyanine Precursors[END_REF] Moreover, the copper used in this reaction can be trapped by the nitriles formed, which require acidic conditions to be separated, and thus lead to the formation of hazardous cyanide salts and HCN.

Figure 18. Rosenmund -Von Braun reaction followed by acid treating to remove cuprous salts c) The Diels-Alder cycloaddition: this is another strategy often used to prepare the phthalonitriles in multi-gram scale given the high yielding reactions employed. In this case, fumaronitrile or dicyanoacetylene is used as dienophile since it contains the two nitrile groups required to obtain an aromatic o-dinitrile (Figure 19). On the other side, the diene selected to react with the dienophile can be used to incorporate different substituents such as: aryl, alkyne, thioalkyl alkoxy, amine, silyl or alkyl. [START_REF] Sharman | Synthesis of Phthalocyanine Precursors[END_REF] This cycloaddition also requires a final dehydration or oxidation step of to recover the aromaticity of the cycle. This step can be facilitated using diene like a thiophene, sulfones or a furane which oxidize by liberating SO2 [START_REF] Swarts | [END_REF] or CO, or using leaving groups like bromine.

Figure 19. Diels Alder pathway to substituted phthalonitrile [START_REF] Swarts | [END_REF] d) Via ditriflates: The Palladium catalyzed reaction of aryl o-ditriflate with a copper salt such as potassium cyanide or zinc cyanide has been reported to yield substituted phthalonitriles. [33,42] This reaction uses palladium (0) with dppf or dba as strong chelating ligands. These ligands greatly improve the yield because they avoid the formation of the inert tetra-cyano palladium complex. Choosing a solvent like DMF or NMP, also helps us to limit the catalyst poisoning by solubilizing the cyanide salts. The catalytic cycle of this reaction was investigated thoroughly and is presented in Figure 20). [START_REF] Sharman | Synthesis of Phthalocyanine Precursors[END_REF] The first step is an oxidative addition of the Pd (0) in the aryl triflate bond to Pd (II). In polar solvents, the triflate leaves the palladium taking an electron which gives a Pd (II) positively charged. The cyanide anion can then bind to the Pd + (II) and this is followed by a reductive elimination to give the aryl nitrile and regenerate the Pd (0). This strategy is a good alternative to the Rosenmund-Von Braun reaction as it avoids the formation of phthalocyanines.

In these routes, cyanation is usually the last step to be carried out and the reaction conditions must be compatible with the various substituents that can be attached to the phthalonitrile precursor. The most commonly-used cyanation protocol involves a pallado-catalyzed reaction in presence of a sterically hindered donor ligand (like dppf, or triphenylphosphine) and Zn(CN)2

as the cyanide source. The synthesis using Zn(CN)2 has the advantage of not producing phthalocyanine as a side product of the reaction. The cyanation step is in generally the most complicated, with the use of cyanide salts, like NaCN, KCN, CuCN, or Zn(CN)2 which are very harmful chemicals. To date, no other alternative, environmentally friendly alternative has been developed.

I.6. Porphyrins and phthalocyanines -Applications

Porphyrins and phthalocyanines have interesting chemical, optical and physical properties which enable them to be employed in various domains. The potential field of applications extends from medicinal therapy to emitting or harvesting optoelectronic materials and chemical catalysts. Several of these main applications will be discussed in the following paragraphs. [43] Originally present in the living processes, porphyrins can be used as photosensitizers in photodynamic therapy. [START_REF] Ben-Hur | Phthalocyanines in Photobiology and Their Medical Applications[END_REF] Porphyrins containing platinum, palladium and zinc in their core are particularly employed in this field [START_REF] Ceroni | [END_REF] since they are strongly absorbing and have the capacity to transform oxygen to reactive singlet oxygen and thus can be used to eliminate cancers cells.

Their reactivity towards oxygen makes them also ideal as oxygen sensors. [46,47][47] Due to their important role in natural photosynthesis, porphyrins and their synthetic analogues phthalocyanines are attractive materials for developing artificial photosynthetic systems light harvesting for solar cell devices or reaction activators for photochemistry. [START_REF] Hiroto | [END_REF]49] Due to their capacity to coordinate to various metals, phthalocyanines have been used as catalysts in homogeneous and heterogenous catalysis. For example, cobalt phthalocyanine has been used as a reductor for the CO2 conversion to CO. [49] Introducing long, linear alkyl chains to the periphery of phthalocyanines result in, discotic liquid crystalline materials. . [32,50] These liquid crystals materials are commonly used as active layers for liquid crystal displays or photovoltaic devices.

Finally, porphyrins and phthalocyanines are also one of the most commonly used aromatic molecules used for the patterning of gold, copper or graphite surfaces to investigate the processes and phenomena related to self-assembly at surfaces. [43]

I.7. Perylenes -Historical background

Reported for the first time in 1912, the perylene-3,4,9,10-tetracarboxylic anhydride (PDA or PTCDA) was at the origin of 3,4,9,10-perylene tetracarboxydiimide, also called perylene bis(imide) (PDI or PBI), chemistry (Figure 22. Perylene, PDA and PDI structures. Starting from the 1950s, PDIs have been widely used as red dyes in the pigment industry [START_REF] Herbst | Industrial Organic Pigments: Production, Properties, Applications[END_REF] because of its air, thermal and photo stability, and due to its good migrational properties when dispersed in polymers. [START_REF] Calzado | [END_REF] Figure 22. Perylene, PDA and PDI structures

In 1959, improving the solubility of the PDI became a focus of interest in order to exploit even further their optical properties. [START_REF] Remy | DE1130099B -Verfahren Zur Herstellung von Fluoreszenzfarbstoffen[END_REF] Their high fluorescent quantum yield places them a as highly attractive materials for light emitting, photoconversion and organic lasing applications. [START_REF] Calzado | [END_REF][START_REF] Ford | [END_REF]55] PDIs have found their place in the field of organic semiconductor devices with its use as the active layer in organic field-effect transistors, photovoltaics or OLEDs. [56]

I.8. Perylene diimide -Structure and chemistry

Perylene diimides are polyaromatic molecules composed by five aromatics rings. Because they are completely conjugated, these molecules are planar. PDIs are also highly symmetric with a D2h symmetry. In a similar way to Pcs and Ps, this aromaticity and resulting planarity leads to a strong aggregation between non-substituted PDA or PDIs in solution. Depending on how these molecules aggregate in relation to one another (head-to-tail or face-to-face) we can generally observe two types of aggregates (J-or H-type respectively). Unsubstituted PDAs can only be slightly solubilized at high temperatures in diluted alkaline solutions or concentrated sulfuric acid. PDI solubility can be increased in common organic solvents with the introduction of sterically hindering groups at the imide group (N-position). On the PDI, we can distinguish three positions that can be functionalized; first, the N position of the imide, the bay positions and the ortho positions located in the perylene core. Substituents on the N positions are usually used to improve the solubility, control the packing arrangement or to graft the PDI to another molecule or macrostructure. These substituents generally have no impact on the electronic or optical properties. [57] On another hand, functionalization on the bay and ortho positions can be used to tune the perylene's chemical and physical properties. Substituents on bay positions can also have an effect on the planarity of the perylene core.

Depending how voluminous they are, they can induce a twist in the planar core. As an example, functionalization with four small radii, fluorines will bring about a 5° twist angle and with four bromine-substituents, a 37° angle. [58] I.9. Functionalized Perylenes diimides -Synthesis

PDA is a molecule produced in industry at a large scale from naphthalene dicarboxylic acid imide. [START_REF] Herbst | Industrial Organic Pigments: Production, Properties, Applications[END_REF] The naphthalene is fused with caustic alkali (NaOH, KOH or AcONa) at 190 to 220 °C and the molten mixture is oxidized under air. After oxidation, perylene diimide is obtained.

The hydrolyzation of PDI in concentrated sulfuric acid at 220 °C affords the perylene dianhydride (Figure 24). PDA is a great scaffold for perylene chemistry. From the dianhydride, various imides can be obtained. Both the bay and ortho positions can be functionalized and by introducing halide groups and thus we can obtain multiple derivatives.

Figure 25. PDA functionalization at different positions in the periphery of the aromatic core

The ortho position has been the least investigated position for functionalization. This position is less reactive than the bay position to thermal, electrophilic aromatic substitution. However, the reduced steric hindrance of substituents in comparison to the bay positions, should favor the substitution reaction. Recent progress in C-H activation have led to obtain approximate 60 to 80% yields of ortho-position functionalization with boron or iodine. [59] Figure 26. Ortho-borylation of PDIs [59] In contrast, the bay position is the most reactive for aromatic electrophilic substitution and many reactions have been described using various substituents. One of the main functionalizations performed on PDAs or PDIs are the bromo or chloro substitution on the bay positions. Dibromo substitution was achieved on PDA using bromine in hot, sulfuric acid with iodine as catalyst.

This reaction leads to a mixture of isomers, as described by Würthner et al. composed of a 76 : 20 : 4 ratio of 1,7-PDA; 1,6-PDA and 1,6,7-PDA substituted products (Figure 27). [60] This results in an insoluble mix of products which can only be purified after further functionalization of the product mixture (for example; imidation) or by substituting the bromine groups by other, more voluminous groups. The tetrachloro-, bay-position substitution of PDA can be achieved in a similar manner using chlorine in sulfuric acid. This reaction is industrially accessible and thus the tetrachloro PDA can be purchased in gram scale at reasonable price.

Starting from these halogenated PDAs, two strategies towards the synthesis of functionalized PDIs are possible. The first strategy starts from the dibromo PDA and involves the substitution of the bromines with a nucleophilic substituent like an alcohol or amine. [61,62] This is then followed by the transformation of the dianhydride into a diimide by the reaction of the modified PDA with an amine. The second strategy, which is usually employed with the tetrachloro PDA;

involves the transformation from anhydride to the imide first before substituting the halide groups with other nucleophiles. [63] The choice of strategy used often depends on the solubility of the targeted product but also of the reactivity of the intermediates. [57] In some cases, the opening of the cyclic anhydride can be more favored than the halide substitution. As presented in Figure 28, in strategy 1, the imide groups (aminopyridine) do not contribute to the improvement of the PDA's solubility, and therefore reactivity; therefore, it is why the ditertbutylphenol was introduced first. In the second synthetic pathway, the introduction of alkyl chains at the N-position increase considerably the solubility of the product, which facilitates the purification. This results also in a more soluble product which as a result, favors the nucleophile substitution conditions.

Figure 28. Imide and bay position functionalization strategies [64][65] The synthesis of asymmetrical PDIs is interesting, as we can use one of the imides to link the perylene core to a more elaborated structure, for example; grafting the perylene to a surface. To perform this asymmetrical syntheses, two main pathways have been investigated. The first route follows a statistical mono imide formation which usually results in a low yield of approximately 40%, in the rare case when the mixture of products can be efficiently separated. [65] The second pathway follows a regiospecific synthesis. This route was first reported by Shi and coworkers and Sengupta et al. [66,67] and starts off with a symmetrical PDA starting material (Figure 29).

To avoid the low-solubility issue, the first step was to transform the PDA to the perylene tetra ester. This tetraester was then made to react with bromine to achieve the bromination of two bay positions. Finally, the regioselective step involved the cyclization of only one side of the diester to obtain a monoanhydride diester perylene. This selective ring-closure reaction was possible due to the low solubility of the monocyclized product which prevents the reaction of going any further (two-sided ring closure). This specific synthesis shown led to the production of the asymmetric product with an 82% yield.

Figure 29. Synthesis of asymmetric perylene monoanhydride [67] This monoanhydride can then be reacted with an amine to give a more soluble (and thus more reactive) monoimide which will enable us to close-off the remaining di-ester and functionalize with a different amine if required (Figure 30). which makes it very attractive to use in many optoelectronic applications such as single molecular spectroscopy, biomolecular imaging, photonic harvesting and emitting devices, organic photovoltaic or electron transport materials. [68] Single molecular spectroscopy is used to observe distribution of properties of a molecule instead of the usual average obtained with solution of solid-state spectroscopy. This brings insight on the mechanism at the molecular scale which can't be observed at the macroscale.

The strong fluorescence of PDI and oligomers PDI based allow us to obtain enough signal to measure these single-molecule properties. [69,70] One of the most sensitive biomolecular imaging tools is based on fluorescent materials. To track the biological processes, perylene derivatives bearing with water soluble functionalities like sulfonate, polyethylene oxide, ammonium groups have been found to be efficient fluorescent tags. [70] Suitably functionalized PDIs allowed to incorporate these derivatives as active layers for different types of emitting devices, like organic light-emitting diodes (OLEDs) or for organicbased lasing. [71,72] Like Pcs and Ps, perylene dianhydrides and diimides are also popular compounds for surface nanopattering. [73] Deposit of thin layer as well as monolayer of PDI on surface received a lot of attention to study oriented molecules and find application surface plasmonic recognition. [74]

II. Synthesis of functionalized phthalonitriles

As discussed in the introduction, several reaction pathways can lead to the synthesis of 4,5dialkylphthalonitriles. To select the best pathway, we focused on the following criteria: Firstly, to obtain an exploitable amount of phthalocyanines to prepare a series of PDI-Pc complexes we had to obtain the 4,5-dialkylphthalonitrile on a multi-gram scale. This requires that the synthetic route employed had to be efficient and adaptable to easily introduce different alkyl chain lengths. Secondly, we wanted to avoid the use of NaCN, CuCN and KCN salts for the cyanation step. Therefore, we focused on a route that employs less reactive cyanide metal complexes like zinc cyanide. Two routes were selected from the literature: one using dibromoveratrole as starting material and reported by Sosa Vargas et al. in 2013 [75] and the second which involves the use of 2,3-dimethylbutadiene [76] .

From here on, and to simplify the discussion in this section, the 4,5-dialkyl phthalonitriles will be abbreviated by CxPn where "x" means the number of carbons in the two same linear alkyl chains in positions 4 and 5 of our phthalonitriles.

We synthesized two CxPn with two different linear alkyl chain lengths: one with n-hexyl the 4,5-dihexylphthalonitrile (C6Pn) and one with n-dodecyl chains (C12Pn). The synthetic route using dibromoveratrole as the starting material (route 1) was chosen due to its high-yielding four steps. [75] Following this pathway, alkyl chains of different lengths can be introduced in the first step through a Kumada cross-coupling reaction. . The second route, starting from 2,3-dimethylbutadiene involves a longer synthetic pathway but has the advantage to avoid the use of cyanide salts to introduce the cyano groups. As each step of this route was reported to be high yielding, we decided to also try this pathway in parallel.

R = C6H13 or C12H25

II.1. Route 1: Synthesis of dialkylphthalonitriles (CxPn) from dibromoveratrole

Figure 32. Synthesis of 4,5-dilakylphthalonitrile from dibromoveratrole Route 1 uses 4,5-dibromoveratrole as precursor. This functional aromatic cycle has an affordable price (130 € for 50 g) and can be stored easily without presenting degradation which makes it a good precursor.

II.1.1.

Step 1: Kumada coupling The first step of this route (Figure 32) involves the substitution of the bromines at the 4,5positions by linear alkyl chains. This reaction was achieved using Kumada-Corriu coupling.

For this cross-coupling reaction, we used a self-made alkylmagnesium bromide as well as a commercial one as reactants. Except for the cost, the main interest in the self-made alkylmagnesium bromide solution is to have access to a more concentrated solution (up to 3.5 M) than the commercial one (sold in concentrations of between 1 and 2 M). Both the hexylmagnesium and dodecylmagnesium bromides were synthesized using standard Grignard conditions, [77] where magnesium turnings are left to react with the corresponding alkylbromide and the alkylmagnesium bromide in an ether solution. The concentrated Grignard reagent resulting from our preparation is highly viscous and as a result the transfer via syringe to the dibromoveratrole solution was complicated. To overcome this, a large gauge cannula was used for the transfer in subsequent reactions. The use of Pd(dppf)Cl2 as a catalyst gave the best results for the coupling reaction, compared to other palladium catalysts. [78] We used 5% of catalyst except in reactions QF023-QF026

where we reduced this rate to 4%. The reduced amount of catalyst led to a 10% lost which showed we couldn't lower the catalyst quantity below 5%. The reaction was done using a small excess of alkylmagnesium bromide (2.1 to 2.3 eq.) in a first time. The total conversion to obtain the disubstituted veratrole never happened so we decided to increase to 3 equivalents. With the dodecyl chains, the yield increased by 13 % this way. This result led us to question the accuracy of the Grignard' concentration, since it seems that it was not as concentrated as we believed it to be. Overestimation of this concentration led to a default of reactant which made it difficult to obtain a total conversion. The mono and disubstituted product mixture were difficult to separate by silica gel column and their close structural properties lead to some loss of the disubstituted product. As we obtained enough materials to continue the synthesis, the reaction parameters were not optimized further. From the results obtained, we have found that using between 2.5 and 3 equivalents of alkylmagnesium bromide with a concentration of 2 to 3 M, and 5% of Pd(dppf)Cl2 resulted in the highest yields of the target products (up to 78 % yield of 1 could be obtained).

II.1.2.

Step 2: Demethylation of the dimethoxy (1)

The dialkylveratroles (1) were then demethylated under acidic conditions to obtain the dialkylated catechol (2). The conversion of the methoxy to hydroxyl groups was done using a 1:1 mixture of concentrated hydrobromic acid and glacial acetic acid. To achieve a quantitative deprotection, the reaction had to be left under a reflux for at least 24 h (Table 2). The catechol obtained (2) presents a strong affinity with silica, which prevented us to purify the product via column chromatography; and so, the crude product was used without further purification (and only after a simple work-up) in the following step. The NMR spectra taken after the work-up revealed only a few impurities present as shown in Figure 34. Given the small fraction of impurities present in the crude mixture, we allowed ourselves to consider the product as almost pure and we could calculate a quite accurate yield. In the third step of the route, we aimed to replace both hydroxyl groups with a good leaving group, in this case two ditriflate groups. This reaction was carried out by a simple substitution using trifluoromethylsulfonic anhydride in basic conditions. We attempted the addition of the anhydride at two temperatures; -78 °C (as reported in the literature [75] ) and at -35 °C. The conversion performed at both temperatures gave the same yield. Moreover, the reaction of triflate chloride on catechol can be facilitated by working at -35 °C rather than -78 °C. This is even better when it comes to working with the catechol with longer alkyl chains because at this temperature the solubility of the catechol is better and the reaction mixture is less viscous.

During the work-up important volume (≈ 100 mL/g) of water and DCM were necessary to lower the quantity of foam that the reaction produced. Indeed, we noted that the salts of the protonated lutidine and trifluoromethylsulfonate produced a lot of foam in presence of brine at pH 7, which drastically increased the extraction time and could be a source of product loss. The-ditriflate product was subsequently purified by column chromatography. Eluting with cyclohexane, hexane or petroleum ether affords the pure product (3) in the first eluted fraction of the column with a yield up to 76%. The reported results showed a lower yield for dihexyl products (Table 3): this is suspected to be the result of more side products present in the dihexylcatechol reactant.

II.1.4. Step 4: Cyanation of ditriflate (3)

The final step to reach the target phthalonitriles (CxPn) was the cyanation of the di-triflate molecule. Several pathways to perform this cyanation reaction have been reported. [35,42] In our case, we used a di-triflate precursor and followed the route described by Hanack et al. . [42] This route allowed us to test Zn(CN)2 instead of the more toxic and hazardous cyanide salts like KCN or NaCN. Another advantage of this method is that we avoid side products like the copper phthalocyanine, which is usually obtained following the Rosenmund-Von Braun reaction. [39] In the reactions we performed, the substitution of the triflate is catalyzed by Pd2(dba)3 in presence of a dppf ligand. The drawback for this method is that by having a palladium 0 species present in the catalyst, the cyanide can poison it and this can rapidly stop the conversion. [START_REF] Sharman | Synthesis of Phthalocyanine Precursors[END_REF] To avoid this catalyst deactivation, the procedure states that the Zn(CN)2 must be added portion-wise in more than 15 fractions over a period of 2 h. Using DMF as solvent also limits the poisoning of the palladium thanks to the low solubility of Zn(CN)2 in DMF. We performed several cyanation reactions with varying conditions (Table 4) and observed an important difference in the yields obtained (≈ 40% difference). To try to explain those differences, we repeated the reaction by changing several parameters: using previously dried Zn(CN)2, anhydrous DMF vs normal DMF (using molecular sieves or commercial anhydrous grade), the addition of more catalyst or ligand, and finally the heating of the reaction over different periods of time. These experiments didn't reveal any relevant effects in the different conversions obtained. In the cases where a mixture of the mono-cyano and di-cyano products were obtained, the separation proved quite complicated because of the similarity between both molecules and therefore decreased even more the yield. This mixture of phthalonitrile with the hydrolyzed product was also reported in the Rosenmund-Von Braun reaction. [START_REF] Sharman | Synthesis of Phthalocyanine Precursors[END_REF] We found however, that the reaction temperature during the addition of the cyanide is crucial. The substitution reaction is exothermic; however, the temperature has to be kept between 62 and 64 °C during the Zn(CN)2 addition. If the temperature goes above this range, the palladium gets poisoned and the reaction stops. If the temperature is too low the reaction is too slow, and as the quantity of cyanide in solution increases, the palladium ends up poisoned as well. Even if this reaction is still not completely mastered, gram-scale quantities of dialkylphthalonitriles (CxPn) were synthesized with yields of up to 88%. The didocylphthalonitrile was obtained as a solid by recrystallization in ethanol, however the dihexylphthalonitrile remained as an oil and was purified by column chromatography.

Following this route, several grams of the C6Pn and C12Pn were obtained with an overall yield up to 55% with the best conditions. However, since the Zn(CN)2 remains a really toxic compound, we wanted to attempt route 2 in which no cyanide salts are necessary. Route 2 begins with 2,3-dimethylbutadiene as precursor. This reactant is cheap, but has to be stored at a low temperature to avoid its polymerization. This route was attempted only to obtain the dihexylphthalonitrile. We wanted to try this path to avoid the use of cyanide salts and to compare how the efficiency of this route with the previous one.

II.2. ROUTE 2: Synthesis of dialkylphthalonitriles (CxPn)

II.2.1.

Step 1: Synthesis of dialkylbutadiene (4)

Figure 36. Dialkylation of dimethylbutadiene using LICKOR

The first step involves the incorporation of the two alkyl chains on the dimethylbutadiene (Figure 36). To activate the butadiene and give it a double anionic character, a dianionic species has to be produced. This can be obtained using the Schlosser's superbase composed by a lithium and potassium mixture. This base is an aggregate obtained by mixing potassium tert-butoxide with n-butyllithium, and is also known as LICKOR. Although its mechanism of action and properties are still not yet well-understood, it has been described to form a dianionic species from dimethylbutadiene. [79] Once the LICKOR was formed at -78 °C, the dimethylbutadiene solution was added. In a second step, the mixture was subsequently transferred into the alkylbromide solution, kept at -78 °C, to give the dialkylbutadiene (Figure 36. Dialkylation of dimethylbutadiene using LICKOR). To obtain the 2,3-dihexylbutadiene (4) we used bromopentane as the alkylbromide reactant. After silica-gel column using petroleum ether as eluent, the product was obtained with an ≈ 80% purity and a yield of 68%. Further purification dropped the reaction yield to about 40%.

When we carried out the reaction, several issues were encountered. During the first step, the dianionic dimethylbutadiene solution which was prepared in anhydrous pentane was poorly solubilized and an orange-brown suspension had to be transferred. The transfer of the dianionic butadiene suspension to the bromopentane solution was complicated because of the aggregated solids. To overcome this issue, the addition was completed using 5 mL of THF to help to transfer the salts to the bromopentane solution via syringe (second step). The reaction with bromopentane led to well soluble mixture but some oligomers and other side products were obtained with the dihexylbutadiene (4). The separation of this mixture was difficult because all products in the mixture had a similar low polarity. The pure product couldn't be obtained from chromatography and as an oily product, and crystallization attempts were not successful.

The reaction was therefore repeated with modified parameters to try to improve the final yield.

As the issues resulted mainly from the transfer of dianionic butadiene intermediate to the bromobutane solution we focused on improving this step. The first parameter we adapted was changing the solvent used for the LICKOR preparation (Table 5, AP02). We changed it from pentane to THF to improve the solubility of the salt. As a result a red precipitate was obtained after adding the butadiene as described in literature. [79] Nevertheless when we look at the result after the second step by NMR the diene protons had completely disappeared and the reaction gave only side products. We believe that using THF instead of pentane increased the solubility of the LICKOR, making it very reactive and when the butadiene was added, the product formed was mostly the oligomers. The second parameter we modified was the temperature of the LICKOR suspension during the butadiene addition and before the transfer to the bromobutane solution (Table 5). We tested the different temperatures; -78, -20 and -5 °C. From the different reaction attempts we proved that the addition of dimethylbutadiene to the LICKOR solution at -78 °C leads to polybutadiene oligomers as the main product. The addition was also performed at -20 °C but we obtained the same mixture as when it was at room temperature (20 °C). We concluded that dianionic butadiene needed to be reacted at room temperature to avoid any polymerization and favor the formation of our product.

The third parameter we changed was the method to transfer the dianion butadiene suspension to the bromobutane solution. We changed to a cannula with a larger diameter (5 vs 3 mm). This resulted in a faster addition however we were unable to control the rate. We also had the cannula block during the addition which required using additional THF (10 mL) to finish the transfer.

Finally, due to this very fast transfer, we mostly obtained oligomers as product (Table 5 :

Dialkylation of dimethylbutadiene parameters, AP015). Syringe transfer was finally preferred to the use of a cannula in order to be able to control the addition rate, even though the syringe blocked-up several times (the needle was changed after each blockage to avoid the use of extra solvent).

The fourth parameter modified was the stirring times of the LICKOR solution, before and after addition of the dimethylbutadiene. But as shown inTable 6 : Stirring time of LICKOR solution, there were no real impact on the conversion. The LICKOR preparation was finished after 30 min of stirring, after which it reacted with the butadiene in 10 min while being left to warm to room temperature. The attempts carried out to improve the protocol for the synthesis of dihexylbutadiene did not help us improve the yield of the reaction. However, we were able to identify the following issues with the reaction: oligomer is the predominant side product of the reaction and to limit its formation the LICKOR must be prepared in an apolar solvent like pentane.

The temperature of the dianionic butadiene must be around room temperature (20 °C) to facilitate the transfer because it limits the formation of side products.

II.2.2.

Step 2: 4+2 cyclisation to benzyl dimethoxycarboxylate The Diels-Alder cyclisation (4+2 cycloaddition) of dihexylbutadiene with dimethyl acetylenedicarboxylate (DMAD) was performed with dichlorodicyanoquinone (DDQ) or air bubbling to obtain the aromatic product (Figure 37). The first step of cyclisation was monitored by NMR following the signal of the terminal alkene's proton. After 3h all the starting material (4) reacted but the product (5) was not the only product observed. As mentioned previously, we used either DDQ or air to oxidize (5). When using air as the oxidant, we observed only a 30% oxidation after 72h. In contrast, a full conversion was obtained after 48h of reaction with DDQ.

Before the work-up of the crude reaction it was important to remove the maximum amount of toluene to avoid the formation of a difficult-to-handle emulsion during the extraction of the organic products. Since the Diels-Alder reaction is reversible, the conversion of the first step was not expected to be quantitative. However, after oxidation and formation of the aromatic ring the reaction is no longer reversible, which is why we expected a complete conversion after the introduction of the oxidant. Unfortunately, under oxidative conditions the cycloaddition equilibrium is interrupted and a total conversion of dihexylbutadiene couldn't be achieved, leading to the formation of other side products. Finally, after some product was lost during the work-up and column purification, the 4,5-dihexyl-1,2-dimethoxybenzene-1,2-dicarboxylate (6) was obtained with a 25% yield.

II.2.3.

Step 3 to 7: Rapid last steps to phthalonitrile (C6Pn) The subsequent saponification of the dimethyldicarboxylate (6) using 20% sodium hydroxide in water was quantitative. After re-acidification of the crude with dilute sulfuric acid (0.5 M, pH 2), the pure product (7) was extracted with Et2O and used without further purification in the following cyclization. Here, the transformation of the phthalic acid (7) into phthalic anhydride (8) was done by refluxing the acid in acetic anhydride. After evaporation of the excess acetic anhydride and acetic acid under reduced pressure, product (8) obtained was used directly for the imidation, since even without any further purification after work-up, the NMR of (8) showed more than 95% of purity. The transformation of phthalic anhydride (8) to phthalimide (9) was then performed by refluxing the anhydride (8) in formamide. The phthalimide (9) was then stirred in concentrated ammonium hydroxide for 12 h to give the phthalamide (10). Finally, the phthalamide was dehydrated with thionyl chloride to afford the dihexylphthalonitrile with a 92% yield after purification by column chromatography. The overall yield of these 5 steps was of 88%.

II.3. Conclusion on phthalonitrile synthesis

Two routes to synthesize the 4,5-dialkylphthalonitriles were studied: the first one starting from dibromoveratrole gives the expected products after four steps with an overall yield of 55% by working on a gram-scale. The second route starting with dimethylbutadiene and dimethylacetylenedicarboxylate produced the dihexylphthalonitrile after seven steps with an overall yield below 10%. Unfortunately, due to the COVID situation of 2020 resulting in the restricted access to the laboratories, the optimization of this route could not be investigated further. Route 1 enabled us to obtain appropriate amounts of both alkylated phthalonitriles in fewer steps and with a higher overall yield. We were able to identify the limiting steps in each route. In route 1, the cyanation remains a tricky step with a range of yields obtained randomly due to partial conversion depending on the run done. In the second route, bad purification of the dihexylbutadiene followed by the low-yielding cyclization and aromization step lowered drastically the overall yield. Future attempts following this route should consider the purification of the dialkylbutadiene by distillation rather than by silica-gel chromatography.

From these two routes several grams of 4,5-dihexylphathalonitrile (C6Pn) and 4,5didodecylphathalonitrile (C12Pn) were obtained to use as precursors for the synthesis of the peripherally-alkylated phthalocyanines.

III. Synthesis of functionalized phthalocyanines

Peripherally substituted octaalkylphthalocyanines (CxPcs) are our target molecules for the onsurface application that will be developed in chapter 3. We used the dialkylphthalonitriles previously synthesized to access to these CxPcs. A family of three of phthalocyanines (Pcs) differing in the atoms located in their central cavity and their alkyl chain lengths were investigated and synthesized. This family is composed of the metal-free, zinc and titanyl phthalocyanines (CxH2Pc, CxZnPc and CxTiOPc respectively). (Figure 39). Unsubstituted

ZnPc and TiOPc play also the role of comparative molecules in the later physical studies, however they are both commercially-obtained molecules, so the syntheses of these two molecules is not discussed. The metalated Pcs were synthesized following two routes: one using the phtalonitrile (CxPn)

as precursor with the corresponding metal salt depending on the desired target molecule; and via the metalation of a metal-free phthalocyanine (CxH2Pc). We also used a previously synthesized 3,5-dihexylnaphthalonitrile to obtain a naphthalocyanine (with an extended conjugated core). This specific phthalonitrile was a sample obtained from I. Chambrier at the University of East Anglia. [80] This product was obtained following the scheme below (where the R group is the hexyl alkyl chain). The cyclotetramerization of the dialkylphthalonitrile to obtain metal free phthalocyanines was carried out following the protocol developed by McKeown et al in 1990. [81] This cyclic tetramerization produces the metal-free octaalkyphthalocyanine in a one-pot, two steps synthesis .

The first step involves the cyclotetramerization of the phthalonitrile with metallic lithium in pentanol under reflux to give the di-lithium octaalkylphthalocyanines. Then, acetic acid was added to the lithium phthalocyanine in order to remove the lithium cations from the Pc cavity.

Using this pathway, both the 2,3,7,8,12,13,17,18-octahexylphthalocyanine (C6H2Pc) and the 2,3,7,8,12,13,17,18-octadodecylphthalocyanine were synthesized. The syntheses performed are summarized in Table 7. The table above shows the important role that the concentration and scale of the reaction have on the yield obtained. As we can see, the yield increases with large scale reactions (from 20% with 0.8 mmol of C6Pn to 48% with 3.4 mmol of phthalonitrile used) because both the workup and purification steps are easier to perform with large quantities in this case. The scale of the reaction is important for two reasons:1) Reaction conditions: Working with small amounts of phthalonitrile (100 mg to 1 g) at concentrated conditions to avoid side reactions, meant the volume of solvent used was extremely small (1 to 12 mL). The 25 mL round bottom flask used for this reaction was not ideal for small quantities (<100 mg, <3 mL solvent) and so we had to dilute the reaction mixture to obtain enough solvent for a homogenous stirring. Small volumes (<3 mL) had to be avoided since at this reflux temperature (138.5°C) the majority of the solvent was in the vapor phase, leaving a near to dry solid at the bottom of the flask. This is why we reported no reaction with less than 3 mL of solvent. 2) Purification step: When we worked at scales of less than 200 mg of phthalonitrile, it was better to recover the product via gravity filtration on paper filter. Above this scale, vacuum filtration can be used to accelerate the filtering process without losing too much material on the filter. (It is important to note that the use of sintered funnels should be avoided since the removal of Pc material from the sinter is only possible with the use of a piranha solution).

Because of these two main reasons, in reactions with less than 200 mg the maximum yield that could be obtained was of 20%. In contrast, this yield doubled to more than 40% when working at 1 g scale. We also found that the using non-distilled THF (which contains a stabilizer) led to a loss of product at the purification stage. We discovered that the stabilizer presents in reagentgrade THF (butylated hydroxytoluene, BHT), has a good affinity with our CxH2Pcs. After removal of the solvent through filtration, it was not possible to separate the BHT from the CxH2Pcs by either chromatography, crystallization or trituration using various solvents (BHTfree THF, alkanes, DCM, CHCl3, EtOH, MeOH, EtOAc, acetone or toluene).

Purification of the alkylated Pcs by column chromatography must be avoided also to prevent the loss of product by adsorption to the stationary phase. Metal-free Pcs have a strong tendency to aggregate and therefore get stuck on the silica-gel. Recrystallization of the target metal-free Pcs when the amount was higher than 100 milligrams proved to be un-efficient due to their low solubility, so we turned to perform multiple triturations and filtrations using high purity MeOH, cyclohexane and EtOH.

From these limitations identified during the purification process, we realized how difficult it was to obtain metal-free alkyl phthalocyanines of high-purity. To illustrate this complex purification, the proton NMR of C6ZnPc was performed after it was eluted on column chromatography with stabilized THF and followed by trituration in MeOH (Figure 42). From this NMR spectrum we clearly see that methanol trituration didn't succeed in the removal of the BHT and in the zoomed areas of the spectrum we see many impurities among the aromatic and unsaturated chemical shifts. The integration of peaks also revealed about 25% of exceeding aliphatic protons showing side products bearing C6 alkyl chains. This NMR revealed how hard it was to obtain pure CxH2Pcs. The impurities were identified as linear oligomers, which we know are known side products of the cyclotetramerization of phthalonitriles. [75] This inextricable mixture is a result of the strong tendency of the CxH2Pcs to form aggregates, thanks to the long aliphatic chains which also trap the oligomer sideproducts. To give an idea of how low the solubility of metal-free octaalkylphthalocyanines is, 1 µM solutions in toluene or chloroform (CHCl3) crystallized when left for a few days at room temperature.

To conclude, the cyclotetramerization using lithium in pentanol worked well to give both the octadodecylphthalocyanine with a maximum yield of 48%. We obtained about 2 grams of each product after a series of reactions. The side products of the reaction were limited by increasing the scale of the reaction as the reaction could be more concentrated.

These CxH2Pcs were used to obtain the metalated CxZnPcs. We will also present the synthesis of the CxZnPcs directly via the corresponding phthalonitriles. Peripherally substituted zinc phthalocyanines (CxZnPcs) were synthesized following two pathways (Figure 43). The first one, (discussed previously) started from the metal-free phthalocyanines which in presence of zinc (II) acetate (Zn(OAc)2) led to the desired metalated phthalocyanines. [75] The second route used the dialkylated phthalonitrile as a starting material, which could be directly cyclotetramerized to CxZnPc under basic conditions and in the presence of a zinc salt. [82] The synthesis via the metal-free phthalocyanine was preferred as we already disposed of 2 g of the metal-free starting material(CxH2Pc).

III.2. Synthesis of Zinc peripheral octaalkylphthalocyanines (CxZnPcs)

III.2.1.

Route 1: Synthesis of CxZnPcs from metal-free CxH2Pcs The insertion of zinc into the metal-free octaalkylphthalocyanines was easily achieved using zinc acetate in refluxing CHCl3. The remaining salts and acetic acid were removed by rinsing the CxZnPc with methanol. The conversion was total as no CxH2Pc was observed by UV-Vis absorbance but among the reactions that were performed (reported in Table 8), a quantitative yield couldn't be obtained. The time of reaction (from 2h to 16h) and the concentration (from 1 to 0.5 M) didn't affect the conversion. On the contrary, passing from 5 to 10 equivalents of Zn(OAc)2 increased very little the yield with 3 h reaction in the specific case of the C6ZnPc (QF019). The loss of product was mainly attributed to the work up and purification stages. Two main factors conduced to a significant disparity of 49 to 86% yield were identified: the filtration step and the light degradation. As the product aggregated on the filter and considering we were working < 100 mg, some product was lost on the filter. Extensive rinsing with CHCl3 to recover this product, led to creating a highly diluted solution which facilitated the degradation via photobleaching of the ZnPcs. [83] This photobleaching was visible as yellow products appeared on the filter paper after rinsing with several fractions of CHCl3.

The solubility of both CxZnPcs obtained was found to be higher than the metal free derivatives in CHCl3 and toluene. For the CxZnPcs, 10 µM solutions could be prepared and remained stable over several days when protected from the light. Moreover, the C6ZnPc showed a solubility five times higher than the C12ZnPc derivative. This was expected, since long alkyl substituted phthalocyanines (starting from C5) have been reported to form columnar liquid crystalline aggregates and so with longer alkyl chains the aggregation becomes stronger; reducing the solubility. [32,84] To conclude, this route towards metalated CxZnPc was quite efficient, achieving a total conversion of CxH2Pc to CxZnPc. However, care must be taken to obtain the pure product in good yield. The purification condition using a minimum of solvent during the filtration stage leads to an 86% yield of C6ZnPc and a 69% yield for the C12ZnPc. Through this route we accumulated 200 mg of each target molecule.

III.2.2.

Route 2: Synthesis of CxZnPcs from 3,5 dialkylphthalonitriles (CxPns) Using CxPn as starting material, the reaction was performed in presence of DBU as a base with zinc acetate salts in pentanol. The C6ZnPc was obtained with a 45 % yield and the C12ZnPc with a 40% yield after multiple triturations with methanol, ethanol and acetone. Compared to the literature we relied on for this synthesis, the yield was doubled by avoiding the column chromatography purification step. [85] III.2.3.

Conclusion on CxZnPc synthesis

The two routes employed to go from the CxPn to both CxZnPcs allowed us to accumulate a total of about 400 mg of C6ZnPc and C12ZnPc. As expected, the direct synthesis from the CxPns to the CxZnPc led to better yields. The yield during the cyclotetramerization steps were not too different, comparing the C6H2Pc to C6ZnPc (48 and 45%) and the C12H2Pc to C12ZnPc

(both 40% yield). This showed that the zinc and lithium cation have a similar templating effect during the phthalonitrile cyclotetramerization. We noticed a better yield with the phthalonitrile containing hexyl alkyl chains in both cases which could be explained by the better solubility in pentanol of the shorter alkyl chains. The product loss happened during the purification of the products and as we purified both CxH2Pc and CxZnPc in the route 1 the overall yield was way lower than in the route 2. Thus, for future synthesis of alkyl substituted zinc phthalocyanines we highly recommend following the more direct route 2 and to avoid column purification.

III.3. Synthesis of zinc octahexylnaphthalocyanines (C6ZnNc)

Following the same conditions as with the C6ZnPc, we synthesized the C6ZnNc derivative from the dihexylnaphthalonitrile (C6Pn). Attempts to characterize a metal-free naphtalocyanine (C6H2Nc) by NMR completely failed because of the very low solubility of this derivative in most organic solvents, so we couldn't confirm the purity of the product obtained. This also meant that the reaction to insert the zinc into the naphthalocyanine core would be more complicated, so we did not pursue this further.

Figure 46. Synthesis of zinc naphthalocyanine from naphthalonitrile Instead, we followed the "direct" route using the C6-naphthalonitrile as the starting material.

The reaction was carried out in presence of DBU as a base with a zinc acetate salt in pentanol.

C6ZnNc was obtained with a good yield of 68% which is a great improvement compared to the yield obtained with the Pc analogue. This higher yield could be explained by the extended aromatic area of the naphthalonitriles which would lower the reaction kinetics and thus favor the tetramerization over the oligomerization product at the refluxing temperature of the pentanol. Care must be taken during the solubilization of the molecule in any solvent as the photobleaching is quite visible even by the naked eye in around 10 mins. We observed a total photodegradation after 24 h under ambient light. The C6ZnNc was synthesized and characterized here for the first time.

III.4. Synthesis of titanyl peripheral octaalkylphthalocyanines (CxTiOPcs)

After we obtained the CxZnPcs, we focused on the CxTiOPc as a different set of target molecules. These new molecules will enable us later onto exploit other types of binding to axial substituents. In a similar way to the molecule reported by Ballesteros et al., we planned to graft onto the CxTiOPc a fluorescent functionality by strong Ti-O bonding. [86] 1997. [87] They reported the same reaction with a C5 and C7 alkyl chains as peripheral substituents. The second route we tried was based on the metalation of the CxH2Pc using also Ti(OBu)4. Finally, in the third route we used TiCl4 as the titanium source instead of Ti(OBu)4.

This last procedure was described by Seikel et al. in 2011 with a similar CxPn structure. [88] III.4.1. Route 1: Synthesis of CxTiOPc starting from CxPn and Ti(OBu)4

The alkylated phthalonitrile, Ti(OBu)4, were dissolved in a high-boiling point solvent with urea and DBU to catalyze the reaction. Urea has been often used to help the reaction of cyclotetramerization to phthalocyanine since it generates ammonia in situ when in presence of a polar solvent (like pentanol or octanol). [89] The DBU, as we have seen in the CxH2Pc synthesis part, activates the nucleophilic substitution which initiates the cyclotetramerization of the phthalonitrile. The reaction was tried using only DBU but it led to the production of CxH2Pc only. The reaction was also attempted with only urea but the cyclotetramerization never started.

Using both urea and DBU resulted in a mixture of CxH2Pc, CxTiOPc (less than 20%) and unreacted phthalonitrile. Purification by column led to the loss of CxTiOPc. Purification by trituration or crystallization didn't allow us to separate the CxTiOPc from the metal-free Pc.

We repeated this reaction, testing using different solvents like pentanol, dry DMF and octanol.

All these reactions led to almost the same mixture of products formed. Each product was clearly identified by their characteristic absorption spectra in toluene as presented Figure 48. During the quenching step with methanol and water we also observed the formation of TiO2 as a white precipitate which proved to us that the Ti(OBu)4 didn't react. Because we couldn't isolate the product we moved onto the next route.

III.5. Route 2: Synthesis of CxTiOPc starting from CxH2Pc

and Ti(OBu)4 Several attempts to obtain the peripherally functionalized titanylphthalocyanines were based on the reaction using Ti(OBu)4 as the titanium source. First, the reactions were tried using the metal-free octaalkylphthalocyanines as starting materials and performing the reactions with different solvents. The reactions were carried out in dry pentanol, dry octanol and DMF. DBU was used as a base to help the insertion but in all the cases less than 10% of conversion was observed in the crude mixture. Decomposition of the metal-free phthalocyanines was also observed by UV-Vis absorbance (Figure 48). The reactions using a sealed tube or reflux also led to a low conversion with the Ti(OBu)4; which turned to titanium oxide (TiO2) during the workup in methanol or water. The attempts to purify the product using column chromatography led to its decomposition when eluting with CHCl3 or toluene. Attempts to metalation the CxH2Pc using Ti(OBu)4 were stopped at this point and we decided to change the titanium salt for route 3. A new pathway using titanium tetrachloride (TiCl4) as the metal salt was pursued (Figure 50).

The reaction of CxPn with TiCl4 was carried out in distillated chloronaphthalene in a sealed tube. As HCl is formed as a side product of the reaction, the change of pressure in the reaction tube has to be taken into consideration before running the reaction. In our case, we performed the reaction on a hundred-milligram scales, with a maximum of 5 mL of chloronaphthalene in a 25 mL sealed tube at 180 °C. The green product obtained after 8 h was resilient to water and methanol washes in this case, and a purification using EtOAc and cyclohexane was not a problem. This reaction leads in fact to the titanium dichloride Pc first, but in when this product is exposed to MeOH, water or silica, the product oxidizes completely to form the desired CxTiOPc. Thus, we were able to obtain the C6TiOPc and C12TiOPc in good yields of 58 and 61 % respectively. The solubility of CxTiOPc was good in most organic solvents which made it easier to characterize. The pathway using TiCl4 is by far the most efficient, but was not the first attempted since TiCl4 reacts strongly with water to form HCl and TiO2. The handling of this reagent, when not performed in a glovebox, can result in the formation of a cloud of HCl as soon as it is in contact with air, which makes it an undesirable reagent to work with.

III.7. Conclusion on CxTiOPc synthesis

C6TiOPc and C12TiOPc were synthesized successfully from C6Pn and C12Pn in presence of TiCl4 with chloronaphthalene as solvent. These products were purified by column chromatography and the purification was unexpectedly efficient with a good solubility and no degradation of the titanyl phthalocyanine was observed. Three routes were attempted to obtain these products but, only the use of TiCl4 as reactant lead to good conversion and isolation of the pure product. We summarized the attempted conditions to reach the CxTiOPc in Table 9. MHz NMR). This method was used to check the structures of the new phthalocyanines that were synthesized but also provided us with information on the substituent's and central metal's electronic effects. Proton NMR is the most sensitive among solution NMR methods which is important in our case, as we had molecules which had limited solubility in most organic solvents. To lock the NMR magnetic field, we used a deuterium signal of common deuterated solvents like CDCl3, CD2Cl2, but we also had to use toluene-d5 when the aggregation of the Pcs was considerable, like in the case of the naphthalocyanines. When performing the NMR characterization, many parameters were taken in account like temperature, concentration, purity, number of scans, relaxation time, etc. to obtain an optimal NMR spectrum. In our case, the temperature was fixed at 300 K unless specified. The concentration was set as high as possible which means around a maximum of 5 mg/mL. The purity of our target molecules could be assessed with the NMR spectrum, and showed only minimal impurity signals from the solvents used during the purifications. The presence of some solvents which show high affinity for the organic molecules, like water, proved complicated to remove as the molecules sometimes crystallized trapping the solvent molecules. that THF can be trapped during the re-crystallization process of phthalocyanine, benzoporphyrins and mono, di and tri azabenzoporphyrins. [90] Figure 51. Proton assignment of the C6ZnPc 1 H NMR spectra in CDCl3 + 1% pyridine-d5

The peripheral alkyl phthalocyanines synthesized are highly symmetrical and the assignation of their proton NMR signals can be done on focusing on one eighth of the molecule. As an example of the spectra obtained from the series of phthalocyanines synthesized, we will focus on the analysis of the C6ZnPc's spectrum (Figure 51). The equivalent aromatic protons corresponding to the non-peripheral positions, give a singlet signal at 9.28 ppm. The protons belonging to the three methylene groups closest to the aromatic ring, give a clear triplet signal at around 3.2 ppm, then a quintuplet at 2.04 ppm and finally another quintuplet at 1.70 ppm can be observed, which demonstrate a strong de-shielding effect from the phthalocyanine's aromatic core. The remaining -CH2 protons give a multiplet between 1.4 and 1.6 ppm. Finally, the endchain methyl groups will result in a triplet at 0.99 ppm. As we see on Figure 52, a temperature increase of the NMR solution can also improve the resolution of the spectrum. At 20°C, we observe all the proton signals as broad peaks. When the temperature is raised to 50°C, the solubility improves and as a result; the peaks become more defined and shift either up-field (from 8.20 to 8.75 ppm for the Ar-H) or down-field (in the case of the alkyl protons). To obtain well-defined peaks, one volume percent of deuterated pyridine (pyridine-d5) was added to the CDCl3.This results in the coordination of the ZnPc to the pyridine and inhibits the Pc-Pc aggregation. The different proton NMR spectra of the octahexyl phthalocyanines and naphthalocyanine in CDCl3 are reported in Figure 53. We observed similar signals for the C6ZnPc C6H2Pc and C6TiOPc. However, in the C6H2Pc spectrum we can notice an additional signal at -1.6 ppm, corresponding to the two NH protons located in the cavity of the Pc. We also noted that the aggregation was significantly reduced in the case of the C6TiOPc in CHCl3 which allowed us to prepare a more concentrated solution for the NMR analysis at 10 mg/mL. In contrast, the spectra obtained from the naphthalocyanines (Nc), reflects their low solubility in CDCl3. Better quality spectra for the Ncs were later obtained using toluene-d5. The NMR experiments for the octa-dodecyl phthalocyanines (C12H2Pc, C12ZnPc, C12TiOPc)

were carried out the same way in CDCl3. They presented very similar spectra with their C6 homologues albeit with different integration of the multiplet corresponding to the methylene (CH2) between 1.4 and 1.6 ppm.

These NMR experiments confirmed that we achieved the synthesis of pure octaalkyl-substituted phthalocyanines. It also revealed how important the aggregation behavior is on the NMR spectra obtained of the metal-free, zinc, titanium phthalocyanines; and even more so with the zinc naphthalocyanines. Generally, in order to characterize aggregated phthalocyanines by NMR, the use of a complexing solvent like THF or pyridine could help to break the aggregation but drawbacks come with this method. For instance, the complexation will facilitate the oxidation with air under light and result in the decomposition of the molecules. We will discuss this degradation more in detail in the following chapter. In this chapter 2, the NMR technique will also be used to assess the supramolecular association between the Pcs and other molecules;

but this association will also be studied with other techniques like absorbance spectroscopy.

III.9. Absorbance of substituted phthalocyanines

Absorbance characterization brings additional information on the energy between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital LUMO. The UV-Visible part of the absorbance spectrum of organic molecules shows the first energetic transition from the fundamental state to the first or second excited state.

All the absorbance spectra of the substituted phthalocyanines in both toluene and CHCl3 were recorded between 300 and 800 nm (for the Pcs) and up to 900 nm for the naphthalocyanines, to observe the effect of their structural modification in their optical properties. From this study, we noted that the alkyl chain-lengths have very little impact on the absorbance spectra of the molecules. Indeed, the spectra reported below (Figure 54) of C6ZnPc and C6H2Pc are totally identical to their C12 homologues. If we compare them with the absorbance spectrum of the unsubstituted ZnPc (reported in chapter 2), we observe a small red shift (12 nm) of the maximum absorption peak. This demonstrated inductive donor effect of the alkyl chains as the only measurable effect on the absorbance of ZnPc and this effect is the same with either C6 or C12 alkyl chains.

Usually, the spectra of phthalocyanines present two typical absorption bands; at long wavelengths starting from 600 nm (Q-band) and on the short wavelength zone below 450 nm, where we see the B-band (or Soret band). [25] In the absorbance spectra collected in Figure 54, the Q band (670-706 nm) is a sharp and intense band, whilst the B-band (around 350 nm) is always a less intense, broad band. The spectra shown below are the absorbance spectra of the C6 substituted Pc derivatives. As mentioned earlier, because C12 alkyl chain derivatives exhibit the same absorbance as C6 derivatives we didn't represent them for better clarity. The non-metalated phthalocyanines possess two intense peaks (670 and 706 nm) but we observed only a single band for its naphthalocyanine homologues. The splitting of the Q-band in metal free phthalocyanines is related to the loss of their C4H symmetry by the presence of two protons in the aromatic core. This break in the symmetry leads to two degenerated LUMO energy levels. This Q-band splitting was observed to be reduced to a point of disappearing when the aromaticity is extended by Kobayashi et al. [91][92] We can clearly see from the absorbance spectra, that there is a pronounced red-shift of 100 nm in the Q-band signals of the naphthalocyanines in respect those of the Pcs, showing that the extension of the conjugation in the pi-system has a significant impact on the optical properties.

The absorbances measured in THF, CHCl3 and toluene showed that the more the solvent is electron-rich and has a complexing effect, the more blue-shifted (10 nm) the Q-band will be (Figure 55). In contrast, the solvent has the opposite effect on the B-band signals. Lambert law limitation (valid with A<1), the maximum concentration of the solutions was around 10 µM. In order to sufficiently diluted solutions, we prepared a stock solution that we diluted to obtain the target concentrations.

Four or five different concentrations of solutions were prepared from the same stock solution of each molecule. We plotted the different absorbance intensities vs concentration, which after linear fitting led us to calculate the extinction coefficient using the formula above. Using only one stock solution increased the uncertainty in our determinations because it adds a systematic error on every measure prepared from the same stock solution. Nevertheless, we decided to do this way because of the low solubility of the phthalocyanines which required at least 100 mL of CHCl3 or toluene to solubilize about 1 mg of CxPc. If we had to prepare five solutions from weighed solid, we would have to weigh at least 2 mg of solid per solution which represent at the minimum 1 L of solvent. From this 1 L of solvent only 1 mL would be used to prepare the diluted solution. This would mean that 99% of solvent would go to waste. So, we reached the conclusion that the best method to use was the one where only one stock solution is prepared.

Considering the low solubility of the materials; the absorbance spectra were recorded twice.

We also verified the variability of the extinction coefficients obtained by preparing solutions with1 to 5 mg of product diluted in 200 mL of solvent. As a result, we concluded that the uncertainty on the molar extinction coefficients obtained from these different solutions was never lower than 10%, based on, the uncertainty on the mass weighed (± 0.2 mg) and the volume measured (1%) for the dilution. In Figure 56 we describe the data treating process which led us to calculate the extinction coefficients. As an example, we present the process to obtain the C6ZnPc's extinction coefficients at 352, 617 and 685 nm. On the left is the absorbance spectra recorded at five different concentrations. In the middle graph, the variation in intensity is plotted in relation to the different concentrations used for each wavelength. The linear fitting with the parameters described is shown in the table on the right. l.mol -1 .-cm -1 at their maximum absorbance wavelength, the CxPcs show really strong absorbance properties which will be useful for future in-solution and on-surface studies.

Because of their high absorbance we expect to obtain well-defined absorbance spectra of molecular monolayers deposited on a surface.

The highest extinction coefficients were obtained for the zinc phthalocyanines in toluene, with values at 3.5 and 3.9 l.mol -1 .-cm -1 . In CHCl3, CxPcs behave similarly presenting values of around 2.0x10 5 l.mol -1 .-cm -1 . We believe that the C12TiOPc' considerably lower extinction coefficient is a result of the degradation of the stock solution as it was the case with the C6ZnNc.

In general, metalated Pcs have higher extinction coefficients, we believed this comes from the sharp single Q-band peak present compared to the two bands of the CxH2Pc analogues. This could also come from the small population of aggregates present in the stock solutions which was not as important with the metalated CxPcs. We believe that is the major cause of the lower extinction coefficients because in the case of C12ZnPc we clearly observed a decrease and broadening of the Q-band caused by aggregation. The aggregation of the Pcs has also been well described in the literature as witnessed by the Snow book chapter on the subject. [START_REF] Snow | Phthalocyanine Aggregation[END_REF] In the case of zinc phthalocyanines, the measurements were also carried out in THF because of its complexing effect on the zinc atom, which limits the aggregation. The extinction coefficients obtained in this solvent were 33% higher than the ones measured in CHCl3 and close to those measured in toluene. This corroborates that the aggregation present in the stock solution has a noticeable effect on the extinction coefficients reported here. From these results we clearly see that toluene and THF are better solvents than CHCl3 to solubilize the CxZnPcs. UV-visible absorption spectroscopy was an efficient technique to characterize the CxPcs and the C6ZnNc synthesized, helping us to identify their characteristic absorption peaks and the trends observed in their B-band and Q-band absorbance when their structure is modified. A strong red shift could be observed between the Pc and Nc emission but the B-band stayed at the same wavelength. The use of different solvents was also very important to obtain quantitative information like the extinction coefficient in the difference absorbance measurements because only good solubility can give reliable results. Thus, toluene and THF were chosen as the preferred solvents to give reliable extinction coefficients for the CxPcs.

These extinction coefficient studies were performed only once, so they should probably be repeated with freshly-prepared solutions in the future. The results obtained are close to those reported with similarly substituted Pcs, with a range of 20% to 50% of variation. [93]

III.10. Fluorescence of substituted phthalocyanines

The study of the Pc's optical properties was complemented by fluorescence spectroscopy, discussed in the following section. Phthalocyanines, and in particular the octaalkyl phthalocyanines synthesized in this project, exhibited fluorescence in the visible spectrum. As in the absorbance measurements, fluorescence gives us an indication on the energy between the first excited states and the fundamental energy levels of each derivative. Fluorescence spectroscopy is known to be a sensitive technique because in contrast with absorbance or other differential methods, the photon detection is direct which avoids any noise from the instrument. [94] Fluorescence measurements allowed us to characterize diluted solutions of phthalocyanines at 1-0. The excitation wavelength didn't have any effect on the emission spectrum shape, only the intensity is different depending how much the phthalocyanines absorb at the excitation wavelength. The emission spectra of the different derivatives show that varying the metal cations in the phthalocyanine's core has a strong effect in the emission properties of the Pcs.

The zinc derivatives present a blue-shifted emission in comparison to the metal-free Pcs; while the titanyl compound shows a red-shifted emission. The zinc naphthalocyanine emitted at a higher wavelength than phthalocyanines, due to its extended aromatic core.

The fluorescence lifetime was characterized by measuring its lifetime constant. The lifetime constant was obtained by applying a mono decaying exponential fitting function to the fluorescence intensity curve measured (Figure 58). As in the absorbance measurements, the different chain lengths on had no effect on the Pcs emission spectra.

The fluorescence lifetimes were also used to characterize the CxPcs. To obtain the lifetime the occurrence of each delay to emit a photon following a femtosecond pulse excitation were cumulated and we obtained a graph like Figure 58. From this plot, by fitting with an exponential decay we can obtain the lifetime of the molecule measured. The lifetime measures were done using the same solution used for the absorbance measurements. The fitting was done on the linear portion of the decay and the parameter t1 reported is the lifetime value. The lifetime and maximum emission wavelengths as well as photoluminescence quantum yield (PLQY) of the octaalkylphthalocyanines are reported in the Table 11. The measures were done in CHCl3 and in toluene solutions, with the PLQY obtained by direct measurements in an integration sphere. When we compared the CxH2Pcs to the CxZnPcs we observed that the PLQY dropped by half between the PLQY of metal-free phthalocyanines and the zinc one (40% to 20%). The fluorescence lifetime also followed this trend with a lifetime of 6 ns for the metal-free against 3.3 ns for the zinc homologue. The naphthalocyanine's solutions (which decompose quickly under light exposure) showed a lower PLQY (below 11%). Because of their larger aromatic area more de-excitation via vibration states could occur. [92] Photobleaching degradation could also be a reason for this drop in the PLQY.

Bubbling the solutions with nitrogen before each measurement allowed us to increase the PLQY two-fold in the case of the ZnNc's value in toluene. For the other molecules, no significative changes were observed. This shows that the C6ZnNc reacts faster to form oxygen singlet compared to the C6ZnPc. This also explained why C6ZnNc degraded faster in solution compared to the C6ZnPc.

When we compare PLQY and lifetime measured in toluene and CHCl3 we can also conclude that the solvent had very little impact on these properties.

III.11. Photoemission spectroscopy (PES) of substituted phthalocyanines

To have an idea of the energy of first ionization of each of the synthesized octaalkyl-Pcs, some photoemission spectroscopy (PES) measurements were performed. A spin-coated layer of C6H2Pc, C6ZnPc, C6H2Nc and C6ZnNc on silicon was used for the measurements. The emission of electrons was measured under a UV-light beam. The photoemission spectra presented in Figure 59 show the normalized electron occurrence count on the 4,2-5.3 eV scale.

These energies correspond to the lowest range of electron energy detected and thus the ionization energy from the HOMO levels. The ionization energy was read as the intersection of the first linear increase of energy and the 0 eV energy level. Using the Planck-Einstein relation (E= h.c/) to convert the highest wavelength of absorbance to the difference of energy between the first excited energy level of the molecule and the fundamental level, we obtained an approximate energy of the HOMO and LUMO of the octahexyl phthalocyanines by coupling the difference of energy and the ionization energy [95] (Table 12). The Koopman's theorem approximation was used to say that that the HOMO level is equal to minus the ionization potential. We observed a lower in the energy gap HOMO-LUMO with the increasing size of aromatic core (-0.3 eV) and also reduction with the presence of zinc in the core.

III.12. Conclusion on CxPc and CxNc characterization

The synthesized CxH2Pc, CxZnPc and C6ZnNc were characterized by NMR, absorbance, fluorescence and photoelectron spectroscopies for the C6 substituted molecules. The NMR, absorbance and fluorescent characterization were particularly useful as they will be used later on to evaluate the supramolecular association between CxZnPc and the perylenediimides introduced in the following section. The characterization of the CxTiOPc derivatives by absorbance, fluorescence and NMR spectroscopy are also reported and show similar values to the CxZnPc molecules.

IV. Synthesis of zinc meso-5,15-diphenylporphyrin

Porphyrins (Ps) are flat π-conjugated molecules similar to phthalocyanines albeit with a smaller aromatic area. Like Pcs, they can host a variety of metal cations. Porphyrin solubility increases by the introduction of substituents in meso position. In this project, we focused on zinc mesosubstituted porphyrins which are well described in literature since they can form pyridyl-zinc bonds orthogonal to the porphyrin' aromatic core. The tetraphenylporphyrin (TPP) is the most described and most accessible meso-substituted porphyrin because of its high symmetry as explained in the introduction section. However, the work presented here focuses on the mesodiphenyl porphyrins (DPP). We made this choice since the ultimate goal with is surface deposition studies with these materials, and having two phenyl rings (DPP) rather than four as in the TPP would ensure better adsorption and stability when confined to the surface. A more in-depth discussion on this will be presented in the final chapter. Here, we will detail the synthesis of the meso-5,15-diphenylporphyrin (DPP) as reported in 1993 by DiMagno et al (Figure 60). [96] The metalation by zinc salts of the DPP was done according to the protocol used with the Pc metalations. Using pyrrole as starting material, the synthesis was done following three steps: 1) synthesis of the dipyrromethane (11), 2) dimerization to DPP in presence of benzaldehyde and 3) metalation with Zn(OAc)2. Statistically, in this diluted condition formaldehyde has more of a chance to successful collide with a pyrrole molecule than a dipyrromethane one. This way dipyrromethane was obtained as the main product of the reaction.

The pyrrole was distilled prior to use to eliminate any protoxidized-production the reaction mixture. The brownish color of non-distilled pyrrole is characteristic of small pyrrole oligomers induced by a light exposition. [97] The solution used was completely colorless after distillation.

As a first step, the mixture of paraformaldehyde in pyrrole was heated for 3 h to help the paraformaldehyde to solubilize. Then, TFA was added to help complete the solubilization of paraformaldehyde. After 1h of reaction and evaporation of exceeding pyrrole the dipyrromethane (11) obtained was purified by column chromatography to give (11) with 44% yield. The product obtained as a brown powder was stored at in the freezer to avoid decomposition.

IV.2.

Step 2: synthesis of 5,15-diphenylporphyrin (DPP) The dipyrromethane (11) was cyclized to form the intermediate (12) in presence of benzaldehyde and TFA. After 17 h hours stirring at 25 °C, dichlorodicyanoquinone (DDQ) was added to the mixture and left to react 1 h to achieve the aromatization of the macrocycle by oxidizing the two -CH2s of the intermediary 12 to obtain the DPP. We then purified the DPP (12) by column chromatography, to obtain purple crystals with a 29% yield. We varied the reaction conditions in order to improve the efficiency of the reaction. One of the reactions performed was accidently done at 2 °C and this allowed to observe an important effect on the yield of the reaction. At this temperature the maximum yield obtained was 6%. But then when the reaction temperature was raised to 25°C, we can obtain a maximum yield of 29%. Higher temperatures were not attempted but it could be interesting to compare this result with a refluxing reaction.

This reaction like that of the dipyrromethane, needed to take place in really diluted conditions to avoid the linear oligomer formation. Reported protocols used up to 1 L of anhydrous DCM for the reaction. In order to see if we could economize on the amount and type of solvent used without having a negative effect on the yield of the reaction, we studied the reaction at different concentrations. The results of the reactions performed at 1.3 mM, 2.6 mM and 13 mM are reported in Table 13. From the different concentration attempts it was clear that the reaction had to be done in low concentrations, however not as low as those reported in the literature. Our best yields were obtained with a reaction concentration of at least 2.6 mM. Finally, the DPP was metalated using an excess of Zn(OAc)2 (10 eq.) in CHCl3. The reaction was covered with aluminum foil to avoid photobleaching of the ZnDPP even though we never observed any degradation of the molecules in solution. The good solubility of ZnDPP in organic solvents (>0.1 mM) made the purification on a short column efficient with a yield of 95% of pure product obtained as purple crystals.

IV.3. Step 3: Metalation of DPP to ZnDPP

IV.4. Conclusion on ZnDPP synthesis

The three-step synthesis of ZnDPP was reproduced from the reported work of DiMagno et al. [96] and we obtained 500 mg of product with an overall yield of 12%. The lowest yielding step was the dimerization of dipyrromethane with benzaldehyde. We investigated the concentration of this reaction to conclude the dilution had to be at 3 mM to avoid the oligomer formation. The yield could be doubled by passing from a 13 to a 3 mM solution. After the synthesis of well the reported ZnDPP, we attempted to synthesize meso-functionalized tetrabenzoporphyrins, a notso well know type of derivatives.

V. Synthesis of meso-substituted tetrabenzoporphyrins

Tetrabenzoporphyrins (TBP) are porphyrins with a phenyl attached at the end of each pyrrole, making them quite similar to phthalocyanines except for the lack of the four aza nitrogens in the core. The meso-substituted TBPs have not been as widely studied as other meso-substituted porphyrins but because of their extended aromatic core they were appealing to us for their onsurface applications. TBPs were also interesting because in contrast to peripherally substituted ZnPcs, they can allow us to introduce four alkyl chains at the meso positions. The meso substitution is then a practical way to graft four alkyl chain substituents without having a mixture of structural isomers as is the case with substituted phthalocyanines. Since we are interested in molecules that can allow a pyridyl-zinc binding, we focused on the synthesis of meso-tetraalkyl substituted tetrabenzoporphyrins (CxZnTBPs). As most of the literature related to the synthesis of meso-substituted TBPs are focused on the introduction of aromatic substituents, we had to investigate and develop a new synthetic pathway to obtain the desired alkyl substituted porphyrins instead. [98] Figure 64. Pathways to obtain meso-tetraalkylbenzoporphyrin zinc

To synthesize CxZnTBP we attempted four different routes (Figure 64). Route 1, relied on the work of Cammidge et al. using different ratios of Grignard reagents to react with functionalized phthalonitriles to obtain the tetrabenzoporphyrins. [90] Route 2, was adapted from Fujii et al.

protocol using butyl-lithium instead of a Grignard. . [99] Inspired by these two routes we tried a reaction with a dialkyl zinc reactant replacing the alkyl lithium or alkyl magnesium bromide.

In route 3, we tried this reaction using the unsubstituted phthalonitrile as the starting material like the route 1 and 2 to react with dihexyl zinc. Then, based on the work of Yakubov et al. we tested commercial phthalimide as starting material in route 4 with commercial diethylzinc. [100] The tetraalkyl ZnTBP targeted has been reported previously but the harsh conditions used for this reaction (350 °C in sealed steel reactor) described by Qi et al. couldn't be repeated in our facilities. [101] We therefore focused on alternative routes using a more nucleophilic dialkyl zinc reactant rather than the dihexylcarboxylate zinc as reported. As the mechanism of phthalonitrile (Pn) cyclotetramerization to TBP remained unknown, it was complicated to properly understand which kind of reactant to use for this synthesis. To explain the phthalonitrile reactivity we proposed the following path by dividing the formation of tetrabenzoporphyrins in two main steps (Figure 65):

1) The first step is the addition of organometallic reactant on the phthalonitrile, which leads to the formation of the anionic species. After this first step, the low boiling point solvent (generally THF), containing the organometallic species, must be evaporated under an inert atmosphere.

2) The second step is the cyclotetramerization, which occurs only in a high temperature boiling solvent: the high boiling solvent is added to the dry crude intermediate, and after a while under reflux, it should lead to the metalated tetrabenzoporphyrins (CxMTBP) metalated according to the initial organometallic reactant used. Something which is still unclear, and not mentioned in the existing literature is the loss of four nitrogen atoms during the cyclotetramerization process.

V.1. Route 1: Synthesis of CxMTBP from Alkyl magnesium bromide

Our first attempt based on the protocol of Cammidge et al. [90] was the reaction of phtalonitrile with dodecylmagnesium bromide (Figure 66). They reported that by using four equivalents of Grignard reagent, the tetrabenzoporphyrins product will be formed. We prepared a solution of dodecyl magnesium bromide and added approximately the four equivalents required to the phtalonitrile suspension in THF. After evaporation of the THF under argon flow we heated the reaction in a reflux of quinoline.

Unfortunately, no trace of product was observed and only brown oligomers were present in the crude mixture after 16h of reaction. From the previous experience with the synthesis of the dialkylphthalonitriles, we were aware that the concentration of the Grignard reagent was lower than calculated. Given the fact that the ratio of reagent used is crucial to obtain the desired TBP, we needed to determine the accurate concentration of the Grignard prepared. Two different Grignard solutions were titrated using a solution of lithium chloride, where the Grignard is added dropwise until the LiCl solution becomes colorless. From this titration we could accurately calculate the concentration of the Grignard solution. In all cases, the real concentrations were lower than those supposed and the variation between solutions was too great to obtain reliable concentrations. We therefore stopped the investigation of this route and move onto a different approach. Previous synthesis reported of meso-(propyl)triazabenzoporphyrin using a ratio of 1:3 of n-BuLi to phthalonitrile was the basis of this procedure. [99] By increasing the number of equivalents of n-BuLi we hoped to obtain the meso-tetra propyl benzoporphyrin. We tried to adapt the protocol using a 1:1 ratio and then a 5:1 with an excess of commercially available BuLi. However, several attempts only resulted in a mixture of oligomer and some lithium phthalocyanine. At this point we decided to try an assisted metal cyclization using zinc metal as template which drove us to the route 3.

V.3. Route 3: Synthesis of CxMTBP from with dialkyl zinc and phthalonitrile

A zinc-templated cyclotetramerization was tried to obtain the CxMTBP ( Figure 68). To do so, the cyclotetramerization was initiated using a dialkyl zinc reagent. Dioctyl zinc ((octyl)2Zn)

was prepared from octylmagnesium bromide in THF and zinc chloride according to literature [102] . The obtained solution at a concentration of 0.09 M was directly used for the reaction with the phthalonitrile. The (octyl)2Zn in THF was added at 0 °C to a phthalonitrile solution in THF (Figure 68). The mixture was stirred 10 min and then the solvent was evaporated. A high boiling point solvent was then added. We repeated the reaction with two different solvents: cyclohexanol (as it was described in the BuLi protocol) and toluene in a final attempt we kept the THF as solvent and just heated to reflux. After 16 h refluxing, the mixture passed from blue green to brown. This crude was analyzed by UV and NMR after workup however no tetrabenzoporphyrins signals were observed. We think long alkyl chains could be an issue with the reaction, and also since the purity of organozinc could not be confirmed, we changed the (octyl)2Zn to a commercial diethyl zinc ((Et)2Zn) in THF (Figure 69). Quinoline was used as second solvent instead of cyclohexanol or toluene as a non protic and higher boiling point solvent (237 °C). The initially yellow mixture obtained after the (Et)2Zn addition turned to blue green over the course of 16 h. The crude was filtered through silica plug to remove the solvent and eluted with DCM and EtOAc. The recovered blue solution was analyzed by absorbance spectroscopy showing only the presence of zinc phthalocyanine.

As we still didn't observe any tetrabenzoporphyrins in the previous route we decided to do a last attempt using phthalimide instead of phthalonitrile as starting material. We replaced the phthalonitrile by phthalimide as reported by Yakubov et al. to react with the (Et)2Zn. In the reported paper they use a closed reactor heating to 350 °C to perform the reaction without solvent. We adapted the protocol to an in-solution reaction in order to lower the activation temperature of the reaction. Once again, we used quinoline as high boiling solvent.

V.4. Route 3: Synthesis of CxMTBP from with dialkyl zinc and phthalimide

After 10 min addition of (Et)2Zn at 0 °C, drying under argon and reflux in quinoline for 15 h we obtained a brown mixture which according to absorbance did not contain any trace of benzoporphyrins.

Although we pursued four different synthetic approaches, we were unable to obtain any trace of the target zinc meso-CxTBP. These types of derivatives are poorly described in the literature.

We recently found an alternative route to our target tetralkyltetrabenzoporphyrins via post functionalization of a tetrabenzoporphyrin or using a bicycloporphyrin intermediates, which seems much more soluble. [98] VI. Characterization of zinc meso-5,15diphenylporphyrin The ZnDPP previously synthesized was characterized using NMR, absorbance and fluorescence spectroscopy. These methods as seen with the phthalocyanine's characterization are quite appropriate, especially with these more soluble ZnDPP.

VI.1. NMR of ZnDPP

The NMR characterization was carried out with a 10 -4 M solution of ZnDPP in CDCl3. We repeated the measurement of an NMR tube left to ambient light after 7 days to observe in any photobleaching in CDCl3 occurred. We recorded exactly the same spectrum proving no degradation happened in the NMR tube. The assignation of the molecule's proton NMR spectrum is reported in Figure 71. The sharp peaks obtained at concentration of a 10 -4 M demonstrate that the ZnDPP in CDCl3 at room temperature does not aggregate, compared to the CxZnPcs. The NMR of ZnDPP presented all the chemical shift as aromatic proton shifts with a particularly high deshielded shift on the core of the porphyrin (He, at 10.3 ppm). The high deshielding effect observed is induced by the magnetic anisotropy of the large aromatic core.

Because of this strong deshielding effect on the periphery of the aromatic core the closer the proton from the core the more unshielded they are.

The NMR showed little grease (1.26 + 0.8 ppm) and HDO present (1.52 ppm) on the right part of the spectra. The water came essentially from the CDCl3 used but some traces could be also trapped in the ZnDPP crystals. This is not an issue for future physical application on surface as we will work with diluted solutions. Because of the relative intensity between the CHCl3 peak (7.26 ppm) and the grease peak (1.26 ppm) we could also deduce that the aliphatic chains trapped in the product are less than 5 mol% by integration.

After the 1 H NMR characterization of ZnDPP we moved onto the characterization of its optical properties.

VI.2. Absorbance of ZnDPP

The absorbance of ZnDPP was recorded in CHCl3 at three different concentrations and we used these values to determine the molar extinction coefficient in CHCl3. We observed two peaks one at 407 nm and one at 535 nm (Figure 72). The thin and intense 407 nm peak is known as the Soret band (or B-band). This sharp band is characteristic of the porphyrin, its absorption of energy corresponds to the S0➔S2 electronic transition of the ZnDPP. [20] The 535 nm peak is the Q-Band of the ZnDPP, this band of weak intensity correspond to the S0➔S1 electronic transition. These electronic transitions come from the π-π* orbital transition from the conjugated core of the ZnDPP.

The determination of the molar extinction coefficient using the absorbance vs concentration plot gave a 2.47.10 5 L.mol -1 .cm -1 value for the 407 nm peak (Soret band) and of 1.07.10 3 L.mol - 1 .cm -1 value for the 535 nm peak (Q-band). These peaks are the same as in the previous reports . [103]

VI.3. Fluorescence of ZnDPP

To complete the optical characterization of ZnDPP we measured its fluorescence spectra with a 415 nm excitation in the Soret band (Figure 73). The emission spectra are composed by a main peak at 576 nm followed and a shoulder at 619 nm.

The fluorescence lifetime was also measured to be 2.3 ns in the same solution. So far, we synthesized and characterized two families of molecules presenting a zinc atom inside the cavity: the CxZnPc and ZnDPP. These derivatives will be used to build different supramolecular complexes with a series of different a perylenediimide derivatives (PDI), reason why we discuss now the synthesis of these PDIs.

VII. Synthesis of functional perylenediimides

PDIs were selected in this project as the functional components for the complexes that will be prepared in the following chapter. They were chosen due to their excellent luminescent properties and for their versatile chemistry as described in the introduction. Our goal was to associate a series of modified PDIs to the different CxZnPcs and ZnDPP via a zinc pyridyl coordination. This type of bonding will be discussed in the following chapter also. In order to achieve this, all PDI prepared will have a pyridyl function as a N-substituent (Figure 74). Also, we wanted our PDI derivatives to have a good solubility; not only to facilitate their synthesis, but also for the optical experiments. As we saw with the Pcs, aggregation of the compounds limits the conditions in which we can perform the measurements. As reported and summarized by Würthner, [104,105] modification of the bay-positions is a good way to reduce the aggregation of the PDI. In this work, we aimed to prepare different PDIs where two or four bay-positions were functionalized with a mono or di-tertbutyl phenol. This functionalization has been described in the literature and is proven to increase the solubility by decreasing the aggregation. [106,107] To synthesize these PDIs we started from two commercial PDAs: the perylene dianhydride (PDA) and the tetrachloroperylenedianhydride (Cl4-PDA). Both starting materials were interesting because of their low cost and good stability under ambient conditions. The functionalization of the N-position of the PDI from PDA involves only one step and is a highyielding reaction. In presence of a Lewis acid, a primary amine will substitute the anhydride to the afford the imide product. The main condition to take care in this reaction was to work under reflux with a high-boiling point and an aprotic solvent (quinoline or NMP), in order to cyclize the 1-amide-3-carboxylate intermediate to an imide. [108] An imidization catalyzed by a Bronsted acid (acetic acid) in isopropanol was also possible with an alkylamine. [109] From these two PDAs selected, we explored two routes to introduce sterically hindering groups on the PDAs (Figure 75), to reach either a 1,7-disubstituted PDA substituted with ( 15) or 1,6,7,12-tetrasubstituted PDA (18) with using 4-tertbutylphenol a bulky reactant. The second route was developed later to increase the steric hindrance on the PDI core. However, as we estimated the steric hindrance of 15 was already providing efficient protection against aggregation, we mainly developed PDIs based on this backbone.

From the PDA 15 and 18 we used as well two approaches to prepare the final N-pyridyl substituted PDIs. The first is the most straight-forward approach and involves the symmetrical synthesis of a dipyridyl PDI. The second one and more challenging from a synthetic perspective was the preparation of an asymmetric PDI with only one N-pyridyl substituent.

We prepared the symmetrical PDIs from PDA 15. This synthesis was described by Rodríguez-Morgade et al. using 4 aminopyridine. [110] Then, we prepared different pyridyl derivatives of PDI using the same method (Figure 76). The preparation of asymmetric PDIs was reported previously by Wang et al without bay substituents and by Sengupta et al. with dibromo substituents. [66,67] The strategy to obtain the asymmetric perylene mono anhydride and then a perylene mono imide, relied on the product's different solubilities. To obtain the monoanhydride as major product of the reaction, the monoanhydride had to be less reactive than the starting material. This explains why the asymmetric step to obtain the monoanhydride product started from the N-dialkylamine or perylene-tetraester in the Wang and Sengupta articles, these intermediates being in all cases very soluble compared with the monoanhydride product (Figure 77). High selectivity was possible from the tetraester as 82% of one of the regioisomers could be isolated using dibromo PDA. As presented above, the two PDAs 15 and 18 are key building blocks for the PDI dipyridyl derivatives. We report in the following section their syntheses via route 1 and route 2.

VII.1. Synthesis of sterically hindered perylene dianhydrides VII.1.1. Route 1: Synthesis of the di-substituted PDA 15

* The 1 % left was the three bromo substituted PDA, the ratio was done after purification of 15 available PDA. [64] Nevertheless, major modifications were introduced in order to improve this protocol since the original method resulted in a mixture of products and a low yield (<20%).

More precisely in this two-step route, the PDA was first set to react with bromine using iodine as catalyst in sulfuric acid to obtain the 1,7-dibromo PDA 13 as major product. Then, the bromines were substituted by a 3,5-di-tertbutylphenol to give the sterically-hindered PDA derivative 15.

Step 1: Dibromation of PDA The first step involved the bromination of two bay positions (1,7) of the PDA (Figure 79). As the PDA is poorly soluble, it had to be first solubilized using sulfuric acid by stirring the solution for 12 h at 55 °C. Once a part of PDA was solubilized, iodine was added in a catalytic amount (2%) before the molecular bromine was added to the mixture. The role of the iodine was to help activate the bay positions of the PDA and facilitate the substitution reaction with the bromine.

After 24 h of stirring at 85 °C, the products were recovered by filtration and rinsed to remove any excess acid or bromine. Controlling the temperature at 85 °C is also an essential requirement for the reaction to happen, since at this temperature, the PDI is almost completely dissolved whilst at the same time, it was low enough to ensure that the bromine remains in the reaction mixture and not leave the reaction as vapor.

To work-up the crude, acidic conditions had to be ensured to avoid hydrolysis of the anhydride in water. The products were obtained as a statistical mixture of regioisomers; 1,6-(14%), 1,7di-bromo (85%) and also a minor amount of the tri-bromo product (about 1%) which matched with Würthner et al. reports. [60] This ratio came from analysis of the crude in the synthesis of product 15, but the uncertainty in this ratio is high due to the poor solubility of the brominated derivatives. The mixture of both di-bromo isomers 13 and 14 couldn't be characterized with anything else than IR because they are not soluble in any organic solvent.

Initial attempts with this reaction involved the use of fuming sulfuric acid as solvent instead of the standard acid at 96%. In these conditions, the expected red brick product turned green and was very soluble in water. The yield of the reaction after rinsing was quite low in comparison to what was reported (less than 20%). We then realized, that the bromination in fuming sulfuric acid was leading to the conversion to the sulfonated product as well (Figure 80). After this, care was taken to only use concentrated sulfuric acid at 96% for the reaction, which led us to regain the quantitative yield of the di-bromo PDA. The second step to obtain compound 15, was the substitution of the bromine groups by a tertbutyl phenol. 15. The SEAr was performed in basic conditions with cesium carbonate in refluxing DMF. During the substitution reaction of the bromines in 13 & 14, the solubility increased and the product changed from brick red to a bright red then to purple-red color. The first run of the reaction lasted for 16 h at reflux (against the 4 h reported). TLC analysis of the crude eluted with DCM revealed a purple unpolar product present also with the 15 red product.

Further purification and NMR analysis of this product showed that it consisted of one open anhydride position substituted with a phenol (Figure 82). To avoid the formation of this side product, the progress of subsequent reactions was monitored by TLC and showed that a total conversion to the desired product could be achieved after only 2 h 20 mins in DMF at 160 °C. To isolate product 15, the initial protocol proposes to crystallize the crude in AcOH at -8 °C. In our case however, the product never resulted in crystals large enough to be filtered properly without considerable loss of product, so another purification method was investigated. We first forced the product to precipitate by adding some methanol and water to the acid solution, but the purple side product couldn't be removed by rinsing with methanol. So, we performed a column separation on silica-gel eluting with DCM. About 80% of the initial crude product remained adsorbed on the silica during the column separation. We believe that the acidity of the silica on the column was enough to hydrolyze the anhydride to the dicarboxylic acid and this resulting perylene stayed bonded to the silica. To avoid this problem, we therefore decided to replace the chromatography separation by a soxhlet extraction with methanol since we know that the major purple impurity is partially soluble in this solvent.

After 16 h of washing with soxhlet, we were able to remove all the purple impurity and a relatively pure product was obtained. We were then able to determine by NMR that the red product recovered was a mixture of about 10% of 1,6-diphenoxyperylene and 90% of the desired 1,7-diphenoxyperylene 15. Considering the overall reaction, the yield of 15 was calculated to be 72% after the soxhlet wash and considering 15 as a mixture of the other isomer.

We moved on to the next step with this mixture as column separation was not possible with the mixture of regioisomers. To obtain the tetrasubstituted PDA 18 , we followed the Dotcheva et al. protocol using Cl4-PDA as starting material. [63] In our case, only the type of amine was changed from the reported protocol. This three-step route starts with the substitution of the dianhydride by a branched dialkylamine in acidic conditions which gives the diamide 16 (Figure 83). The choice of a branched amine for this step was to improve the solubility to the PDI obtained and thus simplify the following steps.

VII.1.2. Route 2: Synthesis of the tetra-substituted PDA 18

Step 1: Diimidization to PDI (16) The branched, diimide derivative 16 was synthesized by reacting 2-ethylhexylamine with Cl4-PDA in isopropanol with a catalytic amount of acetic acid (Figure 84). Acetic acid was used to increase the anhydride's nucleophilic character. We discovered that if the reaction was not heated high enough (>120°C) or long enough (>16h), the 1-3 carboxylic acid-amide product could be obtained as a side product. As the imide cyclization was the favored thermodynamic product this reaction led to a total conversion. This diimide 16 was then purified through a short silica plug as the only side product (the carboxylic acid) remained stuck on the top of the plug.

The diimide 16 was quite soluble in organic solvents, in contrast to the PDA and we were able to isolate it with a 95% yield. This reaction was particularly clean as it only released water.

Step 2: Tetrachloro-substitution to PDI (17) Following the Panda et al. protocol [65] , the chlorine atoms at the bay positions of PDI 16 were substituted by 4-tertbutylphenol in basic conditions with potassium carbonate in NMP (Figure 85). The product was obtained after heating at 120°C for 18 h, and recovered as a mixture of di, tri and tetrasubstituted products. A column chromatography allowed to obtain the pure product with 65 % yield. After several attempts, we found out that in order to obtain a better yield of the desired product we should increase the time of reaction. Since we used eight equivalents of 4-tertbutylphenol (two for each chlorine atom) we did not believe it would be useful to modify the stoichiometric ratios of the reaction.

Step 3: Hydrolysis of PDI (17) to PDA (18) Finally, converting the imide back to the anhydride (PDA 18) was performed via a two-step procedure (Figure 86). This involved firstly, the cleaving of the diimides in basic conditions with potassium hydroxide in refluxing isopropanol. The progress of the reaction was easy to follow as the reaction passed from a pink-red color to purple when both diimide-groups are removed. In the second step, the purple tetraacid product was closed to a dianhydride after addition of AcOH to the basic mixture. The reaction mixture turned back to a bright-red color, indicating the successful completion of the reaction. Upon cooling, the product precipitated and could be filtered easily and rinsed with water to give the pure product. The aqueous wash proved sufficient to remove all of the cleaved amine. Therefore, the use of column chromatography was avoided, which as previously discussed with PDA 15, leads to the loss of PDA product.

The PDA 18 was obtained with a quantitative yield after 2 days of drying under 0.1 mbar at 60 °C.

Two sets of PDAs with sterically hindering-groups at the bay positions (di and tetra-substituted)

were obtained with overall yields of 72% and 65% respectively. During the synthesis of PDA (15) we encountered various problems in the purification phase, specifically with the decomposition and subsequent loss of the product on silica. To overcome this issue, we used a soxhlet extraction instead which enabled us to obtain the product with a better purity and yield than reported. In the case of PDA ( 18), its solubility was considerably better than the disubstituted PDA so we didn't attempt the soxhlet purification for this derivative. A simple rinsing by water afforded the pure product.As described in the introduction of this part, the two PDA synthesized are good precursors to tune the N-position as desired. PDA 15 was used to synthesize 4 different PDIs with pyridyl substituents and PDA 18 in the asymmetric Nsubstituted PDI.

In the following part, we will discuss the synthesis of symmetric PDIs with different pyridyl substituents and the asymmetric synthesis will be discussed after.

VIII. Synthesis of dipyridyl perylenediimides

PDI with N-pyridyl substituents were synthesized following the protocol reported by Rodríguez-Morgade et al. [110] The PDA 15 was reacted with 4-aminopyridine in quinoline, catalyzed by Zn(OAc)2 (Figure 87). The zinc acetate played the role of a Lewis acid here.

Because the pyridyl group reduces the amine's nucleophilic character via an electronwithdrawing effect and charge delocalization, a catalyst and high temperatures are needed to obtain the imide. After precipitation with a 2M HCl solution, filtration and rinsing to remove the biggest part of the quinoline solvent, the product was purified by chromatography on silica-gel. Recrystallization with a DCM-heptane mixture (5:5) and drying at 80 °C under 10 -2 mbar were necessary to remove last traces of quinoline present in the product. The purple precipitate obtained after acid treatment was extremely fine and passed through the filter. Thus, multiple filtrations were carried out with increasing quantities of water, which helped form larger aggregates. Separation of the product using solvent extractions with DCM was also tried but the quantity of solvent needed to solubilize completely the product was too much (500 mL of DCM at least for 100 mg or product) and the quinoline was still present after those extractions.

Since the PDI obtained should now be more soluble than the PDA precursor, we once again attempted purification by column chromatography with DCM and 2% of methanol (to avoid adsorption on the silica). A maximum of 68 % yield of the target product PDI4 was finally obtained but depending on the work-up this yield could vary from 7% to 68%. The product was obtained as 95:5 mixture of the 1,7 and 1,6 regioisomers. We were able to obtain the pure 1,7diphenoxy PDI4 after two subsequent recrystallizations using a DCM-heptane mixture.

However, since having both isomers mixture was not an issue for the desired application, we used the mixture of isomers for the physical studies even if only the major PDI4 1,7-diphenoxy is represented in the figures.

Following the protocol to synthesize PDI4 and using the appropriate amines, similarly PDI3, PDI3Ph3Py and PDI4Ph4Py were obtained as new products (Figure 88). In each reaction, the target compounds had to be purified via column chromatography and thus led to loss of the product on the column. PDI3, PDI3Ph3Py and PDI4Ph4Py were obtained with yields of 38%, 51% and 42% respectively. They presented similar color and solubility as PDI4. To synthesize an asymmetric PDI with a phenyl on one extremity and a pyridyl on the other we first attempted the simplest approach which is a statistic one. This means that by reacting the PDA 15 with the two different groups we want to attach (4-aminopyridine and aniline) we expected to obtain a statistical mixture of three different products: the target N-pyridyl-N'phenyl PDI 19, and also the dipyridyl PDI4 and the diphenyl PDI 20 (Figure 89). This reaction was carried out following the same conditions used to obtain the PDI4. We started the reaction with one equivalent of 4-aminopyridine which was left to react with 15 for 8 h, then we added two equivalents of aniline. After a simple work-up we attempted to separate the mixture of products obtained by column chromatography. By TLC analysis we observed the presence of at least five different products with very similar retention factors (Rf) meaning that they would be very difficult to separate. We attempted the purification all the same and even after multiple columns we were not able to isolate all components of the mixture, only the PDI4 could be isolated with a 30% yield. The reaction was repeated with the different 3-aminopyridine and aniline and the results were the same; the asymmetric product couldn't be isolated.

In retrospective, we could have chosen a ramified alkylamine instead of the aniline to have a more drastic change in solubilities. However, we do not know at what degree this will help the purification later on so but we to pursue a regiospecific approach. This second strategy to synthesize the monopyridyl-PDI was followed starting with PDA (18) to ensure that we are in the best conditions for solubility.

VIII.2. Regioselective synthesis of asymmetric monopyridyl-PDI from PDA (18)

The regiospecific synthesis was done starting from PDA 18. As we had the opportunity to choose between PDA 15 and 18, we decided to go with the most soluble derivative. This route took four steps to obtain the asymmetric product. The tetraester intermediate of this reaction was very soluble in comparison to both starting and final products, which makes it very easy to follow the reaction. When the tetraester was made to react with the TsOH, the monoanhydride product precipitates as soon as the reaction takes place. This immediate separation prevented the product to react further and thus avoided the formation of the second anhydride. The asymmetric anhydride was obtained with a relatively good yield of 85%.

VIII.2.1. Step 1-2: Synthesis of monoanhydride-diester perylene (22)

We applied this strategy using our tetrasubstituted PDA 18, expecting similar results, but during the first step to obtain the tetraester, we actually succeeded to isolate 55 % of the target monoanhydride-diester perylene 22. Surprisingly, this product could be efficiently purified by column chromatography even though it bears an anhydride group which had posed problems in previous purifications. Thus, we were able to obtain the desired compound in a single step. The reaction also gave us the tetraester product 21 as well, so we used it to try the selective monoanhydride cyclization. To our surprise, no conversion was observed using the conditions reported on. [65,66] Since we were able to directly pass from PDA 18 to perylene monoanhydride 22, we didn't pursue the optimization of this reaction further.

VIII.2.2. Step 3-4: Synthesis of monoanhydride-diester perylene (22)

Figure 91. Synthesis of monoanhydride perylenemonoimide 24

The perylene monoanhydride 22 was converted to the monoimide 23 by heating with 2ethylhexylamine in DMF at 110 °C (Figure 91, 1 st step). The reaction was done using DMF and without acid catalyst to avoid the trans-esterification as well as the imidization of the diester of

22.

Product 23 is very soluble and was obtained with an 85% yield. Subsequently, the diester 23 was cyclized to anhydride using once again TsOH in refluxing heptane (Figure 91, 2 nd step).

The anhydride-imide perylene 24 was obtained with a 75% yield.

The resulting monoanhydride is a convenient precursor to any monopyridyl perylene. By reacting with any different aminopyridines in presence of Zn(OAc)2 in a high boiling point solvent (quinoline, NMP or DMF), a variety of monopyridyl PDIs would be readily accessible.

The preparation of those monopyridyl perylene remains to be done.

To obtain a N,N'-asymmetric perylene diimide we attempted two strategies. The first one involved a statistic mixture where we set to react a PDA (15), with an aminopyridine and an aniline. This led to a mixture of PDIs which couldn't be purified by crystallization or column chromatography because of strong interactions between them and a close structure. Only a very diluted solution on TLC helped us observe that the mixture contained at least five different PDIs. This led us to pursue the reaction via a regioselective synthesis.

With this second strategy the asymmetric precursor to PDI (24) was successfully synthesized with a total of three steps and an overall yield of 25%. The synthesis of different PDIs were stopped at this stage and we carried on to perform the physical characterizations of the four PDIs produced.

IX. Characterization and physical properties of synthesized PDIs

The structural and fluorescent properties of the PDI4, PDI3, PDI4Ph4Py and PDI3Ph3Py derivatives we prepared were characterized by NMR, absorption and fluorescence spectroscopy in a similar manner as the phthalocyanine and porphyrin materials.

IX.1. 1H-NMR characterization of PDIs

We first took advantage of 1 H NMR to characterize our PDIs. These derivatives present a good solubility in comparison to the Pc materials, facilitating the collection of well-resolved spectra for each compound. We still observed broad signal peaks when concentrated solutions were studied (>22 mM) solution, so we limited the NMR solutions to concentrations of a few mM to obtain acceptable spectra. From the all PDI derivatives studied, the PDI with diphenoxy substituents showed the lowest solubility in CDCl3. However, the spectra obtained were good enough to perform NMR measurements upon standard temperatures of 300 K, unlike with some Pcs which required heating to 323 K to acquire the NMR spectra. Finally, the (f) and (g) pyridyl protons are the ones we will focus on to distinguish all the different PDIs.

Pyridyl and phenyl-pyridyl protons correspond to the highlighted signals. The PDIs 1 H NMR spectra in CDCl3 are reported in Figure 93, where PDI4 is used as reference to indicate the proton assignations. The perylene core's (a) to (e) peak shifts are almost the same for the four PDIs; it is only on the protons of the pyridyl substituents we observe visible differences. The N-substituents are highlighted in red (structure) and grey in the spectra;

showing the difference of structure and symmetry between our PDIs.

These NMR spectra were acquired by solubilizing a few milligrams of each derivative in CDCl3, taking care to not have saturated solutions so the peaks are well-defined. Above 10 mg /mL the peaks start to broaden and also shift. We found that filtration of each solution before transfer to the NMR tube was a good way to avoid any aggregates in the solution However, the solutions were not concentrated enough for us to obtain [START_REF] Buchler | Synthesis and Properties of Metalloporphyrins[END_REF] C spectra with a good signal/noise ratio, even after 2048 scans.

IX.2. Absorbance of PDIs

The absorbance spectra of the PDIs produced were measured together with their molar extinction coefficients in different solvents. The perylenediimides synthesized are soluble in many solvents but the best solvents identified were chloroform and dichloromethane. Although we are aware that, toluene and THF are not so good solvents for PDIs, we performed the measurements in these solvents too since we need to understand the behavior of the PDIs in these conditions. In addition, both absorption and emission measurements require low concentrations so their low solubility in these will not be an issue. As we can see from the absorbance spectra of the four PDIs are quite similar; the maximum absorbance wavelength is between 547 and 548 nm for every compound and the only variations that can be observed are in the shoulder at 511 nm. This similarity is expected, as the perylene's conjugated core is not modified at all between the different molecules. The N-substituents are orthogonal to the conjugated plane of the PDIs and only their electron-donating effect has an impact on the absorbance spectra. As mentioned in the introduction of the chapter, can confirm that imide substituents on the PDI have very little effect on the optical properties of the molecule.

The absorbances were recorded in toluene, THF and CHCl3 (Figure ). The shift related to the different solvents used revealed that the more the solvent is electron-donating and coordinating, the more blue-shifted the spectra of PDIs became. Five different concentrations of solutions were prepared from a stock solution. Once the absorbance spectra were recorded, we plotted the maximum absorbance values against the concentrations used (Figure 95). Linear fitting of the absorbance maxima in each solution gave us the molar extinction coefficient following the Beer-Lambert law (Figure 95, table ). The solubility of the PDIs was quite good at a mM scale in CHCl3 or DCM, however in toluene the saturated concentration had to be reduced 10 µM. The stock solution prepared using toluene had to use at least 200 mL volume of solvent and less than 5 mg of PDIs. The uncertainty calculated for the molar extinction coefficients presented takes into account mass and dilution precision and was determined to be around10%. The molar extinction coefficients of the PDIs in CHCl3, toluene and THF are presented in Table 14. Even if the absorbance maxima are different depending on the solvent chosen, their extinction coefficient are still quite similar (within the 10% uncertainty margin). We also observed that adding a phenyl on the N-substituents (PDI4Ph4Py and PDI3Ph3Py) doesn't impact the molar extinction coefficient. We noticed a lower value of absorption coefficient for PDI4Ph4Py in CHCl3 but afterward we realized that solution was not perfectly clear and that the PDI4Ph4Py contained some microcrystals at the 10 µM concentration. This explains why the coefficient measured was so low compared to the other ones. The absorbance of PDI4, PDI3, PDI4Ph4Ph, PDI3Ph3Ph were measured in three solvents and the molar extinction coefficient was determined with the same value of 5,1x10 4 l.mol -1 .-cm -1 at the absorbance maxima.

IX.3. Fluorescence of PDIs

Measurements of the emission spectra and the photoluminescence quantum yield of PDI4, PDI3 and PDI4Ph4Py were done in chloroform and toluene. The PDIs synthesized exhibit a strong fluorescence in the visible wavelength region. The fluorescence measure was done using different excitation wavelength between 300 and 540 nm, showing the same emission independently of the excitation wavelength used. The difference of excitation wavelengths only affected the intensity or emission recorded. All PDI derivatives (PDI4, PDI3 and PDI4Ph4Py)

gave similar emissions spectra in toluene, with two distinct peaks at 576 and 616 nm (Figure 96). The lifetime and maximum emission wavelengths as well as the PLQY of PDIs are presented in Table 15. The PLQY was obtained by direct measure in an integration sphere. The PLQY measured were between 79 and 92% which is common with PDIs. [111] The reported PLQYs were selected as the best value within a range of measures at different excitation wavelength around the maximum of absorbance. The difference between the highest and the lowest PLQY measured could reach up to 10% of the reported PLQY. The lifetimes measured for all the PDIs were of around 5 ns, with the PDI4Ph4Py showing a slightly shorter lifetime in both toluene and CHCl3. This shorter lifetime case also with a slightly higher PLQY. As the fluorescence emission is faster other ways of de-excitations are a little less accessible (phosphorescence or vibrational).

IX.4. Photoemission spectroscopy of PDIs

Photoemission spectroscopy (PES) measures were done on thin layers of the PDI3 and PDI4Ph4Py to determine the energy of the first ionization. Because of the similar structure of the molecules, we selected one with a single pyridyl substituent and one with a phenyl-pyridyl substituents as main references. The molecules were deposited by spin coating to get a thin film on a silicon substrate and the emission of electrons was measured under a UV-light beam. The photoemission spectra presented in Figure 98 shows the normalized electron counts on the 4,5-6.7 eV scale. The ionization energy of PDI3 was measured at 6.25 eV and PDI4Ph4Py at 6.35 eV. The increasing number of phenyl ring on N-substituents seems to increase slightly the ionization energy of the PDIs.

The chemical structure of the PDI4, PDI3, PDI4Ph4Py and PDI3Ph3Py derivatives was confirmed by proton NMR spectroscopy. Their similar backbone was differentiated by the different pyridyl groups present at the N-positions. From their optical characterization by absorbance and emission spectroscopy we observed that the pyridyl substituents had almost no effect. Thus, we demonstrated that the modification of all PDI structures resulting in different 3-D geometries do not impact significantly the electronic and optical properties of the PDIs.

This result is extremely important for the on-surface investigations, since it means that any variation observed will be due to the interaction with the surface and not due to the chemical structure differences between each PDI derivative. The PLQYs recorded in solution were high (>79%) for all derivatives The lifetime of PDIs was measured at around 5 ± 0.6 ns which showed a fast emission which reduces the competition with other decay pathways. These techniques of characterization (fluorescence and absorption) will prove to be key tools to monitor and confirm the formation of supramolecular complexes between the Pcs, Ps and PDIs, which will be described in the following chapter.

X. Synthesis of catechol functionalities

In the previous sections, we have mentioned that the PDIs bearing pyridyl substituents will be used to form supramolecular complexes with zinc phthalocyanines and porphyrins. In this section, we will describe the synthesis of a different functionality that will enable us to prepare a covalently-bound complex with the titanyl phthalocyanine. The titanium (IV) cation inside the Pcs prepared was chosen for its ability to create tetrahedral covalent bonds. Though these, a dihydroxy group located on the Ti cation could be strongly associated with the previously described CxTiOPc. This kind of axial substitution has already been explored with molecules like catechol and other similar derivatives by Hanack et al. in 2000 (Figure 99). [112] Figure 99. Axial catechol derivative substituent of titanium phthalocyanine reported by Hanack et al. [112] With this new type of association, we looked for a functional molecule bearing a catechol function. Ideally, we aimed to introduce a chromophore with similar properties to the PDI to attach to the titanium, however this was difficult to achieve without having to develop a specific synthetic route. So, we decided to use another electronically-active molecule; the fullerene (C60). This three-dimensional antiaromatic molecule composed by 60 sp 2 carbons is known as a strong electron acceptor and was particularly interesting because of its shape, which is easily recognizable by scanning tunnelling microscopy (technique described in chapter 3).

X.1. Synthesis of catechol-fullerene

In order to functionalize the titanylphthalocyanines, in particular the novel C6TiOPc and the C12TiOPc synthesized, we looked for an appropriate catechol substituent to link on the titanium IV cation. An example of a system consisting of a fullerene attached to a titanyl Pc is reported by Ballesteros et al. [86] . The synthesis of the fullerene precursor used to attach it to the Pc is presented in Figure 100. the reaction longer increased the quantity of di-addition on one fullerene. The product was purified using a toluene-EtOAc mixture (95:5) instead of toluene-THF (9:1) as described in the reported protocol. During the purification, the unreacted fullerene could be recovered as a violet fraction, and although it was poorly soluble it still eluted faster than the other products.

Compound 26 was recovered in the second fraction eluted, as a brown band, and was soluble enough to give well-resolved proton NMR spectrum in CDCl3. Finally, the catechol-C60 (cat-C60) was obtained after deprotection of the carboxylate groups s in acidic conditions. The cat-C60 was lost once by attempting a purification by chromatography on silica gel but in a second attempt we found it could be purified by washing the crude with cyclohexane and solubilizing in a hot toluene-ethanol mixture (1:2). Cat-C60 is completely insoluble in organic solvents and could only be characterized by mass spectrometry (ESI-orbitrap in negative mode, solubilized as much as possible in MeOH,). Cat-C60 was obtained with a 65% yield as brown powder.

A catechol functionalized with a fullerene unit was synthesized with an overall 24% yield. This two-step reaction enabled us to obtain 80 mg of product which will be grafted on both CxTiOPcs prepared in order to create new functional complexes to deposit on a graphenoid surface. The association of these units is not discussed in this thesis, since most of the work was focused on studying the Zn-pyridyl association.

XI. Conclusion on the synthesis

In this first chapter we discussed the design, synthesis and characterization of several phthalocyanines, porphyrins and perylenediimide derivatives and a catechol-bearing fullerene.

These derivatives will be used to build a series of self-assembling molecular complexes that will be studied after deposition on a graphenoid substrate.

The new phthalocyanines prepared possess eight linear alkyl chains at the peripheral positions.

Chain lengths of six and twelve carbons were chosen to help us modulate later on their selfassembling properties. We also prepared a naphthalocyanine (C6ZnNc) and a porphyrin (ZnDPP) to observe how the size of the conjugated core affects its self-assembly on the graphene surface. Finally, we attempted to synthesize a tetraalkyltetrabenzoporphyrin, which would allow us to incorporate four alkyl chains (in a symmetrical manner), whilst retaining a similar conjugated structure as the Pcs. These attempts were unsuccessful; however, these types of derivatives show excellent promise. Indeed, the tetraalkyltetrabenzoporphyrins could lead to a surface patterning using only four symmetric alkyl chains, are completely flat molecules and have a conjugated core extended which are good criteria for surface patterning (chapter 3). The heart of this work was centered on zinc derivatives since our main goal was to obtain a variety of complexes via the metal-ligand coordination between the zinc cation within the macrocycle's cavity and the pyridyl functionalities from the PDI derivatives. A covalent approach was also attempted, this time using a titanyl Pc covalently bound to a fullerene via two Ti-O bonds.

We prepared as well a series of specifically engineered PDIs which would enable us to control the distance and orientation between the PDI core and the Pc or P via the use of different Nsubstituents. The introduction of the bulky substituents at the bay positions are there to help us facilitate the coordination with the macrocycles (limiting their self-aggregation) and also to impede the physisorption onto the surface, as will be shown in chapter 3. We prepared four symmetric PDI4, PDI3, PDI4Ph4PY and PDI3Ph3Py compounds and a precursor to obtain asymmetric mono-pyridyl PDIs with an even more hindered aromatic core. All the CxZnPc, ZnDPP and PDIs were fully characterized with different and complementary spectroscopic methods. Their structures were validated using proton NMR spectroscopy and the optoelectronic properties characterized by absorbance, fluorescence and photoelectron emission. The three first techniques will be the basic tools used to study the supramolecular complexes in the following chapter.

XII. Experimental methods and materials

XII.1. General experimental conditions

All solvents were purchased from commercial suppliers and used without further purification.

Anhydrous dimethylformamide was prepared by drying it overnight with activated 4 Å molecular sieves and bubbling argon through a sealed septum for 1h. Anhydrous dichloromethane, toluene, tetrahydrofuran and diethyl ether were obtained from MBraun solvent purification system (MB SPS-800). Anhydrous chloronaphthalene was distilled on calcium hydride under reduced pressure (0.2 mBar, 83-85 °C) and kept on 4 Å molecular sieves under argon atmosphere. Other common reagents were used as received from Merck®, ABCR®, FluoroChem®, TCI Europe® and Acros®.

Heating of the reactions was done using heat-on blocks or oil bath. When temperature control was needed, an inner glass covered probe (thermometer) was used to monitor/control the temperature. Lithium wire was kept in silicone oil and rinsed with cyclohexane prior to use.

The mass weighed includes some LiOH visible on the surface, therefore the mass weighed is higher than that stated in the protocols by approximately 10 %. The purifications performed by chromatography were either carried out by traditional column chromatography using silica-gel as the stationary phase (Si 60, 40-63 μm, Merck®) or by flash chromatography using a Bucchi® Combiflash X-Revelaris with pre-packed Bucchi FlashPure EcoFlex® silica columns (12 to 330 g).

XII.1.1. NMR & Mass Spectrometry characterization

XII.1.2. Optical characterizations

Absorbance was recorded in 1 cm quartz or glass cuvettes. The solutions were prepared at concentration ranges of 10 -5 to 10 -7 M in CHCl3, THF of toluene. These diluted solutions were prepared from the dilution of the stock solutions. Atypical preparation method for the preparation of a stock solution was by solubilizing between 1 and 10 mg of compound in a volumetric flask of 100 or 200 mL. This solution was placed in an ultrasound with heating (temperature depended on the solvent used until no solid was visible to the naked eye. The absorbance spectra were recorded using a spectrometer Agilent® Cary 50 or Cary 100 using an automatic baseline. Fluorescence was recorded using a Varian Cary eclipse fluorescence spectrophotometer using the same solutions as for the absorbance measurements after a tenfold dilution. The fluorescence lifetime measures were done with a Quantaurus-Tau fluorescence lifetime system (C11367-03, Hamamatsu Photonics). The PLQY was determined using an integrating sphere with a Quantaurus-QY measurement system (C11347-11, Hamamatsu Photonics). UV photoelectron emission spectrometer (PES) (Riken Keiki AC-3) was used determine the HOMO energy levels of the compounds in the neat films. The neat films were prepared on glass substrates previously cleaned in an ultrasonic water bath, rinsed with acetone, isopropanol and distilled water, dried in oven for 1 h and cleaned under ozone for 5 minutes.

XII.2. Synthesis of 4,5 alkylphthalonitriles

Route 1: From 4,5-dibromoveratrole 1,2-dihexyl-4,5-dimethoxybenzene [75] (1-C6) (300 mL). The recovered filtrate was washed with an HCl solution (1M, 2x50 mL) and brine (150 mL). The organic layer was dried on MgSO4 and the solvent evaporated under reduced pressure. The resulting brown oil was purified via chromatoflash, using a 120 g silica column, loaded by solid deposition, eluted with PE and subsequently with a gradient from 0 to 5% of EtOAc over 15 CV. The pure product was recovered in the first fraction, followed by a mix of the mono-and di-alkylated product. The fraction containing the pure product was dried under reduce pressure to afford 1-C6 as a translucent oil (6.10 g, 59%). 1,2-didocecyl-4,5-dimethoxybenzene [75] (1-C12)

Following the 1,2-dihexyl-4,5-dimethoxybenzene 1-C6 protocol: 1,2-dihexyl-4,5-dihydroxybenzene [75] (2-C6) 1,2-didodecyl-4,5-dihydroxybenzene [75] (2-C12)

Following the 1,2-dihexyl-4,5-dihydroxybenzene 2-C6 protocol:1-C12 reacted in 100 mL of HBr (48% in water) -AcOH (1-1). DCM was used instead of EtOAc to extract the product. 2-C12 was obtained as a dark red oil (6.04 g, 95%). [75] 4,5-didodecyl-1,2-phenylene bis(trifluoromethanesulfonate) [75] (3-C12)

4,5-dihexyl-1,2-phenylene bis(trifluoromethanesulfonate

Following the 4,5-dihexyl- 4,5-dihexylphthalonitrile [75] (C6Pn)

Dppf (400 mg, 0.72 mmol, 0.09 eq.) and Pd2(dba)3 (230 mg, 0.25 mmol, 0.04 eq.) were added to anhydrous DMF (5 mL) in a 50 mL 3-neck-RBF under an argon atmosphere. The mixture was stirred for 10 min and a solution of ditriflate 4,5-didodecylphthalonitrile [75] (C12Pn)

Following the 4,5-dihexylphthalonitrile C6Pn protocol: Ditriflate 3-C12 (5,5 g, 7,7 mmol, 1 eq.), DPPF (0.69 g, 1,2 mmol, 0.16 eq.), Pd2(dba)3 (1,1 g, 0.31 mmol, 0.04 eq.) reacted in anhydrous DMF (18 mL). C12Pn was obtained a white crystalline solid (3,15 g, 88%). Route 2: From dimethylbutadiene 2,3-dihexylbutadiene [76] (4)

t-BuOK (2.8 g, 25 mmol, 2.0 eq.) was weighted in a 3-neck-RBF and anhydrous pentane (25 mL) was added under inert atmosphere. n-BuLi (2.5 M in hexane, 10 mL, 25mmol, 2.0 eq.) is

then added dropwise at -5 °C. The mixture was stirred 30 min and 2,3-dimethyl-1,3-butadiene (1,4 mL, 12.5 mmol, 1 eq.) solubilized in anhydrous pentane (10 mL) was slowly added via syringe (2 mL/min), at rt. The mixture turns into a brown-orange suspension over the addition.

In the meantime, 1-Bromopentane (3,1 mL, 25 mmol, 2.0 eq.) in THF (25 mL) are poured in 2neck-RBF under inert atmosphere. Whilst stirring, the media was cooled to -78 °C and the previous suspension of 2,3-dimethyl-1,3-butadiene was slowly added via syringe over 20 min.

THF (5 mL) was used to rinse the solid remaining from the first 2,3-dimethyl-1,3-butadiene solution. The yellowish mixture was stirred 1 h at -78 °C, then 16 h at rt. The mixture was poured to a mix of ice and water (80 mL) and the organic phase dried under reduced pressure.

The aqueous phase was extracted 3 times with DCM and the organic layer washed with brine.

The organic layer was dried on MgSO4 and evaporated under reduced pressure to afford a yellowish oil. The product was purified by silicagel column with petroleum ether as eluent to give (4) as a translucent oil (3,8 g, 68%). Dimethyl 4,5-dihexylphthalate [76] (6)

2,3-dihexylbutadiene (4) (3,34 g, 15 mmol, 1.0 eq.), was weighed in a 3-neck-RBF equipped with a magnetic stirrer and a condenser. The system was put under inert atmosphere, then, anhydrous toluene (30 mL) and dimethyl acetylenedicarboxylate (1,84 mL, 15 mmol, 2.0 eq.)

were added. Whilst stirring, the reaction was heated to 130 °C for 16 h. The media was turned orange-reddish when the heating was stopped.

In the crude mixture at rt was added 2,3-dichloro-5,6-dicyanobenzoquinone (3,74 g, 16.5 mmol, 1,1 eq.). The media turned immediately red/dark red. The reaction was heated at 130°C for 6 h.

The reaction mixture was cooled to rt and filtered. The dark solid was rinsed with toluene and the recovered filtra was evaporated under reduced pressure. The dark oil was solubilized in DCM, rinsed with brine and dry on MgSO4. The organic layer was evaporated under reduced pressure to give a reddish oil. The product was purified by silicagel column chromatography with pentane/diethyl ether (9/1) to afford (6) as a yellow oil (1,7 g, 31%). 4,5-dihexylphthalic acid [76] (7)

Dimethyl 4,5-dihexylphthalate ( 6) (1,6 g, 4,41 mmol, 1,0 eq.) was put inside a 200 mL RBF filled with a NaOH solution (20% in water, 15 mL). The solution was heated during 6 h at 120 °C. The reaction was cooled to rt and H2SO4 solution (1 M) was added to reach pH 2. The organic product was extracted with diethyl ether and washed with water and brine. The organic layer was dried with MgSO4, evaporated under reduced pressure to an off-white solid. The product obtain was used in the next step without further purification. 4,5-dihexylphthalic anhydride [76] (8)

The dihexylphthalic acid (7) 4,5-dihexylphthalimide [113] (9)

Dihexylphthalic anhydride 8 (1,22 g, 3,86 mmol, 1 eq.) and formamide (6mL) were added to a 50 mL RBF capped with a condenser. The dark brown mixture was stirred at reflux 4 h. After cooling it down to room temperature, 30 mL of toluene were added to the black solution. The organic phase was washed with brine 3 times and dried over MgSO4. The brown solid was recrystallized in EtOH to give 9 as a grey powder (835 mg, 69%). 1 H NMR (300 MHz, CDCl3) δ 7,63 (s, 2H), 2,73 (t, 4H), 1.61 (q, 4H), 1,40 (m, 4H), 1,33 (m, 8H) 0.90 (t, 6H).

4,5-dihexylphthlamide [113] (10) Dihexylphthalimide (9) (0.835 g, 2,65 mmol, 1.0 eq.) in a 250 mL RBF was dissolved in an aqueous ammonium hydroxide solution (28-30% in water, 90 mL) and heated at 40 °C 16 h. A brown precipitate appears over the reaction. After cooling down to room temperature the media, the organic material was extracted with chloroform and washed with brine. The organic phase was dried over MgSO4 and the solvent was removed under reduce pressure. The product was obtained as a brown powder (0.92 g, 100%) and used in the last step without further purification. 4,5-dihexylphthalonitrile [113] (C6Pn)

Anhydrous DMF (10 mL) was cooled at 0 °C under an inert atmosphere in a 100 mL 2-neck-RBF capped with a base bath trap (concentrated NaHCO3). SOCl2 (7 mL) was added and the mixture was stirred for 2 h. (10) (0.92 g, 2,6 mmol) was added and the mixture stirred for 5 h at 0 °C. The mixture was left to stir 24 furthers hours at rt then ice water (50 mL) was slowly added to the mixture. The mixture was then extracted and rinsed with Et2O (3x20 mL). The organic layers were gathered and rinsed with water (2x40 mL) then NaHCO3 (saturated, 2x40 mL) and brine (2x40 mL). The organic layer was dried on MgSO4 and then evaporated under reduced pressure. The resulting oil was purified via chromatoflash, using a 120 g silica column, loaded by solid deposition, eluted with PE and subsequently a gradient from 0 to 5% of EtOAc over 15 CV. After the main fraction was dried under reduced pressure, and C6Pn was obtained as a translucent oil (0.71 g, 92%).

XII.3. Synthesis of non-metalated octaalkylphthalocyanines

2,3,9,10,16,17,23,24-octahexylphthalocyanine [75] (C6H2Pc)

4,5-dihexylphthalonitrile C6Pn (1.0 g, 3.37 mmol, 1 eq.) was solubilized in 1-pentanol (12 mL) and heated to 140 °c for 10 min whilst stirring under a normal atmosphere. Small pieces of lithium (ca 52 mg, 7.49 mmol, 2.2 eq.) were added to the hot mixture. The temperature was increased to 155 °C, and mixture started to turn dark blue. After 3 h the mixture was left to cool to 80 °C and AcOH (6 mL) was added. After 30 min a dark blue suspension was formed and was let to cool to rt.

The crude formed a blue suspension, was poured in water-methanol (1-1, 80 mL) and the blue solid was recovered by filtration. The blue solid was rinsed with hot methanol (500 mL) and ethanol (80 mL). Hot chloroform was used to recover the product before being evaporated under reduced pressure. The product was triturated in hot ethanol to give pure C6H2Pc as a dark blue powder (480 mg, 48%). [75] (C12H2Pc)

4,5-didodecylphthalonitrile C12Pn (500 mg, 1.07 mmol, 1 eq.) was solubilized in 1-pentanol (5 mL) and heated to 140 °c for 10 min whilst stirring. Small pieces of lithium (ca 20 mg, 2.9 mmol, 2.8 eq.) were added to the mixture at 120 °C. The temperature was increased to 155 °C, and the color mixture started to turn dark blue. After 3h the mixture was left to cool to 80 °C and AcOH (6 mL) was added to the mixture. After 30 min the mixture was let to cool to rt.

The resulting dark blue mixture was poured in water (80 mL) and a blue precipitate appeared.

The blue solid was filtered and rinsed with methanol (200 mL) and cyclohexane (50 mL). The blue product was collected from the filter paper by solubilizing with chloroform. The solvent was later evaporated under vacuum to obtain the C12H2Pc as a dark blue powder (68 mg, 25%). The dark product was solubilized in hot chloroform, concentrated under vacuum to obtain a dark green solid. The solid was triturated in EtOH and filtered to obtain the pure metal-free C6H2Nc (25mg, 25% yield). [85] (C6ZnPc)

C6Pn (300 mg, 1.0 mmol, 1 eq.) and Zn(OAc)2 (61 mg, 0.30 mmol, 0.33 eq.) were added to pentanol (2 mL) in a 25 mL RBF and the flask was placed under inert atmosphere. Whilst stirring, the mixture was heated to 110 °C and 2 drops of DBU were added. The heating was increased to 180 °C for 5 h. After cooling to rt, MeOH (10 mL) was added to precipitate the blue product. The precipitate was filtered, rinsed with MeOH (100 mL) and acetone (50 mL).

The product was triturated in a mix EtOAc-MeOH (8-2) and filtered then recrystallized by adding MeOH to a solution in chloroform (15 mL). After 5 h at 4 °C, the blue crystals were filtered and dried under reduced pressure to give C6ZnPc (106 mg, 45%). Zinc 2,3,9,10,16,17,23,24-octadodecylphthalocyaninato [85] (C12ZnPc)

C12Pn (300 mg, 65 mmol, 1eq.) and Zn(OAc)2 (36 mg, 0.20 mmol, 0.31 eq.) were added to pentanol (2mL) in a 25 mL RBF and the flask was placed under inert atmosphere. Whilst stirring, the mixture was heated to 110 °C and 2 drops of DBU were added. The heating was increased to 180 °C for 8 h. After cooling to rt, MeOH (10 mL) was added to precipitate the blue product. The precipitate was filtered, rinsed with MeOH (100 mL) and acetone (50 mL).

The blue crystals were filtered and dried under reduced pressure to give C6ZnPc (126 mg, 40%). Zinc 3,4,12,13,21,22,30,31-octadecyl-2,3-naphthalocyanine [85] (C6ZnNc) 6,7-dihexylnaphthalonitrile (150 mg, 0.43 mmol, 1 eq.) and Zn(OAc)2 were solubilized in 1pentanol (3 mL) and heated to 100 °c for 10 min whilst stirring under an inert atmosphere. 1 drop of DBU was added to the hot mixture. The temperature was increased to 160 °C, and mixture started to turn green. After 3 h the mixture was left to cool to rt.

The crude was poured in methanol (20 mL) and the green solid was recovered by filtration. The blue solid was rinsed with methanol (100 mL) and dried under high vacuum (10 -2 mbar) to give pure C6ZnNc as a slightly green powder (95 mg, 61%).

XII.6. Synthesis of CxTiOPc

2,3,9,10,16,17,23,24-octahexyltitanylphthalocyanine [88] (C6TiOPc) C6Pn (100 mg, 0,34 mmol, 1,8 eq.) was added to chloro-naphthalene (1 mL) in a RBF equipped with a reflux. The mixture was placed under inert atmosphere and TiCl4 (0.02 mL, 0.18 mmol, 1eq.). Whilst stirring, the mixture was heated to 180 °C for 14h30. After cooling the dark sticky paste was solubilized in hexane (20 mL) with EtOAc (5 mL). The dark green solution was used to adsorbed the crude product on silica (1 g). The product was purified using chromatoflash with a 12 g prepacked column. The gradient used was from 10-0 hexane-EtOAc to 9-2 hexane-EtOAc over 20 CV. C6TiOPc was recovered as the second fraction and dry under reduced pressure. The dark green solid was triturated in acetone (15 mL) then filtered and rinsed with acetone (3x10 mL). After drying under reduced pressure, the titled C6TiOPc was obtained as green powder (53 mg, 50%). 1 H NMR (400 MHz, CDCl3) δ 9.03 (s, 8H), 3.32 -3.12 (m, 16H), 2.06 (p, J = 2,3,9,10,16,17,23,24-octahexyltitanylphthalocyanine [88] (C12TiOPc) C12Pn (110 mg, 0,24 mmol, 1,3 eq.) was added to chloro-naphthalene (1,5 mL) in a RBF equipped with a reflux. The mixture was placed under inert atmosphere and TiCl4 (0.02 mL, 0.18 mmol, 1eq.). Whilst stirring, the mixture was heated to 180 °C for 14h30. After cooling the dark sticky paste was solubilized in hexane (30 mL) with EtOAc (5 mL). The dark green solution was used to adsorbed the crude product on silica (1 g). The product was purified using chromatoflash with a 12 g prepacked column. The gradient used was from 10-0 hexane-EtOAc to 9-2 hexane-EtOAc over 20 CV. C6TiOPc was recovered as the second fraction and dry under reduced pressure. The sticky dark green solid was triturated in acetone (15 mL) then filtered and rinsed with acetone (3x10 mL). After drying under reduced pressure, the titled C12TiOPc was obtained as green powder (40 mg, 35%).

1 H NMR (300 MHz, CDCl3) δ 9.06 (s, 8H), 3.37 -3.07 (m, 16H), 2.06 (q, 16H), 1.73 (q, J = 7.7 Hz, 16H), 1.65 -1.15 (m, 128H), 0.89 (t, J = 6.4 Hz, 24H). [START_REF] Buchler | Synthesis and Properties of Metalloporphyrins[END_REF]

XII.7. Synthesis of ZnDPP

Dipyrromethane [96] (11)

Paraformaldehyde (0.77 g, 25 mmol, 1 eq.) and pyrrole (175 mL, 2.5 mol, 100 eq.) were added to a 500 mL 3-neck-RBF under inert atmosphere. Whilst stirring, the suspension was heated to 55 °C for 3 h to partially solubilized the paraformaldehyde. The mixture was cooled at rt and TFA was slowly added via syringe. The mixture was stirred for 1 h and the color passed from pale yellow to pale orange. NaOH was added and the mixture stirred 45 further minutes at rt.

The pyrrole was evaporated under reduced pressure and the crude purified by chromatoflash.

The gradient used was PE-DCM from 10-0 to 8-2 over 5 CV, the product was the second fraction collected. After evaporation under reduced pressure, the product 11 was obtained as a brown powder (1,65 g, 44%). 1 H RMN (300 MHz, CDCl3) : δ (ppm) = 7,89 (s, 2H) ; 6,67 (s, 2H) ; 6,16 (t, J = 3 Hz, 2H) ; 6,04 (s, 2H) ; 4,00 (s, 2H)

Diphenylporphyrin [96] (DPP) 11 (0.20 g, 1,24 mmol, 1 eq.) and benzaldehyde (0.14 mL, 1.24 mmol, 1 eq.) were weighted in a 1 L RBF. DCM (500 mL) previously degassed 20 min with bubbling argon was added and the stirring mixture degassed another 20 min. TFA (0.20 mL, 2,28 mmol, 2 eq.) was slowly added via syringe and the mixture was stirred at 25 °C for 1 h. DDQ was added (0.55 g, 2,28 mmol, 2 eq.) and the mixture stirred at 25 °C for 16 h. Triethylamine (5 mL) was slowly added and the solvent was evaporated under reduced pressure. The crude product was purified by chromatoflash. The gradient used was cyclohexane-DCM from 10-0 to 5-5 over 4 CV. After evaporating the fraction collected under reduced pressure, the DPP was obtained as a purple solid (174 mg, 29%). 1 Zinc diphenylporphyrin [96] (ZnDPP) DPP (0.50 g, 1,1 mmol, 1 eq.) was solubilized in chloroform (150 mL) in 3-neck-RBF. Whilst stirring, the solution was bubbled with argon for 20 min and Zn(OAc)2 (2,2 g, 12 mmol, 12 eq.)

were added. The stirring mixture was heated to reflux for 20 h. After cooling to rt, the crude solution was filtered through a silica plug and eluted with chloroform. The solvent was evaporated under reduced pressure to give ZnDPP as purple crystalline solid (545 mg, 96%). 1,7-dibromoperylene-3,4 :9,10-tetracarboxydianhydride PDA-Br2 [107] (13&14) PDA (28.5 g, 72.7 mmol, 1 eq.) was added to concentrated sulfuric acid (96%, 420 mL) in a 1

L RBF and the mixture was stirred at 55 °C for a period of 24 h. The mixture was pink-violet with a red solid in suspension. Iodine (0.685 g, 2.7mmol, 0.04 eq.) is then added and the mixture stirred for a further 1 h period at 55°C. Bromine (8.3 mL, 162 mmol) is then slowly added (0.14 mL/min) to the reaction mixture. After addition is completed, the reaction is heated to 85°C for further 22 h. The red suspension was left to cool to rt before to add cold distilled water (70 mL), the exothermic conditions were controlled with an ice bath. The red solid was filtered under vacuum, rinsed with distilled water (2 x 100 mL) and ethanol (300 mL).

Bromine vapor quenching

The excess bromine in vapor phase was pushed by argon to a basic sodium thiosulfate solution (Na2S2O3 8w% in water with 0.2w% of NaOH). The following equations show the products obtained after this bromine neutralization. The two reactions happened in parallel.

Eq. 1: 2 𝑆 2 𝑂

XII.8.2. Synthesis of the tetra-substituted PDA 18

Cl4-PDI [63] (16)

Cl4-PDA (2.12 g, 4,0 mmol, 1 eq.) and 2-ethylhexamine (1.29 g, 10 mmol, 2.5 eq.) were solubilized in isopropanol (200 mL) in a 500 mL 3-neck-RBF. The mixture was placed under an inert atmosphere and a drop of acetic acid (ca. 0.25 mL) was added, whilst stirring. The mixture was heated at reflux for a 16 h period, it turned from dark red to brick red over this time. The mixture was left to cool at rt and poured in an ice bath (250 mL). The red-orange precipitate was filtered, rinsed with water (100 mL) and dried under reduced pressure. The crude product was filtered with a silica gel plug and eluted with DCM. The resulting filtra was evaporated under reduce pressure to give 16 as a red solid (2.88 g, 95%).

XII.9. Synthesis of dipyridyl Perylenediimides

N,N'-Di(4-(pyridin-4-yl)phenyl)-1,7-bis(3',5'-di-tert-butylphenoxy)perylene-3,4:9,10tetracarboxylic Bisiimide (PDI4Ph4Py)

Following the general protocol: Using (15) (200 mg, 0.25 mmol) and 4-(pyridin-4-yl)aniline (128 mg, 0.75 mmol 3.0 eq.) we obtained PDI4Ph4Py as a red solid (115 mg, 42%).

XII.12. Synthesis of catechol-fullerene

The catechol-C60 synthesis was reproduced according to Ballesteros et al. [86] The cat-C60 was obtained as a brown crystalline solid (80 mg, 24%). The product was characterized by UV-vis absorbance and ESI negative-orbitrap as follows.

I. Introduction

In 1978 J.M. Lehn introduced the term of supramolecular chemistry. He defined it as "the chemistry of molecular assemblies and intermolecular bonds". Later on, this field will be known to as "the chemistry beyond the molecules" or "the chemistry of non-covalent bonds". [114] Supramolecular chemistry is based on assembly of molecules or atoms with noncovalent bonds, giving an organized structure in space. In contrast with molecular chemistry where chemists create and break covalent bonds to obtain a target molecule, supramolecular chemistry focuses around the concept of host and guest between two or more molecules to give a complex.

The Nobel prize was awarded to Lehn, Pederson and Cram in 1987 for their pioneering works in supramolecular chemistry. Their works were based on host-guest system mostly. Cryptands were the works of Lehn, [115] crown ethers of Pederson and spherands for Cram (Figure 104).

These studies gave the field a significant boost to become a major interdisciplinary research field in the present.

Figure 104. Pioneer molecules used in host-guest systems. [115] The field is now no longer limited to organic chemists, being also the playground for physicists, solid-state chemist, theorists, inorganic chemists and biologists who work together to develop new materials with unique properties and applications.

Supramolecular systems can combine the molecular properties of their components to obtain novel properties, in particular physical ones with nanometric objects, but numerous applications can derive when such systems are moreover made to interact with environmental stimuli.

Supramolecular materials have found use in the following applications:

• Molecular imaging with fluorescent probes based on supramolecular interactions [116] • Chemical sensing for cation or oxygen detection [117] • Metal extraction based on coordination

• Drug delivery

More precisely, supramolecular objects result from an addition of non-covalent intermolecular forces. [118] Non-covalent interactions gather all interactions that do not involve the sharing of an electron. They are quite varied in nature and are weaker than covalent bonds. Table 16 summarizes these most common interactions. [119] Table 16: Non-covalent interaction summary [119] Interaction nature Bond energies

I -•••I2, Me3N•••Br2
Understanding how these interactions lead to the formation of structured systems is the key to be able to build complex, multicomponent and functional supramolecular architectures. The main types of interactions are briefly described in the following section.

Ion-ion interactions

Anions, cations and molecules each share between the strong attractions described by Coulomb forces. These interactions can also be repulsive in the case of charges of same sign.

Ion-dipole interactions

Cations which are surrounded by electron-rich molecules, coordinated metals, are supramolecular structures which result from of ion-dipole interactions.

Figure 106. Lithium coordinated by crown ether and ruthenium by three bipyridyl

The lack of electrons in a cation, like lithium (Li + ) in the example shown above, have a good affinity with the electrons located around it. This affinity drives the phenomenon of ligand or solvation, depending on the medium. Electrons high in energy, like in lone pairs or π-bonds, are attracted by cations which creates bonds. Ligand field theory, which combines principles from molecular and crystal field theory, helps us explain the variety of geometries which can be obtained by ion-dipole interactions of transition-metals with various molecules. In some case ion-dipole interactions can be almost as strong as covalent bonds but they can also be extremely labile in solution. This long range of affinity is of great interest when developing reversible systems in supramolecular chemistry.

Dipole-dipole interactions

Dipole-dipole interactions result from the attraction between partial charges on neutral molecules. In the case of acetone shown in Figure 107,the difference of electronegativity between the oxygen and the carbon atoms leads to the polarization of the bond between them.

As the oxygen is electronegative, the electronic cloud surrounding the C-O bond is closer to the oxygen than the two carbons. This creates partial charges: a negative on the oxygen and a positive one on the carbon. A close-range organization can then appear when several dipoles are presents. The organization is limited at a close range because these interactions are weaker compared to ion-ion interactions involving full charges.

Hydrogen bonding

This interaction appears when a hydrogen atom is linked to an electronegative group or atom and this hydrogen is in presence of an electron-rich element, presenting a lone pair of electrons.

The electronegative group bearing the proton is called a hydrogen donor (D) because its attractive effect lowers the charge around the hydrogen proton and repulses the proton. The hydrogen then takes on an electrophilic character and will attempt to pair with a hydrogen acceptor (A) with lone pair or π electron. Cation/anionπ interactions [120] Cation interactions with π-systems are mostly reported for alkaline or alkaline-earth metal cations because they don't involve d orbitals in the interaction. This interaction is considered electrostatic between the quadrupole induced by an aromatic structure (related to carbon's sp 2 hybridization) and the positive cation (Figure 109).

Figure 109. Reproduced structure of the benzene quadruple and a cation associated [START_REF] Steed | Definition and Emergence of Supramolecular ChemistryAdapted in Part from Supramolecular Chemistry[END_REF] The interaction can be as strong as an H-bond with can have a binding energy of up to 75 kJ.mol - 1 between the K + and the benzene. [START_REF] Steed | Definition and Emergence of Supramolecular ChemistryAdapted in Part from Supramolecular Chemistry[END_REF] In contrast, anionic-π-interactions are encountered with reversely polarized aromatic rings. As an example, in hexafluorobenzene the aromatic core is positively charged and this allows it to bind with an anion. The chloride anion binding to hexafluoro benzene was computed to be of a strength of 14.1 kcal.mol -1 . [START_REF] Gamez | [END_REF] Van der Waals forces [119] Van der Waals are weak, distance-dependent interactions with energies between 0.4 to 4 kJ.mol - 1 , and which are induced by the polarization of an electron cloud. This polarization appears when a nucleus gets close to another and disrupts its electron cloud. Van der Waals forces result from the combination of the following:

• The interaction between permanent multipoles (also called Keesom interactions).

• The polarization of an electron cloud by the proximity of a permanent dipole (Debye interactions).

• The dispersion forces between the electron clouds of two close molecules which induce a temporary dipole (London forces).

Because of the proximity required for molecules to present dipole (or multipole), the Van der Waals interactions are mostly observed at the solid state. They are not directional forces because they are induced by their environment; they are cumulative at the solid state and the more surface area of contact there is, the stronger is the effect. Van der Waals forces are particularly present in surfaces because they are one of the main molecules which at interfaces.

π-π Interactions

π-π interactions (also called π-π stacking) are observed between the interaction of aromatic species. They are related to the charge repartition of the p orbitals which create quadrupole moments within the aromatic ring. As a result, aromatic ring is negative charged above the aromatic faces and positively charged on the periphery in the carbon atoms' plane. Three possibilities of associations exist between two aromatic rings (Figure 111); such as:

• A face-to-face conformation, which is the less energetically favored because of the charge repulsion between the rings.

• An edge-to-face conformation, which is the most energetically favored because of the charge complementarity.

• A parallel, displaced conformation, also energetically favored with less charge repulsion than the face-to-face.

Figure 111. Conformations of association of two benzene by π-π interaction [124] From these three types of association, different short-range aggregate species can be present.

In extended stacking, Van der Waals forces, play a more important role than electrostatic interaction and this can lead to long columnar structures. This is a reason why π-π stacking is the main force that drives the aggregation of aromatic molecules.

Metal-ligand bond

The transition metals in their oxidized state exist in solution as coordinated species. A coordinate bond between a metal and a donor species is related to the 3d orbitals of the metal and a pair of electrons brought by the ligand (lone pair, electrons in p-orbitals). As a reminder, a covalent bond is formed by two atoms sharing one electron each in a hybrid orbital; an ionic bond is a charge dipole attraction of two oppositely-charged species and the coordinate bond is when an electron pair is shared by atom with another (generally a transition metal) (Figure 112). Figure 113. Coordination bond between a pyridine ligand and a metal [START_REF] Pandey | IntechOpen[END_REF] Because of the multiple orbitals implied in the bonding, the coordination bond is directional.

The binding energy is quite variable and can range from a few kJ.mol-1 up to 1000 kJ.mol-1 with single-ligand complexes attached to a transition metal. [START_REF] Pandey | IntechOpen[END_REF] The work presented in this thesis is focused mostly on zinc coordination, therefore I will describe briefly some of zinc's properties and its metal-ligand configuration.

I.1. Porphyrin and phthalocyanine zinc complexes I.1.1. Zinc metal coordination

Zinc is a transition metal with only one stable oxidized state of 2 + . The electronic configuration of Zn 2+ is [Ar] 3d [START_REF] Snow | Phthalocyanine Aggregation[END_REF] , with completely filled 3d orbitals, which explains its  donor character and that it creates stronger bonds with  acceptor ligands. In the covalent bond classification, the Zn 2+ has two X-type ligands (ligands which bring one electron for covalent or ionic bond) which donate each one electron to compensate its 2+ charge and maintain the neutral charge of the complex. To complete the octet rule with 18 valence electrons (as transition metal often do), three L-type ligands (lone pair electron donors) will bind to it. Thus, when Zn 2+ has an X2L3 ligand configuration, the zinc cation is stable with five coordination bonds. However, X2L2 and an L4 ligand sphere can also exist depending of the geometry of the ligands. Zinc can present a four, five and six coordination number, nevertheless the six coordinated Zn 2+ is rare and is only present with weak ligands. In a four coordination complex, the geometry can be tetrahedral or square-planar, with five it can be trigonal-pyramidal or square-pyramidal and with 6 coordination it will adapt an octahedral geometry (Figure 114). [START_REF] Patel | [END_REF] Figure 114. Encountered geometry of coordinated Zinc by 4, 5, and 6 coordination bonds

The geometry adopted will depends on the nature of its ligand and in our case, it will be constrained by the porphyrin and phthalocyanine ligands used.

I.1.2. Porphyrin and phthalocyanine ligand

As we previously discussed in Chapter 1's introduction; porphyrins and phthalocyanines are strong ligands which are negatively charged (2 -) when complexing transition metals. They coordinate to metals with four sigma bonds at a fixed distance because of its rigid cyclic structure. Because of this particularity, ZnPcs or Ps can only adopt two possible geometries: a square-planar geometry with a coordination of four, and in presence of sigma donor like an oxygen or a nitrogen-based ligand, the geometry of the zinc coordination can acquire a fivecoordination number and present a square based pyramid geometry (Figure 115).

Figure 115. Common geometry of zinc porphyrins or zinc phthalocyanines [127] Because of the small size of Zn 2+ , the cation fits well inside the macrocycle's cavity and is considered to be in the same plane of the Pc or P when complexed. [128] When the Zn 2+ is inside the core of Pc or P a fifth position for coordination becomes available in the axial position. This position is accessible to a sigma donor and  back-bonding ligand, which makes the pyridyl species the ligand which commonly complies with these criteria. Other similar heteroaromatic rings with a nitrogen heteroatom like imidazole, pyrazole, etc. can also bind in a similar manner as axial ligands. The oxygen of carbonyl or ether functions like THF can also coordinate the zinc Pc/P axial position, albeit in a weaker way since they are only sigma donor ligands.

I.1.3. Axial ligand to Zn Pc/P

This type of pyridyl-zinc and zinc imidazolyl coordination has been reported with various types of functionalized of zinc phthalocyanines, porphyrins and naphthalocyanines. From these reports, the association of ZnPc/P to perylenediimides (PDIs) in particular attracted our interest. ZnPc, ZnP and ZnNc macrocycles all exhibit similar ligand-donor effect and complex geometry. Nevertheless, two main differences are present in their structure which have an impact on their axial coordination.

• The four additional nitrogen atoms (aza-nitrogens) in the ZnPc and ZnNc compared to the ZnP give a more electron-rich donor effect to the macrocycle. Therefore, the Zn 2+ electron cloud becomes denser, it reduces the sigma donor effect of an axial ligand and thus will weaken this type of bond.

• The second difference is the area of the aromatic macrocycle. The ZnNc's area is larger than the ZnPc, and then the ZnPs. This affects the electronic shielding effect on the Zn 2+ but also the possibility of -interactions which increase with the aromatic macrocycle size.

The pyridyl or imidazolyl axial ligand also has a different effect on the axial coordination on Zn 2+ . The imidazole group has a stronger p-acceptor effect as well as a stronger sigma donor which should result in a stronger coordination than the pyridyl ligand. We also looked the diimidazolyl and dipyridyl PDIs which can bind to two ZnPc/Nc/P. A complex composed of a ZnPc and two imidazolyl in a 1:2 ratio; an association constant was reported of 1.5 x 10 5 M -1 .

In contrast, with a ZnPc and two pyridyls only one association was observed in a 1:1 ratio with a reported association of 4,4 x 10 5 M -1 . [129] The K values reported were obtained using different methods but all the calculated values are between 2.3 x 10 4 and 4.5 x 10 5 M -1 . Except for the first K association of an unsubstituted PDI with ZnNc which is smaller, all the association constants measured are close (less than a magnitude order of difference). Using the ranking of association established in Figure 116, we can establish that the association is stronger with porphyrins and the weakest with a naphthalocyanine, with phthalocyanines being between both.

The imidazolyl and pyridyl binding strength can't be compared because of steric hindrance effects from the PDI, which can lower the association constant. NMR, absorbance and fluorescence in chlorinated solvents (CH2Cl2, CDCl3). The NMR couldn't be used to calculate the association constant because of the low rate of association, so the CDCl3 absorbance was the only solvent where the value could be calculated from. A titration experiment using fluorescence was used to obtain the value for the 1:1 association between one ZnPc and one imidazolyl-PDI (1 x 10 -6 M -1 ). This comparison shows how close all the reported associations are using different methods in different experimental conditions.

The only common parameter, was that the concentration of host molecules was kept quite similar within a concentration range of 10 -5 to 10 -7 . The methods used revealed to be more or less successful depending the stoichiometry evaluated and the kinetic rate of association.

I.1.4. Definition of binding constant

In this series of experiments, different calculation methods were used to determine the binding constant. The different methodologies applied varied from one report to another; however, the main parameters sed to quantify the binding energy and the presence of the complex remained the same. One of those parameters is the stoichiometric ratio of the association: which means how many molecules of the host molecule (H) are associated with molecules of the guest (G) in a complex HxGy. This association is depicted in the equation (1).

𝑥[𝐻] + 𝑦[𝐺] → [𝐻 𝑥 𝐺 𝑦 ] (1)
The simplest case is when x and y equal 1, we talk of a 1:1 stoichiometry represented in the first equilibrium (K1) of Figure 117. The "H" ad "G" nomenclature is the most commonly used to discuss supramolecular complexes. The host and guest molecules in a system can be arbitrarily chosen; in titration experiments however, the host is the molecule kept at a constant concentration while the guest molecule's concentration will vary during the experiment. The association constant K defined by equation ( 2):

𝐾 = [𝐻𝐺] [𝐻].[𝐺]
(2) This is the simplest definition of K with a 1:1 stoichiometry. This constant is the K1 of the Figure 117; however, when multiple associations occur, the association constants will be different for every system, and so each K must be defined. It goes without saying that the higher the K value is, the stronger is the association as we can see in the Gibbs energy change definition equation ( 3):

∆𝐺 = -𝑅𝑇𝑙𝑛(𝐾) (3)
A negative Gibbs energy difference means the association is favored; and the lower the value is, the more favorable is the association. The definitions given by equations ( 1), ( 2) and ( 3) are the basis of the supramolecular complex association studies.

Unfortunately, the experimental studies are never as straight-forward as this theoretical definition and many parameters like the competition between multiple associations (association kinetics, Figure 118), temperature effects, concentration, etc. have to be considered when studying supramolecular associations. The theoretical definition is close to reality only in the case when one type of association can be considered, which also means in a diluted concentration range below 10 -6 M. Because temperature influences the kinetics of association, and has an effect on which interactions dominate, it becomes an important parameter to consider in a supramolecular association study. Therefore, we can say that in all the past examples discussed, the results obtained can only be considered as qualitative. We can only rely on the trends observed and not on the values obtained as they do not reflect the complexity of these systems. We now will focus on discussing the experimental methods used to range below calculate the association between zinc and pyridyl ligands. These methods were used to determine the association constants presented in Figure 116, and are based on the changes observed in their physical properties (mostly optical) as the molecular complex is formed.

I.1.5. Definition of titration, tool of association assessment

The most commonly used tool to investigate the supramolecular association of two species isa titrations. This is a common quantitative method used in analytical chemistry to determine the concentration of an analyte. It is based on the principle that a standard solution of a reagent (titrant) will react with a specific, known ratio of the analyte that is being studied. By measuring how much of the titrant has reacted with the analyte, we can calculate the concentration of the species formed. In supramolecular systems however, this method becomes more complex, as we are now working with dynamic systems where multiple species can be present and so to obtain an accurate, quantitative analysis is quite challenging. In the examples discussed, the formation of the metal-ligand complex could be detected by observing a change in the system's physical properties. Common properties observed in supramolecular chemistry titrations rely on absorbance, fluorescence, NMR spectroscopy or calorimetry for their measurement. The measurements collected during the titrations are compared and fitted using mathematical models to obtain quantitative information like the binding constant, the association energy and their stoichiometry ratios. We will now present a summary of the most used methods to obtain this information. [START_REF] Steed | Definition and Emergence of Supramolecular ChemistryAdapted in Part from Supramolecular Chemistry[END_REF]130] UV-visible spectroscopy is a powerful tool to measure and quantify the association between highly-colored molecules. This method usually works with diluted solutions in order to respect the Beer-Lambert law limit (A= l.C.ε, with A<1), which means the solutions used are often at concentrations below 10 -5 M. A detectable difference in the absorption spectrum of at least one component must be observed to be able to follow a titration. In the host-guest association represented below in Figure 119, the host's absorbance can be seen to decrease as the quantity of guest is increased, and the signal of the of the 1: In the absorbance titration reported of an imidazolyl-PDI complex with a soluble ZnPc derivative (Figure 120), the association was visible with the increase of the peak at 365 nm and at 681 nm. [131] Figure 120. Reported absorbance titration of a imidazolyl-PDI added to a ZnPc derivative solution [131] In this association study, the PDI possesses one imidazolyl which will coordinate to the Zn 2+ , with a single 1:1 association ratio.

I.2. Absorbance titration

To obtain the association constant for this system, a non-linear fitting model of the varying wavelength intensities is needed to give an association constant value from this titration experiment. [130] This more complex analysis is needed because the [HG] peak at 365 nm overlaps with the host's and guests' absorption peak . Since linear regression in absorbance studies can lead to distorted results in many situations, non-linear fittings are the best alternative to treat the data when determining association constants. The different process of data treatment and additional calculations used to determine the association constants will be discussed later on in the section after the presentation of the different titration methods. [START_REF] Steed | Definition and Emergence of Supramolecular ChemistryAdapted in Part from Supramolecular Chemistry[END_REF]130] A second way to monitor the supramolecular association between molecules, which is closely related to absorbance, is the through emission spectroscopy(fluorescence). This method is performed usually with solutions of even lower concentrations than for the absorbance titrations, (nm. vs µM) and thus makes it a much more sensitive method. The fluorescence observed is proportional to the concentration of really diluted solutions (A<0.05). [START_REF] Steed | Definition and Emergence of Supramolecular ChemistryAdapted in Part from Supramolecular Chemistry[END_REF] Generally, we start from the principle that the formation of a supramolecular complex [HG] will increase or decrease (quench) the initial fluorescence intensity of either [H] or [G]; and so, the progress of this association is then monitored by following the variation in the emission intensity. Although, it is not always mentioned in fluorescence titrations, that when the addition of [G] involves a quenching of the fluorescence; two types of quenching mechanisms are possible. On the one hand the dynamic quenching, which is related to collisions between molecules; on the other hand, the static quenching, which is related to properties of the complex formed. Unfortunately, in a 1:1 association the fluorescence intensity behaves the same during the quenching with the two processes. Therefore, the study of the fluorescence lifetime can bring us additional information on the processes involved. This is because static quenching has no effect on the lifetime, contrary to dynamic quenching, which reduces it with increasing concentration of the quencher. The figure obtained from Ulrike Alexeev and David L. Farren's studies' give a clear representation of this phenomenon (Figure 121).

I.2.1. Fluorescence titration

𝐼 0 𝐼 = 1 + 𝐾 𝑆𝑉 × [𝑄] (4)
In this equation, I0 is the emission intensity measured for [H], I am the emission intensity with

[G] added, KS is the Stern-Volmer constant related to the quenching effect and [Q] is the concentration of quencher added, also presented as the guest [G]. Once the quenching pathway is identified, the association constant K can be obtained if the static quenching pathway is dominating.

Finally, when the fluorescence titration is performed with [H] and [G] absorbing and emitting

in the UV-Visible region, the selection of excitation wavelength can help us discriminate one of the two components and help us visualize better the signal from the complex. Figure 122 illustrates this selectivity with the excitation of a 1:1 ZnPc-PDI4 mixture. A 500 nm wavelength excitation enables a selective excitation of the PDI4 fluorescence while, conversely, a 600 nm excitation leads to the selective excitation of the ZnPc. In the fluorescence titration of a ZnNc by a pyridyl-PDI. [133] the quenching was observed during the increasing addition of ZnNc (Figure 123). The excitation wavelength at 540 nm allowed the observation of only the fluorescence related to the PDI. The quenching was identified to be static (intramolecular) quenching because the quenching rate measured (2.31 x 10 12 M -1 s -1) is a hundred times higher than the intermolecular dynamic quenching predicted in similar cases.

Figure 123. Reported fluorescence intensity changes of pyridyl-PDI over increasing concentration of ZnNc, excitation wavelength was 540 nm [133] Based on this fluorescence titration, an association constant of 2.4 10 4 M -1 was calculated for the pyridyl-PDI with a ZnNc, with Stern-Volmer quenching constant at 1.15 x 10 4 M -1 . This data could be then compared with absorbance titration results to confirm the previously calculated association constant.

The study of fluorescence lifetimes was also used together with changes in the fluorescence spectra to investigate the supramolecular association of porphyrin and phthalocyanines in the systems described by S. M. B. Costa et al.. [134,135] Here, the quenching of fluorescence was related to the binding of a tertiary amine to an aluminum phthalocyanine which resulted in a reduction of the lifetime. In this experiment, an acid buffer was used to compare the binding of a protonated tertiary amine (which is not expected to bind) against the non-protonated amine.

The decay of the fluorescence was used to monitor this binding and the result is presented in Figure 124.

Figure 124. Image extracted from Pedro M. R. Paulo work [135] . It represents Tetra sulfonated aluminum phthalocyanine (Pc) in water fluorescence decay. G4 is the dendrimer binding the Pc.

The shorter fluorescence decay observed when the dendrimer is linked to the phthalocyanine was explained by charge transfer between the phthalocyanine excited state to the dendrimers.

In this case the decay became multiexponential because of the presence of multiple binding sites in the dendrimer. This multiexponential decay was described by the statistical distribution of decay time in the inset. In the case of multiple binding, each system with a different number of guests presents a different decay lifetime. Thus, multi-exponential lifetime decay can give information on the number of interactions in a host to multiple guest associations. [START_REF] Steed | Definition and Emergence of Supramolecular ChemistryAdapted in Part from Supramolecular Chemistry[END_REF]130] This is the third most often used technique to follow and determine the supramolecular association constant. This technique is based on monitoring specific proton signals ( 1 H) of either the host/guest molecules and see how changes in their magnetic environment affect their chemical shift. Compared to fluorescence or absorbance spectroscopy's, titrations monitored by NMR have the advantage that the host and guest molecules do not have to be optically active.

I.2.2. NMR titration

Nevertheless, this method is less sensitive and works only in concentrations of at least mM scale to obtain reliable results without having to perform thousands of scans per sample. As the number of scans in NMR evolves with the square root of the signal/noise ratio, increasing the number of scans allows to access to higher sensitivity but takes up a lot of time than absorption/emission measurements. As the 1 H uses relatively concentrated solutions, it is suitable for Ks with values lower than 10 6 M -1 . Because each magnetically-different proton is assigned to a specific chemical shift, NMR also provides information on where the supramolecular interaction is taking place. The NMR chemical shift (up a) induced by hostguest association is the key physical parameter that we follow in this titration: this shift can directly be used to obtain the association constant. A specific limitation of Norton study associations occurs only in the case where is when we are observing a fast exchange (reversible association). This means when the lifetime of the proton signal of [H] and [HG] in solution is a lot shorter than the shift of the resonance frequency. Equation (5) defines this fast exchange limit.

2𝜋|𝜐 𝐻 -𝜐 𝐻𝐺 | ≪ ( 1 𝜏 𝐻 + 1 𝜏 𝐻𝐺 ) (5)
In this equation 𝜐 𝐻 -𝜐 𝐻𝐺 is the difference of frequency of one nucleus in the [H] system and in the [HG] system; 𝜏 𝐻 and 𝜏 𝐻𝐺 are the nucleus' resonance lifetime of the free host and the complex. This fast exchange limit is directly related with the fact that the association constant has to be lower than 10 -6 M -1 to be able to perform the titration. Additionally, the concentrated conditions required to carry out the NMR titration can also interfere with the observed changes in chemical shift. With concentrations of [H] and [G] at mM ranges, the competition between self-aggregation and complex association makes the association constant a lot more complicated to determine. In the case of aggregating molecules, the multiple equilibriums present in the system leads to a loss of accuracy in the association determined.

This type of NMR titration was applied to a pyridyl ZnPc association study which have a relatively good solubility. Fernández-Ariza et al. reported the titration of a phthalocyanine with a pyridyl-bearing PDI in deuterated chloroform (Figure 125). The phthalocyanine was substituted in the periphery by ferrocenes, but as they don't participate to the binding we can focus solely on the zinc-phthalocyanine association with the pyridyl function without considering the ferrocene shifts. From this titration two things could be determined; a 1:1 stoichiometric ratio could be confirmed and the association constant was determined to be 6.0 x 10 3 M -1 . In this result and in other studies on similar ZnPc or ZnP titrations with pyridyl ligands a clear trend on NMR signals is evident. [136][137][138] The peaks associated to the protons of the pyridyl which bind to the zinc and which are located at the ortho position, (Figure 125, marked in blue) become broad before disappearing. The second set of protons at meta position (Figure 125, in green) can be seen to gradually shift up field as the PDI starts coordinating to the Zn. This titration method helped to confirm the results obtained by absorbance or fluorescence spectroscopy, giving key additional information on where the association process takes place.

Finally, another method commonly used to monitor supramolecular complex associations in solution is isothermal calorimetry titration. This method is quite sensitive and allows us to determine the thermodynamic parameters of the supramolecular interactions occurring in solution via the study of the sample in a closed adiabatic system. Given that the experimental conditions required are not suitable for the systems concerned by this thesis we will not discuss this technique in detail. From the three spectroscopic methods presented above, different association constants and stoichiometric ratios were calculated. To arrive at these final values however, some data treatment is necessary. The most common methods used in the literature for these type of systems (ZnPc/ZnP/ZnNc with pyridyl or imidazolyl ligands) will be introduced in the following section.

I.3. Data treatment techniques

In host-guest association studies, it is important to know the stoichiometry of the association.

A basic knowledge of chemistry gives the preliminary information concerning the system's stoichiometry. Since secondary interactions could have been neglected it is however interesting to check the compatibility between theory and experiment.

I.3.1. The Job plots

The most common method to determine supramolecular association is the Job plot. This method relies on a continuous variation method, which consists in measuring a parameter linked to a A typical example that employs this method is that of the imidazolyl-PDI association previously discussed which was followed by absorbance spectroscopy (Figure 126). The Job plot was created using the different absorbance intensities observed at 365 nm. This wavelength was reported by the authors as the one matching with the host-complex signature.

Figure 126. Absorbance intensity shift at 365 nm (Acomplex 1) with 1-9 to 8-2 ratio of ZnPc-imidazolylPDI, the job plot is in the inset [137] The maxima obtained for the Job plot shows us the stoichiometry of the association between the imidazolyl and the ZnPc. In this case the 0.5 maxima at 0.5 corresponds to the 1:1 stoichiometry expected for this complex. As we can see, the Job plot is a relatively simple method which turned to be an attractive strategy to validate an association and confirm the stoichiometry.

In the Benesi-Hildebrand method, we also obtain the association constant by relating the concentration of [H] and [G] used in the titration with a variation of the physical parameter measured (absorbance intensity, emission intensity or NMR shift). The general Benesi-Hildebrand equation ( 6) is usually applied to systems with a for 1:1 association, and follows the equation below.

In this equation, ∆𝑌 is the change of a physical property during the titration, 𝑌 ∆𝐻𝐺 is the physical shift value between the complex [HG] and the non-complexed guest [H], K the association constant and [G] is the concentration of host. From this relation the plot of

𝑌 ∆𝐻𝐺 ∆𝑌 𝑣𝑠 1 [𝐺]
results in a linear plot with as slope factor 1/K. This approach works on the assumption that when either host or guest is in excess in relation to the other, the characteristic absorption/emission spectra are negligible in the collective range of the system. This way, when we measure the spectra of the system before, after and at the equilibrium of the complex formation, we can determine the association constant. From the fluorescence titrations previously presented between a pyridyl-PDI and ZnNc the following Benesi-Hildebrand plot (Figure 127) was generated. Based on the emission intensity obtained during the fluorescence measurements, the Benesi-Hildebrand became equation ( 7):

𝐼 0 𝐼 0 -𝐼 = 1 𝐴 + 1 𝐾.𝐴.[𝑍𝑛𝑁𝑐] (7)
Figure 127. Fluorescence intensity change over addition of ZnNc to pyridyl-PDI, the Benesis-Hildebrand plot is in the inset [133] As a result, the plot of I0/(I0-I) vs 1/[ZnNc] shown in the inset gives a straight line with a slope coefficient that is inversely proportional to K. Using this linear regression, K was determined to be 2.4 x 10 4 M -1 .

To sum up, the Benesi-Hildebrand method is also a relatively simple plot to obtain association values without the need of complicated mathematic approaches. Like Job plot, this method is ubiquitous in the studies of supramolecular systems until as recently as 2012. However, recent studies are bringing into question the results obtained from these "old school" methods; demonstrating important inaccuracies in the results, especially when large excesses of guest solution are used. [139]

I.3.2. Evolution of data treatment

A landmark study was initiated by Pall Thordarson on the methodology to study supramolecular complex titrations [140,141] His 2011 and 2016 reviews demonstrate the obsoleteness of the previously discussed methods. In Thordarsons' communication (aptly named "The death of Job plot)" [141] the method is described as being accurate only with 1:1 systems or in 1:2 models when the first association constant (K1) is smaller than second association constant (K2) or when both are "large". This means that the Job plot cannot be used for anything else but to confirm those precise models, which is hardly the case in most new systems.

To determine a stoichiometry, the best approach would involve the systematic fitting of the data obtained during a titration experiment with all the possible models of associations available, using the residual plot to determine which model reflects better the system. This residual plot

shows the difference of each data from the fitting obtained and is a good tool to observe how the accurate is the model selected. An incorrect model is characterized by a sinusoidal distribution of the residual plot (graphs plotted in black). from Jurak et al. [142] demonstrates what incorrect 1:1 models looks like at different ranges of K and different concentrations when applied to 1:1 and 1:2 systems.

Table 17 : Titration Data Simulated for a HG + HG2 (1:1 and 1:2 association) system. Fitted with a Simple 1:1 Model: Titration Curves and Residual Distributions [142] Similarly, to the Job plot, the Benesi-Hildebrand method was also shown to be not reliable.

Two main issues with this linear regression method were highlighted by Thordarson:

1)Following this method, the experimental error is distorted by applying a transformation of the experiment value fitting the data.

2)The main assumptions required to apply this method are often wrong. For example, the guest concentration is always in large excess or the shift of [HG] complex physical parameter measured is assumed to be the one of a fully formed complex at the end of the titration.

𝐾 = [𝐻𝐺] [𝐻][𝐺]

(2)

∆𝑌 = 𝑌 ∆𝐻𝐺 . [𝐻𝐺] (8)
[𝐻𝐺] = The 1:2 and 2:1 models are way more complex to describe and the developed equation can be found in the Pall Thordarson review. [130] After choosing the appropriate model, the non-linear regression gives us a K value as well as the relative concentrations of [H], [G] and [HG] over the host-guest ratio. Residual error will give an idea of the match between the model used and the experiment.

Considering the different spectroscopic techniques and methods of data treatment available, we can say that the calculation of association constant is far from straightforward. Multiple analyses are required to give a good reliability and accuracy to the presented results. Therefore, to obtain a matching association model between ZnPc or ZnP and dipyridyl-PDI we will use for each system studied, the three spectroscopic techniques to follow the titration experiments:

absorbance, fluorescence and nuclear magnetic resonance spectroscopy. The data will be treated following Thordarsons suggested approach to first prove that a complexation happens in solution between pyridyl and zinc and an association constant will be calculated to evaluate the strength of the binding based on non-linear fitting data treatment methods.

II. Association of ZnPcs, ZnPs with dipyridylperylene

Numerous reports exist in the literature of zinc phthalocyanines or porphyrins coordinated to pyridyl and imidazole-functionalized perylenediimides. [65,133,137,143,144] As discussed previously in the introduction section, a wide range of association constants have been experimentally

obtained for these types of complexes, using different spectroscopic methods such as NMR and UV-Visible and fluorescence spectroscopy. However, to date, very few reports are available describing in detail the conditions required for these associations to occur and the study of their robustness in solution. Therefore, in this section, we will discuss our investigations into the association occurring between phthalocyanine (Pc), porphyrin (P) and perylenediimide (PDI) derivatives in solution. Through this study, we aim to understand and later on control the conditions to obtain stable complexes that will be used later on as three-dimensional building blocks for surface functionalization (Chapter 3). dipyridyl functionalized PDI (Figure 128). This specific zinc-pyridyl coordination should allow us to achieve an orthogonal orientation and "rigid" binding between both components which will be important for the on-surface studies. From figure 1, we can observe two possible combinations between each of the zinc macrocycles and the PDIs available, resulting in eight complexes to be studied. To start, we focused on the associations between the PDI4 derivative with an unsubstituted ZnPc and/or a diphenyl-functionalized ZnP. As mentioned previously, several complexes involving zinc phthalocyanines or porphyrins had already been reported and so we used their experimental conditions as the basis for our preliminary studies. [65,133,137,143,144] We expected to obtain similar results from the titration experiments and data treatment available employing three spectroscopic techniques (NMR, UV-visible and fluorescence spectroscopy)

to optimize the experimental conditions before moving on to the more complex, alkylsubstituted ZnPcs. However, given the complexity of supramolecular chemistry, we needed to also consider how the structural differences between the reported systems and ours would affect the experimental set-up and therefore the results obtained. In the following paragraphs, we analyze the following phenomena:

• simple and double association occurring between the ZnPc/P -PDI components

• self-association (aggregation) effect of the ZnPc, P and PDI

• degradation of the components in solution (in light, air)

Firstly, we are interested in the 1:1 association between the dipyridyl PDI (PDI4, PDI3 and PDI4Ph4Py) with ZnPc or ZnP. However, due to the fact that all PDIs prepared are functionalized at both extremities with the pyridyl group we also had to consider the possible formation of a 1:2 association. The association equilibria are presented in Figure 129 with K1 being the association constant of a 1:1 (ZnPc-PDI4) complex and K2 the second association constant for the 1:2 complex (ZnPc-PDI4-ZnPc). One of the titration studies used as reference was based on a 1:2 complex, where the PDI4 is coordinated to two RuPcs who are in turn bound to a carbonyl group. As discussed in the introduction section, the type of cation and ligand used determines the geometry of the coordination complex. And so, by changing to zinc, we are expecting to obtain the formation of only a tetragonal square planar complex. For the Ru complexes, the phthalocyanine used has also four tert-butyl substituents. We assume that these bulky substituents were incorporated to improve the solubility of the Pc and thus facilitate the complexation. In our case, our first system contains an unsubstituted ZnPc, and therefore we know that overcoming the aggregation of the ZnPc will be important for our studies. Later on, with the CxZnPcs, the introduction of alkyl chain lengths should improve the solubility in relation to the unsubstituted ZnPc. However, as these linear alkyls get longer (>5 carbons), we also expect to observe aggregation due to the formation of columnar assemblies via intermolecular π-π stacking and chain interdigitation. A visual representation of these phenomena is shown in Figure 131. As we can see, the larger conjugated plane of the phthalocyanine derivatives leads to a stronger π-π stacking compared to the porphyrin. When the peripheral alkyl chains are introduced, these induce repulsions between Pc cores via the steric effects, resulting in an improved solubility when using a C6 alkyl chain. However, as the chain length increases (C12-carbon chain), this effect is reversed and the interdigitation of alkyl chains favors intermolecular packing. If we now look at the ZnDPP, the phenyl groups located at the meso-sites will have a tendency to be oriented perpendicularly to the aromatic plane, reducing the π-π stacking and thus increasing the solubility of both porphyrins. Finally, for the PDI4 we can also observe two bulky phenol groups incorporated in the bay positions of the perylene. These have the same purpose as the phenyls on the ZnDPP, to induce steric hinderance and avoid self-aggregation. From this analysis, we can conclude that the zinc-pyridyl association with our components will be greatly affected by aggregation.

To study the association rates, the stoichiometry and stability of the complexes we performed titration experiments using three different techniques which have been previously employed as standard techniques to evidence the formation of Zn-pyridyl complexes in solution. These focus on different physical interactions at different ranges of concentration: µM in the case of absorbance and fluorescence and mM for NMR. Taking into consideration these sensitivity and solubility limitations, an in-depth preliminary study of solution preparation was performed.

II.1. Preliminary solution studies of ZnPc and CxZnPc

ZnPc was used as a reference to select the solvent to use during the titration experiments because of its particularly bad solubility in comparison to the alkyl-functionalized ZnPcs. There are three types of solvent in which these compounds are soluble: strongly coordinating solvents like DMSO, DMF, THF or pyridine; halogenated solvents like DCM or CHCl3 and finally, aromatic solvents like toluene, chlorobenzene, dichlorobenzene or chloronaphthalene, which also weakly interact (via π-π) to the aromatic Pc core. To select the solvent, we also took into consideration the photobleaching quantum yield of ZnPc reported by Ogunsipe et al. [145] This helped us select a solvent which avoids fast photooxidation (degradation) of our Pc derivatives in solution (Table 1).

Table 18 : ZnPc photobleaching in various solvents

Solvent

Guttman donor number Photobleaching quantum yield /10 5 Pyridine 33.1 5.85 [145] DMSO 29.8 2.61 [145] DMF 26.6 2.23 [145] THF 20 0.15 [145] Chloroform 4 ND The table shows a correlation between the donor effect of the solvent and photobleaching of ZnPc in solution. The Guttman donor number represents the donor-effect of the solvent; the higher the number, the greater the solvation effect observed. The solvents showing high donoreffects are also those that favor photobleaching. We therefore decided to compare the degradation of our ZnPc using toluene, chlorobenzene and dichlorobenzene as solvents, which have not been studied for photobleaching before. We found that after leaving the solutions exposed to daylight during a week, they all degraded at similar rates. This was observed by a drop of the absorbance peak maxima and the appearance of a signal corresponding to degradation products. We then evaluated chloroform (CHCl3) as solvent, preparing ZnPc stock solutions at different concentration ranges. These demonstrated good stability over time when kept in the dark and degradation in daylight was only observed after a couple of weeks.

However, we noticed that some aggregation was always present in the chloroform solutions, even at low concentrations of 10 -6 M. To see how fast this aggregation phenomena occurred, we followed by absorption spectroscopy a solution of ZnPc in CHCl3 at a concentration of 2 x 10 -5 M (Figure 132). As we can see on the absorbance spectrum, after 17 minutes, the main absorption peak for the ZnPc (at 672 nm) showed a drastic decrease in intensity, as well as global increase of the baseline level of the spectrum. The presence of aggregates is usually revealed by the presence of a shoulder at the right of the maximum absorbance (672 nm).

However, in the present case we observed that once formed, the aggregates collect on the edge of the cuvette and therefore did not show up on the absorbance spectrum. signal of aggregates.

The figure also shows that no photobleaching occurred at this timescale, with the absence of a peak in the zone identified. In the literature, pyridine is commonly introduced in small quantities (up to 5 mol%) to improve the solubility of the unsubstituted ZnPc. [146] However, as shown in table 1, this can produce photobleaching, with a broad band appearing between 450 and 550 nm (photobleaching area) as a result of the cleaving and opening of the aromatic macrocycle. This phenomenon was observed only when using pyridine in the solutions so we avoided its use as much as possible.

So, in order to solubilize as much as possible, the ZnPc and CxZnPc derivatives, we prepared the solutions using an ultrasonic bath and heating at 40 °C for a period of one hour. Once cooled back to room temperature, we filtered the solutions through a 45 µM PTFE filter, which would remove any aggregates that were invisible to the naked eye. This method of solution preparation allowed us to keep a constant concentration during one-hour periods, however this process led to us to lose track of the real and accurate concentration of the ZnPc because of the filtration step and the presence of other smaller aggregates still present in the solution. Like with the ZnPc, we also noticed that both C6ZnPc and C12ZnPc were aggregating around the edges of the quartz cuvette and its corresponding Teflon cap. This resulted in a drop in the concentration each time a solution was transferred to the measurement cell. Based on these observations, we are well aware that significant precision is lost when it comes to the concentration of solubilized molecules.

II.2. ZnDPP and PDI4 in solution

When studying the porphyrin and perylenediimide derivatives, we found that neither exhibited photobleaching or aggregation in chloroform at concentrations up to 10 -4 M. The PDI4 shows a lower solubility in toluene, as we can observe a loss in the absorption signal at concentrations of 10 -5 M, but proved to be very soluble in CHCl3. PDI4 and the ZnDPP also displayed good stability and no aggregation at room temperature over several months. The perylene could be kept under light, however the porphyrin was kept in the dark.

From this preliminary study, we were able to discern the best conditions to perform the various titration experiments; the choice of solvent, the solubility limits of each component in toluene and in chloroform, their preparation method and their stability over time.

III. Absorbance studies

Titration (volumetric analysis) experiments followed by absorption spectroscopy are the most commonly used for evidencing porphyrin/phthalocyanine and perylene association by metal ligand coordination. [65,131,133] This method allows us to work with a low concentration of molecules (<10 5 M) which absorb in the UV-Visible range, and is compatible with the solubility limitations identified previously for some of the molecules studied. The solutions used are also in the same conditions (concentration, temperature) required for surface deposition, which will be important in the following chapter.

The first absorbance titrations performed were based on El-Khouly et al.'s. association between a zinc tetra tert-butyl phthalocyanine and a gold tetrapyridylporphyrin (AuPpy). [143] This titration consisted in adding a pyridyl-capped porphyrin ligand to a ZnPc solution. The association between both components was proven by a decay of the ZnPc's absorption signal (684 nm) observed during the course of the titration (Figure 133). [143] After the absorbance spectra were obtained, the different absorption maxima were plotted against the inverse of the concentration of the AuPpy used. Through the Benesi-Hildebrand method (linear fitting) an association constant was determined.

For our titration studies, we prepared stock solutions of all components (Pcs, Ps and PDIs), in CHCl3. As in El-Khouly works, these solutions were prepared in concentration ranges of 10 -7 to 10 -5 M avoid aggregation and to keep within the Beer-Lambert limit. Figure 134 These titrations were performed by adding an increasing amount of ZnPc or ZnDPP solution to a constant volume of PDI, and also in the reverse order; an increasing volume of PDI solution to a fixed volume of ZnPc or ZnDPP. During these experiments, we monitored the evolution of the Q and Soret bands, as these are the most sensitive to supramolecular interactions. The absorption signal corresponding to the PDIs was also monitored, however no major changes could be observed. In the following paragraphs, we will discuss the specific conditions and methods tested for each set of experiments using the ZnPc and ZnDPP.

III.1. Absorbance titration methods

These titrations were based on previously reported experiments. [133] However, in our case, the Pc used is significantly less soluble, therefore the conditions had to be adapted to overcome the aggregation. To find the optimal conditions we first performed a series of preliminary tests summarized below: a) Qualitative analysis (addition of excess species): We first wanted to corroborate that we will observe variations in the absorption spectra which will indicate that the complex is being formed. Our main goal was to follow these spectral evolutions, so we forced the formation of the complex by introducing an excess of one of the components. Two concentrated toluene solutions of ZnPc (130 μM) and PDI4 (63 μM) were prepared. We used toluene as solvent in this case, since it enabled us to increase considerably the concentration of ZnPc. The coordinative quality of toluene is not relevant in these tests as we are we are only concerned with identifying changes in the absorption spectra when in extreme conditions (excess of one of the components). We assume that any change observed in these toluene solutions will also be present when changing to CHCl3.

In a first instance, increasing amounts of the ZnPc solution (at 130 μM) were added to a fixed amount of a PDI solution (2.5 mL, at 3 μM) until an excess ZnPc-PDI4 ratio could be observed (Figure 135, route A). The effect of addition order was also studied by doing the opposite and adding an increasing amount of PDI4 (at 63 μM) to a ZnPc aliquot (2.5 mL, 1.3 μM) as shown in Figure 135 (route B). These changes are usually attributed to the metal-ligand association, nevertheless we cannot confirm this at this point. We know that our ZnPc has a tendency to aggregate and so this decrease observed could also be the result of this phenomenon. This method is not ideal also, since it involves numerous transfers of volume which reduces the accuracy of the titration.

b) Quantitative analysis (dry complexation):

In this method we wanted to ensure that both ZnPc and PDI species were fully solubilized and that we could keep an accurate track of the concentration of one of the species. For this, we used a PDI4 solution of 68 μM and took 10 aliquots (0.5 mL). To these aliquots, we added increasing volumes (50 μL to 500 μL) of a saturated ZnPc solution at ≈130 μM (Figure 137). We aimed to force the complexation by evaporating the solvent after adding the ZnPc and heating at 50 °C. We expected that by slowly increasing the concentration of the mixture, we would favor the formation of the complex, which could subsequently be re-solubilized by adding 2 mL of CHCl3. Unfortunately, once evaporated the solutions did not fully re-dissolve (even after sonication), resulting in random variations of the absorption spectra (Figure 138). We believe also that at these concentrations the self-aggregation of Pcs is the most likely process to occur. After each addition, 100 µL of the stirring solution mixture were transferred into a quartz cuvette. 2.5 mL of CHCl3 were added to this cuvette and the resulting spectra were recorded.

The recorded spectra are presented in the figure below (Figure 140). In this experiment, we observe the decay of the PDI absorption intensity (557, 517 nm) and the increase of the ZnPc absorption (672 nm). We can also observe a clear shoulder on the right of the Pc signal (grey zone). This shoulder is clear evidence of the presence of small ZnPc aggregates throughout the whole experiment. This means that the drastic change of temperature (40 to 20 °C) when the aliquots are taken promotes the aggregation of ZnPc.We found that the variation observed in PDI absorbance cannot be attributed to the complex formation, since it is directly proportional to the dilution of the initial PDI mixture used.

d) Use of Pyridine (reducing ZnPc aggregation):

In all previous tests the ZnPc aggregation in the stock solution posed problems with the titration experiments, so we decided to add 2 to 5 mol% of pyridines to a ZnPc solution at 35 µM in CHCl3. This solution was diluted ten times to obtain a total volume of 2 mL with a final concentration of 3.5 µM. A solution of PDI ( 63µM) was radually added to the 2 mL cuvette (0-0.08 mL) whilst recording the absorption spectra after each addition. In parallel, we also monitored the ZnPc (5% Py) solution to detect any degradation during the experiment (Figure 141). As mentioned before, the addition of pyridine increases the photobleaching degradation in presence of air. So, to inhibit this process, once the ZnPc (5% Py) solution was prepared we bubbled it with argon over a period of 15 mins and kept it protected from light. This was not enough, as we observed degradation after just 10 mins. This degradation is confirmed by the typical photobleaching signal appearing in the grey area of the figure below. We also observed that the ZnPc's maximum absorption peak decreases over time (672 nm), and that the shoulder corresponding to aggregates increases at the same time. In fact, the aggregates are always present despite the use of pyridine. Moreover, the pyridine also increases the photobleaching rate and thus degradation of the ZnPc solution. From the titration experiment, we selected one sample corresponding to a 1:1 ratio of ZnPc-PDI4 and observed its stability over a period of time. Here, we also observed the decay of the ZnPc's Q-band, as was the case for the reference solution (Figure 143). In this series of spectra, the PDI4's absorbance bands are located at the same region where the photobleaching signature is observed. However, by looking only at the 557 nm wavelength we confirm that the concentration of PDI does not change. The photobleaching can be detected in the variation at 517 nm. Like the ZnPc reference solution, aggregation is also present from the start (713 nm), but it does not increase over time. This means that aggregation is limited by the presence of the PDI4 and could indicate an association occurring with the ZnPc. We decided that the introduction of pyridine increases the complexity of our experiment and so we discontinued its use in the experiments that follow. These four experiments allowed us to determine the limitations of our system and to define a set of conditions that would enable us to study the association of the ZnPc with the PDI4. We arrived at the following conclusions:

1. The concentration of the ZnPc solutions must not be higher than 10 -6 M in CHCl3 (can go up to 10 -5 M in toluene). In contrast, the concentration of the PDI should not go over 10 -4 M in CHCl3 and 10 -5 M in toluene).

2. The ZnPc solutions are not stable over time. Even at concentrations below 10 -6 M, aggregation can still be observed. These solutions must be stored in the dark.

3. The concentration of ZnPc species in solution can never be determined from the weight of the ZnPc solid used to prepare the solution. When the solutions are prepared, there is always undissolved ZnPc aggregates. (up to 2 mg/L).

4. To calculate the real concentration of the dissolved ZnPc, we must use the extinction coefficient () of a similar species which is more soluble (C6ZnPc).

5. To prepare the solutions, the temperature must be kept constant throughout the titration experiment to avoid the aggregation (re-crystallization) of the ZnPc.

6. The titration experiments must be performed over a short period of time (no longer than 2 h), since the degradation of the solutions will affect the results.

7. The titration must be performed on only one sample (cuvette) to avoid experimental errors when analyzing several samples in different cuvettes.

III.2. ZnPc-PDI4 Absorbance titration experiments

In a quartz cuvette, a diluted solution of ZnPc in CHCl3 (2.5 mL, 1.2 µM) was titrated with increasing volumes of a PDI4 solution (0-300µL, 63 µM, CHCl3). We observed a linear increase of the intensity of the PDI4's main peak (557 nm), which is directly related to the addition of PDI4. The ZnPc's Q-band decreases in intensity, and since we can see also an increase in the shoulder signal (aggregate peak at 713 nm), we can infer that the variation is mostly due to the aggregation. At a first glance, this experiment does not give us evidence of a complexation/association between both species (Pc-PDI).

We analyzed these results in more detail, by plotting the absorbance intensities (PDI4 and ZnPc maxima) against the concentration of PDI4 added (Figure 144). The PDI4 evolution (black, 557 nm), shows a clear linear trend respecting the Beer-Lambert law (no interaction effect observed). In contrast, the ZnPc plot (red, 671 nm) shows us three distinct regimes occurring From these three distinct absorbance regimes we can deduce that two different types of association are taking place; firstly the 1:2 PDI4-ZnPc association, and as we continue the addition of PDI4 we obtain the 1:1 association. When we compare our results to those reported by El-Khouly, we see that they concluded that the association took place by looking at the decay of the ZnPc Q-band without discussing if the dilution effects were taken into consideration during the titration.

We also performed the experiment in reverse order, with the increasing addition of ZnPc (0-300 µL, saturated solution ≈130 µM) to a PDI4 solution (2.5 mL, 1.3 µM). As we can see from the resulting absorption spectra in Figure 145, the PDI4 peaks (517 and 557 nm) increase slightly during the addition. In a similar fashion, the Q-band of the ZnPc (672 nm) increases.

Interestingly, the aggregation signal (713 nm) increases as the ZnPc is added until we reach a ZnPc concentration of 4µm. Here we see a drop of the absorbance at this wavelength. We think that this is due to the kinetic diffusion of the saturated ZnPc solution, which at the beginning shows the presence of mostly ZnPc aggregates. As they start to interact with the PDI4, they break them up until becoming fully solubilized. The titration spectra were analyzed further by plotting as before the absorbance peaks of the ZnPc (672, 713 nm) and the PDI4 against the concentration of ZnPc added. In this case, only two regimes are observed; before and after 4 µM of ZnPc added. In the first regime the ZnPc used is saturated and therefore we know aggregates are present. This can be confirmed by the shoulder observed at 713 nm. These aggregates also absorb in the same region as the PDI4 and therefore are the main reason for the increase shown by the PDI's absorption (red 517 nm, pink 557 nm). After 4 µM, the slope of the ZnPc's absorbance (672 nm) becomes more pronounced.

This increase however is not just correlated to the cumulative volume of ZnPc added. The absorption measured at this point is higher than the predicted for the corresponding volume added. Therefore, we assume that an association occurs between the PDI4 and the ZnPc leading to solubilization of the aggregated present in the solution.

III.2.1. Determination of stoichiometric ratios

To determine the stoichiometric ratios of the species, present during the titration, we plotted the two absorption maxima signals from each species against the ratio of the ZnPc and PDI4 concentration (Figure 146, left: PDI4 to ZnPc, right: ZnPc to PDI4). The initial concentration of ZnPc was calculated using the Beer-Lambert law, and the extinction coefficient of (C6ZnPc, ε=2.7x10 5 L.mol -1 .cm -1 ). These plots show similar results to those discussed previously for both titrations, however the ratios do not correspond to those expected. In the plot on the left, 0.5 and 1 equivalents of PDI4 to ZnPc are expected for the respective 1:2 and the 1:1 association. We can conclude that the association between ZnPc and PDI4 can be observed by absorbance titration experiments. Clear changes in the absorption of the ZnPc could be measured which were not related to its aggregation. We observed the presence of two types of association, confirming the 1:1 and 2:1 association between both species. Attempts were made to confirm this stoichiometric ratio, however the results obtained are not accurate, as they deviate by at least 40 and 60%.

III.3. ZnDPP-PDI4 absorbance titration

We repeated the titration experiment, this time changing the ZnPc to the more-soluble ZnDPP.

In this case, we also performed the experiments in toluene as we wanted to see if there was an effect depending on the solvent used. The titrations gave the same results in CHCl3 and toluene and their resulting spectra were extremely close (Figure 147). A red-shift of only 6 nm in both ZnDPP and PDI4's main peaks could be observed when changing from toluene to CHCl3. This shift can be explained since toluene is more of a donor solvent and so the complex formation should be a little more facilitated in CHCl3. We performed the titrations like those of the ZnPc-PDI, in both directions; changing the species that remains constant. In the first experiment, ZnDPP aliquots (0-250 µL, 74 µM) were added to a cuvette containing the PDI4 solution (2.5 mL, 1.2 µM). The PDI4 and ZnDPP maximum absorbance intensity was plotted with the increasing volume of ZnDPP (Figure 148).

In this case, we can only see the increase of the ZnDPP absorption at 411 nm (Soret band -ZnDPP) related to the volume added. The porphyrin also absorbs at the region corresponding to the PDI4's absorption maxima, so the variation we see around 555 nm comes mostly from the ZnDPP contribution. Plotting these two absorbance maxima against the ZnDPP concentration, confirms this observation. The negative peak at 414 nm results from the subtraction of the pure ZnDPP spectra to the titration spectra. In theory, if no association is present, the subtraction of the ZnDPP signal would lead to no signal observed. Because we observe a negative signal, this means that the ZnDPP absorption is lower in the presence of PDI4. Using this treatment, we were also able to perceive the appearance of a new signal at 404 nm, which we attribute to the ZnDPP-PDI4 complex.

On the PDI4's peak (556 nm) we only see a small difference, which can be related to the varying baseline. This might be related to the mathematical data treatment, so we didn't use this signal to evaluate the complex formation.

The reversed titration was done by adding increasing volumes of PDI4 (0-250 µL, 50µL) to a cuvette containing a ZnDPP solution (2.5 mL, 1.6 µM). In this experiment, we were able to observe directly, for the first time a clear shift of 0.7 nm of the ZnDPP's Soret peak (412 nm)

during the PDI4 addition (Figure 150). We plotted the absorbance values obtained at 411 and 555 nm against the concentration of PDI4 added. As in the previous experiments, we see the PDI4 peak intensity behaves in a linear fashion with increasing volume. On the other hand, the ZnDPP signal at 411 nm first decreases sharply until 0.8 µM of PDI4 are added. A break in the slope is also observed at this point, showing two regimes/species are present. In contrast to the ZnPc systems, the fact that the ZnDPP is a lot more soluble means that no aggregates are ever present in the association process.

III.4. Stoichiometry determination

From both absorbance titration experiments, we plotted the differential absorbance intensities after subtracting the ZnDPP's initial absorbance to the spectra. We plotted these values against the ratio between ZnDPP and PDI4 (depending on the titration direction). The data from 413 nm corresponds to the negative peak observed after subtraction, and the one at 404 nm is the new peak that appears as the complex forms (Figure 151). The first plot on the left, shows the titration experiment where the PDI4 is added to the ZnDPP. In this case, we observe a break of slope in both 413 nm and 404 nm plots at the same point (≈0. For the ZnDPP-PDI4 system, the absorbance titration was quite an efficient method to observe the supramolecular association both components in 1:1 and 2:1 complexes. Although the absorbance signal of the PDI4 and ZnDPP overlap, we were able to extract the variation via the appropriate treatment of the spectra. In this case, the absorbance titration helped us obtain quantitative and accurate results thanks to the good solubility of the molecules.

Besides helping us accurately to put in evidence the supramolecular associations, the ZnDPP-PDI4 system provided us with information on how the 1:1 and 2:1 complex can be formed. By carrying out the titration in both directions (changing the host molecule), we realized that by using the PDI as guest we will only form the 2:1 (porphyrin-PDI) complex. But, if we change the guest to ZnDPP, we can obtain both 1:1 and 1:2 (PDI-porphyrin) complexes.

In contrast, we cannot conclude the same for the ZnPc-PDI4 system. Although we observe the presence of two and three regimes, it does not follow the same trends as observed with ZnDPP.

In fact, the result is the opposite. This makes us realize that the interaction between ZnPc and PDI4 is not the same as that with the ZnDPP.

By observing changes in the optical properties of a host-guest system, we can observe and sometimes quantify the interactions that occur and also the type of species formed. However, this technique cannot help us confirm that it is indeed the metal-ligand association that is taking place. We know that aromatic molecules are subject to π-π interactions, so given that both PDI and the ZnPcs and ZnDPP are aromatic this means that they can associate through this supramolecular force as well. Therefore, we decided to probe this type of π-π association using in this case a PDI where there are no pyridyl groups that coordinate with the zinc cation in the Pc or DPP molecules.

III.5. ZnPc/ZnDPP-PDIC7 absorbance titration N,N'-diheptyl-1,7-(3',5'-di-t-butylphenoxy)perylene (PDIC7

) is a PDI which doesn't bear any pyridyl on N-positions. Instead, the N-substituents are linear heptyl chains which improve the solubility of the perylene. PDIC7 was used to check if other associations like π-π could be in competition with Zn-pyridyl binding (Figure 152). We performed the experiments using the same method and conditions as the previously discussed titration experiments. We used the PDIC7 as guest molecule in the titration with

CHCl3 as solvent as it is ten times more soluble than the pyridyl-PDIs.

III.5.1. ZnPc-PDIC7 absorbance titration

Two concentrations of PDIC7 solutions were prepared to cover a large range of PDIC7-ZnPc ratios (17 and 330µM) and to limit the volume increase inside the cuvette. Thirty-one aliquots (0-290 µL) were added to a saturated and filtered solution of ZnPc (1.7 µM, 2.5 mL). During the addition, we observed linear increase of the absorbance of PDIC7 peak. On the contrary, the ZnPc's Q-band intensity varies following two regimes. We first observe a more or less linear increase, which at 4.2 µM reaches a slowly decaying plateau as the PDIC7 volume is increased.

This trend is quite similar to that observed in the ZnPc-PDI4 titration. We believe that the initial increase in absorbance observed must be related to an interaction between the PDIC7 and the ZnPc. This proves that even without the pyridyl functionalizations, the PDIC7 is still able to interact with the ZnPc. So, if coordination is not possible, this means only π-π stacking is responsible. Although absorbance spectroscopy is not a method which can help us determine which type of association we are observing, we can still use it to help us differentiate them.

The stoichiometry of the ZnPc-PDIC7 complex was assessed by plotting the absorbance vs ratio of PDIC7/ZnPc. As expected, the association could not be confirmed as either 1:1 or 1:2 but we see multiple interactions (regimes). Figure 154 shows us three breaks in the intensity shift slope for the ZnPc's Q-band (671 nm) at 0.2, 2.7 and 6.3 equivalents of PDIC7 added. This result cannot be explained by a simple model of association, and all we can conclude is that multiple associations are present. We believe that a mixture of homo-and hetero-molecular aggregates, as well as supramolecular oligomers are the cause of this observations. This led us to the conclusion that we must also consider the π-π interactions between the PDI4 and ZnPc in the first titration experiment. And the observed break of slope in the intensity evolution of Q-band can't be used alone to conclude on PDI4-ZnPc association with Zn-pyridyl coordination.

III.5.2. ZnDPP-PDIC7 absorbance titration

The same titration was done using the ZnDPP and PDIC7 to verify if this interaction also takes place. Using the same conditions, we monitored the evolution of the ZnDPP solution after addition of PDIC7. A decay of the ZnDPP's Soret band was observed following as the concentration of PDIC7 increases. This decay is so drastic that we can neglect any dilution effects. The trend of intensity shift is presented in (Figure 155) with different values of absorbance recorded at 412 nm. After this decay, we can discern a second regime with a lesspronounced decay (0.5-1.7 µM). After adding 1.7 µM of PDIC7, the absorption starts to increase because the PDIC7 absorbance component also absorbs at this wavelength. This titration also proves the existence of a supramolecular interaction between PDIC7 and ZnDPP. As we did with ZnDPP-PDI4 titration, subtracted absorbance values were obtained by subtracting pure PDIC7 and pure ZnDPP spectra to the titration spectra (Figure 156). A bathochromic shift of the Soret band of the ZnDPP was observed. This shift is opposite to the one observed during the ZnDPP titration with PDI4. The decay of absorption monitored at 404 and 413 nm doesn't match with any standard 1:1 or 1:2 association models. The growth of the 422 nm peak followed by a strong decay could only be explained by the formation of a dimer, which can keep stacking to form supramolecular oligomers. Thanks to this reference experiment with PDIC7 in the place of PDI4 we can say that the π-π interaction can't be neglected either, with the ZnDPP. The distinct differences in the absorbance plots between these two types of interactions and the fact that the absorption peak shifts in opposite directions in each case, seems to be a way to distinguish the two types of association (metalligand vs π-π).

The PDIC7 was not expected to interact with the ZnPc or ZnDPP because of the absence of a coordinating pyridyl group, however the absorbance titration showed the contrary. In the case of the ZnPc-PDIC7, we observed a similar trend as with ZnPc-PDI4. However, more PDIC7 had to be added in order to observe the different regimes of association. In both experiments, no stoichiometry ratios could be clearly identified. With the ZnDPP, we can identify a 10 nm blue shift in the absorption with the PDI4 species and a 10 nm red shift when using the PDIC7.

This shows us the different nature of association between ZnDPP-PDI4 and ZnDPP-PDIC7 complexes.

Finally, we performed the titration experiments using the alkylated ZnPcs (CxZnPc) with the dipyridyl-PDI. A fast screening of this association was carried out to verify if the trends were similar to the ZnPc or ZnDPP-based complexes.

III.6. CxZnPc-dipyridylPDI absorbance titration

We investigated association behaviour of both C6ZnPc and C12ZnPc with the same approach.

The only difference in these studies is the presence of the alkyl chains, which will either favour or hinder the association. We observed fast photobleaching when working with the CxZnPcs in CHCl3, so we changed to toluene as the CxZnPcs were also more soluble in this solvent.

However, PDI precipitated in toluene at concentrations of 10 -5 M so we attempted the titrations using THF.

III.6.1. Titration in THF

No association was observed in the titrations with THF with the C6ZnPc because we assume the coordinating effect of the solvent on the Pc macrocycle was too strong (Figure 157). Right: the extinction coefficient of 506, 543, 679 nm peaks were plotted with the increasing ratio of PDI4.

In this case, we decided to use the extinction coefficient of the CxZnPcs to follow the titration instead of absorption values. This enabled us to avoid the dilution effect. In the end, no association between them could be observed, but also no aggregation of either molecule was detected. The same results were obtained with C12ZnPc.

Only one titration experiment was carried out with the CxZnPcs, nevertheless, we learnt that the choice of solvent is important. Future titrations should incorporate the degassing of the solvent (CHCl3) and performing the experiments at higher temperatures.

IV. Fluorescence studies

Titration experiments using fluorescence spectroscopy have been also used to monitor Znpyridyl associations, as a complementary method to the absorbance titration in order to corroborate the results obtained.

As a reminder, the association of zinc naphthalocyanine with a perylene derivative was studied by fluorescence titration and reported by El-Khouly et al. . [133] As presented in Figure 158, they observed a quenching of the perylene emission upon addition of increasing quantities of naphthalocyanine. In the inset is the Benesi-Hildebrand plot they used to obtain the association constant. [133] They used the decrease in fluorescence intensity to determine an association constant using a Benesi-Hildebrand plot. We therefore adapted this method to our system in order to clarify the absorbance results obtained. Our objective was to obtain additional proof that our complex is formed in solution, and were expecting a similar quenching of fluorescence when the complex is formed. Indeed, fluorescence is an interesting technique because it is very sensitive (dark background measurements), with the possibility to compare volume measurements (solutions)

with surface studies via fluorescence spectro-microscopy characterizations. We also performed fluorescence lifetime measurements to get complementary information regarding the complex formation in solution.

As discussed in the absorbance section, the main difference in our system was that the ZnPc used was a lot less soluble compared to the Pc of El Khouly's report. The titrations here were carried out in toluene, to try to avoid all the aggregation issues that hindered us in the absorbance experiments. Toluene was the best compromise to solubilize the ZnPc and also the PDI4 without worrying of photobleaching occurring during the measurements.

The fluorescence titrations we performed upon addition of the ZnPc, CxZnPc or ZnDPP molecules to PDI4 solutions (same as in the absorbance studies) and the emission of both molecules were then recorded.

To record the fluorescence spectra, we used two different set-ups. The first one was a commercial "all-in-one" spectrofluorometer (Cary® Eclipse). The second and most used was a time-resolved laser spectromicroscopy set-up which is described in the corresponding "material and methods section". This set-up has a higher sensibility compared to the commercial system; with detectors working in the single photon counting regime. Moreover, the laser tunability allowed us to define precisely the excitation wavelength and width whilst precisely controlling the laser intensity to avoid any photochemical degradation. This set-up was particularly interesting because we could directly measure the fluorescence lifetime at the same time as the emission spectra. On the other hand, the main advantages of using a commercial device are that we can perform measurements quicker (≈ 1 min vs 20 min per measurement on the timeresolved fluorescence instrument). It is important to note that the acquisition of the spectra using the time-resolved set-up does not take 20 minutes. This time range comes from taking into account the sample insertion, optical density adjustment, and the filter and mirror changes when changing from emission and lifetime measurements. The emission measurements of our molecules were done focusing on three excitation wavelength areas as represented in Figure 159. The first, which matches the absorbance peak of PDI molecules between 450 and 540 nm, a second wavelength between 600 and 660 nm to achieve the maximum excitation of the ZnPc or CxZnPc molecules and the last one, between 300 and 450 nm, for the simultaneous excitation of the two types of molecules. Excitation wavelengths were selected to excite only one molecule at a time. The screening of several excitation wavelengths (Figure 160), showed that we could indeed independently select either ZnPc/CxZnPc or PDI4 emissions. Due to  variation, only the intensity of emission was affected by the selected excitation wavelengths. In our experiments, we had two distinct emission peaks to observe during the titration: the 584 nm peak which corresponds to PDI4 emission and the 691 nm peak which corresponds to the C6ZnPc (or 677 nm in the case of ZnPc). In the case of ZnDPP with PDI4 however, the absorbance spectra of both components overlap, (Figure 2, right) which makes it impossible for us to excitate the porphyrin alone. The secondary peaks for each emission band can be affected in case of symmetry changes of the molecules and were closely observed as well. In these emission spectra we could also notice that depending on the excitation wavelength, we observed Rayleigh second order diffraction peaks at twice the excitation wavelength. Those peaks appeared when exciting at short wavelengths i.e., 340 nm and 400 nm and had to be taken into account in the emission spectra interpretation.

Wavelengths of 532 or 620 nm laser excitation were chosen when using the time-resolved laser spectromicroscopy set-up which was perfectly adapted to excite either the PDIs (532 nm) or the ZnPc/CxZnPcs (620 nm). As super-continuum laser was also used to explore other wavelengths. As described in the "Materials and Methods" section, specific sets of complementary filters were used to ensure very pure laser lines for excitation (and complete cut-off of the laser at the detection systems) to prevent artefacts and ensure that the measured spectra are exclusively due to the fluorescence of the molecules of interest.

Under these conditions, we were looking to observe a change in the emission intensity of the host molecule for an increasing concentration of the guest counterpart. We looked at both host and guest emission signals in case one would be more sensitive to the complex formation. We report in the following experiments the different conditions attempted with the ZnPc-PDI4, C6ZnPc-PDI4 and the ZnDPP-PDI4 systems. Other complexes (with PDI3, ZnTPP, C12ZnPc, C6ZnNc) were also studied, but no conclusive results have been obtained at this point.

IV.1. ZnPc-PDI4 titration

The ZnPc-PDI4 association in toluene was studied by fluorescence emission by keeping a constant concentration of PDI4. We preferred to fix the PDI4 as the host molecule in the titration because we know that due to the low solubility of the ZnPc, we cannot assure that its solution will be able to maintain an accurate and constant concentration over the time required to run the experiment. The general protocol involved the preparation of stock solutions of PDI4 and ZnPc at 100 µM and 4 µM respectively. We mixed increasing volumes of PDI4 (0.2-1.0 mL, 2.6 µM) to a solution of PDI4 (0.056 mL, 28 µM) and adjusted the total volume with the toluene to keep the PDI4 concentration constant at 0.52 µM. The solutions used were very dilute in order to totally solubilize the molecules and to obtain an accurate idea of the concentrations in solution. The ZnPc concentration was increased from 0.5 to 3 equivalents with PDI4.

For each solution, we measured the emission under excitation at 532 nm. The results of the titration are presented in Figure 161, where we focus on PDI4 emission. Zone A shows a highintensity signal which is supposed to correspond to 1.4 equivalents of ZnPc added. This result seemed somewhat abnormal and so a new solution was prepared. Zone B shows no quenching occurring on the PDI4's emission over increasing addition of ZnPc (0-1 equivalents), and no global trend of increasing or decreasing emission signals. In zone C, we see the emission using the new solution, whose intensity is lower than expected (x2 compared to the 1 eq.). We confirmed that this decrease in the signal is real by preparing a third solution this time with 1.8 equivalents of ZnPc. The emission observed is similar to the second solution prepared at 1.4

eq., so we deduced that after this ratio (1.4 eq.) PDI4 crystallises and precipitates. The fluorescence lifetime of each solution was also measured and gave us the same values of 4.3 ns for each solution, which also corresponds to the PDI lifetime of pure PDI solutions.

Therefore, there seems to be no sign of any complex formation. However, this first experiment helped us arrive at the conclusion that PDI4's aggregation in toluene might limit the association with the ZnPc and that at 0.5 µM concentration in toluene, the association of ZnPc with PDI4 is negligible. The aggregation within the same species of molecules will always be a process that will compete with the zinc-pyridyl coordination. This was the case with ZnPc in CHCl3 in the absorbance studies (discussed in the previous section).

IV.2. Concentration effect on the ZnPc-PDI4 association

At low concentrations in toluene, we observed no ZnPc-PDI4 association by fluorescence spectroscopy. We therefore decided use the "dry complexation" method described in the absorbance titration section to prepare a solution of a 1:1 PDI4-ZnPc system (2.5 mL, 4.4 µM).

The emission spectra and the lifetime measurements recorded for this solution once again showed no difference in comparison to the pure ZnPc and the pure PDI4 emission.

Nevertheless, we know now from the previous absorbance experiments that this method to prepare the complex is not ideal since as the solution becomes more concentrated, selfaggregation becomes the predominant process and the resulting aggregates cannot be resolubilized.

IV.3. C6ZnPc-PDI4 titration

The second set of experiments were performed using C6ZnPc. We know that this Pc is a lot more soluble in toluene than ZnPc, so we can be confident that no aggregation effects will negatively impact our measurements. In this case, we could observe an effect the emission spectra of the C6ZnPc upon increasing concentrations of PDI4. In this experiment, we made sure that all the PDI solutions would be used in less than 1h after preparation to avoid any aggregation occurring. PDI4 was added through several aliquots (0.25 to 1. The excitation at 520 nm showed the intensity of the PDI4 emission increasing with the concentration of PDI4, whilst the C6ZnPc emission peak decreases. We know that this decrease is not due to aggregation or dilution effects, and the results observed replicate those reported by El-Khouly. We believe that as the PDI associates with the C6ZnPc, the PDI's fluorescence is quenched.

The fluorescence lifetimes for each solution of this titration were also simultaneously measured.

However, we observed no changes in the fluorescence lifetimes during the titration. A constant lifetime of 2.8 ns was measured for theC6ZnPc excited at 620 nm and 4.3 ns for PDI4 excited at 520 nm. We think that the reason for this result is that the association we previously observed between C6ZnPc and PDI4 is quite weak. If we also take into account what we learnt from the absorption studies, for Pc-PDI systems the association is mostly due to π-π interactions which are weaker than the metal-ligand coordination. This would confirm that the association observed in this experiment is mostly driven by the C6ZnPc-PDI4's π-π association.

Similar experiments were performed using the C12ZnPc however, we encountered similar aggregation problems as with the ZnPc previously studied.

IV.4. ZnDPP-PDI4 titration

A final experiment was performed, this time with ZnDPP, which is quite soluble in toluene.

Here, we added increasing amounts of ZnDPP aliquots to a PDI4 solution in toluene. For the experiment, we prepared two PDI4 solutions at two concentrations to cover a range of equivalents (0.1 to 4.7) of ZnDPP and to keep the volume as constant as possible. The solutions were excited at 415 nm and 520 nm, and the emission spectra as well as the fluorescence lifetimes were collected. As we can see on Figure 163, the 415 nm excitation led to the emission of both the PDI4 and ZnDPP which have overlapping absorption spectra. The increase of emission of ZnDPP at 642 nm was correlated with the increasing concentration in solution. The PDI4 peak at 578 nm was observed to be almost constant over the 1.2 equivalents of ZnDPP added. By using a 520 nm excitation wavelength we could obtain only the PDI4 emission as seen in We then, analysed the lifetime results. The 415 nm excitation was observed to lead to a biexponential decay of the fluorescence lifetime corresponding to the contribution of both ZnDPP and PDI4 species. In Figure 165 we show the fluorescence decay fitted with three models. In the equations "a" was the initial value of the fit and "b" was used to correct the beginning of the fit axis as the decay fit does not start at 0 ns. Equations (2) and (3) are the mono-exponential decay models which represent respectively the pure ZnDPP and PDI4 decay. We clearly see that both components have to be taken in account in this decay. Our hypothesis was that the decay measured is composed of the two mono-exponential decay fits with different contributions depending on the ZnDPP-PDI4 ratio in solution. The maximal deviation could be reduced by a factor of 2 by passing from a mono-exponential (eq. 2 & 3) to a bi-exponential fit (eq. 1), confirming our hypothesis. The maximal deviation remains high (80.7) with the best bi-exponential fit we did because of the uncertainty of the acquired data at long delay times. As the concentration of PDI4 was kept constant its contribution was set to 1 in the bi-exponential functions. Equation (1) was used considering that the ZnDPP and PDI4 lifetimes do not change when mixing the two molecules. As a two-component decay, fluorescence lifetime of the mixture should vary according to the ratio of each molecule in the solution.. The "c" factor in the fit reflects the ratio of the contribution of ZnDPP relative to PDI4 (denoted lifetime ratio ZnDPP/PDI4 in the following). By comparing the "c" ratio with the ratio of molecules introduced in solution we observed that for a 1:3 ratio of ZnDPP-PDI4 we observed a "c" ratio of 5.6. This important difference led us to deeper investigate the lifetime contribution along the titration.

IV.5. Fluorescence decay analysis

Based on equation ( 1) the fluorescence decay of the fluorescence signal of each solution was fitted to derive the ratio of the relative contributions of ZnDPP (2.3 ns lifetime) and PDI4 (4.3 ns lifetime). Then this so-called "lifetime ratio" was plotted vs the ratio of concentrations

[ZnDPP]/[PDI4], as reported in Figure 166. With the more concentrated PDI4 solution, over the addition of 0.2 to 1.2 ZnDPP equivalents the lifetime ratio follows the concentration ratio. With the second PDI4 solution, over the addition of 1.7 to 4.7 ZnDPP equivalents, we have a change in the slope after passing two equivalents of ZnDPP used. The contribution of the ZnDPP in the lifetime fluorescence increases over the increasing quantity of ZnDPP. By extrapolation of the line passing through the points at 1.7 and 2 equivalents of ZnDPP we have a slope passing by 0 which corroborates this idea. As a drastic change of ratio was observed from this extrapolation, we found here evidence of an association between ZnDPP and PDI4. The conclusion we discern from these results is that above two equivalents of ZnDPP, the PDI4 emission decreases and so does its contribution to the lifetime. This points to a 2:1 association of ZnDPP with PDI4 in accordance with the absorbance titration results. Nevertheless, this interpretation is based on the fact that the ratio at 1.7 equivalents was the only point for which the concentration ratio was miscalculated. The concentration of PDI4 stock solution was monitored by absorbance before the titration of both series to detect if any aggregation became present and which could annul our hypothesis. However, to confirm our result an additional titration using only one PDI4 concentration (preparing a single solution) for the full series is necessary.

Fluorescence titration was used to monitor the Zn-pyridyl ligand interactions. The zinc atom was part of the ZnPc, CxZnPc and ZnDPP derivatives and the pyridyl functions were located on the N-position of the PDIs. Aggregation of ZnPc, C12ZnPc and PDI4 in solution at 10 µM concentration had a negative impact on the fluorescence titrations. In addition, using toluene for these experiments was not the best choice since led to many titrations ruined by the formation of micro-aggregates. This is very similar to what we observed in the absorbance titrations in CHCl3.

The ZnDPP-PDI4 system could be studied a lot more easily given its good solubility in the experiment conditions. The titration experiment based on a strong association with small excess of guest molecules led to uncertain conclusions. However, the association observed using fluorescence lifetime analysis indicates that a 2:1 association exists between ZnDPP and PDI4.

This experiment must be repeated to validate this method but the results obtained corroborate the conclusions deduced from the absorbance titrations which also show a 2:1 association.

coordination was the predominant association. Finally, if clear chemical shifts could be followed, we could use it to determine an association constant and to compare it with the absorbance and fluorescence data. As it was the case with the absorbance and fluorescence titrations, we started with the ZnPc-PDI4 titration. This being the less soluble complex, we decided to use pyridine-D5 to increase the concentration of the ZnPc in the solution. Although we mentioned in previous sections that the use of pyridine promotes degradation of our ZnPc solutions via photobleaching, this effect should be negligible in the NMR experimental conditions as they are hardly exposed to light.

V.3. ZnPc-PDI4 1 H NMR titration Titration using Pyridine-D5

A saturated solution of ZnPc using 1 vol% pyridine-D5 in CDCl3 was prepared for this titration.

Increasing amounts of a PDI4 solution (6.3 mM) were added to a filtered, saturated ZnPc solution (0.5 mL, 7.6 µM). We determined the molar ratio of PDI4/ZnPc using NMR integration. In the Figure 168. we observed the shift of aromatic peaks with the increasing of volume of PDI4 solution added. and (e) protons. This shielding effect was stronger on the (d) protons with a 1.2 ppm shift. On the other hand, we observed a weak un-shielding effect on the (a) and (b) pyridyl protons of PDI4. This shift of less than 0.2 ppm was also paired with a better resolution of the doublets.

From these results we deduced that no pyridyl-zinc binding between PDI4 and ZnPc was observed during this titration. In fact, the ZnPc's aromatic core produces an anisotropic magnetic field and the protons close to the zinc atoms undergo a shielding effect. We observed that the shielding effect was on the perylene's core protons (ortho and bay-positions) which means in solution the PDI4 and ZnPc are predominantly associated face-to-face as Figure 169 shows (left, association A). The un-shielding effect of the Pc macrocycle on the pyridyl protons also showed these protons are outside from the phthalocyanine core's region. If we had Zn-Pyridyl bonds, we would observe a shielding effect occurring on the pyridyl protons as the complex is formed. We should also note that as pyridine-D5 acts as a smaller ligand on the ZnPc and since its present in the solvent at relatively high concentrations than the PDI4 (10 -2 M vs 10 -4 M), it surely coordinates to the ZnPc, and probably this also favors the π-π ZnPc-PDI4 association. To prove this hypothesis, we repeated the titration without pyridine. This lowered the ZnPc's solubility which meant the concentration of solubilized ZnPc in the NMR tube was not accurately known.

V.4. NMR titration of ZnPc with PDI4 addition

This titration was done using a filtered, saturated solution of ZnPc (0.5 mL, 130µM) in CDCl3 with the addition of PDI4 aliquots (0-800 µL, 2.3 mM) as the guest solution. The NMR spectrum was recorded after each addition. The results are presented in Figure 170. We assume that the progressive shifting of these peaks, describes the average of a fast exchange occurring between the host and the guest during the NMR measurement. This means that the signals observed show the average of the dissociate and associated molecules and not that there is only one distinct species present in the solution. The association demonstrated here shows the same behavior we observed in presence of pyridine. Thus, we believe the π-π stacking interaction was again predominant versus the coordination bond. To verify this, we repeated the experiment this type reversing the host and guest assignment, by adding the ZnPc to a PDI4 host solution.

V.5. NMR titration of PDI4 with ZnPc addition

Using the same stock solutions as in the previous experiments, we added aliquots of the saturated ZnPc solution to the PDI4 and recorded the NMR spectra after each addition. The results are presented in the following Figure 171. Over the increasing concentration of ZnPc to PDI4 solution we observed again the same trend.

The (a) and (b) pyridyl peaks were not that affected, whilst the (c), (d) and (e) perylene core peaks are. The shielding effect is noticeably stronger with in this type of addition (ZnPc to PDI4). This means the association is stronger with increasing concentration of ZnPc than in the reverse direction. This has to be related with the ZnPc's aggregation which is more important when the ZnPc is the host. Because it is aggregated, it does not bind as easily when the PDI4 guest is added. In the opposite experiment, as the saturated ZnPc is added, the Pc-Pc aggregates are more easily dissociated and the association with PDI is more likely to occur. We therefore believe that a kinetic parameter has a determining influence in this process.

We observed by NMR at concentrated solutions of 0.1-1 mM that the unsubstituted ZnPc s is mostly associated with PDI4 via π-π stacking rather than by metal-ligand coordination. This type of interaction between ZnPc-PDI has never been reported before, mainly because all the ZnPcs studied have been substituted with at least four bulky groups at their periphery to limit their aggregation. This also reduces the chances of π-π stacking interactions occurring with the PDIs evaluated. The association/dissociation exchanges of the ZnPc-PDI4 complexes observed in solution are relatively fast and we know there are multiple other associations possible; therefore, we are unable to determine in a reliable manner the stoichiometry of this system or its corresponding association constant.

We then pursued the titration with ZnDPP and PDI4. As ZnDPP is considerably more soluble than the ZnPc, we expect the titration can provide us with quantitative results.

V.6. ZnDPP-PDI4 1 H NMR titration V.6.1. NMR titration of ZnDPP with PDI4 addition

NMR titration of a ZnDPP solution in CDCl3 by addition of PDI4 aliquots was performed. The reported NMR spectra in Figure 172 shows a completely different trend than the one observed with ZnPc. Depending of the host selected, the shift of the PDI4 protons over the binding with ZnDPP is different. When ZnDPP is the host, we observe a faster convergence and a less important shielding effect of the proton shifts until reaching a stable value of -0.4 ppm for Hd and -1.35 ppm for Hb. When PDI4 is the host, the shift changes of Hd and Hb is not yet asymptotic after 7.4 equivalents of ZnDPP added, and at this point the shift is already -0.6 ppm for Hd and -1.6 ppm for Hb. This difference might come from possible aggregation of ZnDPP not visible to the naked eye. Indeed, the association is less important when we have ZnDPP as host, which means in relatively concentrated concentrations at the beginning of the titration. This concentration limits the association with the PDI4 added and so the signal is less shifted. We observed no change by leaving more time between measurements (up to 24h total experiment time) in both ways of addition. An increase of temperature might be necessary to observe similar results in both ways of titration. The association was better described here by adding ZnDPP to PDI4 because the coordination of PDI4 by ZnDPP seems overcome the competing process of aggregation of ZnDPP in this case. In fact, ZnDPP is strongly diluted as guest molecule at the beginning of the titration and this make it association with PDI4 more accessible.

We proved the association of ZnDPP with PDI4 in solution by proton NMR. The plot of the chemicals shifts changes with the ratio of ZnDPP/PDI4 didn't help us to obtain the stoichiometry of association. We observed a fast exchange and all the possible association processes mixed result in a mean signal. We also showed that aggregation of ZnDPP reduces the association with PDI4 and the progressive increase of ZnDPP concentration to a PDI4 is the best way to form the complex.

With the NMR titration ZnPc or ZnDPP with PDI4 we observe two different behaviors. We deduce that π-π stacking interactions are dominant in the ZnPc complex, whist the metal-ligand coordination is responsible for the formation of ZnDPP-PDI4 complex. To confirm this, we decided to compare PDI4 with PDIC7. Because PDIC7 has alkyl substituent instead of the pyridyl of PDI4 this PDI can only associate with ZnDPP or ZnPc by π-π stacking.

V.7. ZnPc and ZnDPP association with PDIC7 1 H NMR titration NMR titration of PDIC7 with ZnPc or ZnDPP addition

This is a reference experiment to investigate if a complex based on a - interaction can be formed with ZnDPP. PDI4 was replaced by PDIC7 which has the same bay-substituents as PDI4, but has no pyridyl substituent on the N-positions. Since we know from previous experiments that the association can be better observed by adding the zinc macrocycle to the PDI host so we performed the titration this way. For this titration, we used a diluted solution of C7PDI (0.055 mM). As ZnDPP is more soluble, a more concentrated stock solution could be prepared (0.13 mM). In Figure 175 we compare the two titrations of C7PDI with the ZnPc (left) with ZnDPP (right). By looking at the three peaks (a, b and c) of the PDIC7's aromatic core we observe a shielding effect resulting with the addition of ZnPc or ZnDPP. This shift is quite similar in both systems.

To compare more quantitatively the trends, the shift of peaks (b)and (c) of both were plotted with increasing ratio of ZnPc or ZnDPP regarding to PDIC7 (Figure 176). From this plot we observe a stronger shielding effect of the PDIC7 protons with the ZnPc addition compared to the ZnDPP. The shifts observed were also linear with the increasing ratio so we monitored a dynamic system, far from a total association of the PDIC7. After 4 equivalents of zinc macrocycle added we see almost no interaction between ZnDPP and PDI4 so we believe the -stacking between the molecules is negligible compared to the zinc pyridyl coordination of ZnDPP-PDI4. In the case of ZnPc and PDIC7 the shift of 0.3 ppm after 4 equivalents of ZnPc added show a stronger interaction. This shielding effect is reduced compared to the ZnPc-PDI4 system because the heptyl alkyl chains that replaced the pyridyl bring more steric hindrance which we believe reduces the -stacking interaction. Thus, PDIC7 interacts via π-π stacking with both ZnPc and the ZnDPP in a lesser extent. This interaction is somewhat weaker with PDIC7 compared to PDI4 because of the alkyl chains. Taking account of this we believe the comparison between the two PDIs justify the presence of - interactions during the titration of ZnPc with PDI4. We could go further by saying the - stacking is the predominant association in solution between PDI4 and ZnPc. But this is not the case for the ZnDPP which binds preferentially to PDI4 via a coordination bond. NMR titration worked with only the unsubstituted ZnPc. We were unable to replicate the experiment with CxZnPcs because of the considerable aggregation observed at 300 K in the NMR solvent used. We therefore decided to increase the solubility by raising the temperature at which the NMR titration was performed, using C12ZnPc.

V.8. 1 H NMR titration of C12ZnPc with PDI4

The titration experiment between C12ZnPc and PDI4 was carried out at 323 K. At this temperature, C12ZnPc aggregation is reduced enough to obtain a resolved NMR spectrum. We did the addition of PDI4 to C12ZnPc because we believe the use of a stock solution at room temperature would recrystallize during the titration. We added four aliquots of the PDI4 solution to the C12ZnPc kept in an NMR tube. After each addition the tube was left to stabilize to 323 K over 10 min and then the acquisition was carried out. After the last NMR was recorded (ratio 1:1.3) at 323 K, we repeated the measurement at 300 K. The results of this titration are presented in Figure 177. The pink-colored peak which belongs to C12ZnPc presented an important shift during this titration which had never observed with ZnDPP or ZnPc. It seems the temperature reduces enough the aggregation of C12ZnPc so all the molecules could interact with PDI4. The introduction of PDI4 also decreased the aggregation of C12ZnPc, as we observed a strong narrowing of the peak which is characteristic of a product well solubilized.

This aggregation decrease is due to the coordination of PDI4 with C12ZnPc, blocking the - interaction. The up-field shift observed along the peak narrowing on C12ZnPc aromatic was related to this reduced aggregation. So, we proved here that by increasing the temperature we can observe a C12ZnPc-PDI4 bond.

The complex is well soluble at 323 K and when we did the NMR at 300 K we observed again the C12ZnPc aggregation and - stacking with a shielding effect on the PDI4 protons. We conclude that at room temperature multiple interactions are in competition and at 50 °C we are able to observe only the coordination bond.

The NMR titration of our complexes ZnPc-PDI4, ZnDPP-PDI4 and C12ZnPc-PDI4 brought valuable information on the type of interactions engaged. The ZnPc-PDI4 interacts weakly by - interactions and no Zn-pyridyl coordination was observed. ZnDPP-PDI4 interacts predominantly by metal-ligand coordination with a stronger interaction which resulted in more affected chemical shift than with ZnPc-PDI4 - interaction. C12ZnPc-PDI4 association

VI. Determination of the association constant

As described in the introduction the stoichiometry and association constant determination relied a lot on Job plots and Benesi-Hildebrand linear regressions. These "outdated" methods of data treatment were particularly inaccurate when more than a simple 1:1 association was studied. In the case of ZnPc/ZnP and PDI association, from all the previous titration experiments we performed; that 1:1 and 1:2 associations are possible. We know that the host-host and guestguest associations exist because of π-π interactions. From this statement we decided to study the ZnDPP-PDI4 association as the simplest dyad which showed the least number of interactions in the absorbance and NMR titrations. We were unable to develop the data analysis and fitting with all the complexes because we lacked measurements of the π-π interactions of molecules alone in solution. The Job plot and Benesi-Hildebrand method were not used for the study. We instead used 1:1 and 1:2 association models to fit the data with non-linear fitting curves. By comparing the fitting between the 1:1 and 1:2 models we could confirm what type of ZnDPP-PDI4 complex is predominant at µM range concentrations. Then from the fitting selected we could obtain an association constant.

The fitting of data was preferentially done from the NMR titration which was more accurate to determine the concentration and was not subject to any issue from aggregation or light sensitivity like it was the case with absorbance and fluorescence solutions.

VI.1. PDI4 titration by adding ZnDPP

To fit the data we used the supramolecular.org website developed by Pall Thordarson. [140] This website gave a non-linear fitting of our data based on a 1:1, 2-1 or 1:2 model of association. As output the association constant was obtained from the fitting performed. The residual errors' plot allowed us to check the reliability of our model used (as seen in the introduction). The titration measures used for the addition of ZnDPP to PDI4 are reported in Figure 178. We selected the proton (a) from the pyridyl group and proton (b) from the tert-butyl protons to plot the shift with the concentration of guest molecule added (ZnDPP). These two peaks were intense and narrow facilitated the monitoring of the peak, but selecting any other peak of PDI4

will also lead to the same result. From the above titration data, we fitted the chemical shift changes with a 1:1 and 1:2 model.

The fits are reported in Figure 179. The two models are accurate when we look at the residual error plots with an error of less than 0.05 ppm in the 1:1 model and less than 0.025 ppm in the 1:2 model. The 1:1 model's residual plot has a sinusoidal trend compare to that of 1:2 which makes us conclude that the 1:2 model association is more appropriate to the ZnDPP-PDI4 system studied. On the right (top to bottom) is the fitting using a 1:1 association model, the residual errors plot and the association constant. On the left is the fitting using a 1:2 association model, the residual errors plot and the association constants.

Then, when we look at the association constants, we obtained K = 946 ± 2.5% M -1 for the 1:1 association. This value is extremely low compares to the 10 5 M -1 reported with these types of systems. However, we know that our titration was performed in solutions 100 to 1000 times more concentrated than with the absorbance and titration experiments, which are the reference for these values. A difference of concentration will change the binding constant measured: when the molecule concentration's increases the association measured will decrease because of side interactions appearing. We compared then this association constant to the 1:1 model between a PDI with one pyridyl and a substituted ZnPc reported by Fernandez et al. [28] They measured a 853 ± 29% M -1 association constant which is in agreement with our value measured. The K = 946 ± 2.5% M -1 for a 1:1 model relies on two possibilities: each pyridyl association bonds in a non-cooperative way, and each association has the same association rate. The other possibility is that the association of one PDI4 with one ZnDPP reduces the possibility of a second ZnDPP to interact with the second pyridyl site and only a 1:1 association can be observed. This second option is less probable because the two pyridyls groups are on opposite sides of the PDI4. In the 1:2 model the two association constants were obtained: a first one for the 1:1 association (K1) and for the subsequent association (K2, 1:2). K1 was determined to be 18.5 x 10 6 ± 4362%

M -1 which is completely meaningless given the high uncertainty. K2 on the other side was measured at 1099 ± 2.3% M -1 which is coherent with the 1:2 model.

VI.2. ZnDPP titration by adding PDI4

We repeated the data fitting with the titration inverting the host and guest. We This fitting revealed that 2:1 model was well adapted to describe the association of ZnDPP-PDI4, the residual plot is low with less 0.02 ppm difference from the data. The association constant determined for this 2:1 complex was also accurate with a 10% of incertitude which is acceptable. The association obtained from this fitting were K1 = 4.53 x 10 3 ± 9.5% M -1 and K2 = 1.84 x 10 4 ± 10.4% M -1 . This confirms that the complex 2:1 is predominantly formed in solution.

Because both titrations give different results even with the simpler ZnDPP-PDI4 system, we can only conclude that the processes involved in the complex formation are numerous and difficult to assign even if the aggregation is limited. The association constant obtained was not reliable enough even after trying 1:1, 2:1 or 1:2 models. More parameters have to be considered to fully describe the association between ZnDPP and PDI4. It goes without saying, that the systems involving ZnPc molecules lead to even more complicated systems given their tendency to aggregate, and we couldn't neither determine any association model neither binding constant with PDIs.

VI.3. ZnDPP-PDI4 absorbance data fitting

Data fitting using ZnDPP-PDI4 absorbance titration values was also done to check if the association system was simplified in diluted conditions compare to the NMR experiments.

From the previously reported absorbance titration of ZnDPP by PDI4, we plotted the intensity at 404 and 411 nm which were the peaks attributed to the decay of ZnDPP (411nm) and the peak of the appearing complex (404 nm). The fitting was done using a 1:1 and a :1 association model and the results obtained are shown below in Figure 181. The results obtained from both 1:1 and the 2:1 models were not reliable as seen in the figure above. The clear sinusoidal residual plots observed for both are the proof that the models are not appropriate to describe our system. The associations constant determined were also meaningless with values obtain that range from 183 M -1 to 6.14 x 10 9 M -1 . The absorbance titration data treatment reported here confirmed that these simple models are not appropriate even for diluted conditions to study the association of ZnDPP with PDI4.

The data treatment of ZnDPP-PDI4 from NMR and absorbance titration experiments led to the conclusion that the associations of ZnDPP-PDI4 couldn't be simply described using simple 1:1, 1:2 or 2:1 models. More interaction between the molecules and also between the complexes formed need to be considered to describe the association. Our studies stopped here because of the high complexity observed of these systems in solution. With this investigation, we want to highlight that the application of models in supramolecular association are not as straight forward as the previous literature makes it out to be, and the results obtained should be questioned more. All the reported systems that we used as reference were similar to ours and the model applied to give the association constants were never really discussed in detail and now makes us question their results and interpretation. We also want to insist on the fact that the linear regression method (Benesi-Hildebrand) commonly used to characterize a supramolecular binding between two species is not at all appropriate to truly discuss a model of association. This leads to meaningless association constants reported which are then used to repeat the same misinterpretation on the supramolecular associations studied.

VII. Conclusion of the Phthalocyanine/Porphyrin -

Perylene complexes

The association of ZnP and ZnPc with PDIs were studied using three spectroscopy methods:

absorbance, the fluorescence and the nuclear magnetic resonance. These methods were used to monitor the changes in physical parameters during a titration based on host-guest associations.

The absorbance titrations quickly revealed that the low solubility of the molecules studied would limit the success of the experiment. The ZnPc and CxZnPc in particular showed aggregation even at µM concentration in CHCl3 or toluene.

The titration of ZnPc and PDI4 showed the same behavior than that with PDIC7, proving for the first time that a complex formed via π-π interaction between the ZnPc and PDI4 can be observed in solution. In contrast, ZnDPP binds to PDI4 predominantly via a coordination bond.

The fluorescence titrations performed in toluene showed really little influence of the interaction between PDIs and ZnPc in the emission properties. Almost no fluorescence quenching effect were observed and which showed the molecules were mostly dissociated in diluted conditions.

Even theZnDPP-PDI4 association which didn't aggregate in diluted solution showed no quenching effect and so really weak interaction. However, this can be due to the fact that PDI4 is located perpendicular to ZnDPP and therefore the charge-transfer is limited. The fluorescence lifetime was the only measurement evidencing an association between the PDI4 and ZnDPP.

This association confirmed the 1:2 association observed by absorbance titration.

The NMR titrations were carried out in considerably more concentrated conditions (>100 times) that the absorbance and fluorescence titrations. These titrations confirmed once again that ZnPc is interacting with PDI4 via π-π interactions while ZnDPP-PDI4 is driven by coordination. The study of C12ZnPc association at 50 °C showed the increase of temperature shifted the equilibrium towards a coordination association. At 50 °C the association of C12ZnPc with PDI4

is the same as ZnDPP-PDI4 with the same shift of protons observed.

We treated the most reliable data obtained using these titration methods by non-linear fitting plots based on 1:1, 1:2 and 2:1 association model. These gave extremely different results depending of the model selected. All the fittings led us to conclude that they couldn't properly describe the association between ZnP or ZnPc and PDIs. A complex combination of associations (coordination, π-π interaction, self-aggregation) are in equilibria and change drastically, depending on the system conditions (concentration, temperature). This means that it is quite difficult to accurately describe these systems in solution. We realize that the data obtained in the titrations performed is still very limited, however we have enough qualitative information to take this study further and investigate the deposition of these complexes on a surface.

VIII. Experimental methods and materials

VIII.1. General experimental conditions

All solvents were purchased at analytical grades from commercial suppliers and used without further purification. ZnPc was obtained from Sigma Aldrich (sublimated, 97% pure) and used as receive. PDIC7 was previously synthesized following PDI4 protocol, using heptylamine instead of 4-aminopyridine. Other molecules syntheses were described in section 1:

experimental method and materials.

Absorbance measurements were recorded on a Agilent® Cary 50 or Cary 100 spectrometer using an automatic baseline. 1 cm or 2 mm large Quartz cell were used, as specified. Volumes measured for the titration were done using a micropipette or Hamilton® syringes. The absorbance measurements were taken at room temperature in a sealed cuvette with a Teflon® cap. Absorbance measurements were also used to control the concentration of the stock solutions using the Beer-Lambert law (A=ε.l.C).

Two set-ups were used for the fluorescence and lifetime studies.Emission and excitation spectra were recorded using a Varian Cary eclipse fluorescence Spectrophotometer at room temperature in a quartz cell, with a 5 nm slit and an averaging scan of 100 milliseconds.

Solutions in toluene were diluted at 10 -5 to 10 -7 M. Confocal microfluorescence with timecorrelated single photon counting analyses were performed using a homemade set-up (Collab CEA/SPEC/LEPO) coupling a picosecond supercontinuum laser (NKT Photonics, SuperK EVO) to an inverted optical microscope (as schematized figure 1 below)

VIII.2. General experimental conditions for the titrations

In all the prepared solutions we used micropipette, Hamilton syringes and volumetric flasks to measure the volumes required. Precise volumes between 1 and 10 mL were weighed. The mass of the products used was weighed using balances with a 0.05 mg uncertainty. Every solution which contained either a ZnP or ZnPc species were protected from light by covering the solutions with aluminum foil to avoid light photobleaching. Stock solutions were prepared with degassed solvent by bubbling with argon for 10 to 20 min (≈1 L of argon used for 500 mL of solvent).

VIII.3. Absorbance Titration protocols

General absorbance titration method of ZnPc / ZnP by PDI

To a ZnPc/ZnP solution in CHCl3 (1.6 x 10 -6 M), 5 µL (from 5 to 50 µL), 10 µL (from 60 to 100 µL), 20 µL (from 120 to 200 µL) and 100 µL (300µL) aliquots of PDI solution (6.8 x 10 - 5 M) were added and the absorbance was recorded after each addition.

General absorbance titration method of PDI by ZnPc / ZnP

To a PDI solution (1,4 x 10 -6 M), 10 µL (from 10 to 100 µL) and 20 µL (from 120 to 300 µL) aliquots of ZnPc/ZnP solution in CHCl3 (1.3 x 10 -4 M) were added and the absorbance was recorded after each addition.

Other titration methods of ZnPc-PDI4:

Qualitative titration with excess of ZnPc added to PDI4 solution

To a solution of PDI4 in toluene (2500 mL, 3

x 10 -6 M) 100, 500 and 1000 µL of ZnPc saturated solution in toluene (prepared at 10 - 4 M and supernatant collected) were added.

The solutions were stirred using fill-empty of a micropipette in the cuvette and the absorbance was recorded from 300 to 800 nm. Research on-molecular assembly on surfaces has increased rapidly since the 90s with the advancement of scanning probe microscopies. As the two main scanning probe techniques, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) were at the origin of this progresses with the possibility to observe molecules with atomic resolution on surface.

The STM technique currently allows us to observe objects as small as the electronic orbitals of atoms. [149] 2-D architectures can be observed on flat surfaces with these tools and the molecular patterning of surfaces has been thoroughly investigated, showing the possibility to observe a variety of morphologies of 2D-patterns according to the molecules used. [150] As a consequence of these new advancements, bottom-up approach to build nano-materials is now more feasible.

This consists in the design of molecules to obtain nano-and microscopic objects by selfassembly thanks to supramolecular interactions. [151] The bottom-up strategy was developed on surfaces which are excellent templates to structure the molecules and obtain functional materials. With the mastered techniques of synthesis in organic chemistry and scanning probe microcopies self-assembled molecular networks have been widely investigated. More and more complex patterns have been recently reported by physisorption on the surfaces (Figure 202). [73] Figure 202. Scanning tunnelling microscopy showing various molecular patterns on highly oriented pyrolytic graphene (HOPG) [73] Assemblies are not only based on one molecule's structure but also from multicomponent assemblies. The use of multiple components greatly increases the diversity of surface patterning as well as potential applications. Using complementary building blocks which exploit Van der Waals interactions, a three components patterning could be obtained as presented in Figure 203Error! Reference source not found.. [152] Figure 203. a) STM images of three component networks on HOPG. b) Model the three components network observed. [152] This three-components network was based on host-guest pairing of the molecules in which the shell 2 molecule formed a porous (host) network which was filled with the guest core (coronene) surrounded by six benzyl dioic acid molecules. The guest molecules could then patterns the surface in an organized way and coronene, fullerene or phthalocyanines could be observed this way. [153][154,155][156] With all these studies we can now say that the patterning of surfaces with flat molecules is now well mastered for growing organized networks; [73] but the main challenge now is to develop the functionality and the reactivity of the modified surfaces. The surface-confined reactivity for polymerization is one of the main focus of development, since novel strategies of synthesis could be developed using the surface to obtain 2D-polymers. [157] Applications of structured, functional surfaces in the optical and electronic fields of research are also quite attractive. More specifically, the field of molecular electronics has advanced rapidly with the use of relatively simple single-molecule components and self-assembled monolayers. We are now expecting that functionalized multilayer films can be a good strategy flexibility, roll to roll graphene electrode preparation is thought to show a huge potential in future organic electronic devices. [166] Graphene has great intrinsic properties but as a semimetal material doesn't provide a high conductance because of its zero band-gap which limits it to an electrode role. [162] To overcome this limit, the graphene can be doped to control its electronic structure and to increase its charge carrier concentration. Two types of doping are possible: the n-type which involves injecting electrons to graphene and the p-type, which involves extracting electrons. This doping can be achieved by the substitution of carbon atoms by nitrogen or boron during the doped graphene preparation through chemical vapor deposition (CVD), as illustrated in Figure 205Error! R eference source not found. (left). [167] This method is effective but it degrades the honeycomb structure in a random way and at the same time the graphene's properties. [168] Another way to bring heteroatom in the carbon network is by chemisorption on graphene or graphene oxide (GO), illustrated in Figure 205 (right). The chemisorption of nitrogen into graphene or GO is done through plasma, annealing treatments or chemical modification and leads to similar doped graphene with heteroatoms but also in a heterogenous (random) way specially on the GO edges. [169] Again, by changing the hybridization of sp 2 carbon atoms to sp 3 with heteroatoms and introduction of nitrogen atoms modifies the honeycomb structure and brings about important loss of its conductive properties. The second method to dope the graphene is the supramolecular physisorption of molecules on the surface. This method doesn't modify the structure of graphene and allows to keep the entirety of its electrical properties. Adsorption on the surface by molecules was investigated with various components like metal ions (AuCl3) [170] , organic molecules (naphthalene, pyrene, anthracene) [171] or polymers (poly(methyl)metacrylate) [172] . In fact, because graphene is just a single layer of molecules anything deposited on it would have a doping effect which is why the real challenge is to achieve precision, reproducibility and stability of the resulting doped graphene system. The satiric article of Pumera et al. entitled "Will any crap we put into graphene increase its electrocatalytic effect?" perfectly summarizes the current problematic. [173] In this unusual article we can see that functionalized graphene can be used for the electrocatalytic effect with any type of doping functionalization.

The application of functionalized graphene in optoelectronic devices is still at its early stages and a lot of work is still to be done on fundamental exploration. The main challenge with graphene is to control the growth and organization of molecular films to enhance the optoelectronic devices' performance. The organization of molecules on its surface enhances its charge carrier properties because they are semi-conductor materials and the transfer is anisotropic in such material. Single layer field effect transistors could be studied relying on the organized anisotropic molecules on pristine graphene. [174] Because graphene is a good substrate to grow supramolecular self-assemblies, many nanodevices based on organization organic molecules can now be developed for the broad application of organic semi-conducting materials in the OLED, OFET and OPV fields. The molecule-solution basic device preparation can also developed using graphene as it already demonstrated consistency between vacuum deposition and solution evaporation deposition. [175] Through the solution functionalization the future of graphene functionalization looks promising.

IX.2. Supramolecular patterning of graphene

As we have seen before covalent functionalization of graphene can lead to the loss of the graphene's properties and the functionalization is usually random and heterogeneous. Thus, it is interesting to use non-covalent interactions to modify the graphene surface.

The non-covalent patterning of graphene's surface relies on two non-covalent interacting systems: molecules-substrate and molecule-molecule. The self-assembly depends only on supramolecular interactions to have a dynamic system. The self-assembly is a result of kinetic and thermodynamic equilibria a can result in large and homogeneous 2D patterning. We discussed in chapter 2's introduction some of the non-covalent interactions, and these can also be applied to on-surface self-assembly.

is based on the controlled spacing of alkyl chains between neighboring molecules. The patterning adopted was described here on highly oriented pyrolytic graphite (HOPG), and since graphene is just a single layer of HOPG, the structure adopted by the molecular clip on graphene is expected to be the same.

Figure 207. Epitaxy of molecular clips on graphene. A are tetradecane [177] Using the molecular clip tool, rational patterning was produced on HOPG as presented in Figure patterns. [177] The semicrystalline 2D-network with regular porosity was exploited to build patterning systems with two components. Among different 2D-porous-networks used [156] we report here the work from Schull et al. which used TSB with decyloxy alkyl chains (TSB-C10) to obtain a hexagonal porous template. In Figure 208, the picture B represents the theoretical network expected from the TSB-C10 and the STM image C on HOPG shows the network observed experimentally.

Coronene and hexabenzylcoronene (HBC) was then used to fill these nano porous networks to fill the graphene surface in a regular and rational pattern.

Figure 209. TSB host network filled with coronene or hexabenzocoronene on HOPG [178] To functionalize graphene or HOPG several optically active (colored) molecules were used like PDA, PDI, CoPc, and 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4-TCNQ). [179,180] PDA was observed to from an ordered monolayer on single layer of graphene deposited on Si/C and on HOPG [181] ( Figure 210). The patterning imaged was explained by the epitaxy of the PDA's aromatic rings on the honeycomb structure of graphene or HOPG. This compact network allowed to tune the graphene and HOPG surface and open up its band gap. HOPG [181] Relying on the - interaction, Van der Waals for epitaxy and for molecular clips, many systems have been described on graphene or HOPG. Slight doping of graphene could be realized by this media but the major part of the electronic properties of the physisorbed molecules used to dope the graphene are quenched by charge transfer.

Charge transfer between molecular functionality and graphene

Charge transfer of molecules to conductive surfaces like graphene operates through two electronic phenomena of energy-transfer. The first one is the dexter energy-transfer which is related to an electron exchange between an excited molecule (Donor D * ) and an acceptor molecule (A). [182] The illustration of this electron exchange in Error! Reference source not f ound. describes the transfer of an LUMO electron of the donor molecule to the acceptor's LUMO, which at the same time leads to a transfer from the HOMO acceptor molecule to the HOMO donor to keep the same charge over the process. This type of energy transfer is a shortrange transfer and it is limited distances of up to 10 Å because of the orbital proximity that is required. The second energy transfer mechanism is the Förster energy-transfer which can be found as

Förster resonance energy transfer (FRET). [183] This mechanism relies on a dipole-dipole interaction between the donor and acceptor as presented in Figure 212. The energy transfer is non-radiative and can only operate when the absorbance and fluorescence of two molecules overlaps. This type of energy transfer is considered long range transfer with radiative transfer that can occur in distances of up to 100 Å.

Self-assembled out of the plane functionalities

Surface functionalization that combines the incorporation of an additional functionality is still at its early stages. To achieve this, different molecular structures (building blocks) have been investigated. Most of these systems are based on a three-dimensional design in which one part of the molecule is used to attach it to the surface. This is usually a flat aromatic component like the ones reported for graphene patterning. The other part, is a "functional" module that is located away from the surface. To achieve this, this functionality can be attached to the flat component via rigid molecular pillars/pedestals or landers. The functional component is usually a chromophore, or an electron donor or accepting molecule.

Pyrene has been used as molecular lander because of its good epitaxy on graphene and its facility to incorporate other molecules to it. As an example, Garrido et al. presented a fullerene grafted with one and three pyrenes as molecular landers to stick onto a graphene surface (Figure 213). A modelization of these C60-pyrene dyads on graphene, shows that for the dyad with three pyrenes, the fullerene is expected to be located orthogonal to the surface. This type of system would ensure that the electronic properties of the C60 can de-coupled from the surface to a certain extent. Other similar examples of tripod-based 3D-building blocks were reported by Mann et al. with Co(II) bis-terpyridyl complexes. [184,185] Figure 213. C60 functionality with one (1) or three (2) pyrenes moiety and the associated modelization of system 1 (a) and 2 (b) on graphene in gas phase. (c) is the system 2 in liquid phase.

The tripodal system allows to attach a decoupled functionality, however but it doesn't afford a practical way to control the growth of an organized layer on the surface.

Feringa et al. using zinc porphyrins substituted with four meso-dodecyl chains (Zn-TDP) to form ordered assemblies on HOPG surfaces and at the same time, these porphyrins could be functionalized at the axial positions with small, pyridyl derivatives. This strategy showed promise as a way to control the organization on surface and bear a functionality at the same time. (Figure 214). [186] The STM images at tetradecane HOPG interface and the absorbance titrations showed that the coordination was favored on surface rather than in solution. 0.05:1 [186] Inspired by this strategy for functionalization, Brisse et al. reported the patterning of HOPG with ZnPc in a TSB-C12 host network. [187] The ZnPc was grafted with a pyridyl axial substituent, that was used as guest molecule in the pore/cavities formed by the TSB-C12 (Figure 215).The STM images below showed empty pores (a), which are subsequently filled Zap with the ZnPc-pyridyl ligand attached by axial coordination. The self-assemblies studied at the air-HOPG interface showing a good robustness of the 3D-patterning was achieved. both on HOPG under air. Right: ZnPc-ligand structure deposit in the porous. [187] Another example of this 3D-building block strategy is reported by Le Liepvre et al. where they demonstrate a strategy to decouple a PDI chromophore from the surface using a design called Janus tecton. [188] In the Janus-tecton, the PDI is grafted via a flexible aliphatic chain to the upper-level of a cyclophane, which played the role of molecular pillar. In turn, this cyclophane was functionalized at the bottom level with a large aromatic system of stilbene derivatives to drive the self-assembly on surface. Grafting the self-assembly and functional component at the different levels of the cyclophane allowed the de-coupling of the PDI from the surface, and they were able to observe a fluorescent emission on a molecular 2D array (Error! Reference source n ot found.). This was the first report of molecular self-assembly on surface which could provide a fluorescence from a single molecular layer. Nevertheless, this design is not optimal, since the PTCDI-Janus tecton had to be deposited as a 1:1 mixture with a non-functionalized pedestal in order to avoid aggregation of the PDIs, as with their long, flexible linkers, these could hover freely above the surface and form π π aggregates with each other. This could be evidenced by From the previous works mentioned, we can see it is not so easy to design and synthesize molecular building blocks that incorporate a functionality out of the plane of graphene, whilst at the same time have the ability to form large-range, ordered self-assemblies in a controlled manner. Moreover, if we are aiming to achieve the level of complexity that can be observed with surface patterning, we need to think of a design that is more synthetically accessible and that will allow us to finely control and study different molecule-molecule and molecule-surface interactions.

IX.3. Scanning tunnelling microscopy for the study of assemblies on surface

Scanning tunnelling microscopy is an imaging technique of electronic relief determination. This electronic image is obtained with a metal tip which is moved close enough from a conductive surface to measure a current at a particular bias voltage (Figure 217). When the tip and the surface are close enough a tunnel current is obtained. This current can then pass-through insulators like air.

Figure 217. Illustration of an STM setup. A bias applied between a tip and a surface separated by few angstroms allow to measure a tunnel current. This current is amplified then convert to a topology signal. To control the distance of the tip from the surface piezoelectric ceramic is used to move slightly the tip. [189] The following equation ( 1) describes the tunnel current intensity as depending on the exponential distance z from the surface. The theoretical curve of the function linking the current to the distance was given as well.

I ∞Vp ρs (EF, z) × 𝑒-2𝜅𝑧

Thus, by measuring the tunnel current between the tip and the surface, the electronic distance can be determined. The tip distance can be controlled precisely (with angstrom precision) thanks to a piezoelectric ceramic which surrounds the tip and which can be controlled following three dimensions. x and y to screen the surface on hundred-nanometre scale and z to control the distance from the surface. The piezoelectric ceramic is a material which can contract or expand with a controlled and reproducible manner under a bias voltage. Because the tuning of the distance with the bias is extremely light the displacement of the tip is well controlled to afford an atomic resolution.

Since tunnel current and height are linked, two modes can be used in STM, here we only discuss one: the constant current mode. This mode relies on a constant current imposed between the tip and the surface and the measure of the tip height. Every move of the tip on an extremely short distance is followed by a correction of the height to adjust the current and keep it constant. The other mode is constant height mode and is mostly appropriate to atomically flat topologies.

The image obtained from an STM device is then a topology profile which corresponds to the trace of a constant current tunnel effect which means the actual height depends of the atom overflown. This is why we only talk about relative height which depends on the bias and the current chosen. Separated image height profiles are complicated to compare because of this but also because the tunnel depends on the tip shape. The tip used is a non-oxidable metal like iridium-platinum, or gold. As the tunnel current tunnel is made from few atoms at the edge of the tip the shape can evolve depending on the environment of the tip but also the bias and the current used. To prepare a tip three methods can be used: the mechanical cut, the chemical attack or the electrochemical method. The faster and most used for solid-air or solid-liquid conditions is the mechanical one, where the tip is cut from a metal wire with a cutting clamp.

This method is not very reproductible but it is quite practical and most importantly it gives good results for the air and liquid conditions. Precise sharp tips can be obtained with electrochemical or chemical preparation but these kinds of tips are better suited for ultrahigh vacuum STM where the tip is not degraded by the environment.

STM can be done under three main conditions. The air-solid interface, the liquid-solid interface and the high vacuum-solid interface. The last one is preferentially used for really precise imaging of single molecules, and their molecular orbitals. However, in these conditions sample loading and tip replacement become more complicated because a high vacuum (10 -10 mbar) has to be attained. Also, this method doesn't forcefully reflect phenomena which happen under ambient conditions which is what we are interested in.

The air-solid interface STM gives therefore the best conditions to observe a surface that is functionalised through solution deposition. However, this measurement gives us often noisy images as a result of all the perturbations present in its environment (molecules in air, sound vibrations, etc) which disrupt the tunnelling current measurements.

Finally, liquid-solid interface is a good way to observe dynamic assemblies like supramolecular self-assemblies because here, the drop of solvent in which the imaging is performed, protects the tip from perturbations, and at the same time acts like an infinite source of molecules that allow a dynamic exchange with the surface. The solvents used for liquid-solid interface scans are un-polar solvents, since these do not affect the tunnelling current. Another criterion for the choice of solvent is that they have to evaporate slowly, since a measurement can take hours.

Based on these criteria two solvents are mostly used in STM: phenyloctane and tetradecane.

IX.4. Other probing techniques for the characterization of functional graphene monolayers

Micro absorbance with a confocal microscope can be used to measure the absorption of a thin layer by focusing the light path on a transparent solid surface like graphene. This method allows to measure the absorbance of surface on a micrometre length size. This size is limited by the wavelength of the incident confocal light at about 10-50 µm. The only difference of these kind of instrument with a general spectrophotometer is the use of confocal light on the sample which allows us to focus the measurement on small areas. The same type of apparatus can be used to measure the Raman signature of a sample. As Error! Reference source not found. shows, the t wo spectroscopic techniques can be installed on the same microscope device. In the case of the confocal micro-absorbance the white lamp source is focalised on the sample, the transmitted signal is then directly sent through an objective (x60) to the spectrophotometer to obtain a spectrum. In the case of the micro-Raman emission the laser selected excites the sample through the objective to focalize on the surface. A dichroic mirror is used to reflect the laser wavelength and let the Raman emission frequencies pass through. Similarly, to absorbance measurements, the light collected is then analysed with spectrometer. investigated. These shifts are related to the strain on the graphene in the local area. [START_REF] Panchal | [END_REF] Figure 219. Optical microscopy (a) and confocal laser scanning microscopy (b) imaging of CVD graphene transferred to Si/SiO2 substrate. Three Raman measures were reported in (c) and (d), matching with the red green and blue spots targeted in the image (b). [START_REF] Panchal | [END_REF] Because the Raman emission of graphene is related to its strain, physisorbed molecular selfassemblies on graphene lead to distinct modifications of these characteristic peaks.

Goal of the project

The aim of this project was to achieve the functionalization of a graphene surface with a fluorescent chromophore via supramolecular association using a controlled and rational approach. The design of the required molecular building blocks to achieve this was vie the development of three molecular components: a pedestal, a spacer and the fluorescent functionality. A fluorescent functionality was chosen to be associated to the graphene because the charge transfer of a chromophore to the graphene can be measured by analyzing its emission signal. The spacer was the necessary part to ensure the energy transfer de-coupling from the fluorescent function to the graphene. As we have seen with the existing 3D molecules so far, the spacer has to be rigid enough to avoid the functionality to collapse on the surface or interact with neighboring functionalities. We were interested in creating a variety of building blocks where we could control not only the distance, but also the orientation of the fluorescent chromophore from the surface. Finally, different pedestals were developed to immobilize the molecules on the surface and create a variety of 2D assemblies where the spacing between each the functionality can be tuned.

Figure 220 shows our proposed molecular design. As the fluorescent unit, we use a sterically hindered PDI to avoid any association to the surface. The first generation of pedestal components were composed of simple (unsubstituted) zinc phthalocyanine and porphyrin (ZnPc, ZnDPP). These pedestals were organized on the surface using a host TSB network. The fluorescent PDI is linked to the Pc/P pedestal via pyridyl substituents, which coordinate to the Zn in the Pcs/Ps's aromatic core, providing a rigid and directional spacing from the pedestal and therefore the surface. The distance and orientation between the functionality and the surface can be modulated by using different spacer (4-pyridyl, 3-pyridyl, 4-phenyl-4-pyridyl etc…).

For the second generation of pedestals, we prepared peripherally-functionalized CxZnPcs containing long, linear alkyl chains to replace the role of the TSB and obtain different 2D-selfassemblies.

Figure 220. Illustration of the rational design to integer and organize a functional building-block on graphene.

In the first two chapters, we presented the synthesis of each molecular component and the formation of different supramolecular complexes in solution. In this last chapter, we will study and characterize the assembling properties of the supramolecular complexes prepared through scanning tunneling microscopy, and the preliminary analysis of the optical and electronic properties of the functionalized graphene monolayers.

X. Self-assembling properties of the molecular pedestals

We studied the ZnPc, CxZnPcs and the ZnDPP as the self-assembling, molecular pedestals of our supramolecular complexes. Two different approaches were pursued to obtain ordered 2D arrays: a two-component assembly and one using a single-component system. The first approach employs the host-guest system with tristyrylbenzene (TSB), which results in a honeycomb pattern (Figure 221)with a pore/cavity that can be filled with either ZnPc or ZnDPP. The TSB's pore size is related to the length of the alkyl chains we select (Figure 222). The TSB derivative with C12 alkyl-chains was chosen as the most suitable for our systems, since this chain-length results in pores of a size large enough to accommodate ZnPc guests. For the ZnDPP system however, C10-TSB was a better choice. The spacing between each cavity within the host system will determine ultimately the spacing between each of our functional supramolecular systems (ZnPc or ZnDPP -PDI4 complexes). This means that through this approach, we have a limited possibility to tune the spacing of our guest molecules (in this case ZnPc and/or ZnDPP).

Figure 222. Top: size of TSB cavities with alkyl chain lengths (C6, C8, C10, C12, C14) from STM images on HOPG. [191] Bottom: ZnPc and ZnP size below the TSB most appropriate as host.

The deposit of a TSB monolayer on HOPG was done in the same solvent as the one selected for the supramolecular complexes deposit. Once a solution of TSB was put on the HOPG substrate, the solvent was left to evaporate under air. Care was taken to have a TSB solution of an appropriate concentration (10 -7 M) to favor the obtaining of a monolayer, since this type of TSB can also form a more-tightly-packed lattice which does not have a pore. The pores in the honeycomb pattern were then filled by drop casting a ZnPc or ZnDPP solution at a similar concentration as the TSB.

The second pathway pursued in this project, exploited a molecular clip-driven self-assembly which replaces the role of the TSB. Feringa et al. reported a 2D system based on this molecular clip on HOPG, using zinc meso-tetraalkylporphyrins which were associating to the surface by - interactions and epitaxy through their four alkyl chains. The molecules interact via Van der Waals forces between themselves to create the patterning observed by STM (Figure 223). We adapted this strategy using zinc phthalocyanines functionalized with alkyl chains at their peripheral positions (C6ZnPc and C12ZnPc). Because the geometry of the pattern formed in the 2D assemblies is closely related to the symmetry of the pedestal and its surrounding alkyl chains, we used only symmetrically substituted phthalocyanines. This meant that the Pcs had to be functionalized with eight alkyl chains rather than the four reported previously with porphyrins. Two possible options are available: the peripheral and non-peripheral positions.

The CxZnPcs prepared were functionalized at the peripheral positions since in the solid state, these have a tendency to lie within the same plane of the Pc core. In contrast, the chains on the non-peripheral positions suffer strong steric-hindrance effects which forces four of them out of the conjugated plane. We assumed that this would have a negative effect on the epitaxy to the surface (Figure 224). We also could not use substituted tetra-alkylphthalocyanines as they are always obtained as a mixture of inseparable isomers which would break the regularity of the surface patterning.

X.1. Design of a functionality to attach to the pedestal

PDIs were selected as the fluorescent functionality for their high fluorescence (as seen in chapters 1 and 2). We modified its structure in such a way to ensure that it would remain above the pedestal, and separated from the surface. Since the PDIs have a flat aromatic core, it would compete with the Pc/P pedestal by also adsorbing on the surface. To prevent this, we introduced two bulky di-t-butylphenyl groups, which would block the aromatic core and thus minimize any interactions with the surface (Figure 225). Since our goal is to retain the PDI's properties when on the surface, it was important to think of a way to graft the PDI to the pedestal. To overcome the problems encountered with the molecules discussed in the introduction (PTCDI-Janus tecton and the C60-pyrene derivatives), we determined that the PDI must be linked to the pedestal through a rigid and directional spacer or linker. This is the main reason behind the selection of the function attached to the modified PDI. The pyridyl group is easy to incorporate to the PDI, making it easy later on to modify the type of pyridyl used to tune the distance and angle of grafting with the Pc/P pedestal and therefore the surface.

XI. Self-assembly studies on HOPG

The patterning of an HOPG surface with ZnPc-PDI complexes was studied by the analysis of the STM images collected. All the experiments were performed using a Keysight STM scanner working with a 5100 AFM/SPM microscope system. The tip-sample bias voltage and tunneling current set points were kept between -1500 mV and -150 mV and between 11 pA and 20 pA, respectively. STM images were recorded in constant current mode, at room temperature in air or at liquid (phenyloctane)solid (HOPG) interface using mechanically cut Pt / Ir (80 / 20) tips (Goodfellow, UK). All experiments were repeated several times with different tips, at different spots on the sample, and the results presented in this work are representative and consistent with the more comprehensive data set. In order to determine the apparent height of brighter spots, assuming that they correspond to the electronic signature of the different molecules studied, Gwyddion software was used. The STM images were flattened and the image level was fixed to 0 height for the lower pixels measured.

XI.1. Surface functionalization with via host-guest strategy

Regarding this first strategy, TSB host network was filled with the different guest supramolecular complexes developed and studied in the previous chapter: ZnPc-PDI4, ZnPc-PDIC7 and ZnDPP-PDI4.

From the studies in solution of the supramolecular complexes (Chapter 2), we know that the predominant association between the phthalocyanine pedestal and the PDI functionality is via - interactions. We also know from the literature, that coordination of a zinc porphyrin with a pyridyl type ligand is favored when the molecules are deposited on the surface rather than present in solution. [186] So, we first studied the deposit of the ZnPc-PDI4 complex to observe if the surface would shift the equilibrium of this association to favor the metal-ligand coordination, or if the - complex was observed. To verify this, we studied as well the ZnPc-PDIC7 association, determine if the - interaction was strong enough to keep the complex formed even on a surface and to compare it to the results obtained with the ZnPc-PDI4 complex.

We also studied a new complex which was formed by the association of a ZnPc with a PDI where the nitrogen atom of the pyridyl group is located at the meta-position in relation to the PDI (PDI3). This new PDI is of interest since it gives us access to an intermediate orientation The TSB and the corresponding complex solutions were prepared in toluene at 1 µM and dropcasted. Toluene was preferred to CHCl3 as solvent since it allows for a longer evaporation time (0.8 µL/10 min vs 1-2 min in CHCl3). This leaves more time for the molecules to selfassemble on the surface and leads to larger, well-ordered domains. Once the deposit of the TSB was dry, the solution containing the ZnPc-PDIs complex was also deposited in the same way.

XI.2. ZnPc-PDI4 self-assembly

A 1:1 mixture of ZnPc-PDI4 (8 µL) was drop-casted on the TSB-C12 network. After the surface was deemed dry, the surface was analyzed by STM under air and showed a partially filled network. The ZnPc-PDI4 solution was drop-casted two more subsequent times, until the pores were observed to be completely filled (95%). The STM image of Figure 227 presents the TSB network with still with some empty cavities. The bright spots observed are objects with an apparent height considerably greater than the TSB network. These were assumed to be the ZnPc-PDI4 complex. Some pores can be seen to be filled with a molecule that is of similar height as the TSB, and we believe it to be a single ZnPc molecule (no PDI attached). These results were observed numerous times and so we conclude that a TSB-C12 based 2D honeycomb self-assembly was successfully used to form a homogeneous and ordered selfassembly of ZnPc-PDI4 complexes on HOPG using the host-guest approach, in scales of up to hundreds-of nanometers.

STM measurements performed in the liquid-solid interface using phenyloctane gave similar results. However, the complex ZnPc-PDI4 (bright spots) was more difficult to observe on larger areas. This might be related to the solvation and the exchange equilibrium of the molecules between the solution and the surface.

XI.3. ZnPc-PDI3 self-assembly

Using the same method, the ZnPc-PDI3 (1:1) complex was deposited on a TSB-C12 network.

STM images of the ZnPc-PDI3 in the cavities were obtained showing the same patterning of the surface observed with ZnPc-PDI4. Again, we see the bright spot matching with higher objects than the TSB network which were assigned to the complex deposited. A comparative height analysis was carried out by the deposition of a known mixture of ZnPc-PDI4 and ZnPc-PDI3 in a TSB-C12 network. However, this analysis was insufficient to prove that any significant differences could be observed between both populations. The analysis was performed in phenyloctane and the resulting image was analysis by statistical count of bright spot representing one complex each. Figure 229 shows an image where two areas were analyzed (a, b) to count the spots and sort them by median height of each red spot marked. The reported height count is plotted on the spectrograms to the right. From the few local maxima (a) and the four observed in area (b) we couldn't conclude that a significant height difference between ZnPc-PDI4 and ZnPc-PDI3 complexes can be detected by STM. The studies performed cannot be used to the study the 3D-architecture of the complex on the surface since we only observe an "apparent" height. Therefore, to confirm this, further micro spectroscopic studies of the surface are necessary. Through these studies, we can confirm that some type of complex can be surface confined within the TSB pores in a controlled and relatively easy manner. These complexes are stable in ambient conditions and present an apparent height which is significantly different to the "flat" TSB system.

In addition, the work performed in Chapter 2 taught us that the ZnPc can associate to the PDI also via - interactions, and this type of association is dominant in solution. So, we decided to also observe the PDIC7-ZnPc complex to see firstly if this type of complex is stable on the same substrate, and to compare its adsorption properties with our ZnPc-PDI4 and PDI3 complexes.

XI.4. ZnPc-PDIC7 self-assembly

Following the previous method, the ZnPc-PDIC7 (1:1) complex was deposited on a TSB-C12 network. The STM images obtained (Figure 230) showed a very similar filling to that with the ZnPc-PDI4 or PDI3 complexes. Again, a complete filling of the TSB pores was possible with three-consecutive deposits of the ZnPc-PDIC7 mixture. The PDIC7 signals (bright spots) are a little broader than with the PDI4 and PDI3 which could be explain by the different orientation expected with the PDIC7 (parallel vs perpendicular or at an angle) compared to PDI4 or PDI3. Similar height values were obtained with this complex. The broader spots observed could also be due to different image acquisition conditions (STM tip, scan rate, etc.), so no conclusive results can be obtained, except that all the STM images obtained with the three complexes that have a ZnPc pedestal are similar. The deposition conditions we are using are similar to those used in the titration studies discussed in Chapter 2. In these solution studies we concluded that different associations were taking place in solution between the ZnPc and the PDI present (selfaggregation, - and metal-ligand interactions). We also arrived at the conclusion that at these conditions, the - interactions between the ZnPc and the PDI are the most predominant so it seems logical that all these systems observed give similar results on surface.

XI.5. ZnDPP-PDI4 self-assembly

By studying the ZnDPP-PDI system, we expected to obtain results that could shed light to the previous ZnPc systems studied. We have confirmed in the solution studies that with the porphyrin, the metal-pyridyl coordination is the strongest association that occurs. In a first instance, we deposited only the ZnDPP on the TSB-C12 network but no images of the filled cavities could be observed. We believe this is because ZnDPP is smaller than ZnPc and its phenyl substituents reduce the - interactions with the surface. Using TSB-C10 (which has smaller pores), ZnDPP was successfully immobilized and we were able to obtain images with filled pores. As seen in in the Figure 231, the TSB-C10 arrays are less organized than TSB-C12 in large areas, however all the cavities are filled. Note we also observe some striation on the ZnDPP molecules, showing that the molecules are not bound to the surface as strongly as with ZnPc pedestal and the electric field between the tip and the surface disturbs ZnDPP physisorption. We then deposed the ZnDPP-PDI4 (1:1) complex on the TSB-C10 host network. The STM images in this case showed a very particular form of patterning (Figure 232). The ZnDPP-PDI4 complex appears to fill only one out of two pores, leading to a more spaced-out PDI4 functionality. In addition, the "naked" ZnDPP pedestal was found to fill all the remaining pores.

We conclude that this could possibly be the result of steric repulsions between the PDIs located out of plane and orthogonal to the surface. It has to be noted that in the case of ZnDPP-PDI4, the complex could only be observed under air and not at the solid-liquid interface. The patterning was also disappearing when we increased the bias over 400 mV, showing that the electric field has an important effect on the deposited complex. Because ZnDPP doesn't stick so well to the surface, the exchange with the solvent might lead to a dynamic system which is complicated to monitor in the time scale of the STM acquisition.

Finally, we tried the same measurement with PDI3 but in this case, only the ZnDPP was observed. We believe that the metal-ligand association is weaker between ZnDPP and PDI3, since the repulsions between the bulky t-butyl groups on the PDI are more important in a 60°

angle and this could impede the formation and/or reduce the stability of the complex.

To conclude this section, the host TSB network proved to be an efficient strategy to obtain wellordered 2D-assemblies with molecules bearing a functionality above the substrate. Two different TSBs were used to modulate the cavity size, making it more suitable to the pedestal used. The pores in this host system could be easily filled with different complexes, following a relatively simple solution deposition. We found that ZnPc forms a stronger and more stable association with the HOPG surface in comparison to the ZnDPP.

However, the two-step deposition process made the STM experiments quite time consuming and sometimes complicated to replicate. In some cases, the presence of aggregates appeared to disturb as well the STM tip. As we worked under ambient conditions, having an operating tip could take time. Therefore, to simplify the system, we then moved onto studying the selfassembly of the single component pedestals (CxZnPcs).

XII. Surface functionalization with single-component system

Phthalocyanines functionalized with two different chain lengths (C6 vs C12) were studied for their self-assembling properties. We chose these chain lengths to study the effect on the arrangement and spacing of these molecules on the surface. This will enable us to see if by modifying the chain lengths we can rationally control the spacing between the functional units when the Pc-PDI complexes are deposited. Moreover, getting rid of the TSB will allow us to increase the number of functional components on the surface and increase the optical and electronic effects that will be studied later on. The self-assembly of octaalkyl phthalocyanines was studied by STM in a similar way as we did with the host-guest system. CxZnPc or CxTiOPc systems were solubilized in toluene at ≈ 1 µM and 8 µL of this solution were dropcasted on the HOPG surface. The molecules were then observed at the air-solid or liquid-solid interface by STM.

XII.1. C6ZnPc and C12ZnPc self-assembly

The C6ZnPc and C12ZnPc systems were easily observed in phenyloctane, but at air-solid interface only small domains could be imaged (≈ 50 to 100 molecules) after evaporation in air.

The tip of STM was also seen to break-up these domains after a trace and retrace motion. In contrast, when scanning under phenyloctane, the CxZnPc self-assemblies are stable under the tip, even after 20 scans over the same area the same pattern could be imaged. Also, the arrangement on the surface was different, with a hexagonal unit cell observed for C6ZnPc and square cell for C12ZnPc. In the C6ZnPc network, the alkyl chains are also not visible along the "y" direction. We believe this is because some of the alkyl chains are not absorbed on the surface in this direction. In the C12ZnPc network, we believe that some alkyl chains are also above the surface plane in a similar manner as to those observed in C6ZnPc image. From these studies, we think that we can form a stable and robust network in solution because the alkyl chains located out of the surface are stabilized by solvation. On the contrary, at the air-solid interface the alkyl chains out of the plain can stick on the tip, causing it to remove and degrade the assemblies formed.

XII.2. C12ZnPc-PDI4 complex self-assembly

Finally, we studied the 1:1 C12ZnPc-PDI4 complex on the HOPG surface following the same drop-casting method. In the STM image shown in Figure 234, we see that very few PDI4 molecules remained coordinated to the C12ZnPc pedestal (bright spots). It was interesting to see that these bright spots could be displaced by the trace and retrace of the STM tip over the same area. We think that since the STM images were obtained in phenyloctane, this could limit the association of PDI4 on the pedestal because the solvation-effect is stronger here than the coordination bond. To conclude, the C12ZnPc-PDI4 functional supramolecular complex was observed in phenyloctane by STM, which shows that a strong-enough interaction is still present between PDI4 and C12ZnPc which can resist several passages of the STM tip. Because the STM image were done in phenyloctane we believe that the alkyl chains that we assume are out of the plane of the surface, can also block the PDI4 association, which would explain the sporadic dispersion of PDI4 unit. Of course, STM is incapable of giving any information of the kind of species that are attached on the pedestal network, even if we assume it is the PDI. So, to confirm that the bright spots are indeed PDI4 molecules attached either by coordination or π-π associations to the porphyrin and phthalocyanine pedestals, other types of spectroscopy analysis will have to be carried out.

XII.3. C6TiOPc and C12TiOPc pedestals self-assembly

Up until now we have been discussing the use of the supramolecular Pc/P-PDI complexes for surface functionalization. We have observed that these complexes are somewhat labile and are complicated to put in evidence. Other types of pedestals, where the functionality is grafted via stronger, covalent bonds were also developed. Here we show the STM studies of these pedestals. Two titanyl phthalocyanines similar to the alkyl-functionalized ZnPcs were studied.

The C6 and C12TiOPc were deposited on surface and analyzed to confirm that the titanyl (Ti=O) function doesn't disturb the self-assembly on the surface. The STM images were obtained in the same conditions that the C6 and C12ZnPc. The STM images in Figure 235 shows similar packing of the molecules as that observed with their CxZnPc homologues. Even though the C6 and C12TiOPc degraded quickly under light in solution (over periods of 1 h), the STM images of their corresponding monolayers in phenyloctane were recorded during a period of over more than 6 h hours and the image didn't reveal any kind of degradation during the experiment. We conclude that changing the metal cation from zinc to titanium in this case does not affect the self-assembling properties of these derivatives. Using the alkylated TiOPc to graft a PDI via a catechol or dicarboxylic acid function could therefore be a more efficient way to attach different functionalities to a graphene surface though simple solution dropcasting.

Different complexes associating ZnPc, CxZnPc and/or ZnDPP pedestals with PDI4 and/or PDI3 units could be assembled on a HOPG surface using two self-assembling methods.

• The host-guest method used a TSB network to control the deposit on the surface and provide an ordered pattern for the functionalization to take place via the deposition of the complexes. The ZnPc-PDI supramolecular complexes were shown to completely fill the pores in the TSB-C12 honeycomb network. In the case of ZnDPP-PDI4 complex with TSB-C10, the filling was more complicated due to the weaker interaction of the porphyrin with the surface.

However, we were still able to evidence the functionalization of the pores with the complex.

This system showed a particular type of filling; where one out of two pores is filled by a single ZnDPP as well. This particular functionalization is interesting to obtain surface with less functions than those using ZnPc in TSB-C12 network. We also believe that this could confirm the difference in associations observed with ZnPc (π-π vs zinc-pyridyl).

• The second method employed alkyl-substituted C6 and C12ZnPcs pedestal which could give more compact self-assemblies at the solid-liquid interface. We proved that the lattice of such patterns could be tuned in two ways by modulation of the alkyl chain lengths. The first way was the distance between each function and the other one was the 2D packing. With longer alkyl chains we observe a more spaced-out, square lattice and a more compact, hexagonal lattice with shorter alkyl chains. The PDI4-C12ZnPc complex was also observed and the STM images revealed the weak association between the PDI4 and the pedestal, probably due to a surfaceinduced effect with the alkyl chains.

These methods have their pro and cons: For the host-guest approach, we are limited by the twostep deposition necessary to functionalize the surface. Also, this method limits the modulation of lattice parameters an in turn between the functions grafted. The advantage is that we observe controlled and reproducible filling of the supramolecular network. The self-assembling pedestal on the other hand, allows us to deposit a single solution to functionalize the surface. The drawback of this method seems to be the alkyl chains that are out of the plane of the surface, which can lead to blocking the association to the PDI function when absorbed. However, a lot more work remains to be done with the CxZnPc pedestals in particular, since only one complex (C12ZnPc-PDI4) has been studied by STM to this date. In addition, the CxTiOPc developed show similarly good self-assembling properties as CxZnPc which make them the most promising derivatives to obtain robust functional self-assemblies.

As mentioned previously, the study of these molecular arrays by STM only gives us limited information about these systems. In the following section, we will discuss the characterization of the optical properties of these 2D-systems that will help clarify the different assumptions that have been made, specifically on the types of association and orientation of the PDIs within the complexes.

XIII. Monolayer analyses by confocal spectroscopy

To control the orientation of the molecules on the surface and the emission from a monolayer we used three spectroscopic techniques: the micro absorbance, the micro-Raman emission and the angle variation absorbance developed for this characterization. These spectroscopic techniques also helped to investigate the process of self-assembly on graphene surface. For these particular experiments, the molecules were all deposited directly on a transparent (glass) substrate with a graphene monolayer. The substrates were prepared manually via the transfer of graphene to the clean glass substrates and were used the day after to avoid any degradation of the graphene surface.

The absorbance measurements are expected to give us information on the chromophore deposited on the surface; Since phthalocyanines and porphyrins are both highly absorbing in visible wavelengths, the absorbance measurements would allow us to follow their association on the graphene which should be reflected in a change of their absorption spectra as they interact with the graphene. Raman spectroscopy was used to obtain information on the graphene layer.

As discussed in the introduction, any molecule deposited on graphene's surface has an effect on its Raman signature. Finally, an angle measurement technique was developed by our collaborators (F. Charra). that would enable us to measure an absorbance along different incident-light source angles, this method was used to study the association angle between the PDI and ZnPc in a monolayer. [192]

XIII.1. Micro absorbance and micro-Raman spectroscopy

The differential transmittance microspectroscopy (absorbance microspectroscopy) experiment (Figure 236) is based on an inversed microscope (Olympus IX71) with a x60 objective (N.A. These results tell us that the "as deposited' monolayer of C12ZnPcs is not really interacting with the graphene monolayer. Even when the solvent of the dropcasted solution appears to have evaporated on the graphene, there are still solvent molecules caught between the Pc monolayers and the graphene, which give spectra similar to in-solution samples. At least 3 h of annealing at 65 °C are necessary to fully adsorb the C12ZnPc, and remove any trace of solvent (toluene) trapped at the interface. The annealing enabled us to pass from this "meta"-solubilized C12ZnPcs to an adsorbed self-assembly on graphene.

For the C6ZnPc we show that in this case an annealing period of 2 h was enough to completely lose the "meta"-solution with the disappearance of the 685 nm peak. The adsorbed C6ZnPc peak appeared at 715 nm which reflects a 30 nm shift when physisorbed on graphene compared to the absorbance "as deposited" (air drying). The spectrum obtained after annealing the C6ZnPc (red) was compared to that obtained after a rinsing of the surface with a 10 mL toluene bath for 15 min (purple). The sample was left to dry for 10 mins before recording the spectrum.

This gave us a similar absorption spectrum to that of the C6ZnPc with the annealing treatment, with the only difference being that we observed a broader peak. We can also see that a slight shoulder appears on the right of this peak, which could be a result of aggregates on the surface.

Finally, the spectrum of C6ZnPc obtained after rinsing plus annealing (black) gave exactly the same spectrum than the one submitted only to annealing (red). We assume that the spectra we are collecting after annealing or rinsing the surface, correspond to the signal of a monolayer of CxZnPcs on the surface. If a multilayer was present, we can detect this with the appearance of the aggregate shoulder (seen in the purple spectra). We would also expect a shift or broadening of the maximum absorbance peak at 715 nm. We conclude that by rinsing or annealing the surface, the solvent trapped and multilayer of molecules are spread and only the adsorb monolayer can be observed. It is interesting to note that depending on the self-assembly pattern observed on the graphene surface (related to the C6 and C12 alkyl) the adsorbed C6ZnPc and C12ZnPc show different absorbance spectra. This might be related to the interaction of the ZnPc core to the graphene orbitals which is different depending on the alkyl chains substituents. To conclude the annealing and rinsing of C6ZnPc and C12ZnPc

showed to be an effective method to obtain a monolayer functionalization after dropcasting.

We also observed that without this annealing step the C6 and C12ZnPc are not completely adsorbed on the surface and have the same optical properties as when in solution. Once properly adsorbed, the absorbance peaks undergo a strong bathochromic shift of 26 and 30 nm, demonstrating the strong charge-transfer interaction between the graphene and the CxZnPcs pedestals.

XIII.3. C6TiOPc and C12TiOPc micro-absorbance on graphene

Using the same method that with their zinc homologues, the C6TiOPc and C12ZnPc were deposited on a graphene/glass substrate and annealed 2 h. Error! Reference source not found. s hows the absorbance before and after the annealing of the dropcasted solutions. In contrast to the CxZnPcs, the annealing led to a weak bathochromic shift of 3 nm for C12TiOPc and 8 nm for the C6TiOPc. The annealing was extended to 4 h but it gave the same result than after 2 h with both C6 and C12 derivatives. To conclude, the micro-absorbance by confocal microscopy allowed us to characterize the absorption of C6ZnPc, C12ZnPc, C6TiOPc and C12TiOPc dropcasted on graphene. The measured of absorbance following the deposit revealed two states at the surface: a meta-solution state in which the Pc molecules behave like in solution and an absorbed state which can be evidenced by a bathochromic shift in the absorption maxima of these derivatives. To successfully adsorb the molecules on the graphene, annealing or rinsing of the surface are necessary. We now know that applying this treatment will lead us to better conditions to repeat the STM experiments of CxZnPcs and their corresponding complexes with PDI.

XIII.4. Micro-Raman of pedestals on graphene

The same samples used for the absorbance measurements were studied by Raman spectroscopy.

Because the graphene usually quenches the fluorescence emission of any aromatic molecules that are absorbed on its surface, we could excite the graphene with a 532 nm laser and the To conclude, we were not able to discern an important doping effect on the Graphene layer thanks to the deposited monolayer via Raman spectroscopy. This method however, proved to For incidence-angle-resolved differential transmittance measurements, a white-light collimated beam is formed from a ~500-µm wide white LED source (Thorlabs MWWHL4) using a +100 mm achromatic doublet (Thorlabs AC254-100-A-ML). A diaphragm located near the achromatic doublet is tuned so as to obtain a sample spot size of ~ 1 mm. The divergence is then ~0.8°. A linear film polarizer (Thorlabs LPVISC100) permits to select either the s (i.e.

transverse electric) or p (transverse magnetic) polarization. The sample is rotated using a servomotor driven by a micro-controller board (Arduino) with an angle resolution and repeatability of ~1°. The transmitted light is focused using another achromatic doublet (Thorlabs AC127-025-A-ML) on the entrance of a compact spectrometer (Ocean Optics USB2000) to detect the transmitted light in the 400-750 nm spectral range. The spectra obtained from the sample of interest are divided by those obtained using a reference sample at the same polarization and incidence angle. Accounting for source fluctuations and sensor readout noise, transmission differences (e.g. absorption) as low as 1 x 10 -3 (i.e. Optical densities ~ 5 x 10 -4 ) can be detected.

Whereas the absorbance of the s-polarization is only sensitive to in-plane transition dipole moments, that of the p-polarization is increasingly sensitive with incidence angles to transition dipole moments normal to the sample plane.

The molecules we study absorb light in a direction related to their polarizability. Their polarizability is given by the conjugated aromatic core of either the PDI or Pc and are oriented along the -delocalized plane. Thus, the molecules only absorb electromagnetic wavelengths normal to this polarizability plane. Based on this property, the angle measurement of absorbance can indicate the anisotropy of the molecules studied by scanning the absorbance along different angles. We selected a transverse magnetic polarisation (TM) for the incident light with initial incidence normal to the surface which allows us to observe a growing component of the absorbance in the zy plan with the increasing incident light angle Error! R eference source not found.. The transmitted intensity was measured with the increasing angle from the normal incidence to the surface. The molecules in the plane of the sample will have a maximum of absorbance at 0° and the molecule with their aromatic conjugated plane perpendicular to the surface will have their minimum of absorbance at 0°. The angle measure was limited to 70° as maximum angle because above this, the scattered light becomes too important and the signal measured is no longer reliable. The absorbance curves of the C12ZnPc-PDI4 and ZnPc-PDI4 complexes (left and right) show a similar behavior with the increasing angle of incident light. At 0 ° only the absorption peak of ZnPc or C12ZnPc is visible (712 nm). As we increase the angle of measurement, the PDI4's absorption band (between 550 and 600 nm) starts to appear and becomes more pronounced, whilst the ZnPc / C12ZnPc absorption decreases. This trend confirms without a doubt that the PDI4's conjugated plane is perpendicular to its corresponding ZnPc pedestal. We corroborated this also by the results obtained with the C7PDI, since we know in this case that the only form of association between the PDI and the Pc are through face-to face interactions, which should result in a different outcome. Indeed, the PDIC7-ZnPc complex gave a different result, the maximum absorption intensities for the PDIC7 and ZnPc being obtained at 0 ° for both in this case and both peaks decay in a similar way with the increasing angle. This confirms that PDIC7

and ZnPc components are both parallel to the surface.

To conclude this final section, the angle absorbance measurements helped us to finally proved the orientation of the PDI4 and C7PDI in relation to the ZnPcs pedestals in three different systems. C12ZnPc-PDI4 complex showed the same result than that of the ZnPc in TSB which confirms that the association of PDI4 with the two types of pedestals occurs in a similar way (through the -zinc coordination).

XIV. Conclusion on the self-assembly characterization

Self-assembly of the molecular complexes composed by a CxZnPc, ZnPc, ZnDPP or CxTiOPc pedestal and a PDI4, PDI3 or PDIC7 functionality were carried out on HOPG and graphene surfaces via dropcasting method. Long-range, ordered self-assemblies were obtained through two strategies: one is the host-guest system which relied on a host TSB honeycomb network filled with a phthalocyanine or porphyrin guest molecule. The second strategy employed selfassembling pedestals (C6 or C12ZnPc and C6 or C12TiOPc). STM images recorded at air-solid interface and liquid-solid interface evidenced well-ordered host-guest systems on areas of 100 x100 nm, only limited by the HOPG defects. The assembly of alkylated Pcs showed also a large regular patterning with hexagonal lattice when using C6 alkyl chains and square lattice when using C12.

The different PDI4 and PDI3 and PDIC7 functionalities could be observed on ZnPc or ZnDPP pedestals in the host-guest systems. These showed similar apparent heights observed with all three PDIs studied. In the case of the C12ZnPc pedestals, the association observed with the PDI4 was quite limited (about 1 PDI4 for 30 C12ZnPc).

Absorbance and Raman micro-spectroscopy spectra of CxZnPc or CxTiOPc on graphene revealed that an annealing process of the deposited monolayer on the surface is required to properly adsorb the molecules on the surface. This annealing step could potentially be replaced by a solvent rinsing. The absorbed molecules on graphene were evidenced by a bathochromic shift in their absorbance spectra. This shift was more intense with zinc phthalocyanines than with the titanyl ones (30 nm vs 8 nm).

Finally, angle-dependent absorbance measurements confirmed the expected associations of the C12ZnPc-PDI4 and the ZnPc-PDI4 complexes on graphene. In both cases, the PDI4 unit is orthogonal to the Pc pedestal which confirms a coordination association between them. This also shows a dominating coordinative Zn-interaction on-surface which could not be convincingly confirmed in the solution studies (chapter 2). In contrast, PDIC7-ZnPc forms a ππ driven complex, where both components are oriented face to face and thus parallel to the graphene surface.

By comparing the different spectroscopic methods used to the microscopy studies performed by STM we see how a strong potential can modify the surface observed. Indeed, with micro absorbance we were able to observe a good coverage of the surface with PDI4 absorption close to the ZnPc absorption (1:1 ratio) while by STM we observed a large excess of assembled pedestal compared to the PDI4 on top of it. We believe that the angle dependent absorbance On the other hand, we developed chemical engineering strategies towards the obtaining of symmetrical and modified perylene derivatives, some of them bearing pyridyl groups located at the extremities to favor interactions with the zinc cation-including pedestal via coordination.

These PDIs were synthesized with large, bulky groups close to its aromatic core to avoid interactions with surface and at the same time, to have soluble molecules to work with. A series of four dipyridyl-PDIs were prepared with different substituents: 4-pyridyl, 3-pyridyl, 4phenyl-4'-pyridyl and 3-phenyl-3'-pyridyl PDI. Their optical properties (emission, absorption, photoelectron emission) were measured in order to compare them later when confined to a surface. The good complementary of their absorbance spectra in the visible wavelength is also a good asset to study the molecules on surface by avoiding the confusion related to overlapped peaks. These measures presented the strong absorbance of ZnPcs and ZnDPP with extinction coefficient above 200 000 L.mol -1 .cm -1 as well as the photoluminescence quantum yield above 80% of the PDIs prepared.

Then, we extensively studied by different techniques the ability or not of our building blocks to interact with each other. Indeed, given the extended literature on complexes formed through zinc-pyridyl coordination of phthalocyanines, porphyrins and perylenediimides we expected to be able to obtain a series of association constants that would give us an idea of the stability of each of our new complexes. Thus, we based our studies on different reports in the literature and tried to replicate the experimental results obtained. However, this was not as straight-forward as it appeared. Numerous titration experiments with three different types of spectroscopic techniques had to be applied to obtain some information on the supramolecular interactions present in our systems. We were limited by the low solubility of our molecules in the solvents used for the titrations, resulting in unreliable association constants. However, we also discovered that the experimental and data treatment methods reported in the literature are also not reliable since these systems are much more complex than they appear and most importantly, the fitting methods used have been proven to be obsolete. In particular and surprisingly, we found for the first time that a different type of association could be observed: we were able indeed to report that the ZnPc pedestals predominantly associate with the perylene through π-π interactions, whilst the expected coordination is mostly observed when using porphyrin as a pedestal. We were eventually able to explore two different strategies to achieve 2D arrays. One via the use of a host-guest system which required the use of an additional organic molecule (TSB) to help control the self-assembly. We also developed a second generation of pedestals where alkyl chains could be incorporated on the periphery of the Pc pedestals. The use of different chain lengths was investigated, and we found that it is a good strategy to tune the packing distances and organization of the on-surface assembly. Another pedestal with an extended conjugated core (ZnNc) was also prepared as a possible alternative to the ZnPc, however it did not prove suitable due to its low solubility.

Concerning the HOPG and/or graphene surface-patterning, we observed the same properties shown by the pedestals alone. However, using only STM we were unable to differentiate the different ways (and orientation) the PDI could be located on the Pc or P pedestals. STM conditions could even be observed to displace the PDI located on top of Pc.

We therefore deposited our different supramolecular complexes on a graphene monolayer deposited itself on a glass substrate, to measure the 2D-assemblies's absorbance and emission properties. By using micro absorbance and micro-Raman, we discovered that annealing improves drastically the adsorption of molecules on the surface (through the pedestal), and a bathochromic effect of the pedestal's absorption maxima can help us confirm that the molecule is well-adsorbed. Interestingly, we know now that depending on the nature of the pedestal the annealing time required can vary. Rinsing can also be used to improve the adsorption; however, annealing is preferred. Even more, the angle-dependent absorbance studies of the ZnPc-PDI4 and C12ZnPc-PDI4 were proved critical to evidence the different orientations that the PDI could present when associated to the pedestal, and therefore to the surface. We were able to confirm that both zinc-pyridyl and π-π associations can occur between the PDI functionality and the ZnPc pedestals. Although the STM was not able to show complete functionalization with the C12ZnPc-PDI4 complex, the angle depended studies demonstrate that the signal intensity corresponds to a 1:1 ratio between both Pc and PDI components, meaning we have a homogeneous, functionalized assembly.

To sum up, we can say that the functionalization of graphene though a full supramolecular approach could be successful, even if many parameters must be tuned and controlled. Our main results, combined with a specific chemical engineering and many spectroscopic studies, demonstrate that both two component (host-guest) and one component systems led to achieve an organized layer of PDIs not directly coupled on the graphene.

These kind of nanoscopic functional supramolecular materials are interesting for future molecular organic electronics and nanophotonics applications. In particular, this accessible method of functionalization, combined with the versatility of the molecular design of these building blocks, make them appealing for device preparation in contrast to vacuum deposit chamber methods.

XV. Outlook

To improve the pyridyl-zinc association between the pedestal (Pc or P) and the functionality An extensive in-depth study is also necessary to properly understand and control the association processes occurring in solution. To simplify the system and have a better understanding of the PDIpedestal association in solution we started to prepare asymmetric PDI with just one pyridyl function. This would limit the association to only one coordination bond possible between ZnPc and a monopyridyl-PDI for example. To lower as well the - interactions, the PDI core hindrance could be increased with two more substituents in bay position. Moreover, the STM study of octaalkyl Pc on surface revealed that some alkyl chains were not adsorbed on surface. These alkyl chains above the pattern of phthalocyanine limit the association to the PDI. To improve the association of PDI with a pedestal it would be interesting to reduce the eight alkyl chains to four alkyl chains on periphery of the Pc. As the alkyl chains would be more spaced, they might be able to all adsorb on the surface. Because the symmetry of synthesis become a true issue by working with Pc core molecule, we propose to substitute it by a tetrabenzoporphyrin core. These molecules could be alkylated on the four meso position.

This would afford to keep the symmetry of the molecule in order to obtain self-assemble on the surface.

  Chimie Montpellier ou d'Orsay capital city, sans oublier Dorian et Nicolas, qui m'entourent et font de ma vie un plaisir que je savoure à chaque instant grâce à eux. Et n'oublions pas Juliette qui m'a soutenu en toute circonstance et qui me permet de m'améliorer continuellement. III.8. NMR of substituted phthalocyanines................................................................ III.9. Absorbance of substituted phthalocyanines...................................................... III.10. Fluorescence of substituted phthalocyanines.................................................... III.11. Photoemission spectroscopy (PES) of substituted phthalocyanines ................. III.12. Conclusion on CxPc and CxNc characterization .............................................. IV. Synthesis of zinc meso-5,15-diphenylporphyrin ....................................................... IV.1. Step 1: synthesis of Dipyrromethane (11) from pyrrole ................................... IV.2. Step 2: synthesis of 5,15-diphenylporphyrin (DPP) ......................................... IV.3. Step 3: Metalation of DPP to ZnDPP ...............................................................

Figure 3 .

 3 Figure 3. Serendipitous synthesis of copper phthalocyanine

Figure 6 .

 6 Figure 6. (Left to right) Porphyrin, subporphyrin, phthalocyanine, subphthalocyanine and superphthalocyanine

Figure 7 .

 7 Figure 7. Most encountered geometries of coordinated metals by porphyrins or phthalocyanines

Figure 8 .

 8 Figure 8. Nomenclature of porphyrin and phthalocyanine substitute positions

Figure 11 .

 11 Figure 11. Accessible cyclotetramerization of phthalonitriles

Figure 12 .

 12 Figure 12. Precursors to cyclotetramerization of phthalocyanines[24]

Figure 13 .

 13 Figure 13. Cyclotetramerization and oligomerization equilibrium

Figure 15 .

 15 Figure 15. Mixture of products from a single asymmetric phthalonitrile after cyclotetramerization

Figure 16 .

 16 Figure 16. Peripherally functionalization on the left and non-peripheral functionalization on the right

Figure 17 .

 17 Figure 17. Aryl o-diamide preparation and dehydration to p-substituted phthalonitrile

Figure 20 .

 20 Figure 20. Catalyst cycle of Pd in triflate cyanation reaction

Figure 21 .

 21 Figure 21. Pathways to peripheral substituted phthalocyanines

Figure 23 .

 23 Figure 23. Perylenes diimide structure

Figure 24 .

 24 Figure 24. Synthesis of PDA

Figure 27 .

 27 Figure 27. Dibromination of PDA

Figure 30 .

 30 Figure 30. Synthesis of asymmetric perylene monoimide

Figure 31 .

 31 Figure 31. Two routes to 4,5-dialkylated phthalonitriles

Figure 33 .

 33 Figure 33. Kumada coupling to Dialkylveratrole

Figure 34 : 1 H

 341 Figure 34 : 1 H NMR in CDCl3 revealing impurities (blue circled) in catechol after work-up

Figure 35 .

 35 Figure 35. Synthesis of 4,5-dilakylphthalonitrile from 2,3-dimethylbutadiene

Figure 37 .

 37 Figure 37. Diels-Alder cyclisation and aromatization

Figure 38 .

 38 Figure 38. Synthesis of phthalonitrile from ortho dimethoxycarboxylate

Figure 39 .

 39 Figure 39. Peripherally substituted phthalocyanines

Figure 40 :Figure 41 .

 4041 Figure 40 : Synthesis routes to obtain the 2,3-dihexylphthalocyanines reported by Chambrier et al.[80]

Figure 42 . 1 H

 421 Figure 42. 1 H NMR of C6H2Pc in CDCl3, after column chromatography and trituration. Blue peaks belong to C6H2Pc

Figure 43 .

 43 Figure 43. Synthesis routes to CxZnPcs

Figure 44 .

 44 Figure 44. Zinc Metalation of CxH2Pc

Figure 45 .

 45 Figure 45. Cyclotetramerization of CxPn to CxZnPc

Figure 47 .

 47 Figure 47. Synthesis pathways to titanyl phthalocyanines

Figure 48 :

 48 Figure 48: Absorbance comparison between C12H2Pc, on the left; C12TiOPc, on the right. And the mixture of product from the reaction, at the middle;

Figure 49 .

 49 Figure 49. Titanyl insertion from CxH2Pc

III. 6 . Route 3 :Figure 50 .

 6350 Figure 50. Synthesis of CxTiOPc using TiCl4

Figure 52 .

 52 Figure 52. Temperature and complexing molecule (pyridine) effects on 1 H NMR of C6ZnPc

Figure 53 .

 53 Figure 53. Octahexyl phthalocyanines and naphthalocyanine 1 H NMR in CDCl3

Figure 54 .

 54 Figure 54. Normalized absorbance spectra of octahexylphthalocyanines & naphthalocyanines in toluene.

Figure 55 :

 55 Figure 55 : Solvent effect on C6ZnPc absorbance

Figure 56 .

 56 Figure 56. C6ZnPc molar extinction coefficient measure using Beer-Lambert law

  Figure 57 were excited at their corresponding Q-band wavelengths.

Figure 57 .

 57 Figure 57. Fluorescence of octaalkyl substituted

Figure 58 .

 58 Figure 58. Fluorescence time decay of C6ZnPc in toluene excited at 610 nm

Figure 59 .

 59 Figure 59. Photoemission spectrum of octahexylphthalocyanines

Figure 60 .Figure 61 .

 6061 Figure 60. meso-diphenylporphyrin synthesis

Figure 62 .

 62 Figure 62. Cyclisation and aromatization to obtain DPP

Figure 63 .

 63 Figure 63. Zinc metalation of DPP

Figure 65 .

 65 Figure 65. Proposed path to CxMTBP from Pn

Figure 66 :V. 2 .Figure 67 .

 66267 Figure 66 : Synthesis of meso-tetraundecylbenzoporphyrin using Grignard reactant

Figure 68 .

 68 Figure 68. Synthesis of meso-tetrapropylbenzoporphyrin using (octyl)2Zn

Figure 69 .

 69 Figure 69. Synthesis of meso-tetrapropylbenzoporphyrin using (Et)2Zn

Figure 70 .

 70 Figure 70. Synthesis of meso-tetrapropylbenzoporphyrin using (Et)2Zn from phthalimide

Figure 71 . 1 H

 711 Figure 71. 1 H NMR spectrum of ZnDPP in CDCl3

Figure 72 .

 72 Figure 72. Absorbance spectrum of ZnDPP in CHCl3. In the inset is the Beer-Lambert Coefficient value obtained by linear regression

Figure 73 .

 73 Figure 73. Emission spectrum of ZnDPP in toluene with 415 nm excitation.

Figure 74 .

 74 Figure 74. Sterically hindered PDI with N-pyridyl substituents

Figure 75 .

 75 Figure 75. Routes to sterically hindered PDA-15 and PDA-18

Figure 76 .

 76 Figure 76. Perylenediimides-di-pyridyl prepared from PDA

Figure 77 .

 77 Figure 77. Asymmetric synthesis of Perylene monoanhydride(22)

Figure 78 .

 78 Figure 78. Route 1 to sterically hindered 1,7 disubstituted-PDA

Figure 79 .

 79 Figure 79. Dibromination of PDA

Figure 80 .Step 2 :Figure 81 .

 80281 Figure 80. Side reaction to bromation in fuming sulfuric acid (H2SO4/SO3)

Figure 82 .

 82 Figure 82. Side reaction Phenoxy substitution of 13

Figure 83 .

 83 Figure 83. Route 2 to sterically hindered tetrasubstituted-PDA

Figure 84 .

 84 Figure 84. N-substitution on 1,6,7,12-tetrachloroperylenedianhydride

Figure 85 .

 85 Figure 85. Tetra substitution of product of PDI 16

Figure 86 .

 86 Figure 86. PDI 16 to PDA tetrasubstituted on bay positions

Figure 87 .

 87 Figure 87. Synthesis of N,N'-bis(4-pyridyl)perylenediimide (PDI4)

Figure 88 .VIII. 1 .Figure 89 .

 88189 Figure 88. Synthesis of dipyridyl Perylenediimides

Figure 90 .

 90 Figure 90. Regioselective asymmetric synthesis strategy

Figure 92 : 1 H

 921 Figure 92 : 1 H NMR proton assignation of PDI4 in CDCl3

Figure 93 .

 93 Figure 93. 1H NMR of the PDIs in CDCl3

Figure 94 .

 94 Figure 94. Normalized absorbance of PDIs in toluene

Figure

  Figure . Normalized PDI4 solvatochromy absorbance

Figure 95 .

 95 Figure 95. Beer lambert linear regression of PDI4 absorbance maxima in CHCl3

Figure 96 .Figure 97 .

 9697 Figure 96. Normalized emission of PDIs under different excitation wavelengths in toluene

Figure 98 .

 98 Figure 98. Normalized PES of PDI3 and PDI4Ph4Py on silicon

Figure 100 .

 100 Figure 100. Synthesis of catechol-C60

4, 5 -

 5 Dibromoveratrole (10.0 g, 33.79 mmol, 1 eq.) and Pd[(dppf)Cl2] (1.24g, 1.69 mmol, 5 mol%) were added to dry Et2O (10.0 mL) in a 3-neck-RBF under an inert atmosphere. Whilst stirring, a solution of n-hexylmagnesium bromide in diethyl ether (35 mL, c.a. 2.25 M, 79 mmol, 2.0 eq.) was added to the solid mixture via syringe (10 mL/min) at rt. Upon addition the reaction color changes from white to mustard yellow. After 30 min the temperature was increased to 45 °C and kept refluxing for 20 h. The mixture was then left to cool to rt to give a dark red solution.Water with ice (50 mL) were added whilst stirring to quench the reaction mixture. The resulting suspension was filtered on a short plug of celite and rinsed with Et2O

1 H

 1 (3-C6) Catechol 2-C6 (4,20 g, 15.1 mmol, 1 eq.) and lutidine (5.3 mL, 45.2, 3eq.) were added to dry DCM (25 mL) in a 3-neck-RBF. Whilst stirring, the reaction was set under inert atmosphere and cooled to -70 °C over a period of 15 min. Tf2O (15 mL, 90.5 mmol, 6 eq.) was added via syringe (1.5 mL/min). During the addition, the temperature was kept below -30 °C. The mixture was left stirring at this temperature for 20 min, after which it was left to warm to rt. The reaction was finally left stirring at rt for 2h. A mixture of ice and water (50 mL) were added whilst stirring to quench the mixture. The aqueous layer was extracted with DCM (100mL). The recovered organic layer was washed with water (2x50 mL) and brine (50 mL) before being dried using MgSO4. The solvent was evaporated under reduced pressure. The resulting oil was purified via chromatoflash, using a 330 g silica column, loaded by solid deposition and eluted with PE. Evaporation of the first fraction gave 3-C6 as a translucent oil (3.4 g, 6.3 mmol, 42 %) NMR (300 MHz, CDCl3) δ 7.20 (s, 2H), 2.62 (t, 4H), 1.57 (p, 4H), 1.47 -1.25 (m, 12H), 0.98 -0.83 (m, 6H).

1 H

 1 NMR (300 MHz, CDCl3) δ 8.98 (s, 8H), 3.16 (t, J = 8.2 Hz, 16H), 2.11 -1.93 (m, 16H), 1.71 (p, 16H), 1.63 -1.55 (m, 16H), 1.50 -1.18 (m, 128H), 0.87 (t, 24H), -1.08 (s, 2H).λmax (CHCl3): 672 nm, 708 nm 3,4,12,13,21,22,30,31-octahexyl-2,3-naphthalocyanines[75] (C6H2Nc) 6,7-dihexylnaphthalonitrile (100 mg, 0.29 mmol, 1 eq.) was solubilized in 3 mL of 1-pentanol and heated to reflux (120 °C) for 5 min. Small pieces of lithium washed in cyclohexane (approximatively 12 mg, with LiOH traces on sides), rinsed with cyclohexane, were quickly introduced. The mixture turned green over the first 20 min. It was heated to reflux for 3 h (150°C). The crude mixture was cooled below 80 °C and 8 mL of acetic acid was poured in the flask. It was stirred to 100 °C for 30 min. The mixture was left to cool to rt and poured in 80 mL of a mix water-MeOH (1-1) and a dark green precipitate appeared. The dark solid was filtered and rinsed with methanol (300mL) and hot methanol (100 mL) and ethanol (50mL).

  1 H NMR (300 MHz, CDCl3) δ 8.14 (s, 8H), 3.09 -2.64 (m, 16H), 2.15 -1.83 (m, 16H), 1.75 -1.63 (m, 16H), 1.61 -1.42 (m, 32H), 1.07 (t, 24H). λmax (toluene): 612 nm, 679 nm. HRMS (APCI) m/z: [M+H] + Calc for C80H112N8ZnH 1249.8374. Found 1249.8380; (Error: 0.5 ppm).

8. 0

 0 Hz, 16H), 1.74 (p, J = 6.8 Hz, 16H), 1.67 -1.43 (m, 32H), 1.05 (t, J = 7.0 Hz, 24H). λmax (toluene): 632 nm, 704 nm HRMS (APCI) m/z: [M+H] + Calc for C80H112N8OTiH 1249.8511. Found 1249.8520; (Error: 0.7 ppm).

  H RMN (300 MHz, CDCl3) : δ (ppm) = 10,32 (s, 2H) ; 9,41 -9,39 (d, 4H) ; 9,10 -9,08 (d, 4H) ; 8,30 -8,27 (dd, 4H) ; 7,83 -7,80 (m, 6H) ; -3,1 (s, 2H)

1 H

 1 NMR (600 MHz, CDCl3) δ 10.35 (s, 2H), 9.46 (d, J = 4.4 Hz, 4H), 9.16 (d, J = 4.5 Hz, 4H), 8.28 (d, J = 6.8 Hz, 4H), 7.83 -7.78 (m, 6H).λmax (CHCl3): 407 nm, 535 nm XII.8. Synthesis of bay substituted PDIs XII.8.1. Synthesis of the di-substituted PDA 15

1, 7 -( 3 ', 5 '

 735 -di-t-butylphenoxy)perylene-3,4:9,10-tetracarboxydianhydride[107] (15)13 & 14 mixture (3.01 g, 5.45 mmol, 1eq.), 3,5-di-tert-butylphenol (3.49g, 16.9 mmol, 3.1 eq.),and anhydrous cesium carbonate (3.20 g, 9.81 mmol, 1.8 eq.) were added to a 3-neck-RBF under argon. Whilst stirring, dry N,N-dimethylformamide (180 mL) was added via syringe and the mixture was heat to 160 °C for a 2h20 period. The dark red mixture was cooled to rt, cold acetic acid (60 mL) was added and left the mixture was left over a 2h period in an ice bath.MeOH (20 mL) were added to precipitate the product. The red solid was filtered, washed with cold methanol (200 mL), and purified via a soxhlet with methanol (300 mL, 16 h) as solvent.The dark red paste recovered in the soxhlet was dried under reduced pressure (0.1 mbar) at 40 °C to give 15 as a dark red solid (3.91 g, 72%). 1 H NMR (400 MHz, CDCl3) 9.76 (d, 2H, J= 8.4 Hz), 8.69 (d, 2H, J= 8.4 Hz), 8.37 (s, 2H), 7.42 (s, 2H), 7.04 (s, 4H), 1.36 (s, 36H).

1 H

 1 1 H RMN (CDCl3, 300MHz): δ 8.68 (s, 4H), 4.15 (d, 4H), 1.95 (m, 2H), 1.38 (m, 16H), 0.95 (m, 12H)1,6,7,12-tetra(4-t-butylphenoxy)[63] -PDI (17) (16) (8.20 g, 10.90 mmol, 1eq.), 4-tertbutylphenol (13.1 g, 87.2 mmol, 8 eq.) and Cs2CO3 were solubilized in NMP (500 mL) in an RBF capped with a condenser. Whilst stirring, the mixture was placed under an inert atmosphere and heated to 120 °C for a 18 h period. The mixture turned red to dark purple and was left to cool at rt. HCl 1M (400 mL) was added and the product extracted with DCM (4x50 mL). The combined organic layer was rinsed with distilled water (2x100 mL) and with NaOH 1M (2x 200 mL). The organic layer was dried on MgSO4 and evaporated under reduce pressure. The dry solid was purified by chromatoflash with 2 x 330 g column. PE-EtOAc (9-1) was used as eluent. The red first fraction was evaporated under reduce pressure to 17 as a cherry red sticky solid (8.86 g, 67%). RMN (CDCl3, 300 MHz) : δ 8.24 (s, 4H), 7.23 (d, J = 8.8 Hz, 8H), 6.83 (d, J = 8.7 Hz, 8H), 4.13 -3.96 (m, 4H), 1.86 (m, 2H), 1.29 (m, 52H), 0.97 -0.78 (m, 12H).

1, 6 , 7 ,

 67 12-tetra(4-t-butylphenoxy)[63] -PDA (18)(17) (5,0 g, 4.2 mmol, 1eq.) and KOH (30 g, 0.53 mol, 126 eq.) were solubilized in isopropanol (300 mL) in a RBF capped with a condenser. Whilst stirring, the mixture was heated to 110 °C for 16 h. Then, the dark purple mixture was left to cool to rt and of acetic acid (100 mL) were added. The mixture was stirred for a 1 h period and turned red. The crude mixture was added to distilled water (400 mL) and the precipitate filtered. The red solid was rinsed with cold water (200 mL) and dried under reduced pressure (1 mbar, 50 °C) for 24 h. 18 was obtained as a red solid (6.87 g, 99%). No further purification was carried on to avoid the opening of the anhydrides. 1 H RMN (CDCl3, 300MHz): δ 8.23 (s, 4H), 7.23 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.1 Hz, 2H), 1.26 (s, 36H).

1 H 1 HXII. 10 .

 1110 NMR (400 MHz, CDCl3) δ 9.79 (d, J = 8.4 Hz, 2H), 8.74 -8.67 (m, 6H), 8.39 (s, 2H), 7.78 (d, J = 8.0 Hz, 4H), 7.54 (d, J = 5.2 Hz, 4H), 7.46 (d, J = 8.1 Hz, 4H), 7.37 (s, 2H), 7.06 (s, 4H), 1.34 (s, 36H). Following the general protocol: Using (15) (200 mg, 0.25 mmol) and 2-(pyridin-3-yl)aniline (128 mg, 0.75 mmol 3.0 eq.) we obtained PDI3Ph3Py as a red solid (140 mg, 52%). NMR (400 MHz, CDCl3) δ 9.75 (d, J = 8.4 Hz, 2H), 8.82 (s, 2H), 8.67 (d, J = 8.3 Hz, 2H), 8.58 (d, J = 4.8 Hz, 2H), 8.34 (s, 2H), 7.83 (d, J = 8.0 Hz, 2H), 7.68 -7.53 (m, 6H), 7.40 -7.28 (m, 6H), 7.04 (s, 4H), 1.31 (s, 36H).-Statistical synthesis of monopyridyl-PDI from PDA (15)Synthesis of mono phenyl-monopyridyl-PDI (19)(15) (0.60 g, 0.75 mmol), 4-aminopyridine (70 mg, 0.75mmol, 1 eq.), zinc acetate (0.068 g, 0.37 mmol, 0.5 eq.) and distilled quinoline (10 mL) were added to a 25 mL RBF capped with condenser. The reaction was stirred under an inert atmosphere at 200 °C for 3 h. The mixture was left to cool to rt and aniline was added (0.07 mL, 0.75 mmol, 1eq.). The mixture was heated to 200 °C for a 14 h further period. After cooling to rt, the mixture was added to HCl (1M, 20 mL) and the precipitate was filtered. Two successive chromatoflash with DCM-MeOH(98-2) and DCM-MeOH-Et3N (97-2-1) as eluents didn't allow to separate the mixture of product.

Figure 101 .

 101 Figure 101. 1H NMR of the purest fraction of product obtained

Figure 102 :Figure 103 :

 102103 Figure 102 : Absorbance of saturated solution of C60-cat in o-DCB diluted (blue: 100x, pink: 20x, black 13x)

Figure 105 .

 105 Figure 105. NaCl lattice (on the left) and Coulomb forces involved (on the right)

Figure 107 .

 107 Figure 107. Dipole-dipole interaction between acetone molecules

Figure 108 .

 108 Figure 108. Hydrogen bond in carboxylic acid dimer

Figure 110 .

 110 Figure 110. Surface patterning governed by Van der Waals forces.[123]

Figure 112 .

 112 Figure 112. Covalent, ionic and coordinate bonds illustration (drawn by http://pearlsofrawnerdism.com/)

Figure 116 .

 116 Figure 116. Association constant ranking of ZnPc, ZnP or ZnNc with PDI using Zn-pyridyl or Zn-imidazolyl binding

  These constants were calculated using different spectroscopic methods at different concentration ranges and using different solvents. El-Khouly et al. (Figure 116, far left) measured this association by fluorescence spectroscopy in toluene using a linear regression method. Drewello et al. (Figure 116, second from left) did it via both absorbance and fluorescence titration in o-DCB, calculating the association using a non-linear regression method. Only fluorescence data could be used in this case because no distinguishable effect could be observed by absorbance. Fukuzumi et al. (Figure 116, middle) measured it by 1H

Figure 117 .

 117 Figure 117. Illustration of association with x=1 and y=1 then y=2. One host with one guest then one host with two guests

Figure 118 .

 118 Figure 118. Possible associations that can be present in the solution systems.

  figure, we chose to represent a guest which does not absorb in the same wavelength range. The relationship between the increase of [HG] complex's absorption together with the decrease of the hosts' signal, can give us information on the association occurring between [H] and [G].

Figure 119 .

 119 Figure 119. Simulated absorbance plot of increasing ratio of guest [G] (not absorbing in UV-Vis) in a host solution [H], keeping the host concentration constant

Figure 121 .

 121 Figure 121. Reported differences between dynamic and static quenching fluorescence by Ulrike Alexeev and David L. Farren's. [132] (A) is steady-state fluorescence, (B) time resolved fluorescence, (C) is Stern-Volmer plot of static quenching and (D) is Stern-Volmer plot of dynamic quenching

Figure 122 .

 122 Figure 122. left: Absorbance curves of ZnPc and PDI4. Right: emission of a 1-1 mix of ZnPc and PDI4 with 2 different excitation wavelengths, 500 and 600 nm.

Figure 125 . 1 H

 1251 Figure 125. 1 H NMR titration of pyridyl-PDI by addition of zinc-phthalocyanine

  host-guest association [HG] by varying the ratio of [H] and [G]. In this method the total concentration of [H] [G], complexed or not, is kept constant and measurements by use of different spectroscopic techniques are performed in samples (aliquots) with different ratios of either [H] or [G]. The Job plot is obtained by plotting the varying absorbance values at a defined wavelength against the mole fraction of titrant used (guest molecule). This plot can then give us information about the species/complexes present in solution and their stochiometric ratios.

  As a consequence, new mathematical fitting models to replace the old methods rely on two types of solutions. The first one consists in the use of an expensive software which doesn't give us access to the algorithm used to perform the fitting. Hypersquad® and Octet® are the main examples of these types of software. The second option, is to use/develop a custom macro of Excel or Matlab. This kind of macro is available at supramolecular.org, and is an open-source binding calculator developed by Pall Thordarson which can be used to perform 1:1 and 1:2 model fittings on experimental titrations. In the 1:1 model the fitting is based on three equations: equation (2) which defines the association constant for this model, equation (8) which links the change of physical parameter measured to [HG] and equation (9) which links [HG] to the initial concentration of H0 and G0 in the solution.

Figure 128 .

 128 Figure 128. Pyridylzinc coordination systems studied in solution

Figure 129 .

 129 Figure 129. Simple and di association of ZnPc on PDI4

Figure 130 .

 130 Figure 130. [Ru(CO)Pc-PDI4-Ru(CO)Pc] complex

Figure 131 .

 131 Figure 131. π-stacking and Steric hindrance balance involved in the solubility

*

  Not quantified but observed during solvent tests

Figure 132 .

 132 Figure 132. Absorbance spectra of ZnPc at 2 x 10 -5 M in CHCl3 recorded over 17 min

Figure 133 .

 133 Figure 133. El-Khouly et al. Absorbance titration of AuPpy added to a ZnPc solution in o-dichlorobenzene[143]

  shows the characteristic signals of the ZnDPP, ZnPc PDI4 and PDIC7 solutions studied in CHCl3. We can observe the characteristic signals of the ZnDPP with its intense and sharp absorption of its Soret band, the PDI's typical absorption showing a main peak with a shoulder on its left and finally, the ZnPc, whose main absorption is the Q-band.

Figure 134 .

 134 Figure 134. Characteristic absorption signals (normalized) of ZnDPP, ZnPc PDI4 and PDIC7 in CHCl3, highlighting the Q and Soret band regions that will be monitored during the titration experiments.

Figure 135 .Figure 136 .

 135136 Figure 135. Qualitative methods followed to force the complex formation by adding an excess of each component.

Figure 136 .

 136 Figure 136. Left: large excess of ZnPc to a PDI4 solution. Right: large excess of PDI4 added to ZnPc solution, both in CHCl3

Figure 137 .

 137 Figure 137. Schema of experiment via the dry complexation (titration, evaporation and re-solubilization).

Figure 138 .

 138 Figure 138. Dry mixtures over increasing ratio (C1 to C10) of ZnPc/PDI4 in CHCl3

Figure 139 .

 139 Figure 139. Schema showing titration performed at 40 °C, samples are collected and diluted prior analysis.

Figure 140 .

 140 Figure 140. Absorbance monitoring of a PDI4 solution with increasing concentration of ZnPc in CHCl3.

Figure 141 .

 141 Figure 141. Schema of the experiment with ZnPc (5 mol% Py), the diluted aliquot, adding increasing amounts of a PDI solution prior to analysis.

Figure 142 .

 142 Figure 142. A set of ZnPc absorbance spectra recorded every 2 min in CHCl3 +5 mol% pyridine.

Figure 143 .

 143 Figure 143. Accumulated absorbance spectra of a 1:1 ZnPC-PDI4 solution with pyridine 5 mol% (over 10 min).

( 1 ,

 1 2, 3). At the beginning of the addition, the absorbance increases in a linear fashion as PDI4 is added (1). This can mean that the PDI reduces the aggregation of the ZnPc via some form of association. This trend is present until we reach a PDI4 concentration of 1.4 µM. After this concentration, the absorbance stays constant until it changes again at 2.8 µM(2). At this point, the absorbance drops once again in a linear fashion, proportional to the dilution of the ZnPc (3).

Figure 144 .

 144 Figure 144. Left: absorbance plots over addition of PDI4 to a solution of ZnPc in CHCl3. Right: the absorbance maximum intensities of ZnPc (in red) and the PDI4 (in black) plotted against the concentration of PDI4.

Figure 145 .

 145 Figure 145. Left: absorbance of a PDI4 solution in CHCl3 (1.3 µM) with increasing concentration of ZnPc solution (0 to 14 µM). Right: plots of the 4 absorbance maxima vs the ZnPc concentration.

Figure 146 .

 146 Figure 146. Absorbance intensity shift over increasing ratio of (left) PDI4 to ZnPc solution and (right) ZnPc to PDI4 in CHCl3.

Figure 147 .

 147 Figure 147. Left: absorbance of PDI4 adding ZnDPP in toluene. Right: same titration in CHCl3

Figure 148 .Figure 149 .

 148149 Figure 148. Absorbance of PDI4 solution (1.2 µM) with increasing concentration of ZnDPP (0 to 10 µM) in CHCl3.

Figure 149 .

 149 Figure 149. PDI4 with increasing concentration of ZnDPP. ZnDPP pure absorbance was subtracted for every concentration of ZnDPP added.

Figure 150 .

 150 Figure 150. Left: titration of ZnDPP solution with increasing concentration of PDI4 in CHCl3. Middle: a zoom on the Soret band peak at 412 nm. Right: absorbance intensity vs concentration of PDI4 added.

  5 equivalents), evidencing a clear change of regime. In the second experiment, where the ZnDPP is added to the PDI4 we can see two different slope changes, also at the same points. In this case, the change is more prominent for the values obtained at 404 nm (new peak). The points where the slopes change match with the 1 and 2 equivalents expected from the 1:1 and 1:2 association model between the PDI4 and ZnDPP. Because of the 10% calculated uncertainty on the weighed mass and that the linear regression was plotted on a few points we can explain this little difference with the model.

Figure 151 .

 151 Figure 151. Left: absorbance intensity of PDI4-ZnDPP mixture subtracted by pure ZnDPP plotted with the increasing ratio of PDI4 added. Right: absorbance intensity of PDI4-ZnDPP mixture subtracted by pure ZnDPP plotted with the increasing ratio of ZnDPP added.

Figure 152 .

 152 Figure 152. PDIC7 structure compared to PDI4 to bind ZnPc of ZnDPP

Figure 153 .

 153 Figure 153. Left: addition of PDIC7 (0 to 15 µM) to a saturated ZnPc solution (1.7 µM). Right: intensity shift of absorbance maximum of PDIC7 (551 nm) and ZnPc (671 nm) over the increasing concentration of PDIC7.

Figure 154 .

 154 Figure 154. Absorbance intensity over increasing ratio of PDIC7 with ZnPc.

Figure 155 .

 155 Figure 155. Left: addition of PDIC7 (0 to 15 µM) to a ZnDPP solution (2.5 µM). Right: intensity shift of absorbance maximum of PDIC7 (551 nm) and ZnDPP (412 nm) over the increasing concentration of PDIC7.

Figure 156 .

 156 Figure 156. Left: absorbance titration of a ZnDPP by PDIC7 subtracted by pure ZnDPP and pure PDIC7 absorbance spectra. Right: the intensity of 412 nm and 422 nm peaks over increasing ratio of PDIC7.

Figure 157 .

 157 Figure 157. Left: absorbance of C6ZnPc solution (1.8 µM) with increasing concentration of PDI4 (0 to 22 µM).

Figure 158 .

 158 Figure 158. Complexes studied by El-Khouly et al. with fluorescence titration results of ZnNc-PDIim dyad (2).

Figure 159 .

 159 Figure 159. On the left, absorbance and emission of PDIs and CxZnPc/ZnPc in toluene with a representation of 3 excitation areas possibly enabling a selective excitation of the different molecules. On the right, the ZnDPP and PDI4 absorbance.

Figure 160 .

 160 Figure 160. C6ZnPc-PDI4 (1-1) in toluene, emission spectra with different excitation wavelengths. NB: 680 and 800 nm peaks are only Rayleigh second order diffraction peaks

Figure 161 .

 161 Figure 161. Emission of PDI4 (0.52 µM) with increasing concentration of ZnPc in toluene. The solution was excited at 532 nm. * Solutions prepared the next day from same stock solutions. A is an abnormally high emission, B shows almost no modification of the PDI emission upon addition of ZnPc, C shows aggregation of PDI4 on the emission.

  5 equivalents) to a fixed volume of C6ZnPc (2.5 mL) in a fluorescence cuvette. The emission spectra for this titration are shown in the figure below.

Figure 162 .

 162 Figure 162. Emission of C6ZnPc (6.4 µM) with increasing number of equivalents of PDI4. Dotted lines represent emission spectra obtained with 520 nm excitation and continuous line correspond to the emission spectra acquired with 620 nm excitation.

Figure 163 .

 163 Figure 163. Left: representation of the 2 excitation wavelengths selected for the ZnDPP-PDI4 titration. Right: emission spectra of 0 to 1.2 equivalent addition of ZnDPP to PDI4 in toluene.

Figure 164 .

 164 Figure 164. Over 0 to 1.2 equivalents of ZnDPP, we observed a decrease in intensity. This decrease which continued with 1.7 to 4.7 equivalents of ZnDPP is without a doubt correlated to the dilution factor. The volume increased by 15% over the addition and the emission collected decreased by the same amount. From this data, we found no evidence of association since neither the emission wavelength or the intensities of both ZnDPP and PDI4 are affected.

Figure 164 .

 164 Figure 164. On the left, decay of emission of PDI4 under addition of 0 to 1.2 equivalents of ZnDPP. On the right, the emission with the second PDI4 solution and 1.7 to 4.7 equivalents added.

Figure 165 .

 165 Figure 165. Fitting of fluorescence decay of PDI4-ZnDPP (1-3) in toluene. In (eq. 1): biexponential fit function considering two contributions, one with 4.35 ns as PDI4 lifetime and the other one with 2.3 ns as ZnDPP lifetime, factor c gives the weight of ZnDPP. In (eq. 2): monoexponential fit considering only ZnDPP component with a 2.3 ns lifetime. In (eq. 3): monoexponential fit considering only PDI4 component with a 4.35 ns lifetime.

  y=a*(0*exp(-(x-b)/4.35)+exp(-(x-b)/2.3)) max dev:170, r 2 =0.969 a=1000, b=16.4 Equation 3 : y=a*(exp(-(x-b)/4.35)+0*exp(-(x-b)/2.3)) max dev:185, r 2 =0.948 a=1000, b=14.7 Equation 1 : y=a*(exp(-(x-b)/4.35)+c*exp(-(x-b)/2.3)) max dev:83.

Figure 166 .

 166 Figure 166. Lifetime ratio ZnDPP/PDI4 (as determined from the biexponential fit of each fluorescence decay (eq. 1)) vs ratio of concentration [ZnDPP]/[PDI4]. The red line y=x materializes an identical ratio in lifetime and concentration as it could be expected from a simple mix without any interactions between the molecules. The first point of the second part of titration doesn't belong to y=x line which might be due to a little underestimated concentration of PDI4 solution.

Figure 168 .

 168 Figure 168. 1H NMR titration of ZnPc solution with increasing volume of PDI4 solution in CDCl3 (1% Pyridine-D5)

Figure 169 .

 169 Figure 169. Shielding and un-shielding effect of ZnPc on PDI4 with the π-π stacking model (association A), and Zn-pyridyl coordination model (association B).

Figure 170 . 1 H

 1701 Figure 170. 1 H NMR in CDCl3 of saturated ZnPc over the addition of 0 to 800 µL of PDI4 solution (C = 2.3 mM).

Figure 171 . 1 H

 1711 Figure 171. 1 H NMR in CDCl3 of PDI4 solution (0.5 mM) over the addition of 0 to 180 µL of saturated ZnPc.

Figure 172 . 1 H

 1721 Figure 172. 1 H NMR in CDCl3 of ZnDPP solution (0.84 mM) with addition of 0 to 290 µL of PDI4 (2.3 mM)

Figure 174 .

 174 Figure 174. NMR shift of PDI4 protons Hb and Hd in both titrations with ZnDPP.

Figure 175 . 1 H

 1751 Figure 175. 1 H NMR titration in CDCl3. Left: addition of saturated and filtered solution of ZnPc to a PDIC7 solution (0.055 mM). Right: Addition of a ZnDPP solution (2.3 mM) to a PDIC7 solution (0.13 mM).

Figure 176 .

 176 Figure 176. Chemical shift of PDIC7 Hb and Hc protons with the increasing quantity of ZnPc (cross) and the increasing quantity of ZnDPP (lozenge)

Figure 177 .

 177 Figure 177. 1H NMR in CDCl3 of C12ZnPc (0.05 mM) over four additions of PDI4 aliquots. Temperature was 323 K and we repeated the last measure after cooling at 300 K.

Figure 178 . 1 H

 1781 Figure 178. 1 H NMR of PDI4 over ZnDPP increasing concentration in CDCl3. a and b proton were used for the non-linear fitting.

Figure 179 .

 179 Figure 179. Nelder-Mead fitting of the NMR data ZnDPP-PDI4. [G]0 is the PDI4 guest and [H]0 the ZnDPP host.

  used the same proton (a) and (b) to plot the chemical shift with the ratio [H]/[G]. This resulted to a divergent fitting with the 1:1 model. The fitting with the 2:1 model resulted in the following plot (Figure 180).

Figure 180 . 2 :

 1802 Figure 180. 2:1 model fitting for the titration of ZnDPP ([H]0) by PDI4 ([G]0) by NMR based on Ha and Hb shifts. Top is the fitting plot and below the residual plot.

Figure 181 .

 181 Figure 181. Left: 1:1 model fitting for the titration of ZnDPP ([H]0) by PDI4 ([G]0) by absorbance based on 404 nm and 411 nm absorbance intensity shift in CHCl3. Right: 2:1 model fitting for the same titration curves. Top are the non-linear fitting plot and bottom are the residual plots of the fits.

Figure 182 :

 182 Figure 182 : confocal microscopy set-up involving an inverted microscope (Olympus IX71) coupled to picosecond laser excitation (NKT Photonics-SuperKEVO, 30-50 ps, 20 MHz) associated to a filter module (SuperK varia) enabling the tunable selection of a specific wavelength line for excitation (from =400 to 800 nm, with   5 nm). Complementary filters are also used for further laser cleanup (LL01-532-12.5 or SP01-633RU-25). After reflexion on a semi-transparent plate, the excitation beam is focused into the cell containing the dye solution using a 40x microscope objective. The emitted signal is collected through the same microscope objective and then sent both to a channel plate multiplier (CPM) working in the photon counting mode (Hamamatsu MCP-PMT R3809U-50) or to a spectrometer coupled to a CCD camera (Andor DU401-BR-DD) for a detailed study of the dye solution emission spectra. A set of long pass filters is used to cut the exciting laser beam (SemRock BLP01-532R-25 or BLP01-633R-25). Fluorescence lifetime measurements are made using time correlated measurements (PiquoQuant TimeHarp module)

Figure 183 .

 183 Figure 183. Absorbance curves of PDI4 with increasing volumes of ZnPc solution in toluene

Figure 184 :

 184 Figure 184 : Absorbance curves of ZnPc with increasing volume of PDI4 solution in toluene

Figure 185 :

 185 Figure 185 : Absorbance curves of solubilized mixture (ZnPc-PDI4) with increasing quantity of ZnPc added to PDI4 in CHCl3 (C1 to C10)

Figure 186 :VIII. 3 . 1 .

 18631 Figure 186 : Absorbance curves of PDI4 solution heated at 40 °C with increasing volume of ZnPc solution in CHCl3 (from light blue to dark red)

Figure 187 .

 187 Figure 187 . Absorbance curves of ZnPc solution (in CHCl3 + 5 mol% pyridine) with increasing volume of PDI4 solution added in CHCl3

Figure 190 :

 190 Figure 190 : PDI3 (2.6 µM), PDI3-ZnPc (1:1) and PDI4-ZnPc (1:1) emission with 532 nm excitation in toluene. Left axis is for PDI3.

Figure 193 .To a 6 . 4 µMFigure 196 .

 19364196 Figure 193. PDI4 (C6ZnPc (9.2 µM), PDI4 (10µM) and PDI4-ZnPc (1-1) emission in toluene.

Figure 197 .

 197 Figure 197. Smoothed lifetime fluorescence of C6ZnPc with increasing concentration of PDI4 in toluene, excited at 520 nm

VIII. 6 .

 6 C12ZnPc-PDI4To a 4.5 µM C12ZnPc solution in toluene (0.7 mL) were added aliquots of 5.2 µL of PDI4 (0.21 mM) ([PDI4] =1.6 to 9.4 µM). The fluorescence emission was measured 10 min after each addition with 532 nm and 620 nm excitation using the confocal microfluorescence setup. The measure of fluorescence were repeated 3x to monitor if any degradation happened. The lifetime was recorded using the same setup, changing the detector.

Figure 198 . 1 :

 1981 Figure 198. Emission spectra of C12ZnPc upon increasing concentration of PDI4 in toluene

Figure 199 .Table 23 :

 19923 Figure 199. Emission spectra excited at 415 nm (on the left) and excited at 520 nm (on the right)

Figure 201. 1 HChapter 3 :

 13 Figure 201. 1 H NMR 400 MHz of ZnDPP with increasing volume of PDI4

Figure 205 .

 205 Figure 205. Preparation of Nitrogen-doped graphene by left: chemical vapor deposition of methane and ammoniac, right transformation of graphene or GO.

207Error!

  Reference source not found.. Depending on the number of clips (1, 2 or 3) around a tristyrylbenzene (TSB) different patterns could be predicted (D, E; F) and then observed on the surface (G, H, F). With the last example with three clips, TSB formed a 2D-network with honeycomb cavities similar on some points to the graphene topology but at a superior scale.

Figure 208 .

 208 Figure 208. Tristyrylbenzene (TSB) with one clip (A), two clips (B), or three clips (C) forming different selfassemblies respectively represented by d, E and F. At the bottom are the STM images on HOPG of these

Figure 210 .

 210 Figure 210. Perylenetetracarboxylate dianhydride (PDA) pattern on surface. Left is theoretical organization on surface to represent the image (a) and (b). Right (a) is the organization on graphene and (b) is the organization on

Figure 211 .

 211 Figure 211. Dexter electron energy-transfer

Figure 212 .

 212 Figure 212. Förster electron energy-transfer

Figure 214 .

 214 Figure 214. STM images on HOPG of a mix of an increasing quantity of 3-nitrobenzene with zinc mesotetradodecylporphyrin (Zn-TDP) in tetradecane. Ratio 3-nitrobenzene -(Zn-TDP) are: (a) 0.01:1, (b) 0.02:1, (c)

Figure 215

 215 Figure 215. a: STM images a: TSB-C2 host honeycomb network, b: ZnPc-ligand in the TSB-C12 host network,

  Figure 216. Left: Pedestal structure and STM image of the self-assembly network on HOPG. Right: STM image of a 1:1 mixture of pedestal with PDI Janus tecton and single pedestal on HOPG.

Figure 218 .

 218 Figure 218. Confocal laser Raman spectrophotometer, associated to a confocal differential visible absorbance spectrophotometer

Figure 221 .

 221 Figure 221. Schema of self-assembly of Tristyrylbenzene on HOPG

  This regular pattern can then be used as a molecular pedestal to a functional molecule attached through axial coordination. Feringa et al. demonstrated they could observe a 3-nitropyridine association by axial coordination.

Figure 223 .

 223 Figure 223. Self-assemble monolayer of tetradodecylporphyrins on HOPG. (a) STM image, (b) model of the packing (only 2 alkyl chains represented for clarity, the other ones are disordered and not observed)

Figure 224 .

 224 Figure 224. Structure of functionalized zinc phthalocyanines

Figure 225 .

 225 Figure 225. PDI design, left is a 3D-structure of the right molecule

(

  ≈60°) compared to the complexes formed via -, and metal-ligand interactions which have either parallel (0°) or perpendicular (90°) arrangements between both Pc and PDI components.Finally, we also studied the functional assemblies where ZnDPP is employed as the pedestal instead of ZnPc. In Figure226, we show the different supramolecular complexes studied by STM on an HOPG surface with TSB-12 and 10 (for ZnDPP) as host network.

Figure 226 .

 226 Figure 226. Graphical representation of the expected set of host-guest systems studied using the complexes formed with the ZnDPP, ZnPC and the three different PDIs (PDI4, PDI3 and PDIC7).

Figure 227 .

 227 Figure 227.30x30 nm² STM image of TSB-C12 + ZnPc-PDI4 (1-1) at air interface. Bias: -1,0 V, current: 25 pA

Figure 228 .

 228 Figure 228. 30x30 nm² STM image of TSB-C12 + ZnPc-PDI3 (1-1) at air interface. Bias : -1,0 V, current : 25 pA

Figure 229 .

 229 Figure 229. Left: STM image of ZnPc-PDI4 and ZnPc-PDI3 1:1 mix in TSB-C12 on HOPG in phenyloctane. Right: Count of median high of each light red spot in area (a) and (b).

Figure 230 .

 230 Figure 230. STM images of TSB-C12 + ZnPc-PDIC7 (1-1) in phenyloctane. Bias: -1,6 V, current: 12 pA

Figure 231 .

 231 Figure 231. 77x77 nm² STM image of TSB-C10 + ZnDPP at air interface. Bias: -0.6 V, current: 13 pA

Figure 232 .

 232 Figure 232. 72x72 nm² STM image of TSB-C10 + ZnDPP-PDI4 (1-1) at air interface. Bias: -0.2 V, current: 20 pA

  Figure 233 shows the STM images of C6ZnPc and C12ZnPc acquired under phenyloctane. The resolution (related to the tip at this time) was better with the C6ZnPc which explains why we can see the alkyl chains in this picture whilst they are almost completely masked in C12ZnPc image. From the images' trace and retrace we measured the lattice of the network. As expected, 6ZnPc resulted to a more compact network (1 molecule in 4.3 nm² vs 1 molecule in 7.3 nm² for the C12ZnPc).

Figure 233 .

 233 Figure 233. Left: 24 x 24 nm² STM image of C6ZnPc in phenyloctane. Bias: -0.55 V, current: 22 pA. Right: 26 x 26 nm² STM image of C12ZnPc in phenyloctane. Bias: -0.95 V, current: 15 pA. The table gives the lattices parameters of the two images.

Figure 234 .

 234 Figure 234. 40 x 40 nm STM image of C12ZnPc-PDI4 (1-1) in phenyloctane. Bias: -0.35 V, current: 12 pA

Figure 235 .

 235 Figure 235. Left: 20 x 20 nm² STM image of C6TiOPc in phenyloctane. Bias: -0.35 V, current: 12 pA. Right: 35 x 35 nm² STM image of C12TiOPc in phenyloctane. Bias: -0.5 V, current: 30 pA.

0. 85 )

 85 . An imaging output port is coupled to a spectrometer (Andor Kymera 193i) with a motorized wide-aperture entrance slit and a scientific-CMOS camera (Andor Zyla 5.5) as the detector. It is an imaging spectrometer with a magnification of 1.07 and a focal distance of 193mm. The spectrometer is equipped with a motorized grating-holder turret with two automatically interchangeable gratings: a first one with 150 line/mm blazed at 500nm and a second one with 1200 line/mm blazed at 600nm. The sample is illuminated using a wide spectral range thermal lamp. The combination of the detector sensitivity and illumination spectrum permits to analyze a spectral range of 400 -950 nm.

Figure 236 .

 236 Figure 236. Schema of the set-up microabsorbance (white lamp source) and microRaman (lasers 532 nm and 633 nm sources) used for the measurements

Figure 238 .

 238 Figure 238. Absorbance curves of C6ZnPc on graphene after drying at air for 10 min at air (blue), rinsing with toluene for 15 min + drying (purple), 2 h of annealing (red), and rinsing+ annealing (black).

Figure 239 .

 239 Figure 239. Left: Absorbance curves of C12TiOPc on graphene after drying at air for 10 min at air (blue) and with 2 h annealing (black). Right: Absorbance curves of C6TiOPcon graphene a after drying at air for 10 min at air (blue) and with 2 h annealing (black)

  adsorbed phthalocyanine with the 633 nm without the Raman emission being masked by the fluorescence emission. The measurements were done through a one-minute acquisition in order to avoid any degradation of the surface by the laser. This explains the weak intensity of the signal collected. The Raman spectra of C6ZnPc, C12ZnPc, C6TiOPc and C12TiOPc are reported in Figure240. The 532 nm excitation (left) show only the D (1335 nm), G (1579 nm) and 2D (2662 nm) bands of the graphene. No particular shift was observed on these peaks and the different ratio of the peaks result from the difference of the graphene layer quality for each sample (related to the graphene transfer procedure). With the excitation at 633 nm, some of the ZnPc vibrational states were observed. The more intense one matches with the C-N vibrational mode of the ZnPc (1504 nm). The 2D band was the only band of the graphene still visible at 633 nm. We used these Raman spectra to observe the behavior of the molecular monolayer on the surface. Indeed, the quenching of fluorescence can directly be observed on the Raman spectra. Here we see that the C12TiOPc (in green) was not completely adsorbed as a fluorescent peak was still visible around a 1700 cm -1 .

Figure 240 .

 240 Figure 240. Raman spectroscopy of graphene surface functionalized with C6ZnPc (red), C12ZnPc (yellow), C6TiOPc (blue) and C12TiOPc (green) excited at 532 nm (left) and 633 nm (right). NB: The negative drop observed at 2000 cm -1 and 2900 cm -1 in the 633 nm excited spectra are related to a dead pixel on the photon detector

Figure 243 .

 243 Figure 243. Optical traject of the light through the sample depending of the angle  (rotation around the y axis)

Figure 244 .

 244 Figure 244. Left: Angle absorbance spectra of C12ZnPc-PDI4 on graphene. Middle: Angle absorbance spectra of ZnPc-PDIC7 in TSB-C12 network on graphene. Right: Angle absorbance spectra of ZnPc-PDI4 in TSB-C12 network on graphene.

Figure 246 .

 246 Figure 246. Functionnalities synthesized

Figure 247 .

 247 Figure 247. Association described in solutions by titrations

  we started to develop the titanyl oxide bond to replace the zinc-pyridyl one. As proved by the titration experiments the coordination of the PDI with ZnPc is relatively weak. Because Ti-O bond is stronger and the structure of titanium allow to have two oxygen attach to it on the same side of the phthalocyanine. It would reinforce the building-block structure to attach to titanium pedestal a catechol ligand. Fullerene functionality attach by a rigid catechol have been image and could lead to another type of functionalization of surface with fullerene instead of PDI (Figure 248. Of course, this strategy could be developed with other catechol or dicarboxylic acid substituents.

Figure 248 .

 248 Figure 248. CxTiPc coordinated by an axial catechol-fullerene substituent

Figure 249 .

 249 Figure 249. Monopyridyl PDI based building-block

Figure 250 .

 250 Figure 250. Example of patterning involving zinc meso-tetraalkylbenzoporphyn

Table 1 : Kumada coupling conditions

 1

	Reference	R substituent	Mg equivalents	Catalyst	veratrole concentration	Reaction time	Yield
	QF02	Hexyl	2,3	5%	0.75 mol/L	18 h	59%
	QF023-QF026	Hexyl	3	4%	0.59 mol/L	20 h	49%
	QF05-QF07	Dodecyl	2,1 + 2*	5% + 2%	0.49 mol/L	16 +16 h	65%
	QF127	Dodecyl	3	5%	0.41 mol/L	14 h	78%
	* To try to improve the conversion the mixture of mono, di-alkylated veratrole and starting material has been reused with
	less catalyst.

Table 2 : Demethylation conditions

 2

	Reference	R substituent	HBr-AcOH volume (ml)	Veratrole quantity (mmol)	Temperature	Reaction time	Yield
	QF03	Hexyl	100 + 100	17.1	140 °C	14h + 5 d	89%
	QF027	Hexyl	100	22.9	150 °C	20 h	95%
	QF09	Dodecyl	100	11.6	150 °C	38 h	92%

Table 3 : Ditrifluoromethylsulfonation conditions

 3

	Reference	R substituent Tf2O quantity	Catechol quantity	DCM volume	Reaction	Yield
			(mmol)	(mmol)	(mL)	time
	QF08	Hexyl	90.5	15	100	14 h	42%
	QF030	Hexyl	129	21.5	80	2 h	50%
	QF010	Dodecyl	62	10	100	14 h	75%
	QF131	Dodecyl	159	26	200	15 h	76%

Table 4 : Cyanation conditions

 4

	Reference	R substituent	Di-triflate quantity (mmol)	DPPF quantity (mmol)	Pd2[dba]3 quantity (mmol)	Zn(CN)2 quantity (mmol)	DMF volume (mL)	Reaction time	Yield
	QF011	Hexyl	6.3	0.72	0.25	7.5	18	2 h +6 d	76%
	QF031	Hexyl	10.7	1.71	0.43	12.84	30	3h	40%
	QF032	Hexyl	4.88	0.78	0.19	5.9	10	14 h	30%
	QF012	Dodecyl	7.7	1.24	0.31	9.29	18	14 h	88%
	QF132	Dodecyl	6.1	1.38	0.34	10.3	17	14 h	42%

Table 5 : Dialkylation of dimethylbutadiene parameters

 5

	Reference	Solvent of LICKOR solution	Temperature addition during Butadiene	Temperature dianion solution before transfer to bromopentane	NMR conversion
	AP01	Pentane	20 °C	20 °C	68%
	AP02	THF	-5 °C	20 °C	Side products
	AP07	Pentane	-20 °C	20 °C	66%
	AP09	Pentane	-78 °C	-78 °C	Oligomer
	AP15 (canula transfer)	Pentane	-5 °C	-78 °C	Oligomer

Table 6 : Stirring time of LICKOR solution

 6

	Reference	Time LICKOR stirring	Time LICKOR + dimethylbutadiene stirring	NMR conversion
	AP01	30 min	10 min	68%
	AP07	2 h	10 min	66%
	AP09	2 h	30 min	67%
	AP15 (canula transfer)	30 min	10 min	Oligomer

Table 7 : octaalkylphthalocyanines synthesis conditions

 7

	Reference R group	Phthalonitrile quantity (mmol)	Li quantity (mmol)	Pentanol volume (ml)	Reaction time a	Yield
	QF016	Dodecyl	1.07	2.5	5	3 h + 2 h	25%
	QF017	Hexyl	1.01	2.8	3	3 h + 2 h	32%
	QF020	Hexyl	0.84	2.8	3	3 h + 2 h	20%
	QF027	Dodecyl	2.14	4.3 b	8	1 h 30 + 14 h	40%
	QF034	Hexyl	3.37	6.7 c	12	3 h + 30 min	48%

a. Time of reaction with lithium + time of reaction after addition of AcOH, b. Li added in 4 times over 1 h c. Li added in 2 times over 15 min

Table 8 : Zinc metalation of octaalkylphthalocyanines conditions Reference R group R8H2Pc quantity (mmol) Zn(OAc)2 quantity (mmol) CHCl3 volume (ml) Reaction time

 8

	Yield

Table 9 : Results of synthesis of CxTiOPc Characterization and physical properties of substituted phthalocyanines III.8. NMR of substituted phthalocyanines

 9

	Proton Nuclear Magnetic Resonance spectroscopy (1H-NMR) is a very efficient method to
	obtain structural information on organic molecules. It is based on the magnetic resonance
	frequency measure of non-zero spin elements under a high magnetic field (9,31 Tesla for a 400

  As an example, Cammidge et al. showed

	Starting materials	Reactants	Solvent	Result
	CxH2Pc	DBU, Ti(OnBu)4	Pentanol, reflux	No product
	CxH2Pc	DBU, Ti(OnBu)4	DMF, reflux	Low conversion (10-20%)
	CxPn	Urea, DBU, Ti(OnBu)4	Pentanol	Mix with CxH2Pc(10-30%)
	CxPn	TiCl4	Cl-naphthalene	≥58% yield

Table 10

 10

	below summarizes the Q-band's molar extinction coefficients measured in CHCl3,
	toluene and THF for the CxZnPc. With molar extinction coefficients between 1.10 5 and 4.10 5

Table 10 : Molar extinction coefficient of octaalkyl substituted phthalocyanines

 10

		C6H2Pc	C12H2Pc	C6ZnPc	C12ZnPc	C6TiOPc	C12TiOPc	C6H2Nc	C6ZnNc
	ε toluene
	(λmax)	2,2.10 5	1,8.10 5	3,9.10 5	3,5.10 5	2,4.10 5	2,3.10 5	2,3.10 5	3,9.10 5
	(L.mol -	(706 nm)	(706 nm)	(684 nm)	(684 nm)	(704 nm)	(704 nm)	(797 nm)	(785 nm)
	1 .cm -1 )
	ε CHCl3
	(λmax)
	(L.mol -
	1 .cm -1 )

1,7.10 5 (708 nm) 1,5.10 5 (708 nm) 2,0.10 5 (688 nm) ND 1 2,5.10 5 (710 nm) 9,5. 10 4 (709 nm) 7,5.10 4

								(806 nm)	ND 2
	ε THF
	(λmax) (L.mol -	ND	ND	2,9.10 5 (679 nm)	3,3.10 5 (680 nm)	ND	ND	ND	ND
	1 .cm -1 )
	1. Because of aggregation of C12ZnPc in CHCl3 the measure was not reported
	2. Because of high decomposition of C6ZnNc in CHCl3, the measure was not reported

Table 11 : Emission photoluminescence quantum yield and lifetime of substituted phthalocyanines

 11

		C6H2Pc	C12H2Pc	C6ZnPc	C12ZnPc	C6H2Nc	C6ZnNc
	λmax emission toluene (nm) PLQY lifetime	711 41% 5,92 ns	711 40% 5,78 ns	694 23% 3.31 ns	692 16% 3.46 ns	797 11% ND	785 7% 1 ND
	λmax emission CHCl3 (nm) PLQY lifetime	715 43% 5,91 ns	716 39% 6.18 ns	699 21% 3.32 ns	695 21% 3.76 ns	805 6% ND	790 ND 3.32 s
	1.Solvent was degassed 15 min with N2

Table 12 : HOMO-LUMO energies of octahexylphthalocyanines C6H2Pc C6ZnPc C6H2Nc C6ZnNc HOMO energy (eV)

 12

		-5.06	-5.0	-4.84	-4.70
	LUMO energy (eV)	-3.35	-3.24	-3.33	-3.15

Table 13 : Dilution effect on DPP synthesis

 13

	Reference	Dipyrromethane	DCM	Concentration of	Reaction	Yield
		(mmol)	volume (ml)	dipyrromethane (mm)	time (h)
	BK05	1,35	1000	1.3	67	25%
	BK06	1.30	500	2.6	17	29%
	BK07	1.40	100	13	17	17%

Table 14 : Extinction coefficient of PDIs

 14

		PDI4	PDI3	PDI4Ph4Py	PDI3Ph3Py
	ε toluene (λmax) (L.mol -1 .cm -1 )	5.7x10 4 (547 nm)	5.3x10 4 (547 nm)	4.7x10 4 (547 nm)	4.9x10 4 (547 nm)
	ε CHCl3 (λmax) (L.mol -1 .cm -1 )	5.0x10 4 (557 nm)	4.4x10 4 (556 nm)	3.1x10 4 (557 nm)*	ND
	ε THF (λmax) (L.mol -1 .cm -1 )	5.3x10 4 (544 nm)	5.1x10 4 (544 nm)	5.5x10 4 (544 nm)	4.9x10 4 (544 nm)
	*Solution started to form aggregates

Table 15 : PLQY and lifetime fluorescence of PDIs in solution

 15

		PDI4	PDI3	PDI4Ph4Py
	λmax emission toluene (nm)	572	574	576
	PLQY	79%	79%	92%
	lifetime	5,14 ns	4,68 ns	4,24 ns
	λmax emission CHCl3 (nm)	585	585	586
	PLQY	81%	84%	85%
	lifetime	5,09 ns	5,15 ns	4,57 ns

  Nuclear magnetic resonance experiments were recorded on Bruker® Avance spectrometers 300, 400 or 600 MHz equipments from Sorbonne Université's NMR platform. The proton and carbon chemical shifts (δ) are reported in ppm and are referenced to the residual solvent signal: The NMR solvent contains some tetramethyl silane (TMS) which can be used together with the NMR solvent peak to calibrate the NMR chemical shifts. In our case we preferred to use the solvent shift as reference (CHCl3 δ= 7.26 ppm). The purity of our target molecules could be assessed with the NMR spectrum. In intermediary components which

	CDCl3 (7.26, 77.16), toluene (7.26, 7.16, 2.36, 137.88) and THF-D6 (3.75, 68.00 3). The
	abbreviations used to describe the multiplicity of the signals are: (s) for singlet, (d) for doublet,
	(t) for triplet, (q) for quartet, (p) for quintuplet (dd) for doublet of doublets, (dt) for doublet of
	triplets and (m) for multiplet.

were not completely dry some solvent residues were observed: water (from 1.53 up to 1.61 ppm depending on the pH), grease (0.8 ppm and 1.26 broad peaks), acetone (2.17 ppm) and methanol (3.49 ppm) which were used to clean the NMR tubes and the solvents used during the purifications. Mass spectrometry was done with a LC-LTQ-Orbitrap, Thermo-Fisher in positive and negative mode.

  C NMR (101 MHz, CDCl3) δ 146.94, 132.80, 112.81, 56.09, 32.61, 31.93, 31.82, 29.57, 22.80, 14.24.

1

H NMR (400 MHz, CDCl3) δ 6.66 (s, 2H), 2.53 (t, 4H), 1.56 (s, 4H), 1.42 -1.26 (m, 12H), 0.91 (t, 6H).

[START_REF] Buchler | Synthesis and Properties of Metalloporphyrins[END_REF]

  C NMR (101 MHz, CDCl3) δ 146.94, 132.80, 112.81, 56.09, 32.61, 31.93, 31.82, 29.57, 22.80, 14.24.

	4,5-Dibromoveratrole (10.0 g,
	33.8 mmol, 1 eq.), Pd[(dppf)Cl2] (1.24 g, 1.69 mmol, 5 mol%) and n-dodecylmagnesium
	bromide (35 mL, 2.25 M, 79 mmol, 2.1 eq.) reacted in Et2O (10 mL). 1-C12 was obtained as a
	translucent oil (6.30 g, 47%).
	1 H NMR (400 MHz, CDCl3) δ 6.66 (s, 2H), 2.53 (t, 4H), 1.56 (s, 4H), 1.42 -1.26 (m, 12H), 0.91 (t, 6H).

[START_REF] Buchler | Synthesis and Properties of Metalloporphyrins[END_REF]

,9,10,16,17,23,24-octakisdodecylphthalocyanine

	1 H NMR (300 MHz, CDCl3) δ 8.90 (s, 8H), 3.15 (t, J = 8.1 Hz, 16H), 2.12 -1.96 (m, 16H), 1.83 -1.65 (m, 16H),
	1.65 -1.42 (m, 32H), 1.04 (t, J = 6.9 Hz, 24H), -1.29 (s, 2H).
	1 H NMR (300 MHz, Toluene-d8) δ 9.26 (s, 8H), 3.12 (t, J = 8.4 Hz, 16H), 1.96 (p, 16H), 1.62 (p, 16H), 1.51 -
	1.36 (m, 32H), 1.05 (t, 24H), -1.23 (s, 2H). λmax (CHCl3): 672 nm, 708 nm
	2,3

Route 2: From phthalonitriles 2,3,9,10,16,17,23,24-octahexylphthalocyaninato zinc

1 H NMR (400 MHz, Toluene-d8) δ 8.35 (s, 8H), 7.32 (s, 8H), 2.87 -2.40 (m, 16H), 1.90 -1.64 (m, 16H), 1.63 -1.21 (m, 48H), 1.08 (t, 24H). λmax (CHCl3): 712 nm, 791 nm XII.5.

  C NMR (101 MHz, CDCl3) δ 151.50, 144.61, 135.24, 123.60, 34.24, 31.98, 30.36, 29.91 to 29.76 (overlapping picks), 29.44, 22.72, 14.13. λmax (toluene): 632 nm, 704 nm. HRMS

(APCI) m/z: [M+H] + Calc for C128H208N8OTiH 1922.6023. Found 1922.6028; (Error: 0.2 ppm).

  The mixture of 13 & 14 was obtained as a red solid which was dried at 45 °C under reduced pressure (1 mbar) for 48 h. IR:1818, 1768, 1736,1724, 1591, 1560, 1499, 1406, 1375, 1306, 1285, 1229, 1212, 1187, 1164, 1139 cm -1

Table 19 : Fitting parameters of C6ZnPc adding PDI4 lifetime fluorescence excited at 620 nm in toluene Equation y = A1*exp(-x/t1) + y0

 19

	Sample	C6ZnPc	1,2 µM	2,4 µM	3,6 µM	4,8 µM	7,2 µM
			PDI4	PDI4	PDI4	PDI4	PDI4
	Reduced Chi-Sqr	2,04422 1,53201	1,35815	1,23376	1,52539	11,50332
	Adj. R-Square	0,996	0,99481	0,99385	0,99318	0,99365	0,99931

Table 20 : Lifetime coefficient (t1) of C6ZnPc adding PDI4 lifetime fluorescence excited at 620 nm in toluene t1 (ps) Standard Error

 20

	C6ZnPc	2872,755	9,50474
	1,2 µM PDI4	2880,276	10,87353
	2,4 µM PDI4	2826,206	11,49675
	3,6 µM PDI4	2878,773	12,46073
	4,8 µM PDI4	2856,013	11,87812
	7,2 µM PDI4	2843,416	3,88658

Table 21 : Fitting parameters of C6ZnPc adding PDI4 lifetime fluorescence excited at 520 nm in toluene

 21

	Equation	y = A1*exp(-x/t1) + y0
	Sample	1,2 µM	2,4 µM	3,6 µM	4,8 µM	4,8 µM PDI4	7,2 µM
		PDI4	PDI4	PDI4	PDI4	-b	PDI4
	Reduced Chi-Sqr	44,29927 26,75511 20,34076 20,75557	19,78037	8,27114
	Adj. R-Square	0,99962	0,99941	0,99905	0,99929	0,99894	0,99779

Table 22 : Lifetime coefficient (t1) of C6ZnPc adding PDI4 lifetime fluorescence excited at 520 nm in toluene t1

 22

	(ps)	Standard Error

General protocol for the synthesis of dipyridyl-PDI (15) (0.10g, 0.13 mmol), an aminopyridine (X g, 0.44 mmol, 3.3 eq.), zinc acetate (0.012 g, 0.07 mmol) and distilled quinoline (5 mL) were added to a 25 mL RBF capped with condenser.

The mixture was bubbled with argon for 10 min whilst stirring. The mixture was heated to 230 °C for a 16 h period. The reaction was cooled to rt. and poured onto an HCl solution (2N, 30 mL). The precipitate was filtered and rinsed with distilled water (100 mL). The dried solid was purified by chromatoflash. DCM/methanol (50:1) was used as eluent. The product was collected as the main fraction and the solvent evaporated. Recrystallisation from dichloromethane/heptane gave PDIX as dark red solid.

N,N'-Di(4-pyridyl)-1,7-bis(3',5'-di-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic

Bisiimide (PDI4)

Following the general protocol: Using (15) (206 mg, 0.26 mmol) and 4-aminopyridine (86 mg, 0.36 mmol 3.6 eq.) we obtained PDI4 as a red solid (166 mg, 68%).

N,N'-Di(3-pyridyl)-1,7-bis(3',5'-di-tert-butylphenoxy) perylene-3,4:9,10-tetracarboxylic

Bisimide (PDI3)

Following the general protocol: Using (15) (101 mg, 0.13 mmol) and 3-aminopyridine (43 mg, 0.36 mmol 3.6 eq.) we obtained PDI3 as a red solid (48 mg, 38%). Diester peryleneanhydride (22) (18) (4,5 g, 4,5 mmol, 1eq.) and n-butanol (110 mL) were added to a 250 mL 3-neck RBF.

TBAOH (40% in water, 7.5 mL, 11.4 mmol) were added whilst stirring. After complete solubilization, 1-bromobutane (5.8 mL, 68 mmol, 15 eq.) and K2CO3 (1.58 g, 11.4 mmol, 2.5 eq.) were added and the mixture was heated to 120 °C for 21 h. The crude mixture was left to cool to rt and CHCl3 (200 mL) was added. The organic layer was rinsed with distilled water (3x 100 mL), NaHCO3 (concentrated, 2 x 100 mL) and brine (100 mL). The organic layer was dried on MgSO4 and evaporated under reduce pressure. The purification was done by chromatoflash with toluene-DCM (9-1) as eluent. The second fraction was collected and evaporated under reduce pressure to give 22 as a red solid (2,0 g, 55%). 21 could be collected in the first fraction as a red-purple solid (0.88 g, 16%). Using absorbance spectroscopy to evidence the association occurring in ZnPc-PDI4 and ZnDPP-PDI4 systems relies on minor spectral changes that can sometimes be attributed to aggregation or dilution effects. The only reliable results were obtained for the ZnDPP-PDI4 titration, where we can distinguish 1:1 and 1:2 associations (PDI4-ZnDPP).

When we compared the association with PDIC7 derivative, we observed a different association which we believe occurs thanks to the π-π interactions. These results were also similar to those seen in the association with ZnPc itself, so we believe that the predominant interactions in this case are also π-π interactions. Finally, attempts of titration were tested with the C6 and C12ZnPc. These titrations were done in toluene and THF. No association was observed in THF and the preliminary results obtained in toluene are not conclusive.

In conclusion, absorbance spectroscopy is not the ideal method for observing these kinds of supramolecular associations, because the spectral differences between pure and associated molecules are not so evident.

When we started to investigate the supramolecular complexes of ZnPc and other pedestals with PDI4 we were expecting to observe visible wavelength shifts and a noticeable effect on the emission which was not the case at all. Many titration experiments were performed but not a lot of data points were collected given the limited "shelf-life" of our solutions. In the future, to improve the reliability of our results the experiment time must be reduced, and the stock solutions must be monitored at each data point to correct for any variation in the concentrations.

Once again, we see that solubility is a key parameter.

V. Proton NMR studies V.1. NMR studies of ZnPc-dipyridyl PDI

Titration experiments using proton NMR spectroscopy have been previously employed to study the association between ZnPcs or ZnPs with pyridyl-functionalized PDIs. This method is a powerful tool as i) it can give us information on the stoichiometric ratios, ii) it can help us calculate more reliably the association constant as we can use multiple proton signals (one constant per proton shift) and most importantly, iii) it gives us information on which part of the molecules are involved in the association. [28,65,131,147,148] We based our experiments on the work of Torres et al. who reported the titration of a system similar to ours between a dipyridyl-PDI and a ZnPc. [28] In their work, they monitored the association using the di-pyridyl molecule as host, adding increasing amounts of a ferrocene-functionalized ZnPc(Figure 167). In this figure we can observe at the top, the pure PDI 1 H NMR spectrum. Then, from top to the bottom, we can observe the spectra resulting from the addition of 0.2 to 3 equivalents of the ZnPc.

Figure 167. Titration of ZnPc added to BPyPDI solution in CDCl3 reported by Torres et al. [28] Three main phenomena were observed during this titration:

• An increasing shielding effect of ZnPc on PDI protons, visible on all the proton shifts of the PDI (orange, yellow and purple protons).

• The broadening and then disappearing signal of the blue pyridyl protons, which reappear after two equivalents of ZnPc added. Subsequently, by plotting the evolution of chemical shifts with the ratio of host-guest studied, the association stoichiometry was determined to be 1:2, and association constant could be calculated using a nonlinear fitting method.

Our goal was to reproduce this experiment using our own complexes (ZnPc-PDI4, CxZnPc-PDI4 and ZnDPP-PDI4). However, in our case, we are greatly limited by the solubility of our Pc macrocycles in CDCl3, specifically the unsubstituted ZnPc. Thanks to the solubility studies performed in CDCl3, we know that aggregate formation can already be observed at 10 -6 M by absorbance and fluorescence spectra. Therefore, we decided to carry out the titrations at the highest concentration possible without surpassing this limit, and at the same time to be as close as possible of the concentration used in the reported titration.

V.2. Strategy and set-up of NMR titration

We focused on this protocol because of the similarity to our system, since they used the same PDIs as ligand with two pyridyl groups on each end of the PDI. These should also lead to a 1:2 association, so we expected to observe almost the same behavior. The main difference between our systems is that their ZnPc is a lot more soluble compared to ours due to the ferrocenes located at the periphery. In our experiments we also exchanged the assignment of the host and guest roles with every complex studied to have as more data points as possible to describe each system and also to corroborate the results obtained using absorbance and fluorescence spectroscopy. In all our experiments we assume that the pyridyl-zinc coordination is not the only interaction involved in the reaction equilibria between the Zn macrocycles and the PDI.

The titrations of all the complexes were carried out in CDCl3 at 300 K. This temperature was the standard temperature of the NMR instrument used and it was close enough to room temperature to be comparable to the conditions in future surface studies. We added an increasing volume of guest molecules to a volume of known-concentration of host species. This strategy allows us to use a stock solution with an accurate and stable concentration and to avoid the variation of the concentration by dilution. Using only one stock solution also allowed us to work faster, which was necessary for when 15 consecutive NMR samples had to be analyzed in a short period of time to prevent aggregation. Following this methodology, a series of 15 measures took 2 h, which was already quite long compared to the aggregation rate.

In the titration we were looking for a trend which would indicate if we can control the 1:1 or 1:2 association with our complexes. We aimed also to discriminate which group of atoms is interacting the most in the molecules during the association. This, to reveal if the zinc-pyridyl equilibrium between the ZnDPP and PDI4 made the peak so broad it was confused with the base line. However, we were still able to follow the second peak (b) of the pyridyl which shows a strong shielding effect occurs. The shielding effect matches exactly with what is expected from a zinc-pyridyl coordination. The proton shifts of the perylene core are also shielded with less intensity which reveal they are in the shielding zone of the porphyrin as we saw in Figure 169 with the ZnPc. This brought us to the conclusion that ZnDPP's association with the PDI is orthogonal (through axial coordination). Because of the fast exchange of coordination, the signal observed is a mixed of dissociated PDI4, 1:1 and 1:2 association with ZnDPP however the type of association (via coordination) is quite evident. The titration was then repeated using PDI4 as host molecule.

V.6.2. NMR titration of PDI4 with ZnDPP addition

The titration was performed in reverse order, this time using a PDI4 solution as host solution.

The following Figure 173 shows the PDI4 proton peak shift changes with 0.05 to 1.8 equivalents of ZnPc added. The PDI4 peaks monitored show similar shielding effect over the increasing concentration of ZnDPP that was observed in the previous titration with ZnDPP as host. Here the concentration of PDI4 is kept between 5.6 and 3.2 mM (variation due to the dilution effect), and we could follow with a better resolution the (a) and (b) pyridyl peaks. The (a) peak disappears completely between 0.4 and 2.8 equivalents of ZnDPP added. This confirms the fast equilibrium between depended on the temperature of titration: at 323 K we observed a coordination bond like between ZnDPP and PDI4. We observed a 1:2 association between PDI4 and C12ZnPc in solution. We also have seen that the coordination was replaced by a π-π interaction when the temperature decreases to 300 K.

Previously described titrations using absorbance, fluorescence and NMR method aimed to obtain information on the pyridyl-zinc association between CxZnPc, ZnPc and ZnP with PDI4.

The result of these titration showed different behaviors of the complexes and we realized that coordination was not the only interaction involved between the aromatic macrocycles and the PDI. to develop materials with interesting optical and electronic properties. [158,159] The bottom-up approach to fabricate devices on novel surfaces like graphene, semiconducting dichalcogenides coupled with molecular assembly to tune the surface properties are therefore a very attractive area to develop optoelectronic materials. [160] Finally, although supramolecular surface functionalization is a rapidly advancing field of research; it is still relatively young when compared to the field of organic chemistry for example. This means, that we still have a few more decades to go, to obtain as much understanding as we have in the organic chemistry field. The understanding of the selfassembling interactions between molecules and with the surface is still at its early stages and many doors are still to be opened based on the chemistry, surface and optoelectronic physics as well as modelization aspects. [151] IX.1.

VIII.3.3. Titration of PDI4 solution with

Supramolecular self-assemblies on Graphene

Graphene as a surface is particularly attractive for supramolecular functionalization. The study of this materials has attracted a lot of attention in the scientific communities and resulted in a Nobel prize in 2010, awarded to A. Geim and K. Novoselov. [161,162] Graphene is covalently bond carbon monolayer structured in honeycomb lattices (Figure 204). This extended aromatic layer exhibits unique electronic properties with a long pathway for charge carriers and phonons which result in particularly high carrier mobility and thermal conductivity. [163] In a theoretical case the mobility charge transfer of graphene is 200 higher than silicon, which is used everywhere in electronics. [164] Besides its electronic properties, graphene's mechanical properties are also excellent, having one of the highest intrinsic mechanical strength predicted, transparency and flexibility. [165] Because of its strength and Based on the honeycomb structure and conjugated character of its aromatic surface, similar aromatic molecular units are usually the most used systems to be assembled on graphene's surface. This preferred attachment is based on the molecule-graphene interaction, and more specifically on: a) - interactions: Graphene is composed of a conduction plane because of the p-orbitals located perpendicular to the conjugated system. These p-orbitals can interact with aromatic rings and other unsaturated aliphatic chains through the overlap of their orbitals. The more extended and planar the conjugation is on the deposited molecules, the stronger is the association to the graphene.

b) Epitaxy: This is based on Van der Waals interactions and is the second main interaction in the molecule-substrate association. The shape complementarity of graphene's hexagonal lattice with -CH2-alkyl chains on the surface make for a strong interaction by van der Waals forces.

The hydrogen of the -CH2 in alkyl chains fits in the aromatic center of the benzene ring (Figure 206), this interaction was calculated and measured by Groszek et al. [176] The Van der Waals epitaxy also works with structures which possess atoms at close distances to graphene.

Figure 206. Representation of epitaxy of an aliphatic chain on graphene [176] In addition to the molecule-surface interaction, the molecule-molecule interaction is also essential in patterning graphene. These interactions rely mostly on weak van der Waals interactions which are the most predominant as they promote molecule-surface interaction at the same time at molecule-molecule interaction. By controlling the disposition of the alkyl chains on graphene surface molecular clips were designed. Bléger et al. described how optimization in the structure of interdigitating alkyl chains led by a clip process to a controlled lattice formed between the molecules. [177] The molecular clip principle illustrated in Figure 207 Transmission spectra are obtained by dividing the spectrum of interest by a reference one chosen either at a different place of the 1D or 2D image or from a previous measurement. The low readout noise of the scientific-CMOS sensor, typically 2 e -counts, allows us to detect transmission differences (e.g. absorption) as low as 5 x 10 -4 (i.e. optical densities ~ 2 x 10 -4 ) only limited by illumination fluctuations.

To enable Raman micro-spectroscopy on the same imaged area, the setup (Figure 236) is also equipped with two lasers with ultra-stable cavities and spectral linewidths of less than 1 pm.

The first one emits 25 mW at 532 nm and the second one The lasers are aligned with mirrors to center the image of both focused spots on the slit center.

The Raman spectra are acquired using the 1200 line/mm grating for improved spectral resolution.

Sample preparation was prepared as follows for the monolayer observations taking the C12ZnPc-PDI4 as example. A PDI4 solution was prepared in toluene (32 µM). A mixture of C12ZnPc-PDI4 (1:1) was prepared by mixing 160 µL of a PDI4 solution with 280 µL of a C12ZnPc solution in toluene (17 µM). The resulting C12ZnPc-PDI4 solution was drop-casted on the surface and left to dry under air. Its absorbance was measured after 2 h of annealing at 65 °C (on a hot plate). As the surface is expected to present multilayer and aggregates on the top after evaporation of the solvent, the graphene was rinsed with a 10 mL iPrOH bath. The sample was annealed again 1 h before to measuring its absorbance and Raman emission. Raman spectroscopy was done with 532 nm and 633 nm laser excitations.

Following the general protocol, the absorbance of the CxZnPc and CxTiOPc pedestals were measured. In the following absorbance spectra, the baselines are not at zero as we see that the absorbance minima varies between 0.01 and 0.03.This is because graphene absorbs slightly on the visible range, [193] and the variations observed in the baseline are the result of imperfections of the graphene monolayer on a µm scale. In the literature, the electronic effect of a physisorbed organic molecule on graphene is usually measured by the shift or variation of the absorbance peak' intensity. However, in this case we cannot correlate these changes to the doping effect caused by the organic molecules since any of the areas chosen to carry out the absorbance measurements will have different types of defaults and so the intensity of the signal will change as well. This is why, to monitor the changes of the molecule's optical properties when deposited on graphene we only considered the changes in the shape and wavelength of the peak observed to interpret the results.

XIII.2. C6ZnPc and C12ZnPc micro-absorbance on graphene

Figure 237 shows the absorption spectra of the C6 and C12ZnPcs on a graphene monolayer before and after annealing. For the C6ZnPc we also monitored the effects of rinsing the substrates after deposition.

On the C12ZnPc samples, we see an important difference between the "as deposited"

(evaporated) and the annealed spectra. Before annealing, the spectrum from the evaporated in air sample (blue) shows exactly the same absorbance spectrum that the molecule in solution;

we recognize the Q-band signal at 684 nm with the shoulder on the left at 633 nm (as presented in the chapter characterization). After 1 h of annealing (in purple) a second peak appeared at 712 nm but the peak at 684 is still visible. After 3 h (in red) and 5 h (in black) of annealing the 684 nm peak completely disappeared and the full Q-band with the shoulder was shifted by 26 nm compared to the first absorption spectrum.

be useful to confirm that the complete adsorption with the surface occurs, by observing the quenching of the deposited Pc's emission.

XIII.5. Angle variation absorbance spectroscopy

The CxZnPc-PDI complexes were engineered to self-assemble on a graphene layer with a particular orientation. The Pc-based pedestals will attach parallel (face-to-face) to the graphene and the PDI components will protrude from the surface plane at different orientations and distances depending how they are associated to the Pc pedestal. As we saw from the STM studies, all our complexes form well-ordered, homogenous 2D assemblies, however we were not able to determine how the PDI is associated to the Pc, and if its oriented parallel or perpendicular to the surface (Figure 241). Because of this, angle-dependent absorbance can be used as a way to describe the average orientation of absorbing molecules like phthalocyanines and perylenes. We decided to apply this method to better describe how our ZnPc-PDI4 and C12ZnPc-PDI4 complexes are assembled on graphene. To study the orientation of these an angle variation absorbance set-up was developed by F. Charra et. al. This instrumental set-up (Figure 242) allowed us to record the absorbance spectra of a sample with different angles of incident light. [192] Figure 242. Angle absorbance measure set-up for thin layer surfaces.

results also corroborate that the PDI4 is indeed assembled on the surface because of its clear anisotropic absorbance signal with a maximum of absorbance close to 90°.

General conclusion

The objective of this research project was to obtain molecular building-blocks where we can control the formation of long range, well-ordered self-assemblies and be able to introduce a function which does not interact with the graphene surface. To achieve this, the work performed and discussed in this manuscript was focused around three general aspects:

• The chemistry and molecular properties of conjugated molecules such as phthalocyanines, porphyrins and perylenes.

• The investigations of the supramolecular interactions that drive the formation of the supramolecular entities in solution.

• The characterization of the self-assemblies formed on HOPG and graphene based on these 3D non-covalent systems.

First, the molecular-blocks we successfully synthesized are based on two types of organic building blocks to be associated later through non-covalent interactions. On the one hand, we designed and managed to synthesize a series of so-called pedestals, more precisely phthalocyanines and porphyrins derivatives differing from their peripheral alkyl chain lengths (C6 or C12), their aromatic core size (P, Pc or Nc) and the metal they coordinate (zinc or titanium) (Figure 2455).

Abstract

Graphene has been in the spotlight of materials scientists for over a decade, as this highly conductive, translucent and flexible material makes it very attractive to use in future electronic devices. One important challenge in the field is to functionalize it without compromising its intrinsic properties or even better to bring to this material an additional functionality.

To achieve this, we followed a supramolecular, bottom-up approach to design and synthesize a series of molecular building-blocks with which we can control the formation of long range, well-ordered self-assemblies and at the same time be able to introduce a function which does not interact with the graphene surface. We based the design of our molecular building blocks on two main types of aromatic compounds: phthalocyanines (porphyrins) and perylenediimides.

The phthalocyanine and porphyrin derivatives play the role of molecular pedestals to achieve the formation of ordered assemblies, whilst the perylenediimides are expected to bring to the graphene its electronic and photonic properties. These two components are beheld together via non-covalent interactions to form stable supramolecular complexes. We studied the formation of these supramolecular complexes via titrations, monitoring them with NMR, absorption and fluorescence spectroscopy to obtain information on the type, strength and stability of these associations. Finally, we studied the self-assemblies of these complexes on HOPG and graphene by STM, angle-dependent microabsorption and microRaman to confirm the formation of a functional graphene monolayer, resulting from the use of two of our supramolecular complexes. Key words: graphene, supramolecular self-assembly, phthalocyanines, perylene, porphyrin, surface self-assembly, functional molecular monolayer Le graphène est sous les projecteurs des scientifiques depuis plus d'une décennie, car ses propriétés hautement conductrice, translucide et flexible rendent son utilisation très intéressante dans les futurs dispositifs électroniques. Un défi important dans ce domaine est de le fonctionnaliser sans compromettre ses propriétés intrinsèques ou mieux encore, d'apporter à ce matériau une fonctionnalité supplémentaire. Pour y parvenir, nous avons suivi une approche supramoléculaire ascendante pour concevoir et synthétiser une série de briques moléculaires avec lesquelles nous pouvons contrôler la formation d'auto-assemblages bien ordonnés et étendus. En même temps, introduire une fonction qui n'interagit pas avec la surface du graphène. Nous avons basé la conception de nos blocs de construction moléculaires sur deux principaux types de composés aromatiques : les phtalocyanines (porphyrines) et les pérylènediimides. Les dérivés de phtalocyanine et de porphyrine jouent le rôle de piédestaux moléculaires pour parvenir à la formation d'assemblages ordonnés, tandis que les pérylènediimides doivent apporter au graphène ses propriétés électroniques et photoniques. Ces deux composants sont maintenus ensemble par des interactions non covalentes pour former des complexes supramoléculaires stables. Nous avons étudié la formation de ces complexes supramoléculaires via des titrages, en les contrôlant par RMN, absorption et spectroscopie de fluorescence pour obtenir des informations sur le type, la force et la stabilité de ces associations. Enfin, nous avons étudié les autoassemblages de ces complexes sur HOPG et graphène par STM, microabsorption en fonction de l'angle et microRaman pour confirmer la formation d'une monocouche de graphène fonctionnelle, résultant de l'utilisation de deux de nos complexes supramoléculaires. Mots clés : graphène, auto-assemblage supramoléculaire, phtalocyanine, pérylène, porphyrine, auto-assemblage sur surface, monocouche moléculaire fonctionnelle