Keywords: chimie supramoléculaire, chimie organique, auto-assemblage, cages de coordination, tétrathiafulvalène, redox self-organization of functionalized heterocycles supramolecular chemistry, organic chemistry, self-assembly, coordination cages, tetrathiafulvalene, redox. Annex 3.24

Conception de capsules organiques par auto-organisation d'hétérocycles fonctionnalisés

Abstract: This work deals with the synthesis and characterization of new electron-rich discrete molecular cages, prepared via the coordination-driven self-assembly methodology, as well as on evaluating their redox and host-guest properties. The general concepts guiding the metal-driven self-assembly methodology are presented. Three types of redoxactive tetratopic ligands (L) featuring either a tetrathiafulvalene (TTF), a dithiol-fluorene (DTF) or a π-extended tetrathiafulvalene (exTTF) have been designed. Their ability to generate self-assembled cages upon combination with various metal complexes (M) has been studied. In the first case, M8L2 metallacages were obtained, whose geometry offers a unique opportunity to promote close inter-TTF interactions upon oxidation, as confirmed through electrochemical studies as well as from single-crystal DRX from an electrocrystallized oxidized salt. In the second case, several discrete self-assemblies MxLy (cages, clips) were obtained and characterized from new electro-active ligands based on the 9-(1,3-dithiol-2-ylidene)fluorene (DTF) unit. Their redox properties as well as their binding ability towards electrodeficient planar species show a strong dependence to the self-assembly geometry. Considering the exTTF ligand, large (ca. 4000 Å 3 ) electroactive M12L6 metallacages were obtained from combining with trans palladium or silver complexes. Le latter exhibits a disassembling process upon oxidation, giving rise to an unprecedented redox-triggered transformation of discrete metalla-cage into a coordination polymer. Finally, a new benzo [1,2-b:4,5-b'] dithiophene aromatic scaffold is investigated as an alternative πextended electron-rich derivative. The critical role of non-covalent 1,5

Introduction

The synthesis of macrocyclic structures has always focused a strong interest from the chemistry community. This fascination probably results from a combination of several reasons, among which i) the wide range of applications which can be envisaged from such compounds, ii) the synthetic challenge and iii) for some of them, the quest for a certain degree of aesthetic value.

Although a myriad of examples have been obtained for the last few decades, the synthesis of synthetic macrocycles using traditional covalent chemistry often constitutes a challenge and generally results in many-step procedures and low yields. The birth of the metal-driven self-assembly strategy in the early 90's led to a breakthrough in this area. First applied for obtaining macrocyclic compounds, this concept was further used to reach molecular metallocages (3D structures) in a single step and in high yields, starting from organic ligands and metal ions or complexes. Today, this approach has allowed creating a wide variety of functional molecular polygons and polyhedra.

These metallocages possess an intrinsic cavity which in principle, is able to accept a guest species (ion or molecule), giving rise to a host-guest complex. The latter complex can be designed to target various types of applications, such as catalysis and drug transport. In order to control the encapsulation and the subsequent release of the guest, different types of stimulus can be applied to monitor the hostguest binding interaction. The most commonly used are pH variation, irradiation or introduction of a competitive guest. Another approach, recently developed, consists in using a redox stimulus. Indeed, the latter (oxidation or reduction) is prone to modify the electrostatic charges of either the guest, the host, or both subunits.

We propose in this work to design, characterize and study the binding properties of new redoxactive metalloreceptors, issued from the combining of specific metal complexes to electron-rich organic ligands enriched in sulfur atoms.

Chapter One is dedicated to the general principles guiding the metal-driven self-assembly processes, through specific examples of the literature. A special focus is made on redox-active selfassemblies and notably on tetrathiafulvalene-based cages.

Chapter Two is focused on a new generation of self-assembled M8L2 type metallacages, featuring ligands based on the tetrathiafulvalene core and bis-Ruthenium complexes.

Chapter Three depicts the use of a new dithiafulvalene scaffold in the preparation of redoxactive self-assemblies. Two types of ligands are described and compared upon combining with different metal complexes.

Chapter Four describes the use of a π-extended tetrathiafulvalene ligand in creating new metallocages. Self-assemblies of the M12L6 type are depicted, as well as the first example of a redoxtriggered transformation of a discrete cage into a supramolecular 3D polymer.

Chapter Five explores a new aromatic scaffold (benzo [1,2-b:4,5-b'] dithiophene) in designing an alternative π-extended electron-rich derivative. A combined experimental and theoretical study is proposed to characterize the specific structural and electronic properties of this new compound, in comparison with the previous π-extended tetrathiafulvalene.

7

Chapter I. Metal-directed self-assembly (literature review)

Main approaches to self-assembly

The general concept supporting the self-assembly methodology consists of combining several components, which spontaneously organize into a more complex structure, possibly under the influence of different factors. One of the main advantages of such approach lies on its ability to self-correct in the course of the process. Due to the relatively low energy of the intermolecular interactions which are involved (Table 1), the formation of the supramolecular bonds remains reversible within the reaction conditions, favoring the thermodynamic product in front of the kinetic one.

Interaction Energy (kJ/mol) Example

Ion Main approaches to achieve self-assembly can be divided into:

 non-covalent self-assembly, mostly supported by hydrogen bonds;  covalent self-assembly, using reversible organic reactions;  metal-driven self-assembly, using organic ligands and metal ions or complexes.

Non-covalent self-assembly

The first example of non-covalent self-assembly which comes to mind corresponds to the double DNA helix, based on a combination of hydrogen bonds and alternative non-covalent interactions. (figure 1.1.1). By mimicking natural processes, a wide variety of synthetic supramolecular helicates, foldamers and other structures have been obtained.

When considering the specific case of macrocyclic receptors, three illustrative examples (among many existing in the literature) are proposed: i) a self-assembled capsule 1.1, 2 based on the calixarene platform and which is capable of encapsulating small planar guests (figure 1.1.2, a), ii) a capsule 1.2 3 based on the cyclotriveratrylene core and featuring DDAA ureidopyrimidinone groups, which is able to bind large neutral guests such as fullerenes (figure 1.1.2, b), and iii) a hybrid cage 1.3 4 featuring a bis-Ruthenium complex which preorganizes an organic ligand involving the DDAA ureidopyrimidinone group (figure 1.1.3). Figure 1.1.2. Self-assembled cages based on the hydrogen-bond. [2][3] Figure 1.1.3. Self-assembly using a combination of coordination and hydrogen bonds. 4

Covalent self-assembly

Another possibility to circumvent the low yields limitations often reencountered with conventional organic synthesis when synthesizing macrocyclic structures, lies on the use the dynamic covalent reactions approach 5 (figure 1.1.4). This approach is focused on reversible covalent reactions creating a rapid equilibrium. This consecutively allows to move from kinetic to thermodynamic products. (a) and some examples of application (b). 5 These methodology was first introduced using imine chemistry in 2009 6 . Later, other types of reactions were shown to be effective in covalent self-assembly, such as boronic esters [START_REF] Zhang | A Permanent Mesoporous Organic Cage with an Exceptionally High Surface Area[END_REF] , disulfide bonds 8 , alkyne metathesis 5 and others 10 (figure 1.1.4).

The reversible nature of such reactions allows dynamic error corrections, similar to hydrogen bonds methodology. Another advantage lies on the relatively high stability of the resulting structures due to the nature of the covalent bonds, especially for more recent carbon-carbon cages. Nevertheless, one limitation lies on the difficulty to design on purpose the cage structure from the starting building blocks formula.

Metal-directed self-assembly

Despite being first introduced nearly three decades ago, the metal-driven self-assembly remains a hot topic and has been the subject of many recent reviews. [START_REF] Saha | Structure relationships between bis-monodentate ligands and coordination driven self-assemblies[END_REF][START_REF] Kim | Strategies for reversible guest uptake and release from metallosupramolecular architectures[END_REF][START_REF] Zhang | Recent advances in the construction and applications of heterometallic macrocycles and cages[END_REF][START_REF] Yoshizawa | Coordination-driven Nanostructures with Polyaromatic Shells[END_REF][START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF][START_REF] Huang | Metallacyclic assembly of interlocked superstructures[END_REF][START_REF] Bloch | Integrative self-sorting of coordination cages based on 'naked' metal ions[END_REF] It is based on the formation of a coordination bond between a metal and suitably designed organic ligands. One of the main advantages of this methodology in comparison to above-mentioned ones lies on the predictable nature of the coordination bond. Combining this with the appropriate geometry of organic ligand allows efficient designing of the resulting metallocages. At the same time, reversibility of the coordination bond between main components allows transition from the kinetic intermediates to the thermodynamically more favorable macrocyclic 2D and 3D structures (scheme 1.2.1). In this process entropy favors formation of the closed systems with a minimum number of components over long polymeric chains. All these factors allow obtaining metallocycles with high yields in just one step.

For the sake of prediction, the metallocycles structure is often described as high-symmetry polygons/polyhedra [START_REF] Young | Structural design principles for self-assembled coordination polygons and polyhedra[END_REF] with metal atoms in the vertices (V) and organic ligands as edges (E, edge-directed self-assembly) or faces (F, face-directed self-assembly) (figure 1.2.1). Figure 1.2.1. High-symmetry polygons and polyhedra and their projections on the self-assembly structures. [START_REF] Young | Structural design principles for self-assembled coordination polygons and polyhedra[END_REF]

Design using the directional bond approach

The directional bond approach is well-supported by combinatory libraries for using in metaldirected self-assembly. It was first shown by the groups of Fujita [START_REF] Fujita | Preparation of a macrocyclic polynuclear complex[END_REF] and Stang [START_REF] Stang | Transition Metal Based Cationic Molecular Boxes. Self-Assembly of Macrocyclic Platinum(II) and Palladium(II) Tetranuclear Complexes[END_REF] for 2D metallocycles. There are two main requirements for this method to be used:

 Organic ligands should have a rigid geometry and appropriate bite angle,  Starting components must be mixed in exact stoichiometric proportions. Result of the self-assembly process is defined by the combination of geometry and stoichiometric proportions 1 (figure 1.2.2). Creation of the 2D monocyclic assemblies requires subunits having symmetry axes no higher than a 2-fold axis, resulting in the corresponding polygons (figure 1.2.2, a). So, for instance, molecular rectangles can be created using combination of two 0 ° donor units with 180 ° acceptor units or vice versa. Molecular triangles can be designed by combining three 180 ° acceptors with three 60 ° donors. 3D self-assembly (i.e. polyhedra (figure 1.2.2, b)) requires symmetry axes higher than a 2-fold axis and more than 2 binding sites. For instance, a trigonal bipyramid can be designed in few ways: either by combining two tritopic units with orthogonal binding sites, by using three 80-90 ° ditopic components or by mixing two tridentate 60 ° units with three ditopic 90 ° units.

One of the main limitations for this methodology is the assumption that angular components keep their geometry along the self-assembly process. Actually, these angles do change, but due to relatively low energy of coordination bond, the shape of the resulting self-assembled structure usually remains close to prediction. Notably, in the case of long and/or flexible ligands, a mixture of several selfassembled products can be observed, limiting the use of this approach to the case of rigid molecules.

Design using the symmetry interaction approach

The symmetry interaction approach is mostly used for construction based on "naked" metal ions (devoid of any coligand). The outcome of the assembly is determined by the inherent symmetry of the coordination sites on the metal ion, in combination with the chelating mode of the ligand. Similarly to the directional bonding approach, this methodology requires ligands with relatively rigid structures in order to avoid formation of several products or oligomers.

The main terms, such as coordinate vector and chelate plate, and first application of the symmetry interaction approach were demonstrated by the group of Raymond. [START_REF] Caulder | The rational design of high symmetry coordination clusters[END_REF][START_REF] Caulder | Formation and Properties of Tetrahedral M4L4 and M4L6 Supramolecular Clusters[END_REF] The coordinate vector describes the bond between the metal and the ligand. For the ligands, the chelating plane is placed orthogonal to the main symmetry axis of the metal complex and holds chelate vectors of the ligand (figure 1.2.3, a). Further combination of orientation of chelating planes with corresponding coordinate vectors allows prediction of the resulting high-symmetry coordinate structures.

For example, a triple M2L3 helicate has a D3h symmetry and can be designed by combining orthogonal components with C2 and C3 axes. The C3 component is in this case a metal center with parallel chelate planes (figure 1 .3.3, b). In similar fashion М4L6 tetrahedron can be obtained from four metal ions in the vertices and six corresponding ligands. Therefore, C2 axes of the tetrahedron lie inside chelate planes of the metals, while coordinate vectors must maintain 70.6 °. Another way to get tetrahedron is to use a М4L4 stoichiometry, which requires that both ligand and metal have a C3 symmetry. Another example of this methodology in application to the heterometallic self-assembly was demonstrated using a stepwise process [START_REF] Hardy | Stepwise Construction of Heterobimetallic Cages by an Extended Molecular Library Approach[END_REF] . First was obtained precursor 1.4, containing Fe, which upon further reaction with either cis-blocked C2 Pd complex or naked C4 Pd ion, results in formation of a trigonal bipyramide 1.5 or a cube 1.6 respectively (figure 1.2.4) Figure 1.2.4. Heterometallic self-assembly based on the symmetry interaction approach. [START_REF] Hardy | Stepwise Construction of Heterobimetallic Cages by an Extended Molecular Library Approach[END_REF]

Design using the paneling approach

The paneling approach can be illustrated by the pioneering works of the group of Fujita, while creating a variety of coordination polyhedra [START_REF] Fujita | Metal-directed self-assembly of two-and three-dimensional synthetic receptors[END_REF][START_REF] Fujita | Coordination Assemblies from a Pd(II)-Cornered Square Complex[END_REF] . This is an example of a face-directed self-assembly process (contrary to the above-mentioned directional bond and symmetry interaction which are edge-directed methodologies). This means that ligands do not constitute the edges, but the faces of the polyhedra with metal atoms in the vertices. For instance, combination of triangular panels can result in a tetrahedron or an octahedron (figure 1.2.5). In a similar way, square panels may lead to a cube or a prism.

Therefore, this approach requires ligand that gets a rigid planar geometry with coordination sites located on its edges and within the plane of the ligand. As vertices mostly cis-blocked metal complexes are used for the sake of geometry. This allows efficient self-assembly process without oligomeric by-products.

For example, using a triangular ligand with a D3h symmetry leads to the truncated tetrahedron М6L4 (figure 1.2.6, a), while changing the direction of the bonding groups leads to a square pyramidal cone. Square panels with D4h symmetry can lead to either trigonal [START_REF] Norifumi | A Porphyrin Prism: Structural Switching Triggered by Guest Inclusion[END_REF] or hexagonal [START_REF] Kumar | Self-Assembly of a Nanoscopic Pt12Fe12 Heterometallic Open Molecular Box Containing Six Porphyrin Walls[END_REF] One of the main advantages of this approach lies on the formation of cages with large internal cavities. This process often requires the use of a template molecule during the assembly process.

Weak ligand approach

The weak ligand approach was first described by the group of Mirkin [START_REF] Holliday | Strategies for the Construction of Supramolecular Compounds through Coordination Chemistry[END_REF][START_REF] Gianneschi | Development of a Coordination Chemistry-Based Approach for Functional Supramolecular Structures[END_REF][START_REF] Oliveri | Heteroligated Supramolecular Coordination Complexes Formed via the Halide-Induced Ligand Rearrangement Reaction[END_REF] and relies on flexible hemilabile ligands. Such ligands require a coordination with the metal atom in a bidentate mode with one binding site weaker than the other. After the initial formation of the kinetic product ("closed form" (figure 1.3.7, a)), addition of the stronger ligand L leads to the final metallocycles in its "open form". Therefore, in this methodology the ligand must possess a conformational flexibility allowing to switch from the closed to the open form. This is opposite to the demand for rigid ligands in most approaches and allows to widen the potential range of suitable ligands. Another advantage comes from the ancillary ligand L, which can be switched later without impacting the structure, which can be useful both for application in catalysis or for accessing to more complex structures.

Main types of coordination-driven assemblies depending on the metal part

Coordination-driven self-assembly methodology can afford a wide variety of metals. Within this PhD work, we have focused our attention onto square-planar Palladium and Platinum acceptors (both used either as "naked ions" or as cis-/ trans-blocked complexes), as well as on bis-Ruthenium acceptors. Besides having compatible geometry, these metals allow using the NMR techniques, which greatly facilitates both the monitoring of the self-assembly process as well as further characterization related to the resulting cages.

Using cis-blocked metal complexes

In general, cis-blocked acceptors are constituted of square-planar complexes (either charged or neutral) with two over four coordination sites in the cis orientation occupied with strong organic ligands (usually with bidentate ligands, but not necessary). The remaining two sites are occupied by good leaving groups, such as nitrate or triflate in the case of charged complexes, and by 1,5-cyclooctadien in the case of neutral ones. As a result, these complexes constitute very useful 90 ° building blocks, which can be efficiently used to reach 2D or 3D self-assemblies. Figure 1.3.1 summarizes some of the most common cis-blocked acceptor units, while some more exotic ones can also be found in literature. 29 According to figure 1.3.2, the appropriate donor units (ligands) for the formation of metallocycles should be ditopic and have 90 ° or 180 ° angles. As a result, the most common motives consist of molecular triangles [START_REF] Hashiguchi | A Novel Triangular Macrocyclic Compound, [(tmeda)Pt(azpy)]3(PF6)6•13H2O (tmeda: Tetramethylethylenediamine, azpy: 4,4′-Azopyridine)[END_REF] and squares [START_REF] Subhashis | Self-assembled Pd6L4 cage and Pd4L4 square using hydrazide based ligands: synthesis, characterization and catalytic activity in Suzuki-Miyaura coupling reactions[END_REF][START_REF] Shanmugaraju | Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C60 Binding Study[END_REF] (figure 1.3.2). Figure 1.3.2. Self-assembled molecular triangles (a) and squares (b, c). [START_REF] Hashiguchi | A Novel Triangular Macrocyclic Compound, [(tmeda)Pt(azpy)]3(PF6)6•13H2O (tmeda: Tetramethylethylenediamine, azpy: 4,4′-Azopyridine)[END_REF][START_REF] Subhashis | Self-assembled Pd6L4 cage and Pd4L4 square using hydrazide based ligands: synthesis, characterization and catalytic activity in Suzuki-Miyaura coupling reactions[END_REF][START_REF] Shanmugaraju | Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C60 Binding Study[END_REF] As mentioned before, less rigid ligands may sometimes cause the deformation of the binding angles. As a result, an equilibrium between formation of triangles and squares can be observed [START_REF] Ferrer | New Insights into the Factors That Govern the Square/Triangle Equilibria of Pd(II) and Pt(II) Supramolecules. Unexpected Participation of a Mononuclear Species in the Equilibrium[END_REF][START_REF] Fujita | On the structure of transition-metal-linked molecular squares[END_REF][START_REF] Uehara | Synthetic and Computational Studies on Factors Controlling Structures of Molecular Triangles and Squares and Their Equilibrium in Solutions[END_REF] (figure 1.3.3). Using tritopic ligands leads to 3D metallocages. For example, Fujita and coworkers obtained a face-directed assembly starting from a planar tritopic ligand with 60 0 angle in combination with a cisblocked Palladium (figure 1 .3.4, a). This cage was efficiently used for instance for catalyzing cycloaddition reactions between two confined partners [START_REF] Fang | Cavity-promoted Diels-Alder Reactions of Unsubstituted Naphthalene: Fine Reactivity Tuning by Cavity Shrinkage[END_REF] . A similar cage can be obtained by combining linear ditopic and angular tritopic ligands 37 (figure 1.3.4, b). This cage was shown to be able to encapsulate two TTF molecules and to allow their further oxidation into mixed valence species. Figure 1.3.4. Examples of self-assembled metallocages using cis-blocked acceptors. [START_REF] Fang | Cavity-promoted Diels-Alder Reactions of Unsubstituted Naphthalene: Fine Reactivity Tuning by Cavity Shrinkage[END_REF][START_REF] Yoshizawa | Room-Temperature and Solution-State Observation of the Mixed-Valence Cation Radical Dimer of Tetrathiafulvalene, [(TTF)2]+•, within a Self-Assembled Cage[END_REF]

Using trans-blocked metal complexes

Trans-blocked acceptors are isomeric to the above-mentioned cis-blocked units (figure 1.3.5, a). As such they are used as 180 ° linear building block. Most commonly used blocking ligands consist of phosphine ligands with either alkyl or aryl substituents. Aliphatic ligands are often preferable, as they don`t have corresponding 1 H NMR signals in the aromatic region, where signals of the ligand are usually located.

According to figure 1.2.2, linear trans-blocked acceptors can be combined with a large variety of ligands, but the most used are linear 0 ° ligands, resulting in 2D squares 38-39 (figure 1.3.5, b, c), and tritopic ligands, resulting in 3D cages 40 (figure 1.3.5, d). Another cage using the chiral ligand based on the oxocalix [3]arene with trans-blocked Palladium allows for the recognition of chiral molecules 41 (figure 1.3.5, e).

Figure 1.3.5. General structure (a) and examples of application (b, c, d, e) of the trans-blocked acceptor units. [38][START_REF] Ghosh | Self-assembly of metal-organic hybrid nanoscopic rectangles[END_REF][START_REF] Kim | Tripodal oxazoline-based homochiral coordination cages with internal binding sites[END_REF][41]

Using "naked" metal ions

Square-planar metals with the four coordination sites free or with good leaving groups can in principle be used as tetracoordinated building blocks for coordination-driven self-assembly. They are usually used in a form of metal salts, such as triflates, nitrates or tetrafluoroborates. Further possible structure depending on the ligand is summarized in figure 1.3.6 [START_REF] Saha | Structure relationships between bis-monodentate ligands and coordination driven self-assemblies[END_REF] .

Figure 1.3.6. Possible structures using "naked ions" in combination with various types of ligands. [START_REF] Saha | Structure relationships between bis-monodentate ligands and coordination driven self-assemblies[END_REF] One of the most common self-assembly architecture based on naked ions corresponds to a M2L4 stoichiometry. Clever and co-workers have shown the flexibility of related cages by introducing different additional groups pointing inside the cavity 42 (figure 1.3.7, a). This allows to tailor guest molecules, which fit inside the cavity. Cages can also be modified on the outer part, for example by introducing carboxyl group with subsequent reactions [START_REF] Schmidt | Supramolecular exofunctionalized palladium cages: fluorescent properties and biological activity[END_REF] 1.3.7. Examples of inner (a) and outer (b) modification of M2L4 cages. [START_REF] Clever | Cation-Anion Arrangement Patterns in Self-Assembled Pd2L4 and Pd4L8 Coordination Cages[END_REF][START_REF] Schmidt | Supramolecular exofunctionalized palladium cages: fluorescent properties and biological activity[END_REF] As seen from figure 1.3.6, though common, the M2L4 stoichiometry is not the only option. In some cases, one can observe formation of the bigger cages, such as М4L8 [START_REF] Tomoki | Self-Assembly of a Pd4L8 Double-Walled Square Partly Takes Place Through the Formation of Kinetically Trapped Species[END_REF] , within the same stoichiometry of the starting components (figure 1.3.8). Also one can trigger rearrangement of the smaller cage М3L6 into the bigger (up to М7L14) using template molecule or ion 45 (figure 1.3.8, b). Another possibility to fit larger molecule that the cage would not normally allow is to lose some of its components [START_REF] Yazaki | Polyaromatic molecular peanuts[END_REF] . In this example the cage loses one of its three metal centers (yellow sphere) in order to create additional space between the ligands (green) inside the self-assembly for two guest molecules (pink sphere) (figure 1.3.8, c). 1.3.8. Adaptive self-assembled cages based on the "naked" square-planar ions. [START_REF] Tomoki | Self-Assembly of a Pd4L8 Double-Walled Square Partly Takes Place Through the Formation of Kinetically Trapped Species[END_REF][START_REF] Zhang | Adaptive self-assembly and inducedfit transformations of anion-binding metal-organic macrocycles[END_REF][START_REF] Yazaki | Polyaromatic molecular peanuts[END_REF] Fujita and coworkers have used this strategy to reach remarkably large size cages, from М6L12 to М30L60, depending on the angle in the ditopic ligand [START_REF] Fujita | Self-Assembly of M30L60 Icosidodecahedron[END_REF] (figure 1.3.9) 20 Figure 1.3.9. Large cages of the MnL2n type. [START_REF] Kim | Octahedral [Pd6L8]12+ Metallosupramolecular Cages: Synthesis, Structures and Guest-Encapsulation Studies[END_REF] A series of such M12L24 cages were also modified by using functionalized related ditopic ligands allowing chemical modification of the corresponding cavity space [START_REF] Harris | Giant hollow MnL2n spherical complexes: structure, functionalisation and applications[END_REF] (figure 1.3.10). Figure 1.3.10. Functionalized M12L24 cages. 49

Using bis-metal complexes

Another possibility consists in using two bridged metal centers. This can be reached either by direct metal-metal bond 50 (figure 1.3.11) or, more commonly, by introducing a bridging organic ligand between both metal atoms. [START_REF] Cui | Self-assembly and anion sensing of metalorganic [M6L2] cages from fluorescent triphenylamine tri-pyrazoles with dipalladium(ii,ii) corners[END_REF] The second category is much more common and is usually based on Platinum or Ruthenium (also sometimes Iridium or Rhodium [START_REF] Deng | Construction of half-sandwich rhodium-and iridium-based metallamacrocycles with different space conformations via isomeric pyridyl-substituted ligands[END_REF] ). Bis-Ruthenium acceptors consist of two Ru metal atoms associated to a bridging dihydroxy-dione conjugated fragment whose size can be varied (figure 1.3.12). They are best used with linear ligands to create both 2D and 3D sandwich architectures. [START_REF] Bruno | Arene Ruthenium Cages: Boxes Full of Surprises[END_REF][START_REF] Mukherjee | Coordination-driven self-assembly of ruthenium(II) architectures: Synthesis, characterization and cytotoxicity studies[END_REF] Figure 1.3.12. Common bis-Ruthenium acceptors and examples of self-assembly. [START_REF] Mukherjee | Coordination-driven self-assembly of ruthenium(II) architectures: Synthesis, characterization and cytotoxicity studies[END_REF] Another type of bimetallic can be obtained by connecting several atoms of Platinum to organic ligand. In this acceptor units, platinum atoms are covalently bonded to an organic block, leaving free the second bonding site. Depending on the organic unit both 2D [START_REF] Ye | Self-Assembly of Chiral Metallacycles and Metallacages from a Directionally Adaptable BINOL-Derived Donor[END_REF] and 3D [START_REF] Cao | Diamondoid Supramolecular Coordination Frameworks from Discrete Adamantanoid Platinum(II) Cages[END_REF][START_REF] Zhang | Platinum(II)-Based Convex Trigonal-Prismatic Cages via Coordination-Driven Self-Assembly and C60 Encapsulation[END_REF] architectures can be obtained (figure 1.3.13) Figure 1.3.13. Examples of self-assembly using bis-Platinum complexes. [START_REF] Ye | Self-Assembly of Chiral Metallacycles and Metallacages from a Directionally Adaptable BINOL-Derived Donor[END_REF][START_REF] Cao | Diamondoid Supramolecular Coordination Frameworks from Discrete Adamantanoid Platinum(II) Cages[END_REF]

Heteroleptic self-assembly

Interestingly, the self-assembled cages can be formed using several organic ligands. Two situations can be encountered: a narcissistic self-sorting or a social self-sorting (figure 1.3.14). In the first case, two ligands separately bind with metals, resulting in several cages. In contrast, social self-sorting allows incorporating of several ligands into one cage. These processes can be illustrated in both covalent [START_REF] Beuerle | Covalent Organic Frameworks and Cage Compounds: Design and Applications of Polymeric and Discrete Organic Scaffolds[END_REF] and coordination-driven [START_REF] Bloch | Morphological Control of Heteroleptic cis-and trans-Pd2L2L′2 Cages[END_REF] self-assembly cages. [START_REF] Beuerle | Covalent Organic Frameworks and Cage Compounds: Design and Applications of Polymeric and Discrete Organic Scaffolds[END_REF][START_REF] Bloch | Morphological Control of Heteroleptic cis-and trans-Pd2L2L′2 Cages[END_REF] An interesting example of rational design for social self-assembly was demonstrated by Clever and co-workers [START_REF] Zhu | Donor-sitedirected Rational Assembly of Heteroleptic cis-[Pd2L2Lʹ2] Coordination Cages from Picolyl Ligands[END_REF] through the design of a cis-[PdL1 2 L2 2 ] cage. Using ligands with different steric constraints (pointing toward and outside the cage cavity, respectively), results in formation of homoleptic metallocycles in the case of a narcissistic self-assembly, and to a heteroleptic cage involving both ligands in the case of a social self-assembly (figure 1.3.15). Figure 1.3.15. Rational design of a social cage leads to the formation of either mixture of homoleptic cages (left) or heteroleptic cis-[PdL1 2 L2 2 ] cage (right). 60

Interlocked self-assembly

Further progress in the coordination-driven self-assembled cages results in obtaining interlocked architectures. These motifs are interesting both for fundamental research [START_REF] Bruns | The nature of the mechanical bond : from molecules to machines[END_REF] and for application in molecular machines and catalysis. [START_REF] Pease | Switching Devices Based on Interlocked Molecules[END_REF][START_REF] Balzani | Light powered molecular machines[END_REF][START_REF] Van Dongen | Functional interlocked systems[END_REF] The formation of such interlocked self-assemblies is always competitive with preparation of linear products. To favor closed structures, metals can be added both as a template [START_REF] Dietrich-Buchecker | Interlocking of molecular threads: from the statistical approach to the templated synthesis of catenands[END_REF][START_REF] Crowley | Active metal template synthesis of rotaxanes, catenanes and molecular shuttles[END_REF][START_REF] Chambron | Topologically complex molecules obtained by transition metal templation: it is the presentation that determines the synthesis strategy[END_REF][START_REF] Hubin | Template routes to interlocked molecular structures and orderly molecular entanglements[END_REF] (which can be removed later) or as a part of the structure (which is discussed here).

For example, Kuroda and coworkers [START_REF] Fukuda | A Quadruply Stranded Metallohelicate and Its Spontaneous Dimerization into an Interlocked Metallohelicate[END_REF][START_REF] Sekiya | Anion-Directed Formation and Degradation of an Interlocked Metallohelicate[END_REF] showed formation of a catenane using a nitrate anion from the Palladium salt as a template. It should be noted, that changing the anion triggers reversion to the simple cage (figure 1 1.3.16. Interlocked self-assemblies using Palladium complexes. 70-71 . Bis-ruthenium (more rarely Iridium and Rhodium) complexes are also widely employed in preparation of interlocked self-assemblies. The possibility of adjusting their size by changing the linker fragment helps to tailor them for the self-assembly process (see § 1.3.4). For example, Chi and coworkers 72 demonstrated the formation of [2]catenanes using complexes of various size (figure 1.3.17, a). Solvent and concentration also play a substantial role in such systems. Dilution causes formation of a monomer, as well as changing the solvent from methanol to nitromethane. The same group also showed formation of a Solomon knot using more rigid bent ligand [START_REF] Song | Template-Free Synthesis of a Molecular Solomon Link by Two-Component Self-Assembly[END_REF] (figure 1.3.17, b).

Figure 1.3.17. Interlocked self-assemblies using bis-Ruthenium complexes. [START_REF] Jo | Coordination-Driven Self-Assembly Using Ditopic Pyridyl-Pyrazolyl Donor and p-Cymene Ru(II) Acceptors[END_REF][START_REF] Song | Template-Free Synthesis of a Molecular Solomon Link by Two-Component Self-Assembly[END_REF]

Properties and examples of applications of self-assembled cages

Main areas of application for the self-assembled cages are determined by their intrinsic cavity. Thus, 3D cages are mostly used for the recognition and encapsulation of anions [START_REF] Kim | Octahedral [Pd6L8]12+ Metallosupramolecular Cages: Synthesis, Structures and Guest-Encapsulation Studies[END_REF] , organic [START_REF] Yamashina | Preparation of Highly Fluorescent Host-Guest Complexes with Tunable Color upon Encapsulation[END_REF] and inorganic [START_REF] Leenders | Selective Co-Encapsulation Inside an M6L4 Cage[END_REF] molecules and gases [START_REF] Wright | Highly selective CO2vs. N2 adsorption in the cavity of a molecular coordination cage[END_REF] . It should be noted that a well-defined cavity isn`t always necessary, as shown by some 2D architectures [START_REF] Shanmugaraju | Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C60 Binding Study[END_REF] . Considering host-guest properties, a special interest concerns the control over the encapsulation process 10, 78-79 (figure 1.4.1). This can be achieved either by changing the properties of the cage (upon changing its structure or through its partial or complete dissociation) or of the guest. The most commonly used stimuli to promote those changes are controlled pH [START_REF] Chan | Multiaddressable molecular rectangles with reversible host-guest interactions: Modulation of pH-controlled guest release and capture[END_REF] or irradiation. [START_REF] Clever | Light-Triggered Crystallization of a Molecular Host-Guest Complex[END_REF] It should be noted, that optical properties of the cage (beside releasing the host [START_REF] Muxin | Light-Controlled Interconversion between a Self-Assembled Triangle and a Rhombicuboctahedral Sphere[END_REF][START_REF] Muxin | Light-Triggered Guest Uptake and Release by a Photochromic Coordination Cage[END_REF] ) could be also used to either stabilize photosensitive molecules [START_REF] Li | Stepwise Assembly of Pd6(RuL3)8 Nanoscale Rhombododecahedral Metal-Organic Cages via Metalloligand Strategy for Guest Trapping and Protection[END_REF] or for photosensibilisation [START_REF] Yoshizawa | Alkane Oxidation via Photochemical Excitation of a Self-Assembled Molecular Cage[END_REF] . Coordination cages can also be used for drug delivery. [START_REF] Casini | The Promise of Self-Assembled 3D Supramolecular Coordination Complexes for Biomedical Applications[END_REF] Encapsulated biologically active molecules could be protected from the physiological conditions without changing its structure. For example, the anti-cancer cis-Platine drug was encapsulate by a Palladium M2L4 cage. [87][START_REF] Lewis | Stimuli-responsive Pd2L4 metallosupramolecular cages: towards targeted cisplatin drug delivery[END_REF] At the same time, the cage could be modified by specific proteins to increase selectivity of the delivery [START_REF] Han | Bioconjugation strategies to couple supramolecular exo-functionalized palladium cages to peptides for biomedical applications[END_REF] . Moreover, some self-assembled structures can be used as a biologically active compounds. For example, bis-Ruthenium complexes, [START_REF] Tabrizi | Ruthenium(II) p-cymene complexes of naphthoquinone derivatives as antitumor agents: A structure-activity relationship study[END_REF] their corresponding metallocycles [START_REF] Orhan | Cytotoxic double arene ruthenium metalla-cycles that overcome cisplatin resistance[END_REF][START_REF] Dubey | Anticancer Activity and Autophagy Involvement of Self-Assembled Arene-Ruthenium Metallacycles[END_REF][START_REF] Vajpayee | Self-assembled metalla-rectangles bearing azodipyridyl ligands: synthesis, characterization and antitumor activity[END_REF] and metallocages [START_REF] Cook | Biomedical and Biochemical Applications of Self-Assembled Metallacycles and Metallacages[END_REF] have anti-cancer activity. Similar results were shown for cages based on Palladium [START_REF] Bhowmick | Coordination-Driven Self-Assembly of Ionic Irregular Hexagonal Metallamacrocycles via an Organometallic Clip and Their Cytotoxicity Potency[END_REF][START_REF] Mcneill | Biologically active [Pd2L4]4+ quadruply-stranded helicates: stability and cytotoxicity[END_REF] and Platinum. [START_REF] Bhowmick | Coordination-Driven Self-Assembly of Ionic Irregular Hexagonal Metallamacrocycles via an Organometallic Clip and Their Cytotoxicity Potency[END_REF][START_REF] Singh | Self-Assembly of a [1 Ionic Hexagonal Macrocycle and Its Antiproliferative Activity[END_REF] Finally, another application of self-assembled cages concerns catalysis. Depending on the structure, the catalyst can be part of the cage or an encapsulated molecule [START_REF] Lorenzo | Advantages of Catalysis in Self-Assembled Molecular Capsules[END_REF][START_REF] Zhang | Functional Capsules via Subcomponent Self-Assembly[END_REF] . This allows to increase the selectivity towards both the substrate 100-102 and the product [103][104] . In some cases, self-assembly cages could be used to perform tandem reactions in one-pot synthesizes using several catalysts [105][106] .

Electro-active metal-driven self-assemblies

As previously mentioned, a redox stimulus can be used to tune the host-guest properties of electroactive self-assembled cages 107 . Various situations can be encountered depending on the location of the electroactive unit. The latter can be the organic ligand (naked or appended with a redox-active unit), the metal or even a co-ligand on the metal. Moreover, through-space or through-bond interactions between the different components can potentially occur. Several selected illustrative examples are provided below.

Using electron-deficient ligands

Most coordination-driven self-assembled architectures feature electron-poor systems, which is partially caused by the nature of coordination bond. One of the first examples, described by Fujita and colleagues, used triazine panels (2,4,6-tris(4pyridyl)-1,3,5-triazine) and square-planar Pd(II) or Pt(II) as metal corners (figure 1.5.1). The redox behavior of the cage was investigated by cyclic voltammetry (CV) 108 , which showed a reversible redox wave corresponding to a one-electron reduction process at E = -1.02 V vs. Ag/Ag+, followed by pseudoreversible redox waves from E = -1.40 to -2.00 V, assigned to three electrons in total. It is worth noting that the four triazine panels are not simultaneously reduced. The ability of the cage to encapsulate adamantane was evidenced by J. T. Lippard and coworkers who introduced a prodrug made of adamantane modified with platinum 109 (figure 1.5.1).

The same triazine ligand was also used in combination with a bis-Ruthenium complex by B. Therrien and coworkers 110 (figure 1.5.2). Cyclic voltametry showed irreversible oxidation at E = 0.27 V vs. Ag/AgNO3 and a quasi-reversible reduction at E = -2.33 V. Upon encapsulation of a coronene guest, the general behavior remains the same with a small positive shift of potential. The perylene bisimide (PBI) unit is interesting for both electronic and optical properties. F. Wurthner and colleagues have developed metalla-square constructed from a tetraarylsubstituted N,N`-4pyridyl-substituted PBI ligand and a square planar Pt(II) complex 111 (figure 1.5.3, a). The cyclic voltammetry reveals two successive reversible reduction waves at E = -1.01 and -1.14 V vs. Fc/Fc + , which are slightly shifted compared to the free ligand PBI-ligand precursor (E = -1.08 and -1.23 V respectively). They correspond to the successive radical anion and dianion formation for each perylene unit, which behave independently contrary to the above-presented triazine-based cages. Finally, a reversible oxidation process is observed at E = 0.93 V vs. Fc/Fc + . The PBI panels can also be additionally decorated using ferrocene moiety. 112 Interestingly, in this case a splitting of the ferrocene oxidation wave is observed, resulting from intramolecular electronic interactions between the spatially confined ferrocene units. 1.5.3. Redox-active self-assemblies using perylene bisimide (PBI) unit. [113][114] The resulted square is able to modulate the ionic charge from 0 to +12, although authors failed to get guest encapsulation within the cavity. The same group recently designed a robust PBI-based metallacage presenting host-guest properties. 114 The very large M4L6 tetrahedron (figure 1.5.3, b) is assembled from an octahedral Fe(II) ion and a PBI ligand bearing 2,2'-bipyridine units on the imide positions. The resulting Fe4(PBI)6 tetrahedron exhibits a particularly rich electrochemical activity manifested by multiple redox processes. Cyclic voltammetry shows reversible redox waves at E = -0.94 and -1.11 V vs. Fc/Fc + , which correspond to the successively reduced radical-anion and dianion species respectively. They are followed by the three successive reductions of the bpy fragments. In addition, two oxidation waves are observed at E = 0.73 and 0.95 V, assigned to the successive Fe 2+ and PBI oxidation. This results in a broad range of charges surrounding the cavity (from -16 up to +18), which corresponds to a total of 34 electrons which can be switched, simply by controlling the electrochemical potential. A guest encapsulation was successfully demonstrated using a fullerene C60 molecule, as confirmed by ESI-TOF mass spectrometry.

Using electron-rich ligands

Ferrocene is widely used as an electron-rich unit, e.g. in catalysis, electrochemistry and functional materials. 115 In self-assembles structures, it has been incorporated as a substituent either on the ligand or on the metal complex. 116 The groups of Stang and Young have described a series of molecular hexagons and triangles using ferrocene in the exo-position [117][118][119] (exo refers to the respective location related to the cavity) (figure 1.5.4). They were obtained using Platinum-based ligands with 120 0 (for hexagons) and 60 0 (for triangles) angle. All hexagons show one reversible oxidation (figure 1.5.4, a) whereas the molecular triangles lead to a oxidation wave splitting, due to a closer distance between the ferrocene units. Cyclic voltammetry data could be used to calculate the hydrodynamic radius of the self-assemblies using the diffusion coefficient (D) from Randles-Sevcik equation. Using a tritopic ligand results in a 3D metallocage (figure 1.5.4, b). 120 The size of the cage was estimated using cyclic voltammetry (6.7 nm) and is in good correlation with a theoretical estimation (6.9 nm). Similar metallocycles with ferrocene fragment in the endo-position were depicted by H.-B. Yang and coworkers. 121 Interestingly, despite the close location of the ferrocene units, no electronic interaction was observed in the cyclic voltametry experiment for both molecular triangles and hexagons (figure 1.5.5). Also endo-position of the ferrocene makes it harder to approach and thus oxidate, which is confirmed by a higher oxidation potential and a lower current intensity. The ferrocene unit can also be directly engaged as a cavity constituent along the self-assembly. Finally, the ferrocene unit can also be located onto the corners of the self-assembled discrete structure, notably with cis-blocked Pd and Pt complexes. On this basis, Stang and coworkers described various molecular squares involving the dppf complex (diphénylphosphinoferrocene) [125][126] (figure 1.5.7). Upon using tritopic ligands, various metallocages could be also obtained, as shown by R. Yang and coworkers 127 . A rare example of a host-guest redox study was recently proposed by J. R. Nitschke and coworkers 129 from a tetrahedral Fe(II)4L6 tetrahedral cage and a C60 fullerene molecule (figure 1.5.9). The metallacage is based on a porphyrin-based ligand and is capable of encapsulation from one (in nitromethane) to four (in nitrobenzene) C60 molecules. The free cage shows two irreversible redox processes -broad oxidation at +0.17 V vs Fc/Fc + and reduction at -1.73 V vs Fc/Fc + , both assigned to the porphyrin moieties and a reversible reduction at -2.09 V vs Fc/Fc + corresponding to the pyridylimines. The binding of several fullerenes is accompanied by significant changes of these potentials. Therefore, the electronic interaction between fullerene and porphyrin cavity walls strongly impacts the fullerene electronic behavior and lowers the HOMO-LUMO gap. 132 . The interest to this molecule was further fueled by the discovery of high conductivity for its salt TTF + Cl -and first organic conductors in the form of its complex with highly acceptor TCNQ molecule [133][134] . TTF 135 is a non-aromatic molecule with 14π electrons, which presents two fully reversible oxidations at low potential (scheme 1.6.1), giving rise successively to a cation-radical (TTF .+ ) and a dication (TTF 2+ ). Therefore, this unit can exist under three stable redox states, based on the successive formation of one (TTF .+ ) and two (TTF 2+ ) heteroaromatic 1,3-dithiolium rings, upon oxidation of both 1,3-dithiol rings of neutral TTF (often abusively named dithiafulven (DTF)).

More than seven thousand publications covering a wide variety of applications, ranging from organic electronics to chemical sensors, have been produced from TTF and derivatives. [136][137][138][139] In particular, it has been shown to be an efficient redox unit in switchable molecular or supramolecular processes. 107,140 The TTF core can be synthetically modified, e.g. by changing Sulfur atoms for other chalcogens or by extending the conjugated system (figure 1.5.10). [141][142] This results in new derivatives presenting specific structural and electronic properties. For example, truxeneTTF has a concave shape whereas exTTF presents a butterfly conformation. Such varieties are useful in supramolecular chemistry. [143][144] Figure 1.5.10. Examples of TTF derivatives presenting an extended -extension.

Previous works of our group related to electro-active metal-driven self-assemblies

First metallocycles were obtained by our group with the bispyrroloTTF (BPTTF) bearing pyridine groups. [145][146] Upon its coordination with cis-blocked Pt complex, a mixture of a molecular square and a triangle was produced, which could be separated (figure 1 .5.11, a). Cyclic voltammetry shows the two classical reversible oxidation scheme at 0.3 V and 0.63 V vs Fc/Fc + . Ferrocene was used as an internal coulometric standard to confirm the independent oxidation of each BPTTF fragments (figure 1.5.11, b). As a result, charge of the internal cavity can be modulated from 0 to +8 (square) and from 0 to +6 Scheme 1.5.1. Redox behavior of the TTF molecule (triangle). The electron-rich cavity of the molecular triangle М3L3 was shown to bind electron-poor C60 and C70 molecules in a 1/1 ratio (figure 1.5.11, c), whether no interaction was observed for the molecular square М4L4. Figure 1.5.11. BPTTF-based metallocycles (a), their deconvoluted cyclic voltammetry (black, square; grey, triangle) (b) and Job's plot for the interaction between the electron-rich triangle cavity and C60. 145 A redox-active supramolecular cage using BPTTF was obtained by designing a tetratopic ligand (tetrapyridyl BPTTF) [147][148] followed by coordination with a cis-blocked Pt complex. A М6L3 molecular prism was obtained (figure 1.5.12), whose X-ray structure could be solved. This cage exhibits two irreversible oxidations at fairly high potentials (0.43 V and 0.62 V vs Fc/Fc + ) and it was shown by UVvis titration that this cavity is able to encapsulate one electron-poor molecule (tetrafluorotetracyano-pquinodimethane (TCNQ-F4)) in acetonitrile, in a 1/1 stoichiometry. Figure 1.5.12. A BPTTF metallocage and XRD structure (a), cyclic voltammetry (b). 148 As mentioned above, the so-called π-extended tetrathiafulvalene unit (9,10-di(1,3-dithiol-2ylidene)-9,10-dihydroanthracene, abbreviated exTTF) features a dihydroanthracene fragment bridging two five-membered 1,3-dithiol rings. In contrast to the planar parent TTF system, exTTF exhibits a butterfly geometry, due to repulsive 1,6-interactions between S atoms and periplanar anthracenyl H atoms. As a consequence, only one quasi-reversible two-electron oxidation process is observed while generating a dication, which structurally corresponds to an assembly of three independent aromatic entities (figure 1.5.13). Four pyridine groups were introduced onto the exTTF core, generating a tetratopic ligand which was used in combination with cis-blocked Pd and Pt dppf complexes (figure 1.5.14, a). 149 The resulting М4L2 cages both presents an irreversible oxidation at 0.57 V (Pd cage) and 0.65 V (Pt) vs Fc/Fc + and a second reversible oxidation (Eox 2 = 0.80 V) which corresponds to oxidation of ferrocene units from the dppf coligand (figure 1.5.14, b). In order to improve the solubility, a modified version of the exTTF ligand was developed by introducing auxiliary triethylene glycol (TEG) chains (scheme 1.6.2). This allowed to build octacationic cages (M4L2 8+ , M = Pd, Pt) but also a neutral cage (M4L2). The former dissociates upon oxidation due to the geometry change in the ligand and reassemble upon reduction. This property was used to encapsulate an anionic guest cluster (K2B12F12) and to control the guest release by a reversible cage disassembling. 150 Scheme 1.5.2. Redox-active cages using exTTF-TEG ligand. 150 The neutral M4L2 cage shows a better affinity for neutral guests (e.g. coronene, bound in a 1/1 ratio). 151 Interestingly, this M4L2 cage with M = Pt, is remarkably more robust upon oxidation than is the Pd one, and therefore does not disassemble. This means that a sequence of oxidation-reduction leads in this case to a reversible generation of four positive charges on the cavity, without disassembling. This situation allows a controlled release of the coronene guest upon electrochemical oxidation, thanks to an exchange with anions of the supporting electrolyte. 152

Objectives of the thesis

My thesis is part of the project dedicated to the design of new self-assembled coordination-driven redox active cages. Two main objectives are targeted:

 Developing new building blocks for constructing supramolecular redox-active cages endowed with specific properties, through:  designing new electron-rich ligands inspired from the TTF core and its derivatives, including their full characterization and the study of their ability to generate discrete self-assemblies;  exploring new metal complexes and studying their impact upon the self-assembly process;

 Studying the resulting metallocycles and metallocages: electrochemical, structural and guest binding properties.

Chapter II. Tetrathiafulvalene-based self-assemblies

Ligands based on the tetratiafulvalene moiety

Tetra-pyridyl TTF derivatives with 3-pyridyl units (TTF(3Py)4) or 4-pyridyl units (TTF(4Py)4) were first obtained in our group using a C-H activated arylation, as first developed on the TTF motif with alternative aryl groups by Mitamura and coworkers. 153 Further coordination of the tetratopic ligand TTF(4Py)4 with a short bis-Ruthenium complex (Ru1, oxalato linker) resulted in a М8L2 cage (figure 2.1.1,a),while other combinations from TTF(4Py)4 or TTF(3Py)4 with Ru1 or Ru2 gave simple М4L1 metalloplates 154 (figure 2.1.1,. Interestingly, all metalloplates exhibit two reversible oxidations, while the cage displays only one reversible oxidation at 0.44 V vs Fc/Fc + . This is assigned to the rigid geometry of the cage, which does not allow conformational changes upon oxidation. Beside, ligand TTF(4Py)4 in combination with a cis-blocked Pd or a Pt complex results in М8L4 cage 116 . In contrast to the Ruthenium cage above, both cages show two reversible oxidations 149 (figure 2

.1.2).

The ferrocene unit of the dppf coligand is used as an internal standard and confirms independent oxidation of the four TTF fragments.

Design and synthesis of ligand TTF(PhPy)4

The above-mentioned М8L2 cage TTF(4Py)4 featuring bis-Ruthenium complexes is particularly interesting. Indeed such system allows to tune the distance between both facing TTF units depending on the length of the bis-Ruthenium complex, and to the best of our knowledge, only one example exists in the literature where two TTF planes are forced to stand overlapped (figure 2.1.3). 155 Nevertheless, the distance between both TTF units in the latter system is quite important and did not allow to characterize any interaction between the redox units. The peculiar geometry of М8L2 cages (e.g. Figure 2.1.1) offers two promising opportunities:

1) if the Ru-Ru distance is large enough in the bis-Ruthenium complex, an electron-poor guest may be bound according to a sandwich mode between both electron-rich TTF units;

2) if the Ru-Ru distance is short enough in the bis-Ruthenium complex, one may assume that both TTF will interact upon oxidation.

The scheme 2.1.1 illustrates the interaction modes which can be anticipated when two TTF units are in close contact: i/ formation of a mixed-valence dimer (TTF)2 •+ , observed and characterized with covalent poly-TTFs systems; 156 ii/ formation of a -dimer (TTF •+ )2 system, and iii/ a final oxidation step towards dicationic (TTF 2+ ) units, which dissociate due to electrostatic repulsion.

In addition to the well-established conducting properties of some of them in the solid state, 157 the mixed-valence dimer (TTF)2 •+ have known a strong recent interest, as a new interaction mode of the supramolecular toolbox. [158][159] Indeed, such interactions allows to redox-govern the contacts between two units, offering promising perspectives, notably in terms of triggering molecular movement. )2 (1,3 mM,acetone) from TTF •+ CB -(CB -: dodecamethylcarba-closo-dodecaboranate) (in °C, from bottom to top at 740 nm) : 22, -40, -55, -63, -70, -78, -85, and -90).

Moreover, the -dimer (TTF •+ )2 could be observed at rt in very specific cases, either by: i/ confinement of the dimer in a cavity (i.e. in cucurbituril 163 or in a coordination cage [START_REF] Yoshizawa | Room-Temperature and Solution-State Observation of the Mixed-Valence Cation Radical Dimer of Tetrathiafulvalene, [(TTF)2]+•, within a Self-Assembled Cage[END_REF] , ii/ designing covalent species allowing preorganization of the cation-radical dimer [164][165][166][167] or by 3/ dimer stabilization in interlocked structures. 168 On this basis, and in order to get a deeper insight over the occurring interactions, it appears timely to design a system allowing to control the distance between two TTF units.

As shown in figure 2.1.1, long bisRuthenium complexes essentially afford metalloplates instead of the desired М8L2 cages, due to a good matching between the Ru-Ru distance and N-N distance from neighbored pyridine units. One solution to favor the М8L2 cage consists therefore in enlarging the distance between pyridine units compared to TTF(4Py)4, which can be obtained through incorporation of a phenyl linker between the TTF core and pyridyl units and which corresponds to compound TTF(PhPy)4.

Scheme 2.1.2. Synthesis of the TTF(PhPy)4

The ligand TTF(PhPy)4 was synthesized with a 86% yield using a Palladium-catalyzed C-H activated tetraarylation, starting from the commercially available TTF and (4-bromophenyl)pyridine (scheme 2.1.2). The latter was previously obtained through a Palladium-catalyzed Suzuki coupling 169 .

Characterization

TTF(PhPy)4 was characterized by 1 H, [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR spectroscopy, as well as mass-spectroscopy and elemental analysis. Single crystals, suitable for analysis, were obtained by slow evaporation of dichloromethane/methanol mixture and the x-ray analysis was carried out at T = 250 K. X-ray data (see annex 6.1) show a significant disorder of the phenyl units, which confirms the structural flexibility (figure

2.1.5).

The molecule has a rectangular shape with 12.8 x 19.3 Å dimensions between the four Nitrogen atoms, to be compared with the 6.7 x 13.1 Å in the case of the smaller TTF(4Py)4 ligand. This size should avoid formation of undesired metalloplates upon coordination with bis-Ruthenium complexes and remains fully suitable for the formation of М4L2 cages.

Electrochemical properties

The electrochemical properties of the TTF(PhPy)4 ligand were studied in a 1:1 acetonitrile/dichloromethane mixture. As in the case of TTF(4Py)4, this ligand exhibits two reversible oxidation waves (Eox 1 = 0.06 V; Eox 2 = 0.46 V vs. Fc/Fc + ) corresponding to two successive one-electron oxidations to the radical-cation and dication states (Figure 2.1.6). Nevertheless, these oxidations occur at significantly lower potentials comparing with TTF(4Py)4 (Eox 1 = 0.20V and Eox 2 = 0.55V vs. Fc/Fc + ). This difference is explained by the presence of the phenyl spacer which isolate the pyridyl groups from the TTF core, thereby attenuating the withdrawing inductive effect of nitrogen atoms. On this basis, the TTF(PhPy)4 unit appears as a remarkably strong -donating ligand, suitable for generating discrete assemblies endowed with an electron-rich cavity.

Self-assemblies based on the tetrathiafulvalene moiety

M8L2 self-assemblies with Ru complexes: AA1 and AA2

The previous M8L2 cage involving the TTF(4Py)4 ligand in combination with a short bis-Ruthenium acceptor (Ru1, dRu-Ru = 5.5 Å) failed to successfully encapsulate a guest molecule because of the small distance between TTF planes. Longer bis-Ruthenium complexes could not be used since they preferentially afford metalloplates rather than cages (see § 1.4.4). In the case of the new TTF(PhPy)4 ligand, longer bis-Ruthenium complexes Ru3 and Ru4 can be used (dRu-Ru = 8.4 Å) to drive the selfassembly towards metallocages. The reaction was first carried out using acceptor Ru3 in a methanol/nitromethane 1/1 mixture during 3 days, affording in the self-assembly AA1 (scheme 2.2.1). Further optimizations allowed to obtain the same self-assembly AA1 from Ru3 in acetone in only 1 day, as well as AA2 from Ru4.

Formation of the cage AA1 was confirmed 1 H and DOSY NMR (figure 2.2.1). Upon coordination to the metal center, the signals of α(■) and β(•) pyridil protons shift as expected towards stronger field. Well defined signals are observed, suggesting formation of a discrete self-assembled compound. This is further confirmed by a DOSY NMR experiment, for which a single set of aligned signals is observed. The corresponding diffusion coefficient (D = 2,51 x 10 -10 m².s -1 ) allows to estimate the hydrodynamic radius rH = 16 Å for AA1, calculated from the Stokes-Einstein equation (equation 1). [169][170] 6 Equation 1 : Stokes-Einstein Equation; D corresponds to the diffusion coefficient (m².s -1 ), kB Boltzmann constant (1,38 x 10 -23 J.K -1 ), T absolute temperature (K), η viscosity of the solvent (Pa.s) and rH hydrodynamic radius (m).

A similar behavior is observed in the case of AA2 prepared in acetone-d6 (annex 3.1). Following the same procedure, a rH value of 17 Å is found for AA2 (D = 4,34 10 -11 m².s -1 , acetone-d6), which is as expected, slightly larger than for AA1.

Structural properties and intercalation attempts

Such metallocages with electron-rich walls should be effective for the intercalation of planar electron-poor guests in a sandwich mode. Nevertheless, all attempts to introduce guest molecules for both cages AA1 and AA2 failed. An explanation comes from the short distance existing between facing TTF units, which could be demonstrated in the solid state through a single-crystal X-ray diffraction analysis led on AA1 (figure 2.2.3). Crystals, suitable for XRD analysis, were obtained by diffusion of methyl-tert-butyl ether into a solution of AA1 in methanol (see X-Ray data in annex 6.2). From this study, a distance of 33 Å is found between two extreme opposing atoms of AA1 which correlates well with the above calculations using DOSY NMR. The angle between Nitrogen atoms of pyridil units is 64 ° in comparison to 84.7 ° in the free ligand, which illustrates a certain constraint upon self-assembly. But the most striking feature of this solid state structure relies on the close distance of 3.68 Å observed between C atoms of the internal C=C bond in two TTF units (S … S mini: 3.83 Å), which is significantly smaller in comparison to the Ru-Ru distance in the lateral pillar (8.4 Å). This illustrates the significant flexibility of the assembly and results in a severe bending of both TTF units. The latter can be characterized with an angle of 35 • between the pyridine-TTF vector and ideal planar geometry of the TTF(4PhPy)4 ligand. Such bending justifies why no sandwich host-guest complex could be obtained, despite numerous attempts. Crystals of AA2 were obtained using the same conditions. As expected, the spatial organization of AA2 (figure 2.2.4) is similar to the above presented AA1. Notably, the distance between TTF fragments is of the same order (3.72 Å) as for AA1, and is much shorter than the Ru-Ru distance in the lateral pillars (8.34 Å). A noticeable difference with AA1 comes from the cavity collapse which in the case of AA2, is essentially supported by a single TTF unit. The latter displays a severe bending with 33 • and 37 • angles between the pyridine-TTF vectors and an ideal planar geometry, whereas the second TTF unit remains essentially planar.

Electrochemical properties

The electrochemical behavior of cage AA1 was studied in a acetonitrile/dichloromethane 1/1 mixture, using ferrocene for calibration (figure 2.2.5). Interestingly, cage AA1 shows a splitting of the first oxidation process in two waves (-0.03 V and +0.20 V vs Fc/Fc + ) in comparison to the ligand (+0.06V vs Fc/Fc + ) (figure 2.2.5, a). This is indicative for the formation of the mixed-valence dimer ((TTF)2) .+ and the corresponding -dimer (TTF .+ )2. 156, 171 Such phenomenon can be explained by the very close distance between facing TTF subunits which are therefore prone to strongly interact upon oxidation. A third reversible oxidation is located at 0.53 V vs Fc/Fc + and is assigned to the formation of the dication state for each TTF unit resulting in tetracationic cage. Finally, an additional reversible oxidation process is observed at 0.80 V vs Fc/Fc + , which corresponds to the metal center oxidation, as shown from comparison with Ru3. Note that the reversible reduction of the naphthoquinone fragment is observed at -0.87 V vs Fc/Fc + (not shown in Figure 2.2.5). Finally, it is worth noting that the self-assembly AA1 remains stable upon repeated cycles within this potential window, but that higher potentials cause destruction of the cage.

In contrast to AA1, self-assembly AA2 shows the usual two reversible oxidation processes of TTF at 0.17 V and 0.45 V vs Fc/Fc + . The absence of generation of the oxidized dimeric species is surprising since the Ru-Ru distances are similar for both Ru3 and Ru4 pillars. One hypothesis relies on the larger tetracene-based central unit in Ru4 (naphthalene-based in the case of Ru3) which presumably prevents interaction between the TTF planes. These processes are followed by a reversible oxidation at 0.66 V and an irreversible one at 0.85 V vs Fc/Fc + , which are attributed to the Ru4 unit. As for AA1, scanning the potentials beyond 1.20 V leads to the cage disassembling.

Electrocrystallization studies

The electrocrystallization technique allows to grow single crystals of the oxidized (or reduced) compounds upon a controlled galvanostatic or potentiostatic electrolysis (see annex 2). The crystals are generally collected directly onto the working electrode. The main principle is based on the slow oxidation (or reduction) of the electro-active molecule giving rise to charged species which cocrystallyze with the counter-ion present used in the supporting electrolyte. After numerous attempts of constant current electrolysis of AA1, single crystals suitable for XRD analysis could be collected (conditions: CAA1 = 5 x 10 -4 mol.L-1; methanol; Bu4NPF6 (0.1 mol.L -1 ); Tre= 20 °C; i= 0.5 A). The quality of the X-Ray data collection was not optimal, nevertheless the main trends could be drawn. The oxidized form preserves the main geometrical characteristic of the starting AA1 cage, but exhibits some significant differences (figure 2 illustrates occurrence of an intramolecular interaction occurring between the facing TTF units upon oxidation at the first redox process (cation-radical generation).

Absorption studies

In order to get a deeper understanding of the electronic properties of these new architectures, we plane to perform some spectroelectrochemistry measurements (annex 1). This technique allows to follow in real time the changes in the UV-vis spectra during the cyclic voltammetry. These studies are currently done in collaboration with Drs O. Alevêque and E. Levillain (laboratory MOLTECH-Anjou).

Reference UV-vis data of the ligand TTF(4PyPh)4 are first needed in order to tune the spectroelectrochemistry analysis. The latter is very sparingly soluble in the standard dichloromethane/acetonitrile system which we used for the above electrochemical experiments. Therefore the more soluble tetrakis(methylpyridinium) derivative TTF(Me-4PyPh)4 was synthesized (scheme 2.2.2). This compound is considered reminiscent of the corresponding TTF(4PyPh)4 once the latter is engaged in a coordination bond, as it is the case in AA1. Alkylation was carried out in DMF, followed by anion exchange using KPF6.

Scheme 2.2.2. Synthesis of TTF(Me-4PyPh)4.

The UV-vis spectra of TTF(Me-4PyPh)4 (compound 7) (2.5 x 10 -5 М), complex Ru3 (2.5 x 10 -5 М) and cage AA1 (1.5 x 10 -5 М) are shown in figure 2.2.7. The TTF derivative 7 exhibits two strong absorptions at λ= 325 nm (ε = 41110 l.mol -1 .cm -1 ) and λ = 460 nm (ε = 4220 l.mol -1 .cm -1 ), which are typical for pyridinium salts 172 . The Ru3 complex exhibits main absorptions at λ = 320 nm (ε = 12600 l.mol -1 .cm -1 ) and λ = 430 nm (ε = 9100 l.mol -1 .cm -1 ), which correspond to the intra-ligand charge transfer in naphthalene and cymene, and minor absorptions at λ = 630 nm (ε = 3300 l.mol -1 .cm -1 ) and λ = 682 nm (ε = 4250 l.mol -1 .cm -1 ), that correspond to the metal-ligand charge transfer due to the coordination with naphthalene and cymene 173 . Finally, the spectrum of cage AA1 essentially corresponds to the sum of the respective above contributions of TTF(Me-4PyPh)4 and Ru3 with main absorption at λ = 305 nm (ε = 96200 l.mol -1 .cm -1 ) and less intense ones at λm = 435 nm (ε = 26200 l.mol -1 .cm -1 ), λ = 645 nm (ε = 7900 l.mol -1 .cm -1 ) and λ = 695 nm (ε = 7500 l.mol -1 .cm -1 ), which is typical for such systems 174 . The corresponding spectroelectrochemical studies of AA1 are in due course and should contribute to get a better insight over the oxidized species resulting from oxidation of the cage..

Conclusion

A new large tetratopic ligand TTF(4PyPh)4 was designed in order to favor the formation of a M8L2 cage rather than a М4L1 metalloplate upon self-assembling with bis-Ruthenium complexes. The latter are used as the four pillars separating both TTF planes in the M8L2 cage and their respective length is considered to drive the distance between the facing redox-active units. In particular, two selfassemblies AA1 and AA2 were synthesized and fully characterized, including in the solid state (XRD). Whereas in both cases the M8L2 corner-corner distances Ru-Ru are ca 8.3Å, short interplanar C … C and S … S distances of ca 3.68 Å and 3.83 Å respectively are observed between the two TTF units in AA1 (similar values for AA2). This short distance is consecutive to a severe bending of the facing ligands, which collapse towards the center of the cavity. Accordingly, attempts to bind electron-poor planar guests in a sandwich mode, failed from these collapsed M8L2 assemblies. It is worth noting that whereas AA2 exhibits the usual electrochemical two-step oxidation behavior of TTF derivatives, AA1 clearly shows that the two facing TTF units strongly interact upon oxidation, giving rise to an oxidized TTF dimer. This observation is imputable to the unique geometry of those M8L2 assemblies, for which the two TTF units are forced to stack together. Electrocrystallysation experiments where led upon galvanostatic oxidation of AA1 and afforded single-crystals of the oxidized cage. The latter does not disassemble upon oxidation which confirms the robustness of AA1. The resulting oxidized cage shows that the two TTF units are significantly closer than in neutral AA1. The shortest interplanar TTF distances are found to be ca C … C = 3.45 Å and S … S = 3.70 Å, i.e. significantly smaller than in neutral AA1 and in the range of twice the van der Waals radii of C and S atoms respectively (2.RvdW(C) = 3.40 Å and 2.RvdW(S)= S … S = 3.60 Å). This observation illustrates an intramolecular interaction occurring between the facing TTF units upon oxidation at the first redox process (cation-radical generation). Given the fundamental interest of such species in the current literature, additional studies have to be led to finely characterized those oxidized species. This work is in progress through spectroelectrochemical analyses.

Chapter III. Dithiafulvalene-based self-assembly

As previously described in § 1.3.3, a new class of M2L4 "lantern"-shaped self-assemblies has emerged recently. Construction of such structures relies on combination of "naked" square-planar metal centers having all 4 coordination sites available with bent "banana-shaped" ligand. [START_REF] Shanmugaraju | Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C60 Binding Study[END_REF][START_REF] Rongmei | Stepwise Halide-Triggered Double and Triple Catenation of Self-Assembled Coordination Cages[END_REF]175 These cages usually possess a well-defined cavity, which is of a particular interest for host-guest chemistry using either anionic or neutral guests. [START_REF] Clever | Cation-Anion Arrangement Patterns in Self-Assembled Pd2L4 and Pd4L8 Coordination Cages[END_REF] Nevertheless, redox-active M2L4 self-assembly are quite rare in literature (see § 1.5.2). Therefore, an electron-rich redox-active motif suitable for M2L4 cages was developed starting from the dithiafulvalene scaffold (scheme 3.1.1). Nota: By extension, the latter is in this work defined as an association between a 1,3-dithiol heterocycle and the fluorene unit.

Ligands based on dithiafulvalene (DTF)

Scheme 3.1.1. Formation of a M2L4-type self-assembly using "banana-shaped" ligands and "naked" Palladium.

On this basis and in the course of our study related to the preparation of electron-rich metallacages, we designed the 3Py-DTF bent ligand involving dithiafulvalene and fluorine fragments (scheme 3.1.2). Such systems are known to retain interesting electrochemical behavior. 171,[176][177] In order enlarge the scope of such ligand and to achieve effective coordination in a different orientation, the 4Py-DTF isomer was also synthetized. This complementary ligand could allow to generate larger М6L12 cages, such as the one recently reported by Fujita and coworkers. 175 Thioalkyl groups on the dithiol ring are added to improve general solubility.

Synthesis

The fluorene core was obtained in two steps starting from commercially available phenanthrene-9,10-dione (scheme 3.1.3). The first step was performed by radical bromination to compound 21 with 86% yield, followed by oxidation to compound 22 with 60% yield. At this stage, two routes can be followed to produce target ligands. Initial attempts during the PhD thesis of V. Croue involved first a Horner-Wadsworth-Emmons (HWE) reaction using the previously obtained S-hexyl phosphonate 16 to produce the intermediate dibrominated DTF compound. Unfortunately, the subsequent Sonogashira coupling reaction gave very low yield in case of ligand 25 and only traces in case of 26. After numerous attempts, it was chosen to first perform a microwaveassisted Sonogashira coupling reaction on derivative 22. Compounds 23 and 24 were obtained with good yields of 75% and 59% respectively, in only 30 min. Final ligands were obtained after a HWE reaction, with moderate yield of 57% and 55%. Similar ligands 27 (for 3Py-DTF motif) and 28 (for 4Py-DTF motif) bearing propyl chains were also synthetized using the same procedure starting from previously obtained phosphonate 17 with 46% and 40% yield respectively.

Characterization and electrochemical properties

Ligands 25, 27 (3Py-DTF)and 26, 28 (4Py-DTF) were characterized using 1 H, [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] С NMR and high-resolution mass spectrometry. Interestingly, long hexyl chains did not prevent the crystallization and crystals suitable for X-Ray analysis were obtained by slow evaporation of ligands 25 and 26 in a dichloromethane/methanol mixture (figure 3.1.1). Nevertheless, alkyl chains remain slightly disordered in both cases. Both ligands show a nearly planar geometry with a slight folding of the dithiole rings (3.6° and 6° along the S ---S vector for 25 and 26 respectively). The pyridine units are less twisted in 26 than in 25 in relation to the central planar fluorene core with angles of ca. 5° and 13° respectively. Exocyclic double-bond has slightly longer distance (1.36 Å) than for a standard olefinic bond (R2C=CR2). 176 The angle between both ethynyl axes is close to 90° in good accordance with the expected structure. This results in the 3Py-DTF system for which both nitrogen pyridine atoms point towards ca parallel directions, providing therefore a geometry that is suitable for the synthesis of M2L4 coordination cages. In principle, the DTF fragment shows two oxidation processes when studied by cyclic voltammetry. The first, reversible, corresponds to the formation of a radical-cation and the second, irreversible, to a dication. 176 However, in the case of our DTF ligands, only one irreversible oxidation process was observed in DMF, located at 0.54 V and 0.57 V vs Fc/Fc + for ligands b). Scanning at higher potential does not reveal a second oxidation process, although results in the losing the reversibility for the first oxidation. Similar results were previously obtained for an isomeric DTF compound. 177 As expected, ligands 27 and 28 bearing propyl fragments show similar behavior at the same potential 3.2. Self-assembly using "naked" Palladium 178

M2L4 self-assembly with 3Py-DTF ligand: AA3

The self-assembly process using ligand 25 (2 equiv.) and complex Pd(BF4)2(CH3CN)4 (1 equiv.) was carried out in DMSO-d6 at 50 0 C. The reaction was followed by 1 High resolution ESI-FTICR-MS spectrometry was performed in collaboration with Drs Frédéric Aubriet and Vincent Carré from the University of Lorraine. However, initial experiments using an isolated AA3 self-assembled complex resulted in the absence of signal due to its low solubility when analyzed from a DMSO solution. Therefore, we exchanged the BF4 -anion for the bulky tetrakis [3,5bis(trifluoromethyl)phenyl]borate (BArF -) anion in order to improve the solubility of the cage. Addition of an excess of NaBArF to the suspension of AA3 ([Pd2L4] 4+ , 4BF4 -) in a CH2Cl2/CH3NO2 (1/1, v/v) mixture allowed to obtain a 10 -3 M solution of [Pd2L4] 4+ , 4BArF -, which was used directly for the analysis. Thus, ESI-FTICR-MS experiment was able to confirm the M2L4 stoichiometry of AA3, with characteristic multi-charged species at m/z = 1293.2367 corresponding to [[Pd2L4] 4+ , 4BArF --3BArF - ] 3+ . Experimental isotopic pattern also shows good correlation with the theoretical one (figure 3.2.2).

Electrochemical properties

The electrochemical behavior of the cage AA3 in comparison with ligand 25 was investigated by cyclic voltammetry. Due to its solubility, cage AA3 was first studied in DMF, resulting in one irreversible oxidation process at 0.62 V vs Fc/Fc + , therefore having the same behavior as a starting ligand 25 with slightly higher potential (figure 3.2.4, a). Taking into account reversible oxidation of the starting ligand 25 in the CH2Cl2/CH3CN system, as well as literature data for similar compounds, 180 we decided to exchange initial BF4 -anion for better solubility. Therefore, 0.05 M solution of NaBArF in CH2Cl2/CH3CN was used, ensuring both anion exchange with formation of soluble cage [Pd2L4] 4+ (BArF - )4 and serving as a supporting electrolyte. Resulting cage AA3BArF -has one reversible process at E 1/2 = 0.50 V vs Fc/Fc + (figure 3.2.4, b), which is again slightly higher due to the coordination to Palladium ions than the initial ligand 25. Altogether, behavior of the cage is consistent with independent oneelectron oxidation of each DTF fragment within the cage without any electronic interaction between them.

Attempts towards M6L12 cage from 4Py-DTF

As mentioned before, 4Py-DTF motif can be used to obtain larger М6L12 type cages, as demonstrated recently by Fujita and coworkers (figure 3.2.5). 175 In our case we were interested in obtaining larger cages while the maintaining redox properties of the system. Additionally, using ferrocene-containing complexes Pddppf or Ptdppf allows introduction of an additional redox-active ferrocene fragment, which can be used as an internal electrochemical standard (chapter 1.6.2).

M2L2 clips from 4Py-DTF: AA4 and AA5

Self-assembly process between both ligands 26 and 28 and Pd(dppf)OTf2 were carried out in CD2Cl2, and followed by 1 H and DOSY NMR (figure 3.3.1). After only 10 minutes, both reactions converged to the formation of unique structures AA4 and AA5 respectively, that could be isolated by a simple precipitation with Et2O.

56

X-ray structure indicates two separate assemblies within the crystal packing (figure 3.3.3, a). Both structures have the same stoichiometry and general structure, but differ in dihedral angle between DTF planes with values of 88.7 ° and 58.1 ° for blue and turquoise species respectively. Interplanar distance of 3.45 Å between the respective DTF units of two separate assemblies indicates significant π-π interactions, in addition to CH-π interactions between DTF units and SHex chains. Similar to AA3, geometrical parameters of ligand 26 remain mostly the same, despite the increase of twisting between the DTF core and ethynilpyridine units to 12.5 °.

Interaction with C60 and its derivatives

Since the first isolation of fullerene C60, several artificial π-electron rich supramolecular receptors have been synthesized in the context of selective separation of C60 from the fullerite composites containing other large analogues such as C70 and C120. It has been concluded in the reported literature that a bowl-shaped host is considered to be an ideal host to embrace the curved-surface of C60 through concave-convex, "ball-and-socket" π-π interactions, or C-H-π interactions. 183 Recently, a stable inclusion complex with C60 through a π-π interaction by a similar carbazole-based M2L2 self-assembly clip was illustrated by Mukherjee and coworkers (figure 3.3.4). [START_REF] Shanmugaraju | Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C60 Binding Study[END_REF] Therefore, metallocycles AA4 and AA5 should also present compatible geometries for interaction with C60 and should benefit from their electronrich side walls Figure 3.3.4. Example of host-guest complex using C60 and M2L2 self-assembly clip. [START_REF] Shanmugaraju | Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C60 Binding Study[END_REF] Regarding the lack of solubility of C60, interaction was fist studied by UV-vis absorption. UV-Vis spectra of ligand 26 and metalla-macrocycle AA4 were recorded in dichloromethane at C = 1.5 × 10 -5 M (Figure 3.3.5). Ligand 26 shows two high energy absorption bands at 290 nm and 350 nm, which can be attributed to π-π* transitions located on the fluorene and pyridines units respectively. They are followed by an intense low energy band at 460 nm (ε = 46,000 M -1 •cm -1 ), which has an ICT character from the HOMO localized on the DTF unit to the LUMO of the electron accepting pyridyles. 184 Selfassembly AA4 shows a similar profile. It has its maxima shifted to lower energy (λmax = 483 nm) in comparison with starting ligand, which is expected from metal coordination. ε values of the AA4 are also twice higher (ε = 102,000 M -1 •cm -1 ), which correlates well with established M2L2 composition of the metalla-ring.

58

To simplify interpretation of the host-guest interaction, we then moved to phenyl-C61-butyric acid methyl ester (PC61BM) for its higher solubility. Additionally, it is widely used as a component for solar cells or flexible electronics as an electron acceptor.

Electrochemical properties

The electrochemical properties of ligand 26 and complex AA4 were studied by cyclic voltammetry in CH3CN/CH2Cl2 (1/1, v/v) (figure 3.3.9). Metalla-cycle complex AA4 exhibits two reversible oxidation waves. The first process (E1 = 0.59 V vs. Fc/Fc + ) can be assigned to the oxidation of the DTF fragment and is anodically shifted by 20 mV regarding the free ligand as a result of coordination to the metal center. Second process (E2 = 0.83 V vs. Fc/Fc + ) correspond to the oxidation of the ferrocene moieties within the dppf fragment. Both processes present similar intensities, as expected from the M2L2 composition of the self-assembly. Altogether, this behavior suggests that both organic redox active DTF units behave independently upon oxidation to their radical cation state and that they do not interact electronically. Electrochemical behavior of clip AA5 is similar due to the weak influence of the aliphatic groups.

M2L2 clips from 3Py-DTF: AA6 and AA7

Despite slightly different geometry, 3Py-DTF ligands can also participate in a self-assembly process with cis-blocked acceptors. Reaction of ligand 25 (3Py-DTF SPr) and complex Pd(dppf)OTf2 was carried out in similar conditions and converged within 10 minutes. Presence of the non-symmetric 3-pyridyl unit leads to a more complex 1 H NMR spectrum (figure 3.3.10). Nevertheless, all aromatic signals could be attributed using a COSY experiment (annexes 3.4-3.9). All pyridyl proton signals are upfield shifted after coordination to the metal except H6, indicating that the latter does not interact with the dppf coligand. The presence of only one discrete species is confirmed by 1 H DOSY NMR experiment that show a single set of signals with diffusion coefficients D = 4.96 x 10 -10 m².s -1 respectively. This observation suggests that self-assembly structure has similar size to AA4, with an estimated hydrodynamic radius of ca 10 Å extracted from the Stokes-Einstein equation (T = 298K), a value which is compatible with the formation of M2L2 architectures. 182 Attempts to apply IRMPD technique also didn`t give sufficient results, similar to the self-assemblies with 4Py-DTF ligands.

Electrochemical properties

The electrochemical properties of ligand 26 and complex AA6 were studied by cyclic voltammetry in CH3CN/CH2Cl2 (1/1, v/v) (figure 3.3.11). Interestingly, in contrast to the complexes AA4 and AA5 obtained from 4Py-DTF ligands, clip AA6 presents three reversible oxidation waves. The first two correspond to the oxidation of DTF units, while the second is centered on the ferrocene moieties like the previous examples. The splitting of the first oxidation process is most likely due to the formation of the mixed-valence species during the oxidation process, similar to the cage AA1. This process can occur due to either intermolecular 156 or intramolecular interactions. To check this, cyclic voltammetry experiment was performed with different concentrations. Upon dilution data 62 shows diminishing of the current power, but the split structure remains (figure 3.3.12). This confirms that the formation of the mixed-valence species is caused by intramolecular interaction of DTF fragments within one clip.

Structural properties

Unfortunately, attempts to grow single crystal for the x-ray analysis were unsuccessful so far. Nevertheless, theoretical calculations using the MM+ model (HyperChem 8.0.8) for the M2L2 complex show much closer position of the DTF fragments with a S---S distance of 3.55 Å (figure 3.3.13). Such a proximity of the DTF units allows to explain the electrochemical behavior.

Intercalation attempts using DCTNF

According to the theoretical calculations for AA7, close distance between the DTF panels isn`t suitable for interaction with large molecules like C60. Nevertheless, it should efficiently bind planar neutral and specifically electron-accepting molecules. We tested several possible guest molecules, out of which only DCTNF has shown efficient interaction (figure 3.3.14). Host-guest interaction was also studied using 1

Self-assembly using bis-ruthenium complexes

Bis-ruthenium acceptors were previously described in chapters 1.4.4 and 2.2. In addition to having compatible geometry with DTF ligands, they allow to fine-tune the properties of the resulting assembly by changing the size of linker unit in the acceptor complex (scheme 3.4.1). Scheme 3.4.1. Expected of self-assemblies using 4Py-DTF motif in combination with bis-ruthenium acceptors.

Self-assembly using 4Py-DTF and Ru1-4

Only 4Py-DTF ligands gave discrete assemblies upon interaction with the bis-ruthenium acceptors. Reactions were carried out in methanol at 50 0 C for 24h using stoichiometric amounts of ligands 26 or 28 and acceptors Ru1-4 resulting in self-assemblies AA8-AA13 and monitored by 1 H and DOSY NMR. Final self-assemblies can be isolated by precipitation with diethyl ether or used directly without purification. Attempts to obtain single crystal suitable for x-ray diffraction starting from self-assemblies using ligand 26 with thiohexyl groups weren`t successful. However, the ligand 28 with smaller thiopropyl groups allowed to obtain crystals of self-assembly AA9 by liquid diffusion of methyl tert-butyl ether into the solution of self-assembly in methanol. AA9 illustrates the expected M4L2 self-assembly clip (figure 3.4.3). Packing indicates certain degree of π-π interaction between fluorene fragments (with similar distance about 3.4-3.7 Å between two DTF fragments from neighboring clips and within the clip).Mostly unchanged geometry of the ligand indicates good compatibility of the ligand and acceptor.

68

Despite the overall complex structure, 1 H DOSY NMR confirms formation of a single product with corresponding rH = 16.4 Å for АА10 and 14 Å for АА11. a size which is much bigger than the one observed for AA9 using Ru1 complex (figure 3.4.3, а and b). Surprisingly, self-assemblies AA10 and AA11 also exhibit substantial difference in the aromatic region while having only different thioalkyl groups in ligands 26 and 28 respectively. Unlike AA8-9, changing the solvent to dmso-d6 removes the more complicated signal structure, but also probably leads to partial destruction of the cage due to more competitive nature of the solvent. However, DOSY NMR confirms that the self-assembly structure remains present in the solution (figure 3.4.2, c).

Further analysis using COSY and ROESY NMR (annexes 3.8-3.18) shows two distinct sets of signals for both acceptor and ligand. Signals are also better resolved in case of AA11 in comparison to AA10. Therefore, COSY NMR for AA11 allows to identify clear coupling between two sets of ɑ and β pyridil protons respectively, as well as two sets of fluorene protons using COSY and ROESY NMR. Signals of cymene protons give similar two sets of signals (annex 3.11). In case of AA10 COSY and ROESY NMR spectra give similar data, but overlapping signals don`t allow clear identification of all interactions (annex 3.9). Therefore, such set of signals is probably indicative of the geometrically intertwined structure with several distinct molecules, such as described in chapter 1.3.6.

High resolution ESI-FTICR-MS spectrometry was done in collaboration with Drs Frédéric

Aubriet and Vincent Carré in the University of Lorraine. Experiments confirmed the expected M4L2 stoichiometry, along with the aggregation of the higher species (annexes 5.2-5.4) similar to the Palladium-based self-assemblies AA4-7.

Finally, an X-ray analisys allows to explain the difference in the NMR spectra. (figure 3.4.4). the larger distance between both Ru centers acceptor Ru3 allowed the formation of a dimer. AA11 doesn`t create a closed structure similar to the ones described in chapter 1.3.6, but a dimer from two interfold separate clips. This also allows to explain the difference in the 1 H NMR spectra. Most probably one set of signals belongs to the fragments inside the dimer, while second set correspond to the outside protons. Acceptors Ru2 and Ru4 resulted in corresponding M4L2 self-assemblies. However, acceptor Ru2 gave less distinct 1 H NMR, which indicates non-ideal geometrical compatibility between the ligand and acceptor. Therefore, this combination wasn`t studied further. Upon using the biggest acceptor Ru4, 1 H and DOSY of corresponding self-assemblies АА12 (figure 3.4.5) і АА13 have similar double structure to Ru3. At the same time, additional signal from the tetracene core in the aromatic region complicate already complex NMR while having similar properties to Ru3.

Monomer-dimer transformations

The dimer form of the self-assemblies AA10-AA11 is not rigidly fixed and can therefore be reversed back to the monomer. Within the current work, we studied the influence of factors as concentration, solvent or addition of a guest molecules (figure 3.4.8). As was previously shown on the figure 3.4.2, isolation of the self-assembly and subsequent resolubilization in dmso-d6 leads to the formation of a simple 1 H NMR, which is characteristic of a monomer species. In other polar solvents such as acetonitrile, acetone or nitromethane dimer remains the prevalent form (annex 3.19). Monomer-dimer equilibrium depending on the concentration was also studied using cyclic voltammetry. Upon dilution to 10 -5 M, additional oxidation process for the DTF fragment completely disappears (figure 3.4.10), in contrast to the intramolecular character in AA6-7. It allowed to confirm the intermolecular character of the oxidation process, which is consistent with 1 H NMR and crystallographic data. These interactions were also studied by the cyclic voltammetry. Similar to the AA6-7, it illustrates recovery of the single oxidation process for the DTF fragment upon addition of 1 equivalent of the DCTNF guest (figure 3.4.12, a). However, subsequent reduction part of the wave remains splitted, which suggests reformation of the dimer upon oxidation. This assumption correlates well with theoretical calculations for such process (figure 3.4.12, b). This results are quite interesting and require further studies. Reaction of the 3Py-DTF ligand with naked palladium ions resulted in a M2L4 type cage AA3, which exhibits one reversible oxidation upon electrochemical analysis. This suggests that all four DTF fragments are oxidized independently at the same potential. The cage structure was confirmed by HRMS and x-ray analysis, with an internal cavity of ~600 Å 3 . Reaction of the 4Py-DTF ligand with naked palladium ions resulted in the formation of a discrete species which could not be further characterized due to its low solubility.

Combination of cis-blocked palladium complexes with ligands 3Py-DTF and 4Py-DTF afforded self-assembled M2L2 clips AA4-5 and AA6-7 respectively. Clips AA4-5 are characterized by two reversible oxidation, one corresponding to the DTF fragment and the second to the ferrocene unit of Pddppf. Interestingly, in the case of AA6-7, the first oxidation process of DTF splits into two waves, suggesting the formation of the mixed-valence species or a π-dimer similar to AA1. AA4-5 were shown to interact with C60 thanks to their "pincer-like" geometry. However, irradiation with visible light led to its photodecomposition. Speed of the process suggests significant interaction between them. The clips AA6-AA7 were shown to interact with the planar electron-deficient guest DCTNF, resulting in disrupting the formation of a mixed-valence species or a π-dimer.

The 4Py-DTF ligand in combination with bis-ruthenium complexes involving different bridging groups Ru1-4 resulted in a series of M4L2 type self-assembled metallorings AA9-13. Cyclic voltammetry experiments demonstrate the formation of a mixed-valence species or a π-dimer similar to AA6-7. Additionally, clips AA10-11 were shown to form a M8L4 dimer in solution, which can be transformed to its monomeric counterpart upon dilution, or inclusion of the electro-deficient DCTNF unit. Remarkably, expulsion of the later in the resulting host-guest complex could be achieved through a redox stimulus, as confirmed by cyclic voltammetry measurements.

. π-extended tetrathiafulvalene (exTTF) and corresponding ligand exTTF-4Py4

Characteristic feature of the exTTF scaffold lies on its ability to change reversibly its geometry upon oxidation (figure 4.1.2). In the neutral form, it adopts a singular bent "butterfly" shape due to steric hindrance between hydrogens from the dihydroanthracene fragment and sulfur of the 1,3-dithiol rings. After oxidation through a double one electron process leading to the dicationic state, the initial bent structure evolves to a fully aromatic species in which both dithiolium rings are almost perpendicular to the planar anthracenyl moiety.

Ligand exTTF-TEG

One of the main drawbacks of exTTF-4Py4 ligand lies in its relatively low solubility. In order to address this issue, during the PhD thesis of V. Croué, ligand exTTF-TEG 150 was developed by addition of four triethyleneglycol fragments (figure. 4.1.3, a). This allowed to both substantially increase its solubility as well as its donor properties.

Self-assembly M12L6 cages AA14 and AA15

In the current work, we were interested in the self-assembly properties of the ligand exTTF-TEG in combination with linear acceptor units. In particular, trans-blocked Pd and Pt complexes (chapter 1.4.2) as well as silver salt were investigated.

Synthesis

Reaction between exTTF-TEG ligand (1 equiv.) and trans PdCl2(CH3CN)2 (2 equiv.) was carried out in DMSO at 100°C resulting in a neutral self-assembled cage AA14. The final compound was isolated by precipitation with ethyl acetate and characterized in CDCl3 by 1 Interestingly, a similar experiment carried out in pure CH3CN did not show any formation of the self-assembly structure, which demonstrates the important role of solvents in coordination driven selfassembly processes. Also, since the reaction needs only 2 equiv. of silver cations in order to generate the self-assembly, silver coordination by the TEG chains can be ruled out. This is further confirmed by 1

Structural properties

Unfortunately, we were unable to obtain single crystal of AA14 and AA15 suitable for X-Ray analysis. Therefore, a molecular force field (MM+, HyperChem 8.0.3) optimization was performed for both M12L6 structures (figures 4.3.5 and 4.3.6). TEG chains and counter anions were omitted to simplify the calculation. In both cases, simulations result in structures with a square-based bipyramidal geometry. Metal centers in both silver and palladium cages adopt a nearly linear geometry (Pyr-M-Pyr: ca. 175°). exTTF fragments within the self-assembly can be described via the intramolecular angle between both 1,3-dithiol-2-ylidene mean plans. The corresponding value for AA14 and AA15 are about 87°-89° (figures 4.3.5, a and 4.3.6, a respectively), very similar to the 86° value observed in the free ligand (X-Ray). This data shows that no significant conformational change occurs during the self-assembly process and support therefore a good geometrical compatibility between the ligand and the metal complexes. Both cages present large internal cavities with calculated volume of approximately 3658 and3954 Å 3 for AA14 andAA15 respectively (figures 4.3.5, b and4.3

Electrochemical properties

The electrochemical behavior of cages AA14 and AA15 were studied by cyclic voltammetry and compared to ligand exTTF-TEG (figure 4.3.7). The cage AA14 exhibits a single redox process involving two electrons (E1 ox = +0.35 V vs Fc/Fc + ). Its potential is higher compared to the free ligand (E1 ox = +0.05 V vs Fc/Fc + ) as a result of coordination to the metal center. The oxidation process is quasireversible in this case, which is consistent with preserving the integrity of the cage (no disassembling) during the redox process. A similar behavior was previously shown for a neutral Pt4(exTTF-TEG)2 cage. 192 Interestingly, the polycationic cage AA15 shows quite different behavior. One oxidation wave is observed which, as expected from metal coordination, is located at a higher potential (E1 ox = +0.45 V vs Fc/Fc + ) in comparison to ligand exTTF-TEG. In contrast to AA14, the reduction process occurs at a much lower potential (E1 red = -0.36 V). A similar behavior was previously shown for a polycationic exTTF based self-assembly (Pd4(exTTF-TEG)2) 8+ , which was assigned to the cage disassembling upon oxidation. 150

Supramolecular transformation into [(Ag2(exTTF-TEG 2+ )) 2+ ]x

The redox behavior can be investigated by both electrochemical or chemical oxidation/reduction. Therefore, the polycationic AA15 was further studied upon chemical oxidation in order to identify the products following the cage disassembly process. The reaction was monitored by 1 H and DOSY NMR. Such observations are consistent with coordination of additional silver cations to the peripheral TEG chains, resulting in a [Agn(Ag12 exTTF-TEG)6] (n+12)+ species. Thus, no oxidation process involving Ag + was observed, contrary to previous results obtained by the group using other exTTF derivatives. 192 Introduction of a supplementary excess of AgBF4 (up to 30 equiv.) did not result in any additional changes in the 1 H NMR spectrum.

Nevertheless, further exposure of the reaction mixture resulted in slight gray powder and formation of light greenish insoluble crystals. The later were easily isolated in 66% yield by filtration. It should be noted that the initial cage AA15 is stable in the same CD3NO2/CDCl3 system within the same time interval. The oxidation reaction is most probably due to the coordinated silver cations located in the lateral TEG chains, that generate a kinetically delayed oxidation process. To the best of our knowledge, this constitutes a unique example of a supramolecular transformation from a discrete cage to a 3D-polymer. A chemical reduction was further achieved in an attempt to recover the starting cage AA15. Upon addition of a reducing agent (tetrakis(dimethylamino)ethylene, TDAE) to a suspension of [(Ag2(exTTF-TEG 2+ )) 2+ ]x in a CD3NO2/CDCl3 system, the 1 H NMR shows almost instantaneous reappearance of the starting neutral ligand exTTF-TEG and no reformation of the starting cage.

Conclusions to chapter IV

Further exploitation of the exTTF-TEG ligand in combination with 180 ° palladium and silver complexes allowed to obtain two new electro-active large M12L6 metallocages AA14 and AA15. The resulting spherical cages are predicted to have large internal cavities of ca. 4000 Å 3 . Despite similar structure, while cage AA14 remains stable during the electrochemical oxidation, cyclic voltammetry experiment of cage AA15 demonstrates its disassembling.

The chemical oxidation of self-assembly AA15 using silver cations leads to an unprecedented transformation of a discrete cage into an infinite polycationic 3D polymer [(Ag2 exTTF-TEG 2+ ) 2+ ]x. Even though several examples of coordination polymers based on the parent tetrathiafulvalene unit are described, 193 this polymer constitutes the first example of a three dimensional coordination network involving an exTTF derivative. The experimental data suggest an initial binding of the silver cations to the TEG chains promoting a kinetically delayed oxidation process. As a result, the exTTF-TEG fragment is oxidized to the dication state causing a drastic conformational change. The TEG chains also play an important role in the final structure, providing additional coordination sites for the silver cations. Finally, a chemical reduction allows to recover the starting ligand without reformation of the cage.

Chapter V. Compounds based on π-extended dithieno-tetrathiafulvalene (S-exTTF) 194

Introduction

As was shown in a previous chapter, π-extended tetrathiafulvalene corresponds to an efficient structural system for application in self-assembly methodology, along with more traditional use in organic electronics. [195][196][197][198][199][200][201] The-extension, in addition to be possibly promoted by an anthracene spacer bridging both 1,3-dithiol units (as in Chp 4), can be produce by a variety of conjugated units. Examples of alternative -systems inspired by exTTF include the usage of extended aromatic spacers such as indenofluorene, 202 diindenothienoacene, 203 indacene 204 or large polycyclic aromatic hydrocarbons (PAHs). [205][206] Another possibility to control the planarity of the molecule, in contrast to the covalent construction of related π-extended molecules, can be achieved via fine-tuning intramolecular noncovalent interactions between heteroatoms. 142 Importance of such interactions to the conformation has been very recently illustrated for a rationally designed series of benzo bis(thiazole) (BBT) derivatives in the gas phase (computation) and in the solid state. 207 On this basis, we have designed -system S-exTTF, inspired from the exTTF framework but which, contrary to the latter, should be able to generate planar oxidized states thanks to intramolecular non-covalent interactions. The benzo [1,2-b:4,5-b']dithiophene fragment was chosen as a new central core (scheme 5.1.1). Changing the six-membered rings in the anthracene for five-membered thiophene rings is expected to substantially reduce steric strain with 1,3-dithiol rings, while intramolecular S-S interactions are supposed to stabilize more planar conformation in the neutral state. Thioalkyl peripheral groups were added in order to increase solubility, while pyridine fragments could be added to the central core to provide coordination to the metal center. Alternatively, pyridine groups can be added onto the 1,3-dithiol rings, similar to exTTF-4Py4 ligand.

Synthesis

The synthesis of compound S-exTTF was performed according to scheme 5.2.1. Commercially available benzo [1,2-b:4,5-b']dithiophene-4,8-dione was modified via the two-step bis(olefination) using phosphonate esters. 208 First, Horner-Wadsworth-Emmons coupling resulted in the intermediate compounds 29 and 31. The latter was then again treated following similar procedure with an excess of phosphonate ester 18 or 16 respectively. This allowed to obtain the target product 30 (S-exTTF, R=CH3) in a satisfactory yield, taken into account the lowered electrophilic character of the remaining keto function in the mono-substitute intermediates, whereas the corresponding product with R=n-C6H13 could not be obtained from phosphonate ester 16.

Scheme 5.2.1. Synthesis of the S-exTTF

Unlike the intermediate compound 29 and 31, S-exTTF was found to be highly sensitive to acidic conditions. Therefore, all purification steps were performed using chromatography with basic aluminum oxide instead of classic silica gel. For the same reasons, NMR experiments in deuterated chloroform were performed with addition of few drops of triethylamine.

Structural properties of the neutral form

Slow vapor diffusion of methanol in a dichloromethane solution of the S-exTTF afforded single crystals, which were then analyzed by X-ray diffraction (figure 5.3.1). Similarly to the other exTTF derivatives, it appears from these data that the dithieno-TTF derivative S-exTTF possesses a butterfly-shape bent structure in the solid state. This can be illustrated by 1,3-dithiolyliden rings pointing in the opposite direction as well as slight folding of the central dihydrobenzodithiophene moiety. However, the distortion appears less pronounced, as shown below by comparing with its exTTF analogs exTTF and exTTF' (figure 5.3.2) In the neutral state, X-ray data for S-exTTF shows values of α = 22.6°, β = 17.1° and γ = 11.6°. In comparison, all these values are significantly lower than those extracted from the X-ray structures of the parent exTTF (α = 36.6°, β = 30.6° and γ = 14.0°) 209 and exTTF' (α ~38°, β ~31° and γ ~8-12°). 210 The main reason for the distortion in the exTTF motif is due to the close steric repulsion between periplanar hydrogens of the dihydroanthracene unit and S atoms. On the contrary, S-exTTF is able to diminish steric constraint due to the conjunction of: i) occurrence of peripheral five-membered rings (instead of six-membered rings for exTTF) provides more space for periplanar hydrogen atoms, and ii) occurrence of attractive 1,5-S•••S intramolecular contacts in the range 3.01-3.04 Å, which are far shorter than twice the van der Waals radii for S atoms (1.80 Å).

At the same time, C=C bond lengths between the central fragment and 1,3-dithiolyliden rings present similar typical values (1.36-1.37 Å) in both S-exTTF and exTTF'.

Electronic structure

In order to thoroughly characterize the structural, electronic and optical properties, a quantumchemical study was performed for S-exTTF and its analogue exTTF' using the density functional theory (DFT) framework at the B3LYP-D3/6-31G** level in the presence of CH2Cl2. These calculations were performed by Prof E. Ortí and Dr J. Aragó (Universidad de Valencia, Spain).

In both cases, these compounds maintain saddle-like folded structures (figure 5.3.4). In good correlation with the solid-state structure, both show folding to a boat conformation for the central quinoidal ring, while the 1,3-dithiolyliden rings are tilted up. Calculation show smaller distortion for S-exTTF comparing to the exTTF'. Computed α, β and γ angles of S-exTTF (24.6°, 18.9° and 6.7° respectively; figure 5.3.4) are significantly smaller compared with those of exTTF ' (38.1°, 32.1° and 20.7° respectively), and correlates nicely with X-ray data in both cases. The bond lengths show similar values for the dithiole rings of both compounds S-exTTF and exTTF' (figure 5.3.5), and are consistent with the X-ray data. For instance, the exocyclic C=C bonds connecting the 1,3-dithiolyliden rings are calculated to be 1.371 Å (S-exTTF) and 1.361 Å (exTTF'). Alongside with the minimum-energy butterfly-like structures, the fully planar structures of S-exTTF (C2h symmetry) and exTTF' (D2h symmetry) were also optimized at the same conditions (figure 5.3.6). Energy difference for S-exTTF between the planar structure is predicted to be 13.03 kcal mol -1 higher in energy, in comparison to a 46.36 kcal mol -1 increase for exTTF'. Such energy difference is due to the much shorter S•••H intramolecular contact occurring between the sulfur atoms and the periplanar hydrogens in the hypothetical planar conformations of exTTF' (1.981 Å) compared to S-exTTF (2.247 Å). Frontier molecular orbitals calculated for S-exTTF and exTTF' at their minimum-energy geometries are shown in figure 5.3.7. Swapping the benzene rings for thiophene rings in the central fragment of S-exTTF leads to a very significant energy destabilization/stabilization of the highestoccupied/lowest-unoccupied molecular orbital (HOMO/LUMO) by 0.44/0.09 eV in comparison to the exTTF'. This causes a narrower HOMO-LUMO energy gap in S-exTTF (2.89 eV) compared to exTTF' (3.41 eV). Therefore, the electron-donor character of compound S-exTTF is significantly increased comparing to exTTF' due to a much more efficient electronic delocalization (π-conjugation). The latter is ascribed to both a more planar central dihydrobenzodithiophene unit of S-exTTF, and to the larger electronic polarizability of the sulfur atoms.

90

UV-vis spectroscopy was used in order to analyze the electronic absorption properties of compounds S-exTTF and its push-pull precursor 29 (figure 5.3.8). Well-resolved and relatively sharp peaks are observed for both S-exTTF and 29 which is consistent with relatively rigid structures. S-exTTF exhibits an intense absorption band peaking at ca. 495 nm (ε = 55000 M -1 cm -1 ) with a shoulder at 467 nm (ε = 35000 M -1 cm -1 ) whereas 29 shows a less intense band centered at 486 nm (ε = 35000 M -1 cm -1 ).

Electrochemical properties

The electrochemical behavior of compound S-exTTF was studied by cyclic voltammetry in CH2Cl2. A single reversible oxidation wave is observed, located at E 1/2 = -0.18 V vs Fc/Fc + (figure 5.3.10, a).

It appears of course of interest to compare this redox behavior with the one of the -isoelectronic analogue exTTF' (figure 5.3.10, b). The latter, as well as exTTF derivatives in general, exhibits a characteristic single two-electron oxidation wave, resulting in formation of a dicationic state. [188][189] This process is electrochemically irreversible, with a peak-to-peak potential separation (Ep = Epa -Epc) often higher than 200 mV 211 and involving an inverted potential phenomenon (E1 ox > E2 ox ). Other similar illustrative examples of exTTF derivatives are provided above, with compounds exTTF-4Py4 and exTTF-TEG (chapter 4.1.2). Therefore, in contrast to exTTF', dithieno-exTTF (S-exTTF) exhibits a fully reversible process (figure 5.3.10, a), illustrating a drastically different redox process, despite both are -isoelectronic analogs. A plausible reason for that, lies on their different respective geometries in both the neutral and oxidized states. More specifically, it indicates that compound S-exTTF, unlike exTTF', does not undergo a large conformational change upon oxidation. 212 As shown in the above-mentioned calculations, the -donating ability of S-exTTF and exTTF' are significantly different. Compared to the irreversible oxidation process occurring at Epa= +58 mV vs Fc/Fc + for exTTF' 211 , compound S-exTTF exhibits a remarkably higher -donating ability with a redox potential (E1/2) located at -180 mV vs Fc/Fc + . Such difference is fully consistent with the higher HOMO energy predicted for S-exTTF (-4.60 eV) compared to exTTF' (-5.04 eV).

The redox behavior of S-exTTF was further studied by thin-layer cyclic voltammetry (TLCV) (figure 5.3.11). This technique 213 allows to analyze specifically the redox processes of all the species which are confined within the thin layer, avoiding the contribution of diffusion ones. Therefore, it allows to determine the charge exchanged during the redox process and to deduce the number of electrons(s) which take part in the process.

Introduction of a reference compound with a known redox behavior, is therefore required. A quinone derivative (2,3-dichloronaphthoquinone (NQ)) was used as the coulometric standard. The latter exhibits a one-electron reversible reduction. Figure 5.3.11 shows two redox waves, respectively assigned to the reversible oxidation of S-exTTF (positive potentials) and to the reversible reduction of NQ (negative potentials). The ratio of the exchanged charges for each process, calculated from the respective wave areas, is very close to one (QNQ/QS-exTTF = 1.01). Taking into account that a 2/1 concentrations ratio was used, this observation indicates a two-electron nature for the oxidation process of S-exTTF and therefore formation of a dication species.

Structural properties of the oxidized form

The electrocrystallization technique (annex 2) was used in order to obtain single crystals of the oxidized form. Slow oxidation with a constant low-current density (0.5 A cm -2 ) allowed to obtain shiny, dark-red, needle-like single crystals, which were grown on a platinum electrode. The latter were analyzed by X-ray diffraction. The resulting structure corresponds to a cation-radical salt formulated as [S-exTTF][PF6]•THF (figure 5.4.1). Two immediate observations can be drawn from this 1:1 stoichiometry: 1/ this salt strongly differs from the electrocrystallized salts based on the exTTF skeleton, from which dicationic species (exTTF)1(anion)2 are usually formed, 196,[214][215] . This was expected given the strong electronic and geometric differences observed between S-exTTF and exTTF derivatives; 2) this 1:1 stoichiometry was unexpected from the above electrochemical studies, for which a two-electron oxidation process was anticipated. One possible explanation is a comproportionation reaction in the electrocrystallization cell, involving neutral S-exTTF and the corresponding dication. Analysis of the molecular structure of shows that the extended -system of the oxidized form S-exTTF •+ has a planar geometry, with only two methyl substituents out of plane. Value for bond lengths within the -framework of S-exTTF •+ correspond to expectation for a cation-radical salt, with in particular the exocyclic C-C bonds having a value of 1.42 Å (vs 1.37 Å for neutral S-exTTF).

However, the planar molecular structure of S-exTTF •+ is also quite different compared to its exTTF 2+ analog. The latter is characterized by a twisting of both 1,3-dithiolium rings perpendicular to the anthracene platform 196,[214][215] . This is not the case with S-exTTF •+ for which a fully planar conformation is observed, resulting in an exceptionally short S•••S intramolecular distances of 2.82-2.89 Å. This value is intermediate between the sum of the van der Waals radii for S atoms (3.60 Å) and a S-S disulfide bond (2.06 Å). Such short S•••S contacts are quite rare in the literature. Actually, a search using the Cambridge Crystallographic Data base (CCDC), and focusing on conformationally flexible species with divalent sulfur atoms, resulted in only four cases of intramolecular S•••S distances lower than 2.90 Å. [216][217][218][219] Interestingly, all of them are found in positively charged species. Therefore, such a remarkably short S•••S distance may correspond from the contraction of the sulfur sp 2 lone pairs upon oxidation of the molecule.

In order to confirm this hypothesis, theoretical calculations of the charge distribution were performed by E. Ortí and Dr J. Aragó (vide infra, § 5.4.1). They confirm a decrease of the Pauli exchange repulsion between the interacting S atoms upon oxidation to S-exTTF •+ . This then leads to a change from a repulsive S•••S interaction in neutral S-exTTF which has become now attractive in S-exTTF •+ , justifying in part the planarization found for the [S-exTTF][PF6] . THF salt (scheme 5.4.1, a). Importantly and in line with the latter observation, single crystals of the intermediate push-pull compounds 29 (figure 5.4.2) and 31 (annex 6.10) could be obtained by slow evaporation of a methanol/dichloromethane solution. Both compounds appear essentially planar in the solid state, with only alkyl chains being out of plane. Interestingly, they both present remarkably short S•••S contacts in the range of 2.84-2.87 Å (i.e. similar as in S-exTTF •+ ). As a result, while neutral, the push-pull compounds 29 and 31 exhibits the same unique features as does S-exTTF •+ . A plausible explanation lies on a high contribution of a charged mesomeric form in the case of 29 (and 31), which results from the - delocalization between the electron donating 1,3-dithiole unit and the quinone accepting group, and which affords two aromatic moieties (1,3-

Theoretical calculations

In order to further characterize the oxidized states, DFT theoretical calculation were performed at the B3LYP-D3/6-31G** level in CH2Cl2. The oxidized compounds (S-exTTF •+ , S-exTTF 2+ and exTTF' 2+ ) were optimized starting from the neutral S-exTTF and exTTF' derivatives. In the case of S-exTTF, the butterfly-shape conformation observed in the neutral state (see above, In the latter case, the dithiole rings of the C2-butterfly S-exTTF •+ are twisted in such a way that attractive S•••S interactions with short distances (3.01 Å) are favored, whereas S•••H interactions are avoided. In order to create a fully-planar C2h-structure of S-exTTF •+ , additional difference of 7.76 kcal mol -1 has to be applied (5.4.3, a). In order to fully planarize, thiomethyl groups have to be forced to be in the molecular plane, which requires a significant additional energy. Calculations were made also without thiomethyl groups (5.4.3, b), leading to an energy state which is only 3.82 kcal mol -1 higher than for the starting C2-butterfly structure. Consequently, very short S•••S distances (2.87 Å) are found in this C2h-structure, in very good agreement with those obtained from X-ray diffraction (2.82-2.89 Å). Therefore, those calculated energies confirm the possibility of a fully planar S-exTTF •+ unit, with thiomethyl groups which are prone to be impacted by solid-state packing effects in the crystal. Therefore, these calculations correlate well with the X-ray structure obtained for the As sketched in figure 5.4.6, the generation of the dication species for both S-exTTF 2+ and exTTF' 2+ is favored by the combined formation of aromatic 1,3-dithiolium rings (6π electrons) and aromatic planar benzodithiophene/anthracene units central units (14π electrons). This process is accompanied by a drastic conformational change, occurring through rotation of the dithiolium ring around the C-C bond. It appears that the conformational changes predicted for dithieno-exTTF upon oxidation are significantly less drastic than those occurring for exTTF', justifying a reversible two-electron oxidation process observed experimentally for S-exTTF in comparison with the electrochemically irreversible two-electron oxidation observed for exTTF'.

Conclusions to chapter V

Further investigation of the π-extended tetrathiafulvalene scaffold allowed to create new π -isoelectronic dithieno-exTTF derivative S-exTTF using dihydrobenzodithiophene core instead of anthracene fragment. Introduction of additional non-covalent interactions allowed to assert further control over the conformation and planarity of the molecule in both neutral and oxidized states. Comparison with the parent exTTF allowed to highlight the prominent role of 1,5 S•••S interactions on the fundamental level. DFT calculation shows significant destabilization in HOMO (+0.44 eV) of the S-exTTF in comparison to exTTF` as a consequence of more planar conformation. This data is further collaborated by X-ray comparison of neutral S-exTTF and exTTF'. Stronger π-donating character of the S-exTTF leads to lower oxidation potential in comparison with exTTF` (E1/2 = 180 mV and Epa = +58 mV vs Fc/Fc + , respectively). Fully reversible character of the oxidation process for S-exTTF also suggests absence of strong conformational changes during the oxidation unlike the exTTF'. To a degassed solution of commercially available bis(diphenylphosphino)ferrocenedichloropalladium (II) (300 mg, 0.37 mmol) in dichloromethane (50 mL), was added silver triflate (220 mg, 0.85 mmol). The solution was stirred at room temperature for 15 h in the dark. The mixture was filtered on hyflosupersel to remove silver chloride. Diethyl ether (100 mL) was added to the filtrate. The flask was transferred in a freezer until complete crystallization (24 h). The compound 1 was isolated as dark purple crystals (285 mg, 80 %) after filtration.

Analysis

Bis(chloro (p-cymene)Rhuthenium(II))oxalato-1,4-bis(olate) 2 220

To a solution of [RuCl2(h6-p-PriC6H4Me)2] (306 mg, 0.5 mmol) in CHCl3-MeOH (1:1, 30 ml) was added (NH4)2C2O4*H2O (71 mg, 0.5 mmol). The mixture was refluxed for about 6 h, then the solvent was removed. The residue was taken up in CH2Cl2 and the resulting mixture was filtered. The filtrate was evaporated to dryness in vacuo to give compound 2 as an orange powder (280 mg, 89%).

Bis(triflate (p-cymene)Rhuthenium(II))oxalato-1,4-bis(olate) Ru1 220

Solid silver triflate (102.8 mg, 0.40 mmol) was added to a solution of compound 2 (126 mg, 0.2 mmol) in methanol (20 ml). The mixture was stirred at room temperature for 2 h, then filtered. The filtrate was evaporated to dryness to give Ru1 as a yellow solid(184 mg, 99%). To a solution of dichloro(p-cymene)ruthenium (150 mg, 0.25 mmol) in anhydrous ethanol (20 mL), were added 5,8-dihydroxynaphthalene-1,4-dione (47 mg, 0.25 mmol) and sodium acetate (40 mg, 0.49 mmol). The solution was stirred at 90°C overnight and the suspension was filtered and the solid washed successively with: ethanol, water, acetone, diethyl ether and pentane to afford 3 as a dark green powder (136 mg, 76 %).

Bis(triflate(p-cymene)ruthenium(II)) 5,8-dioxo-5,8-dihydronaphthalene-1,4-bis(olate) Ru3 221

To a solution of 3 (100 mg, 0.14 mmol) in dichloromethane (10 mL) was added silver triflate (70 mg, 0.28 mmol). The solution was stirred in the dark overnight and the suspension was filtered on hyflosupersel to remove silver chloride. Diethyl ether was added (20 mL) to the filtrate and the flask was placed in a freezer until complete precipitation. The solid was filtered, washed with diethyl ether and dried under vacuum. The compound Ru3 was isolated as a dark green powder (84 mg, 64 %). To a solution of 4 (100 mg, 0.12 mmol) in dichloromethane (10 mL) was added silver triflate (62 mg, 0.24 mmol). The solution was stirred in the dark overnight and the suspension was filtered on hyflosupersel to remove silver chloride. Diethyl ether was added (20 mL) to the filtrate and the flask was placed in a freezer until complete precipitation. The solid was filtered, washed with diethyl ether and dried under vacuum. The compound Ru4 was isolated as a dark green powder (82 mg, 62 %).

TTF family 4-(4-bromophenyl)pyridine 5 169

To an argon degassed solution of pyridin-4-ylboronic acid (250 mg, 2.03 mmol), 1-bromo-4-iodobenzene (863 mg, 3.05 mmol) and potassium carbonate (843 mg, 6.10 mmol) in dioxane (20 mL) and water (2 mL), was added tetrakis(triphenylphosphine)palladium (II) (117 mg, 0.10 mmol). The mixture was stirred over night at 110°C and the solvent was removed under vacuum. The residue was treated with water and extracted with dichloromethane. The organic extracts were washed with water, and dried over magnesium sulfate. The solvent was removed under vacuum. A chromatography column on silica gel was performed using a gradient of eluent: from dichloromethane to dichloromethane/methanol (99/1). The compound 5 was isolated as a white powder (340 mg, 72 %). To a suspension of palladium acetate (32 mg, 0.143 mmol), tri-tert-butylphosphonium tetrafluoroborate (104 mg, 0.358 mmol) and cesium carbonate (812 mg, 2.49 mmol) in distilled and argon degassed dioxane (3 mL) at 110°C, was added via cannula an argon degassed solution of TTF (100 mg, 0.489 mmol) and 4-(4-bromophenyl)pyridine 5 (420 mg, 1.790 mmol) in distilled dioxane (3 mL). The mixture was stirred at 110°C for 48h. The solvent was evaporated and dichloromethane (20 mL) was added. The resulting suspension was filtered and the filtrate was washed three times with water (20 mL). The organic phase was dried on magnesium sulfate and filtered on cotton. The solvent was evaporated and a chromatography column on silica gel was realized using a gradient of eluent: from dichloromethane/methanol (99/1) to dichloromethane/methanol (92/8) with a constant portion of triethylamine of 0.5%. Compound 6 (TTF(PhPy)4) was isolated as a red powder (251 mg, 86%). [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (76 MHz, CDCl3) δ 150.41, 147.14, 138.21, 133.30, 129.88, 129.23, 127.35, 121.36, 108.54. HRMS m/z found 816.1503, m/z calculated 816.1510.

AA1

Ruthenium complex Ru3 (10.63 mg, 11 μmol) and TTF(PhPy)4 (4.51 mg, 5.5 μmol) were dissolved in deuterated methanol or acetone (0.5 mL) and the solution was stirred at 50°C overnight. After cooling at room temperature, Et20 was added to the solution and the resulting solid was filtered and dried under vacuo to give cage AA1 as a black solid (13.17, 86 %).

AA2

Ruthenium complex Ru4 (11.74 mg, 11 μmol) and TTF(PhPy)4 (4.51 mg, 5.5 μmol) were dissolved in deuterated acetone (0.5 mL) and the solution was stirred at 50°C overnight. After cooling at room temperature, Et20 was added to the solution and the resulting solid was filtered and dried under vacuo to give cage AA1 as a black solid (13.49, 83 %). Formation of the cage AA2 was quantitative according to 1 H NMR, 1 H DOSY NMR and HRMS-ESI-FTICR. 48H). 1 H DOSY NMR (acetone-d6) D = 6.62 x 10 -10 m²s -1 .

DTF family

Bis(tetraethylammonium) bis(1,3-dithiole-2thione-4,5-dithiol) zincate 8

Dimethylformamide (480 mL) and carbon disulfide (240 mL, 4 mol, d = 1.266) were placed in an Erlenmeyer flask and degassed at 0°C. In a three neck round bottom flask with mechanical stirrer, were placed small pieces of sodium (23 g, 1.0 mol) in xylene (80 mL) under argon. The suspension was heated until sodium fusion and then stirred very vigorously to form small balls. The mixture was then cooled to room temperature and xylene was decanted. The sodium balls were cooled at 0°C for 30 min and the dimethylformamide/carbon disulfide solution was added carefully. The mixture was then stirred overnight for 14 h at room temperature and then, methanol (50 mL) was added at 0°C. To the resulting solution was added a solution of zinc chloride (21.3 g, 0.156 mol) in ammonia (35 %, 360 mL) and water (100 mL). Then, a solution of tetraethyl ammonium bromide (66 g, 314 mmol) in water (500 mL) was added slowly via dropping funnel. Then, the solution was stirred overnight until complete precipitation. The red solid was filtered and washed with water (500 mL), methanol (2 x 500 mL) and diethyl ether (500 mL). After drying under vacuum, the zincate 8 was obtained as a red solid (99.12 g, 88%).

General protocol for compounds 9-11

To a solution of zincate 8 (10 g, 13.91 mmol) in acetonitrile (80 mL), was added corresponding alkyl halide (4,5 eq., 61.23 mmol, d = 1.44). The resulting solution was stirred at reflux for 1 h 30 min and the solvent was removed. The residue was partially dissolved in dichloromethane (200 mL), the organic phase was washed with water (2 x 200 mL) and dried with magnesium sulfate. The solvent was removed under vacuum. A chromatography column on a silica gel using appropriate system to obtain a final compound.

4,5-bis(hexylthio)-1,3-dithiole-2-thione 9

A chromatography column on a silica gel was performed using dichloromethane/petroleum ether (20/80) as eluent. The compound 9 was isolated as an orange oil (8.91 g, 87 %).

4,5-bis(propylthio)-1,3-dithiole-2-thione 10

A chromatography column on a silica gel was performed using dichloromethane/petroleum ether (10/90) as eluent. The compound 10 was isolated as an orange oil (14.47 g, 92 %).

4,5-bis(methylthio)-1,3-dithiole-2-thione 11

A chromatography column on a silica gel was performed using dichloromethane/petroleum ether (1/1) as eluent. The compound 11 was isolated as yellow needle crystals (11.5 g, 91 %).

1 H NMR (300 MHz, CDCl3-d) δ 2.49 (s, 6H).

General protocol for compounds 12-15

To a solution of compounds 9-11 or commercially available vinylene tricarbonate (24.27 mmol) in dichloromethane (34 mL), was added under argon methyl trifluoromethanesulfonate (2.9 mL, 24.48 mmol, d = 1.05). After 1 h 30 min at room temperature the solvent was removed under vacuum and an orange oil was obtained (12.21 g). The resulting oil (or a powder in case of vinylene tricarbonate) was dissolved in acetonitrile (55 mL) and isopropanol (25 mL) at 0°C. Sodium borohydride (477 mg, 12.6 mmol) was added in small portions until no degassing was observed. After 2 h at room temperature, the solvents were evaporated. The oily residue was partially dissolved in dichloromethane 200 mL), the organic phase was washed with brine (2 x 200 mL), dried over magnesium sulfate. After evaporation of the solvent product can be used without purification in the next stage. If needed, a chromatography column on silica gel can be perfomed using petroleum ether/dichoromethane (80/20) as eluent.

4,5-bis(hexylthio)-2-(methylthio)-1,3-dithiole 12

Compound 12 was obtained as an orange oil (4.15 g, 91%).

4,5-bis(propylthio)-2-(methylthio)-1,3-dithiole 13

Compound 13 was obtained as an orange oil (14.85 g, 97%).

4,5-bis(methylthio)-2-(methylthio)-1,3-dithiole 14

Compound 14 was obtained as a colorless oil (1.55 g, 98%).

1 H NMR (300 MHz, CDCl3): 5.83 (s, 1H), 2.46 (s, 6H), 2.31 (s, 3H).

2-(methylthio)-1,3-dithiole 15

Compound 15 was obtained as a colorless oil (1.55 g, 98%).

1 H NMR (300 MHz, CDCl3): 6.07 (s, 2H), 3.15 (s, 1H), 2.39 (s, 3H).

General protocol for compounds 16-19

To a solution of compound 12-15 (10.87 mmol) in acetic anhydride (10 mL) at 0°C under argon, was added carefully tetrafluoroboric acid diethyl ether complex (1.78 mL, 13.04 mmol, d = 1.18). After 1 h of stirring at room temperature, the solvent was removed under reduced pressure. The residue was dissolved in anhydrous acetonitrile (70 mL) and sodium iodide (1.79 g, 11.95 mmol) and trimethylphosphite (1.54 mL, 13.04 mmol, d = 1.05) were added. The mixture was stirred for 4 h under argon and then the solvents were removed. The residue was partially dissolved in dichloromethane (200 mL) and the organic phase was washed with water (2 x 50 mL), dried over magnesium sulfate and the solvent was evaporating. A chromatography column on silica gel was performed to isolate final compound 16-20 respectively.

Dimethyl (4,5-bis(hexylthio)-1,3-dithiol-2-yl)phosphonate 16

A chromatography column on a silica gel was performed using ethyl acetate/petroleum ether (4/6) as eluent. The compound 16 was isolated as an orange oil (2.99 g, 62 %).

3,6-dibromophenanthrene-9,10-dione 21 222

To a suspension of phenanthrene-9,10-dione (5 g, 25.0 mmol) and benzoyl peroxide (0.29 g, 0.9 mmol, 0.75 equiv.) in nitrobenzene (25 mL), was added slowly and with precaution (bromine trap with sodium thiosulfate solution) bromine (1.86 g, 0.6 mL, 11.6 mmol, d = 3,10) through a septum. After heating at 120°C, bromine (6.9 g, 2.24 mL, 13.2 mmol, 2.2 equiv.) was added very carefully dropwise. After heating one hour at 120°C, the dark orange solution was cooled to room temperature. Ethanol (25 mL) was then added to precipitate the product. This suspension was filtered under vacuum and washed with ethanol until the filtrate was completely colorless to give 21 as a shiny orange product (9.15 g, 81 %).

3,6-dibromo-9H-fluoren-9-one 22 222

To a solution of potassium hydroxide (12.34 g, 220 mmol) in water (15 mL) at 130°C, was added 3,6dibromophenanthrene-9,10-dione 21 (6.00 g, 16.4 mmol). After 30 min, potassium permanganate (14.15 g, 89.5 mmol) was added by small portions over 1 h 30 min. The solution was stirred for 1 h and cooled to room temperature. The suspension was neutralized with sulfuric acid and then sodium bisulfite was added. The suspension became white. Then the precipitate was filtered and dried over vacuum to give 22 as a white powder (3.34 g, 60 %). ). [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (76 MHz, CDCl3) δ 191.77, 152.08, 152.08, 148.88, 148.88, 143.71, 138.97, 134.09, 133.00, 128.99, 124.54, 123.56, 123.35, 119.95, 92.21, 89.45. FAB-HRMS: found: 382.1104, calculated: 382.1106.

3,6-bis(pyridin-4-ylethynyl)-9H-fluoren-9-one 24

Reaction was carried in the MW tube. To an argon degassed solution of 3,6-dibromo-9H-fluoren-9-one 22 (100 mg, 0.295 mmol) and 3-ethynylpyridine (122 mg, 1.18 mmol, 4 equiv.) in diisopropylamine/toluene (v/v 1/1, 4 mL), Pd(PPh3)4 (68.3 mg, 0.059 mmol, 0.2 equiv.) and CuI (11.3 mg, 0.059 mmol, 0.2 equiv.) were added under argon. Tube was irradiated for 30 min at constant 250 W.

The solvent was evaporated under vacuum. The residue was treated with water and extracted with dichloromethane (50 mL). The organic extracts were washed with water (3 x 50 mL) and dried over magnesium sulfate. The solvent was evaporated under vacuum. A chromatography column on silica gel was performed using a gradient of eluent: from dichloromethane/petroleum ether (80/20) to dichloromethane/methanol (98/2). Compound was further purified by recrystallization dichloromethane/pentane. Compound 24 was obtained as yellow powder (67 mg, 59 %).

1 H NMR (300 MHz, CDCl3) δ 8.64 (d, J = 5.8 Hz, 2H), 7.73 -7.67 (m, 2H), 7.51 (dd, J = 7.6, 1.1 Hz, 1H), 7.40 (dd, J = 4.6, 1.4 Hz, 2H). [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (76 MHz, CDCl3) δ 191.64, 149.95, 143.65, 134.30, 133.28, 130.67, 128.62, 125.59, 124.57, 123.71, 92.93, 90.05. FAB-HRMS: found: 382.1099, calculated: 382.1106.

General protocol for ligands 25-28

To a solution of corresponding phosphonate 16 or 17 (0.37 mmol, 1.5 equiv.) in anhydrous tetrahydrofuran (10 mL) at -78°C, was slowly added n-butyl lithium (0.149 mL, 0.37 mmol, 1.6 M, 1.5 equiv.). The mixture was stirred one hour at -78°C and a suspension of compound 23 or 24 respectively (0.25 mmol, 1 equiv.) in anhydrous tetrahydrofuran (10 mL) at -78°C was added via cannula. The mixture was stirred 1 h at -78°C and overnight at room temperature. The solvent was removed under vacuum.

The residue was treated with water and extracted with dichloromethane. The organic extracts were washed with water, and dried over magnesium sulfate. The solvent was removed under vacuum and the residue was purified by chromatography on silica gel using a gradient of eluent: petroleum ether/dichloromethane (1/1) to dichloromethane/methanol (98/2) with constant 1% of trimethylamine followed by recrystallization using a dichloromethane/methanol mixture. 27, 148.43, 141.61, 138.38, 137.04, 136.80, 130.49, 129.22, 123.08, 123.04, 122.57,120.70, 119.55, 119.04, 93.64, 86.37, 36.67, 31.37, 29.74, 28.29, 22.57, 14.08. FAB-HRMS: found: 700.2067, calculated: 700.2074. 58, 142.70, 137.52, 136.81, 131.86, 130.92, 129.64, 125.63, 123.39, 122.70, 119.49, 118.64, 95.12, 87.17, 36.78, 31.35, 30.96, 28.26, 22.56, 14.05. FAB-HRMS: found: 700.2082, calculated: 700.2074. 148.50, 141.62, 138.39, 137.16, 136.93, 130.63, 129.49, 123.16, 122.69, 119.69, 119.20, 93.49, 86.46, 77.47, 77.05, 76.63, 38.68, 23.18, 13.26. FAB-HRMS: found: 616.1136, calculated: 616.1135.

The ligand exTTF-TEG (100 mg, 0.075 mmol) and AgBF4 (30.6 mg, 0.157 mmol, 2.1 equiv.) were stirred in CHCl3/CH3NO2 (15 mL) for 1 h. Then, Et2O was added, the resulting precipitate was centrifuged and washed 3 times with Et2O, and dried under vacuum to give AA15 (99 mg, 76%) as a dark brown solid.

1 H NMR (300 MHz, CDCl3/CD3NO2) δ 8.35 (s(br), 48H), 7.20 (48H, d, J = 5.9 Hz), 7.03 (s, 48H), 4.13 (s(br), 48H, overlapped with residual solvent signal), (3.73 (s(br), 48H), 3.56 -3.42 (m, 192H), 3.14 (s, 72H); [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (300 МHz, CDCl3/CD3NO2) δ 207. 42, 152.50, 146.82, 142.19, 128.36, 127.96, 126.78, 125.37, 125.14, 124.29, 111.96, 71.64, 70.48, 70.17, 69.40, 69.08, 68.19, 58.49 The residue was treated with water and extracted with dichloromethane. The organic extracts were washed with water, and dried over magnesium sulfate. The solvent was removed under vacuum. A chromatography column on silica gel was performed using a gradient of eluent: from dichloromethane to dichloromethane/methanol (99/1). The compound 29 was isolated as a red powder (180 mg, 99 %). 21, 149.06, 144.71, 140.23, 137.06, 133.99, 131.85, 131.45, 130.98, 126.06, 125.05, 123.76, 113.23, 19.55. EI-HRMS: found: 397.9045, calculated: 397.9056. The residue was treated with water and extracted with dichloromethane. The organic extracts were washed with water, and dried over magnesium sulfate. The solvent was removed under vacuum. A chromatography column on silica gel was performed using a gradient of eluent: from dichloromethane to dichloromethane/methanol (99/1). The compound 31 was isolated as a red powder (240 mg, 25 %).

Conclusions and perspectives

This work deals with the synthesis of new redox-active ligands, enriched in sulfur atoms, and with the building of the corresponding metalloreceptors using a coordination-driven self-assembly approach. The latter is promoted by combining complementary partners, i.e. polytopic ligands and various metal complexes, chosen to drive specific geometries for the corresponding self-assembled host structure. These new families of electroactive receptors are in particular of interest from a fundamental point of view for: i) studying the extensively developed metal-driven self-assembly process, through monitoring of the related redox properties, and ii) for exploring host-guest properties towards electronpoor species.

Three types of self-assembled electroactive architectures have been studied, i.e. 1) M8L2 metallacages involving a tetrathiafulvalene-based ligand, 2) metalla-assemblies MxLy (cages, clips) involving a new dithiol-fluorene-based unit (DTF), and 3) M12L6 metallacages involving an extended tetrathiafulvalene derivative, as well as a new electroactive -conjugated scaffold (S-exTTF). Beyond their synthesis and their characterizations through usual spectroscopic methods, the electrochemical properties of the resulting assemblies have been studied and, in some cases, their solid-state analysis performed through DRX.

M8L2 metallacages based on TTF:

A new family of M8L2 cage was designed, featuring two facing electron-rich panels (TTF units). The four pillars correspond to bis-Ruthenium complexes, with a controlled Ru-Ru length. Two selfassemblies AA1 and AA2 involving different bis-Ruthenium complexes were synthesized and fully characterized, including in the solid state (XRD). A severe bending of the facing ligands is observed in the solid state, with a collapse towards the centre of the cavity, preventing any host-guest binding ability. The unique geometry of those M8L2 assemblies, for which two TTF units are forced to stack, offers a unique opportunity to promote close inter-TTF interactions upon oxidation. This is remarkably observed through electrochemical studies as well as from single-crystal DRX from an electrocrystallized oxidized salt. The resulting cage clearly shows that facing TTF units strongly interact upon oxidation to the cation-radical state. Spectroelectrochemical analyses are in due course.

MxLy assemblies based on DTF:

Several new discrete assemblies were prepared from four electro-active ligands based on the 9-(1,3-dithiol-2-ylidene)fluorene (DTF) unit.

The "banana-shaped" ligand 3Py-DTF (25), featuring two 3-pyridyl units, self-assembles with a naked palladium complex to form a M2L4 coordination cage (AA3). The latter exhibits an internal 600 Å 3 cavity decorated by four electroactive DTF units that can be reversibly oxidized to their radical-cation state at a moderate potential.

Ligands 3Py-DTF (25 or 27) and 4Py-DTF (26 or 28) react with the square planar cis-blocked Pd(dppf)OTf2 salt to form a series of M2L2 selfassembled metalla-macrocycles. Interestingly, while the metalla-cycles (AA4-AA5) constructed from the 4Py-DTF ligands show a single redox wave for the DTF units (no interaction between DTF units), a mixed-valence species is observed for the 3Py-DTF based discrete assemblies (AA6-AA7), illustrating a close proximity between both electro-active species.

Based on this result, the binding properties of AA5 and AA7 with DCTNF were evaluated by UV-Vis and NMR titration. A Job's plot analysis revealed that metalla-macrocycle AA7 forms a 1:1 host-guest complex with DCTNF, while two DCTNF units interact with metalla-cycle AA5.

Finally, we demonstrated that ligands 4Py-DTF (26 or 28) react with bis-Ruthenium complexes to quantitatively form M4L2 metallatweezers AA9-AA13. The close distance between DTF fragments in AA9 and AA11 leads to occurence of a mixed-valence species as for AA6-AA7. Interestingly, because of the internuclear distance in the bisruthenium complex and thanks to - interactions, AA11 forms a stable dimeric structure in the solid phase (confirmed by XRD analysis) and in solution. The later can be transformed to its monomeric counterpart upon dilution, or inclusion of the electro-deficient DCTNF unit. Remarkably, expulsion of the later in the resulting host-guest complex could be achieved through a redox stimulus, as confirmed by cyclic voltammetry measurements.

M12L6 assemblies based on exTTF and redox-triggered transformation into a supramolecular 3D polymer:

The exTTF-TEG ligand was combined with trans palladium and silver complexes, affording two new electro-active large M12L6 metallocages AA14 and AA15 respectively (ca. 4000 Å 3 ). Despite similar structures, cage AA14 (M = Pd) remains stable during the electrochemical oxidation, while the cyclic voltammetry of cage AA15 (M = Ag) demonstrates its disassembling. The chemical oxidation of AA15 using silver cations leads to an unprecedented transformation of a discrete cage into an infinite polycationic 3D polymer [(Ag2exTTF-TEG 2+ ) 2+ ]x, providing a first example of a three dimensional coordination network involving an exTTF derivative.

Annex 1. Spectroelectrochemistry

Spectroelectrochemistry allows to combine electrochemical experiment with spectroscopic observation, thus serving as an additional tool to the classic electrochemistry. As a result, usually an absorption or a fluorescent spectrum is obtained, couples with a cyclic voltammetry data. This allows to identify characteristic spectroscopic signatures of compounds, which are formed during the oxidation or reduction of the sample. Therefore, this method allows to gain additional information about structural and electronic properties of the compound.

In our case, Teflon cell (picture above) is used, which is resistant to most organic solvents. Electrochemical measurements are conducted using the standard system of three electrodes. More importantly, working electrode could be adjusted to work within the semi-infinite diffusion mode similarly to the thin layer cyclic voltammetry. Light source is provided via optical fibers. The light is reflected by the working electrode which is glassy carbon or platinum. The signal is then recovered by the optical fiber is transmitted to the analyzer.

Figure 1 .

 1 Figure 1.1.1. Self-organization of the DNA spiral using hydrogen bonds

Figure 1 .

 1 Figure 1.1.4. Timeline of different organic cages (a) and some examples of application (b).5

Scheme 1 . 2 . 1 .

 121 Scheme 1.2.1. Schematic representation of the self-assembly process.

Figure 1 . 2 . 2 .

 122 Figure 1.2.2. Combination of structural blocks for 2D (a) and 3D (b) architectures. 1

Figure 1 . 2 . 3 .

 123 Figure 1.2.3. Main elements of the symmetry interaction approach (a) and chosen examples (b).1

  prisms depending on the orientation of binding groups (figure 1.2.6, b).

Figure 1 . 2 . 6 .

 126 Figure 1.2.6. Design of coordination cages using triangle (a) and square (b) panels. 1

Figure 1 . 2 . 5 .

 125 Figure 1.2.5. Tetrahedron and octahedron using the paneling approach.1

Figure 1 . 2 . 7 .

 127 Figure 1.2.7. Mechanism of the weak ligand approach (a) and examples of 2D metallocycles (b).1

Figure 1 . 3 . 1 .

 131 Figure 1.3.1. Structures of common cis-blocked acceptor units.

  (figure 1.3.7, b).

Figure

  Figure 1.3.7. Examples of inner (a) and outer (b) modification of M2L4 cages.[START_REF] Clever | Cation-Anion Arrangement Patterns in Self-Assembled Pd2L4 and Pd4L8 Coordination Cages[END_REF][START_REF] Schmidt | Supramolecular exofunctionalized palladium cages: fluorescent properties and biological activity[END_REF]

Figure

  Figure 1.3.8. Adaptive self-assembled cages based on the "naked" square-planar ions.[START_REF] Tomoki | Self-Assembly of a Pd4L8 Double-Walled Square Partly Takes Place Through the Formation of Kinetically Trapped Species[END_REF][START_REF] Zhang | Adaptive self-assembly and inducedfit transformations of anion-binding metal-organic macrocycles[END_REF][START_REF] Yazaki | Polyaromatic molecular peanuts[END_REF]

Figure 1 . 3 . 11 .

 1311 Figure 1.3.11. Some bis-Palladium acceptors (a) and example of self-assembly (b).[START_REF] Cui | Self-assembly and anion sensing of metalorganic [M6L2] cages from fluorescent triphenylamine tri-pyrazoles with dipalladium(ii,ii) corners[END_REF]

Figure 1 . 3 . 14 .

 1314 Figure 1.3.14. Examples of different self-sorting for covalent (a) and coordination (b) self-assembly.[START_REF] Beuerle | Covalent Organic Frameworks and Cage Compounds: Design and Applications of Polymeric and Discrete Organic Scaffolds[END_REF][START_REF] Bloch | Morphological Control of Heteroleptic cis-and trans-Pd2L2L′2 Cages[END_REF]

  .3.16, a). Similar work was showed by Clever and coworkers 71 with formation of a catenane from a simple cage upon addition of the halide anion. Interestingly, further addition of halide anion leads to an infinite catenane (figure 1.3.16, b).

Figure

  Figure 1.3.16. Interlocked self-assemblies using Palladium complexes.70-71 .

Figure 1 . 4 . 1 .

 141 Figure 1.4.1. Different ways to control host-guest chemistry. a) general principle; b) pH c) irradiation d) redox stimuli. 10

Figure 1 . 5 . 2 .

 152 Figure 1.5.2. Ruthenium-based triazine redox-active cage and its cyclic voltammetry. 110

Figure 1 .

 1 Figure1.5.1. Triazine-based electron-poor redox- active cages.[126]

Figure

  Figure 1.5.3. Redox-active self-assemblies using perylene bisimide (PBI) unit.[113][114]

Figure 1 .

 1 Figure 1.5.4. Redox-active self-assemblies using exo-located ferrocene.116

Figure 1 . 5 . 5 .

 155 Figure 1.5.5. Redox-active self-assemblies using endo-located ferrocene.116

  For instance, S.-Y. Yu and coworkers used syn-1,1'-disubstituted ferrocene complexe with di-Palladium corners to obtain metallocycles (figure 1.5.6, a) capable of recognizing Br -anions 122 . Stang and coworkers used anti-1,1'-disubstituted ferrocene unit with cis-blocked Pd and Pt acceptors to prepare molecular rhomboids and squares 123 (figure 1.5.6, b). Similar metallocycles were reached by S.-Y. Yu and coworkers using another anti-1,1'-disubstituted ferrocene complexe which has shown an ability to recognize different anion (with the best affinity towards HSO4 -), as detected by square wave and cyclic voltametry 124 (figure 1.5.6, c).

Figure 1 .

 1 Figure 1.5.6. Redox-active self-assemblies using syn-1,1'-(a) and anti-1,1'-disubstituted (b) ferrocene. 116

Figure 1 . 5 . 7 .

 157 Figure 1.5.7. Redox-active self-assemblies using dppf cis-blocked Palladium and Platinum complexes. 116 M. Yoshizawa and coworkers have recently shown the use of the dihydrophenazine fragments with "naked" Palladium ions in order to obtain electron-rich М2L4 cage (figure 1.5.8, a). 128 Cyclic voltametry of the starting ligand shows two close reversible oxidation processes, corresponding to formation of mono-and di-radicalcation (figure 1.5.8, b). Resulting cage can be reversibly oxidized (figure 1.5.8, d) to the tetracationic state with alternating localisation of oxidized fragments (both electrochemically and chemically using silver nitrate). Increasing the potential leads to irreversible formation of an octacationic structure M2L4 8+ (figure 1.5.8, c). The reversible formation of the tetraradical cage was confirmed by NMR, UV and EPR data.

Figure 1 .

 1 Figure 1.5.8. Redox-active self-assemblies using polyaromaric shell (a), CV of the starting ligand (b) and cage(c, d).128

Figure 1 . 5 . 9

 159 Figure 1.5.9 Modification of the redox behavior of encapsulated C60 molecules.129

Figure 1 .

 1 Figure 1.5.13. exTTF and its drastic conformational change upon a two-electron oxidation.

Figure 1 .

 1 Figure 1.5.14. exTTF-based cages (a) and corresponding cyclic voltammograms (b).149

Figure 2 .

 2 Figure 2.1.1. A TTF-based cage from TTF(4Py)4 (a) and corresponding metalloplates from TTF(4Py)4 and TTF(3Py)4 (b-d).154

Figure 2 .

 2 Figure 2.1.2. A TTF-based М8L4 cage and its cyclic voltammetry. 149

Figure 2 . 1 . 3 .

 213 Figure 2.1.3. Example of a tetrathiafulvalene "belt" involving to facing TTF planes.

2 Figure 2 . 1 . 4 .

 2214 Scheme 2.1.1. Successive oxidation steps of a TTF dimerImportantly, it has to be noted that till now, the radical-cation homodimerisation to produce (TTF •+ )2 has been observed only in the solid state or in highly concentrated solutions at low temperature (Figure2.1.4).[160][161][162]

Figure 2 .

 2 Figure 2.1.5. X-ray structure of TTF(PhPy)4 ligand.

Figure 2 .

 2 Figure 2.1.6. Cyclic voltammetry of the TTF(PhPy)4 and TTF(4Py)4: CH3CN/CH2Cl2 (C = 1 mM, n-Bu4NPF6 (0,1 M)), 100 mV.s -1 , glassy carbon, vs Fc/Fc + .

Scheme 2 . 2 . 1 .

 221 Scheme 2.2.1. Synthesis of the self-assemblies AA1 and AA2.

Figure 2 .

 2 Figure 2.2.1. 1 H NMR of ligand TTF(PhPy)4 in CDCl3 (a), self-assembly AA1 in MeOD/CD3NO2 (b) and corresponding DOSY NMR (c) A ESI-FTCIR analysis was carried out in collaboration with Drs Frédéric Aubriet and Vincent Carré in the University of Lorraine. This analysis confirms the M8L2 stoichiometry, which therefore corresponds to four bis-Ruthenium acceptor units and two ligands which are assembled in one discrete structure as shown by the characteristic ions [(TTF(PhPy)4)2(Ru3)4, 5TfO -] 3+ (m/z = 1671,4093) and [(TTF(PhPy)4)2(Ru3)4, 4TfO -] 4+ (m/z = 1216,3185) (figure 2.2.1, a). Isotopic distribution also correlates well with the theoretical data (figure 2.2.1, b, c).

Figure 2 .

 2 Figure 2.2.2. ESI-FTCIR of AA1 (a) and theoretical vs experiment (b, c)

Figure 2 .

 2 Figure 2.2.3. X-ray structure of AA1. Hydrogens, anions and molecules of solvent omitted for clarity.

Figure 2 .

 2 Figure 2.2.4. X-ray structure of AA2. Hydrogens, anions (PF6 -) and molecules of solvent omitted for clarity

Figure 2 . 2 . 5 .

 225 Figure 2.2.5. Cyclic voltammetry of AA1 (a) and AA2 (b) (CH3CN/CH2Cl2 (C = 1 mM, n-Bu4NPF6 (0,1 M)), 100 мV.s -1 , Pt, vs Fc/Fc + )

Figure 2 .

 2 Figure 2.2.6. X-ray structure of oxidized AA1. Hydrogens, anions (PF6 -) and molecules of solvent omitted for clarity

  .2.6). Most notably, the TTF planes of both ligands are shifted relative to one another (figure 2.2.6, a) and a significantly shorter distance is observed between both TTF planes. The shortest interplanar TTF distances are found to be ca C … C = 3.47 Å and S … S = 3.70 Å (figure 2.2.6, b), i.e. significantly smaller than in neutral AA1. The generation of oxidized TTF units is furthermore confirmed by comparing the length of the central S2C -CS2 bonds (1.38 Å for both TTF units in the electrocrystallized salt) with the S2C = CS2 bond in neutral AA1 (1.33 Å for both TTF units). Such observations are consistent with the formation of a cation-radical dimer (TTF .+ )2 and

Figure 2

 2 Figure 2.2.7. UV-vis spectra of Ru3, TTF(Me-4PyPh)4 and AA1 (CH3CN/DCM 1/1)

  Scheme 3.1.3. Synthesis of the SHex DTF based ligands.

Figure 3

 3 Figure 3.1.1. X-ray analysis of ligands 25 (a) and 26 (b). Hydrogen atoms omitted for clarity.

  25 and 26 respectively (figure 3.1.2, a).

Figure 3 .

 3 Figure 3.1.2. Cyclic voltammetry of ligands 25 and 26 in DMF (a) and CH3CN/CH2Cl2 (b) (C = 1 mM, n-Bu4NPF6 (0,1 M)), 100 mV.s -1 , Pt, vs Fc/Fc + . Changing the solvent to the more conventional CH3CN/CH2Cl2 mixture results in one reversible oxidation at 0.49 V and 0.53 V vs Fc/Fc + for ligands 25 and 26 respectively (figure 3.1.2,b). Scanning at higher potential does not reveal a second oxidation process, although results in the losing the reversibility for the first oxidation. Similar results were previously obtained for an isomeric DTF compound.177 As expected, ligands 27 and 28 bearing propyl fragments show similar behavior at the same potential

  H and DOSY NMR (figure 3.2.1) and converged within 10 minutes resulting in unique species. Cage AA3 could be easily isolated by precipitation with AcOEt after cooling down to room temperature. 1 H NMR spectrum of AA3 (figure 3.2.1, b) is characterized by well-defined signals which confirms symmetric discrete compound. Upon formation of the cage, signals of both fluorene and pyridyl moieties are downfield-shifted due to the coordination to the Pd metal center. 1 H DOSY NMR spectrum (figure 3.2.1, c) exhibits a single set of signals, which confirms one discrete species in solution. As expected from a larger self-assembly structure, it exhibits a smaller D value (7.94 x 10 -11 m 2 .s -1 ) than the corresponding ligand (D = 1.86 x 10 - 11 m 2 .s -1 ).

Figure 3 .

 3 Figure 3.2.1. 1 H (a, b) and DOSY (c) NMR for the 25 (a, c) and AA3 (b, c) in DMSO-d6.

Figure 3

 3 Figure 3.2.2. ESI-FTICR-MS of cage AA3 ([Pd2L4] 4+ ,4BArF -) in CH2Cl2/CH3NO2 (C = 10 -3 M). Despite long alkyl chains, single crystals of the self-assembly were obtained by slow vapor diffusion of AcOEt into a DMSO solution of AA3. X-ray data shows distance between both Palladium centers of 13.5 Å, which correlates well with DOSY data (figure 3.2.3). They are connected via four 9-(1,3-dithiol-2-ylidene)fluorene ligands 25. Geometrical parameters for the ligand 25 inside the cage AA3 remain mostly the same, which confirms good compatibility of the ligand and metal center. Resulting M2L4 self-assembled structure has an internal cavity of approximately 600 Å 3 (Figure 3.2.3, left).179

Figure 3

 3 Figure 3.2.3. X-Ray crystal structure of AA3, lateral view (left) and top view through the Pd … Pd axis (right). Counter anions, solvent molecules and hydrogens were omitted for clarity. The cavity is depicted as a grey volume.

Figure 3 .

 3 Figure 3.2.4. Normalized cyclic voltammograms of ligand 25 (C = 10 -3 M, 0.1 M nBu4NPF6, 50 mV•s -1 , Pt) and AA3 in DMF (a) and CH3CN/CH2Cl2 (b) (C = 5 × 10 -4 M, 0.1 M nBu4NPF6 or 0.05 M NaBArF for a) and b) respectively, 50 mV•s -1 , Pt), V vs Fc/Fc + .

Figure 3 .

 3 Figure 3.2.5. Example of M6L8 self-assembly by Fujita and coworkers.The self-assembly process was carried out in DMSO-d6 at 50 0 C. The reaction of ligand 26 (2 equiv.) and complex Pd(NO3)2 (1 equiv.) resulted in clear orange solution within 10 minutes. Even though resulting 1 H NMR spectra shows clear downfield shift of signal for ɑ pyridil protons, which indicates successful coordination (figure 3.2.6), low solubility of the resulting compound prevented further characterization using DOSY NMR. Attempts to grow crystal, as well as performing anion exchange using NaBArF did not succeed.

Figure 3 .

 3 Figure 3.2.6. 1 H NMR for the 26 (a) and corresponding self-assembly (b) (in DMSO-d6) 3.3. Self-assembly using cis-blocked Palladium 181 Coordination of DTF-based ligands 4Py-DTF (26 or 28) and 3Py-DTF (25 or 27) with cisblocked Pd and Pt complexes should allow for obtaining M2L2 metallocycles (scheme 3.3.1).Additionally, using ferrocene-containing complexes Pddppf or Ptdppf allows introduction of an additional redox-active ferrocene fragment, which can be used as an internal electrochemical standard (chapter 1.6.2).

Scheme 3 .

 3 Scheme 3.3.1. Self-assembly process for M2L2 self-assembled clips using 4Py-DTF ligands. 1 H NMR spectrum of the resulting solid shows a single set of well resolved signals, which is characteristic for a symmetrical discrete self-assembly structure (figure 3.3.1, b). Signals of pyridyl protons H4 and H5 are upfield shifted in comparison to the starting ligand 26, as a result of through-space interactions between the pyridyl groups and the coligand phenyl units (dppf), therefore confirming coordination to the acceptor. A 1 H DOSY NMR experiment exhibits a single set of signals with a diffusion value of D = 5.03 x 10 -10 m 2 •s -1 , indicating formation of a single discrete structure. Stokes-Einstein equation REF allows to calculate a hydrodynamic radius of ca. 10 Å (T = 298 K), which is consistent with expected M2L2 architecture [Pd2L2(OTf)4].

Figure 3 .

 3 Figure 3.3.1. 1 H (a, b) and DOSY (c) NMR for the 26 (in CDCl3) and AA4 (in CD2Cl2). High resolution ESI-FTICR-MS spectrometry was done in collaboration with Drs Frédéric Aubriet and Vincent Carré in the University of Lorraine. Surprisingly, in addition to signal of expected M2L2 molecular clip ([Pd2(25)2(OTf)4] -2OTf] 2+ ; m/z = 1510.1598), peaks of higher molecular mass were observed despite the variation of the instrumental conditions, the concentration (10 -5 M< C < 10 -3 M) and the solvent (figure 3.3.2).

Figure 3 .

 3 Figure 3.3.2. ESI-FTICR mass spectrum of AA4 in CH2Cl2 (9/1) (C = 10 -3 M), in black experimental isotopic pattern, in blue theoretical isotopic pattern. Some additional signals were identified as M4L4 ([[Pd4(25)4(OTf)8] -3OTf] 3+ ; m/z = 2064.1986) and sometimes M6L6 species. Taken into account previous DOSY NMR data, this data suggests aggregation of the starting M2L2 cage upon ESI with formation of dimer and trimer associates. Such occurrences are known in literature at high concentration and with soft ionization conditions. 182 Attempts to apply IRMPD technique didn`t give sufficient results.3.3.2. Structural propertiesFortunately, single crystals could be grown by slow diffusion of MeOtBu in a CH2Cl2 solution containing AA4 (C = 1 mM). X-ray crystallography analyses confirmed unambiguously the expected M2L2 stoichiometry (figure 3.3.3).

Figure 3 .

 3 Figure 3.3.3. X-ray crystal structure of AA4, (a) crystal packing showing two independent discrete assemblies (blue and turquoise respectively), (b) top view and (c) lateral view of turquoise metalla-macrocycle (related to (a)). Counter anions, solvent molecules and hydrogen atoms (b, c) omitted for clarity.

57

 57

Figure 3 .

 3 Figure 3.3.5. UV-vis absorption spectra of ligand 26 and metalla-macrocycle AA4, r.t. (C = 1.5 × 10 -5 M in CH2Cl2).

  Unfortunately, subsequent attempts to evaluate interaction between the supramolecular clip AA4 and C60 by UV-vis titration gave conflicting results. Therefore 1 H NMR studies were carried out.Study by1 H NMR of a stoichiometric mixture of C60 and metallacyle AA4 in tetrachloroethane-d2 showed no significant shift in the signals of the cage. However, appearance of new signals in the aromatic region was observed along with the deterioration of the signals belonging the cage (figure 3.3.6, a). This data suggests photodestruction of the cage. Control experiment using the mixture of starting ligand 26 and C60 resulted in the similar 1 H NMR (figure 3.3.6, b). Interestingly, only the fluorene signals change significantly, while pyridil protons remain the same. Therefore, the most probable mechanism is a photooxidation of the exocyclic double bond resulting in ketone 24. This was further confirmed by mass-spectra of the fully decomposed mixture, which showed signals of ketone 24 for both self-assembly and pure ligand. However, in the absence of light or in the inert atmosphere the mixture remains stable. Nevertheless, one can note that degradation of ligand 26 in AA4 occurs much faster indicating efficient interaction between C60 and AA4.

Figure 3 .

 3 Figure 3.3.6. Progression of 1 H NMR for the mixture of C60 with clip AA4 (a) and ligand 26 (b) upon irradiation, (C2H2Cl4-d2).

  185 1 H and DOSY NMR experiments were performed in deuterated chloroform (figure 3.3.8). Unfortunately, no significant shift for the signals of the clip was observed. Nevertheless, DOSY NMR shows change in the D value of PC61BM from 4,23 x 10 -10 m 2 s -1 to 1,85 x 10 -10 m 2 s -1 . This confirms substantial interaction between the clip and guest PC61BM. However, irradiation of the mixture results in the similar decomposition (figure 3.3.8, d)

Figure 3 .

 3 Figure 3.3.8. 1 H and DOSY NMR of PC61BM (a), AA4 (b) and their mixture as formed (c) and after 2hr irradiation(d).

Figure 3 .

 3 Figure 3.3.7. Phenyl-C61-butyric acid methyl ester (PC61BM)

Figure 3 .

 3 Figure 3.3.10. 1 H (a, b) and DOSY (c) NMR for the 25 (a) and AA6 (b,c) (in CD2Cl2). High resolution ESI-FTICR-MS spectrometry was done in collaboration with Drs Frédéric Aubriet and Vincent Carré in the University of Lorraine in order to confirm the stoichiometry of selfassembly AA6. Surprisingly, in addition to signal of expected M2L2 molecular clip ([Pd2(25)2(OTf)4] -2OTf] 2+ ; m/z = 1510.1598), peaks of higher molecular mass were observed despite the variation of the instrumental conditions, the concentration (10 -5 M< C < 10 -3 M) and the solvent (annex 5.1). Some additional signals were identified as M4L4 ([[Pd4(25)4(OTf)8] -3OTf] 3+ ; m/z = 2064.1986) and sometimes M6L6 species. Taken into account previous DOSY NMR data, this data suggests aggregation of the starting M2L2 cage upon ESI with formation of dimer and trimer associates. Such occurrences are known in literature and were already observed in case or AA4. 182 Attempts to apply IRMPD technique also didn`t give sufficient results, similar to the self-assemblies with 4Py-DTF ligands.

Figure 3 .

 3 Figure 3.3.11. Normalized cyclic voltammograms of ligand 25 and metalla-ring AA6 (C = 10 -3 M, CH3CN/CH2Cl2, 0.1 M nBu4NPF6, 100 mV•s -1 , Pt) V vs. Fc/Fc + .

Figure 3 . 3 . 12 .

 3312 Figure 3.3.12. Cyclic voltammograms of metalla-ring AA6 at different concentration (CH3CN/CH2Cl2, 0.1 M nBu4NPF6, 100 mV•s -1 , Pt) V vs. Fc/Fc + .

Figure 3 .

 3 Figure 3.3.13. MM+ model of the self-assembly AA7.

Figure 3 . 3 . 14 .

 3314 Figure 3.3.14. Possible guest molecules In this case, the redox-active behavior of the ligand and of the corresponding cage allows to study the host-guest interaction through cyclic voltammetry. Upon intercalating between the DTF panels, guest molecule disrupts formation of the mixed-valence species. This results in recovering the conventional oxidation process (figure 3.3.15, a). As expected, similar studies with AA5 did not show significant changes upon interaction with DCTNF (figure 3.3.15, b).

Figure 3 .

 3 Figure 3.3.15. Normalized cyclic voltammograms of metalla-ring AA5 (b) and AA7 (a) with DCTNF guest (C = 5 x 10 -4 M, CH3CN/CH2Cl2, 0.1 M nBu4NPF6, 100 mV•s -1 , Pt) V vs. Fc/Fc + .

  H and DOSY NMR. Even though 1 H NMR shows shift in the signals, the resulting broadening and overlap of the signals does not allow to interpret the result (figure 3.3.16). DOSY NMR does not show significant change in the clip (D = 5.01 x 10 -10 m 2 .s -1for free clip), but confirms binding of the guest (D = 1.12 x 10 -9 m 2 .s -1 for free guest in CDCl3).

Figure 3 .

 3 Figure 3.3.16. 1 H (a, c, d) and DOSY (b) NMR for the AA6, DCTNF and their mixture1/1 (in CD2Cl2 for a,b,c and CDCl3 for d)

Figure 3 .

 3 Figure 3.3.17. 1 H and DOSY NMR for the AA5 (a), DCTNF (b) and their mixture 1/1 (c) (in CDCl3).

Further 1 H

 1 NMR titration and corresponding Job`s plot indicates a 1:2 interaction with DCTNF, as shown by the shift of H2 and H3 protons (figure 3.3.18). This correlates well with larger distance between DTF fragments and resulting interaction of each DTF panel with one guest molecule separately.

Figure 3 .

 3 Figure 3.3.18. 1 H NMR for AA5/DCTNF mixture (a) and Job`s plot for H2 (b) and H3 (c) (in CDCl3) This correlates well with a similar shift for 1/1 mixture of initial ligand 28 and DCTNF guest in pure CDCl3 (figure 3.3.19).

Figure 3 .

 3 Figure 3.3.19. 1 H NMR of ligand 27 (a), guest DCTNF (c) and their 1/1 mixture (c) in CDCl3

  Self-assemblies АА8 and АА9 obtained from the smallest acceptor Ru1 and ligands 26 and 28 respectively, show a relatively simple 1 H NMR(figure 3.4.1). Well-defined structure of 1 H NMR state for the formation of a probable unique discrete structure. 1 H DOSY NMR confirms formation of a single product with corresponding rH = 13,2 Å for АА8 and 11,4 Å for АА9, which correlates well with expected size of a М4L2 assembly (figure 3.4.1). After precipitation, self-assembly can be solubilized in dmso-d6 without structure modification (figure 3.4.1, b).

67

 67

Figure 3 .

 3 Figure 3.4.1. 1 H and DOSY NMR for the starting ligand 28 in CDCl3 (a),

Figure 3 .

 3 Figure 3.4.2. X-ray crystal structure of AA9 and its schematic representation. Counter anions, solvent molecules and hydrogen atoms omitted for clarity. Interestingly, moving to the bis-ruthenium acceptor Ru3 for which distance between both Ru centers is increased to 7.9 Å leads to a drastic change in the NMR spectra (figure 3.4.3, a) with the presence of aromatic upfield shifted signals and a splitting of  and  protons.

Figure 3 .

 3 Figure 3.4.3. 1 H and DOSY NMR for the AA11 (a) and AA10 (b) in methanol-d4 and dmso-d6 (c)

Figure 3 .

 3 Figure 3.4.4. X-ray crystal structure of AA11 (a) and its schematic representation (b). Counter anions, solvent molecules and hydrogen atoms omitted for clarity.

Figure 3 .

 3 Figure 3.4.5. 1 H and DOSY NMR for ligand Ru4 (a), 26 (b) and AA12 (c) in methanol-d4, CDCl3 and CD3CN (c) respectively 3.4.2. Electrochemical properties The electrochemical behavior of self-assemblies AA8-13 were studied by cyclic voltammetry in CH3CN/CH2Cl2 (1/1, v/v). Smaller clips AA8-9 show reversible oxidation to the radical-cation with a formation of intermediate mix-valence species (figure 3.4.6), similar to the clips AA6-7. The intramolecular nature of this process is in good relation to the close distance between DTF fragments within the clip due to the smaller size of the Ru1 acceptor. As expected, larger self-assemblies AA10-11 retain split wave oxidation of the DTF fragment to the radical cation (figure 3.4.7, a). It is followed by the oxidation of the Ru acceptor unit at higher potential (figure 3.4.7, b). Scanning at the higher potential leads to the second irreversible oxidation of a Ruthenium fragment.

Figure 3 . 70 Figure 3

 3703 Figure 3.4.6. Normalized cyclic voltammograms of ligand 26 and metalla-ring AA8 (C = 10 -3 M, CH3CN/CH2Cl2, 0.1 M nBu4NPF6, 100 mV•s -1 , Pt) V vs. Fc/Fc + .

Figure 3 . 4 . 8 .

 348 Figure 3.4.8. Schematic representation of a monomer-dimer transformation.

Figure 3 .

 3 Figure 3.4.9. 1 H NMR of self-assembly AA11 in methanol-d4 Influence of the concentration was studied in the range 10 -3 M -10 -5 M (figure 3.4.9). Within the concentration of 10 -3 M and higher, 1 H NMR spectra shows only signals of the dimer. Upon dilution to 10 -4 M, signals of a monomer appear and further dilution to 10 -5 M results in only monomer being present in the solution. Usually, such type of equilibrium can be evaluated via the correlation between the ratio of signals for both forms at different concentrations. Therefore, association constant of Ka = 4006 ± 160 was calculated based on the 1 H NMR experiment using the ɑ pyridil protons (annex 3.20).

Figure 3 .

 3 Figure 3.4.10. Conventional (a) and normalized (b) cyclic voltammograms of AA11 upon dilution (C = 10 -3 M -10 -5 M, CH3CN/CH2Cl2, 0.1 M nBu4NPF6, 100 mV•s -1 , Pt) V vs. Fc/Fc + Another possibility to break the dimer is to introduce a competitive guest molecule. From the variety of planar guests (figure 3.3.11), only the DCTNF molecule showed significant results. 1 H NMR shows complete disappearance of signals from the dimer upon addition of 1 equivalent of DCTNF (figure 3.4.11). At the same time, shift of the 1 H NMR signals of the resulting complex isn`t the same as for the pure monomer upon dilution, which confirms interaction between the clip and the guest.

Figure 3 .

 3 Figure 3.4.11. 1 H and DOSY NMR of guest DCTNF (a), self-assembly AA11 (b -dimer, f -monomer) and their mixture (c, d, e) in methanol-d4

Figure 3 .

 3 Figure 3.4.12. Experimental (a) and theoretical (b) cyclic voltammograms of AA11 and its mixture with DCTNF (1/1) (C = 5 x 10 -4 M, CH3CN/CH2Cl2, 0.1 M nBu4NPF6, 100 mV•s -1 , Pt) V vs. Fc/Fc + 3.5. Conclusions to chapter III. Two new types of angular ligands were designed based on the dithiafulvalene (DTF) scaffold in combination with ethynylpyridine groups for use in coordination-driven self-assembly. Both 3Py-DTF and 4Py-DTF ligands are characterized by one reversible oxidation resulting in the formation of a radical-cation.

  Compounds based on π-extended tetrathiafulvalene fragments were introduced in chapter 1.6.4. In our group, the first ligand constructed from such motif was developed using the dihydroanthracene fragment during the PhD thesis of Dr. S. Bivaud (Figure4.1.1).187 Introduction of 4-pyridil units via direct arylation allowed for creation of exTTF-4Py4 ligand, which successfully react with cis-blocked Pd and Pt acceptors to produce M4L2 cages, capable of binding the perylene molecule.149

Figure 4 .

 4 Figure 4.1.1. π-extended tetrathiafulvalene (exTTF) and corresponding ligand exTTF-4Py4

Figure 4 . 1 . 2 .

 412 Figure 4.1.2. Conformational change of exTTF molecule upon oxidation/reduction process

Figure 4 .

 4 Figure 4.1.3. Structure (a) and cyclic voltammetry of the exTTF-TEG ligand It`s worth describing the electrochemical behavior of exTTF-based ligands. The electrochemical oxidation process of exTTF derivatives is usually manifested by a single two-electron oxidation wave to the dicationic state, involving an inverted potential phenomenon (E1 ox > E2 ox ). 188-189 Both ligands exTTF-TEG and ex-TTF-4Py4 present a single pseudo-reversible oxidation wave with formation of a dication (figure 4.1.3, b). Ligand exTTF-TEG exhibits a lower oxidation potential (Eox = 0.05 V and Ered = -0.20 V vs. Fc/Fc + ) in comparison to the parent exTTF-4Py4 (Eox = 0.30 V vs. Fc/Fc + ), which is caused by donating mesomeric effect promoted by the TEG groups.

  During the PhD thesis of S. Bivaud and later V. Croué, exTTF-based ligands were used in combination with cis-blocked Pd and Pt charged acceptors with different substituents and afforded M2L4 type cages, be they neutral or octacationic (figure 4.2.1). The M4L2 8+ cage has proven to efficiently bind two B12F12 2-anions, 150 while the homologue neutral M4L2 cage was effective in binding neutral molecules such as coronene.[151][152]

Figure 4 .

 4 Figure 4.2.1. Self-assemblies using exTTF-TEG ligand in combination with different cis-blocked acceptors

  H NMR and 1 H DOSY NMR (figure 4.3.1). In comparison to the starting ligand exTTF-TEG (figure 4.3.1, a), AA14 exhibits broader NMR signals, which is common for large discrete structures (figure 4.3.1, b). 190 1 H DOSY NMR was able to further confirm the formation of a single discrete compound. A hydrodynamic radius rH of 21 Å was calculated from the corresponding diffusion value of the cage (D = 1.93 x 10 -10 m².s -1 ), which is consistent with a large size self-assembled structure.

Figure 4 .

 4 Figure 4.3.1. 1 H and DOSY NMR for the exTTF-TEG ligand (a) and resulting self-assembly AA14(b) in dmso-d6High resolution ESI-FTICR-MS spectrometry was achieved in collaboration with Drs Frédéric Aubriet and Vincent Carré from the University of Lorraine. As previously described by the group,151 KOTf was added to the analyzed solution in order to produce ionic species after interaction of the latter with peripheral TEG chains. We were able to determine a M12L6 stoichiometry, for which characteristic peaks corresponding to the [Pd12(exTTF-TEG)6 + (KOTf)n = 9-12 -7OTf] 7+ and to the [Pd12(exTTF-TEG)6 + (KOTf)n = 7-11 -6OTf] 6+ cations show good correlation with theoretical estimates (figure 4.3.2).

Figure 4 .

 4 Figure 4.3.2. ESI-FTICR spectrum of AA14 recorded in CH2Cl2/CH3NO2 (C = 5 x 10 -4 M) after addition of 24 equiv. of KOTf (solution in CH3NO2)A similar reaction was carry out with AgBF4 in CDCl3/CD3NO2 (1/1) affording a polycationic species. The reaction process was followed by 1 H NMR and showed almost instantaneous formation of a single discrete structure, which was further confirmed with 1 H DOSY NMR (figure 4.3.3). The corresponding Stokes radius (R = 20.5 Å) for D = 2.19 x 10 -10 m².s -1 is coherent with formation of a large discrete assembly AA15 having a size similar to the above mentioned palladium cage AA14.

Figure 4 .

 4 Figure 4.3.3. 1 H and DOSY NMR for the exTTF-TEG ligand (a) and resulting self-assembly AA15 after reaction with AgOTf (b) in CDCl3/CD3NO2

  H NMR data that do not show any change in the TEG signals during the reaction (figure 4.3.3). Similarly to experiments led with AA14, a ESI-FTICR MS analysis of AA15 was run in presence of 12 equivalents of AgBF4 in order to stabilize TEG chains. This allowed to confirm a M12L6 stoichiometry. The characteristic signals [Ag12(exTTF-TEG)6 + (AgBF4)9-15 -6BF4] 6+ and [Ag12(exTTF-TEG)6 + (AgBF4)8-12 -5BF4] 5+ show a good correlation with theoretical estimates (figure 4.3.4).

Figure 4 .

 4 Figure 4.3.4. ESI-FTICR spectrum of AA15 recorded in CH2Cl2/CH3NO2 (C = 5 x 10 -4 M) after addition of 12 equiv. of AgBF4 (solution in CH3NO2).

Figure 4 .

 4 Figure 4.3.5. MM+ simulation of cage AA14 (a), cavity is depicted in grey (V = 3658 Å 3 )(b)

  .6, b). 191

Figure 4 .

 4 Figure 4.3.6. MM+ simulation of cage AA15 (a), cavity is depicted in grey (V = 3954 Å 3 )(b)

Figure 4 . 3 . 7 .

 437 Figure 4.3.7. Normalized cyclic voltammogram of ligand exTTF-TEG (C = 10 -3 M, CH3CN) and of cages AA14 (C = 5 x 10 -4 M, CH3CN/CH2Cl2 (1/1)) and AA15 (C = 5 x 10 -4 M, CH3NO2/CH2Cl2 (1/1)), 0.1 M nBu4NPF6, 100 mV.s -1 , GC, V vs Fc/Fc +

Figure 4 .

 4 Figure 4.4.1. 1 H and DOSY NMR for the self-assembly AA15 (a) and resulting complex [Ag12(Ag2(exTTF-TEG)6] 24+ (b) in CDCl3/CD3NO2

Figure 4 .

 4 Figure 4.4.2. X-Ray structure of the [(Ag2(exTTF-TEG 2+ )) 2+ ]x three-dimensional supramolecular polymer, BF4 -anions are located in the free space Fortunately, we were able to analyze single crystal. An X-Ray diffraction analysis shows the evolution of the initial [Ag12(exTTF-TEG)6] 12+ discrete structure to an infinite [(Ag2 exTTF-TEG 2+ ) 2+ ]x three-dimensional supramolecular polymer (figure 4.4.2), according to a self-oxidation process.

Figure 4 .

 4 Figure 4.4.3. Partial [(Ag2(exTTF-TEG 2+ )) 2+ ]x X-ray structure showing a) the repeating (Ag2exTTF-TEG 2+ ) 2+ motifs and b) the silver coordination sphere. BF4 -anions omitted for clarity X-ray data of [(Ag2(exTTF-TEG 2+ )) 2+ ]x shows a polycationic polymeric backbone which is constituted from the repeating unit (Ag2(exTTF-TEG 2+ ) 2+ (figure 4.4.3, a). The dication state of the exTTF fragment (exTTF-TEG 2+ ) is confirmed by both the length of the C-C bond (1.47 Å) between the planar central anthracene moiety and the 1,3-dithiolium rings and by the corresponding dihedral angles of 83.4°. The TEG fragments play a substantial role in the final structure, since they provide additional coordination sites for silver cations (figure 4.4.3, b). The pyridine units are slightly distorted (N-Ag-N = 157°) in comparison to the starting cage AA15 (N-Ag-N: ca. 175°). In general, three independent exTTF ligands take part simultaneously to the silver coordination.

  Scheme 5.1.1. Design of the S-exTTF-based ligands.

Figure 5 . 3 . 1 .

 531 Figure 5.3.1. Molecular structure determined by single crystal X-ray diffraction of dithieno-exTTF S-exTTF. Top (left) and side (right) views, respectively.

Figure 5 . 3 . 2 .Figure 5 . 3 . 3 .

 532533 Figure 5.3.2. Molecular structure of exTTF, exTTF' and S-exTTF Main common parameters characterizing the geometrical structure of these systems can be defined by i) the folding angle of the central quinoidal ring (angle α), ii) the tilting angle defined by the 1,3-dithiolyliden rings with respect to the plane formed by the central four carbon atoms of the quinoidal ring (angle β), and iii) the 1,3-dithiolyliden folding angle along the S•••S axis (angle γ). (figure 5.3.3)

Figure 5 .

 5 Figure 5.3.4. Minimum-energy B3LYP-D3/6-31G**-optimized geometries calculated for compound S-exTTF (a) and exTTF' (b) in CH2Cl2

Figure 5 .

 5 Figure 5.3.5. B3LYP-D3/6-31G**-optimized bond lengths (in Å) computed for compound S-exTTF (a) and exTTF' (b) in CH2Cl2. Hydrogen atoms have been omitted for clarity

Figure 5 .

 5 Figure 5.3.6 B3LYP-D3/6-31G**-optimized butterfly and planar structures computed for compound S-exTTF (a) and exTTF' (b) in CH2Cl2. The molecular symmetry, the intramolecular contacts and the energy difference between both structures are indicated.

Figure 5 . 3 . 7

 537 Figure 5.3.7 Energy diagram showing the frontier molecular orbitals computed for exTTF' and S-exTTF at the B3LYP-D3/6-31G** level in CH2Cl2. H and L denote HOMO and LUMO, respectively.

Figure 5 .

 5 Figure 5.3.8. UV-vis spectra of 29 and S-exTTF in CH2Cl2 (C = 1.38 × 10 -5 M) To complete the study, time-dependent DFT (TDDFT) calculations of the lowest-energy singlet excited electronic states (Sn) were performed for compounds S-exTTF and 29 as well as for exTTF' at the B3LYP/6-31G** level in CH2Cl2. The main experimental absorption bands recorded for S-exTTF and 29, are attributed to intense S0 → S1 electronic transitions predicted at 483 and 445 nm, respectively (figure 5.3.9, a). These electronic transitions are of π → π* nature and mainly imply the HOMO → LUMO one-electron excitation (figure 5.3.9, b). Calculations for exTTF' show an intense S0 → S1 electronic transition at 423 nm, which has a dominant HOMO → LUMO character. The narrower HOMO-LUMO gap in the S-exTTF and 29 compared to exTTF' explains the corresponding red shift between them and is likely due to the smaller distortion from planarity of the molecular structure for the S-exTTF compared to exTTF'.

Figure 5 .

 5 Figure 5.3.9. a) Lowest singlet excited states calculated at the TDDFT B3LYP-D3/6-31G** level for S-exTTF, intermediate 1S-exTTF and exTTF' in CH2Cl2 solution. Vertical excitation energies (E), oscillator strengths (f) and dominant monoexcitations with contributions (within parentheses) greater than 10%. b) frontier molecular orbitals computed for S-exTTF, 29 and exTTF' at the B3LYP-D3/6-31G** level in CH2Cl2. Isovalue contours (±0.03 a.u.) were used. Molecular orbital energies are given within parentheses in eV.

Figure 5 . 3 . 10 .

 5310 Figure 5.3.10. Cyclic voltammograms of S-exTTF (a) and exTTF' (b), CH2Cl2, C = 1 mM, Bu4NPF6 (0.1 M), 100mV.s -1 , Pt working electrode;

Figure 5 .

 5 Figure 5.3.11. Thin-layer cyclic voltammogram ([S-exTTF] = 1.3 mM) in presence of 2,3-dichloronaphthoquinone (NQ) as a coulometric standard ([NQ] = 2.6 mM), CH2Cl2/CH3CN 2/1 (v/v), Bu4NPF6 (0.1M)), 10mV.s -1 , r.t., Pt working electrode.

Figure 5 .

 5 Figure 5.4.1. Molecular structures determined by single crystal X-ray diffraction of the electrocrystallized salt [S-exTTF].[PF6]•THF. Top (left) and side (right) views, respectively. Note that a the thiophene rings are disordered and the occupation ratios of S and C atoms in respective 1,3-positions have been refined till a convergence value of ca. 0.5.

  Scheme 5.4.1 Scheme figuring the S•••S interaction in planar S-exTTF •+ (a) and 29 (b).

  dithiolium and benzene rings) (scheme 5.4.1, b). Such mesomeric form promotes a certain degree of positive charge over the S atoms, showing therefore a clear analogy with the case of S-exTTF •+ and resulting in exceptionally short S•••S intramolecular distances.

Figure 5 . 4 . 2 .

 542 Figure 5.4.2. Molecular structures determined by single crystal X-ray diffraction of the push-pull derivative 29. Left and right columns correspond to top and side views, respectively. Both thiophene rings are disordered with an occupation ratios of S / C atoms of 0.5.

  Figure 5.3.4: α = 24.6°, β = 18.9° and γ = 6.7°) tends to planarize significantly upon oxidation. This is notably illustrated by the significant decrease of the folding angles in S-exTTF •+ (α = 16.7°, β = 13.1°, γ = 0.9°, figure 5.4.3, a).

Figure 5 .

 5 Figure 5.4.3 B3LYP-D3/6-31G**-optimized structure (left) and forced planar structure (right) computed for the radical cation S-exTTF •+ (a) and S-exTTF •+ in which the thiomethyl groups have been removed (b) in CH2Cl2. The molecular symmetry, the intramolecular contacts and the energy difference between both structures are indicated.

  [S-exTTF][PF6]•THF salt. Further oxidation to S-exTTF 2+ leads to the fully planar central dihydrobenzodithiophene core (figure 5.4.4, a), while dithiole rings are tilted by ~50° with respect to the plane formed by the central unit, similarly to what is observed with the exTTF 2+ parent molecule (figure 5.4.4, b). Therefore, the structural transformation upon oxidation follows the same trend as for exTTF 2+ or exTTF' 2+ . Nevertheless, a significant difference occurs with S-exTTF 2+ , since the latter involves short S•••S intramolecular contacts (3.30 Å) (2Rvdw(S)= 3.60 Å), which therefore also occurs in the dication states.

Figure 5 .

 5 Figure 5.4.4. Minimum-energy B3LYP-D3/6-31G**-optimized geometries computed for S-exTTF 2+ (a) and exTTF' 2+ (b) in CH2Cl2. Further analysis of the Mulliken atomic charges calculated for S-exTTF, S-exTTF •+ and S-exTTF 2+ allows to investigate charges localization in the neutral and oxidized states. Data clearly show that upon oxidation, the charge is essentially located on the dithiole rings with a noticeable contribution of the thiomethyl groups (figure 5.4.5). Upon passing from S-exTTF to S-exTTF •+ , 0.75e are extracted from the dithiole rings and the thiomethyl groups and especially from the S atoms of the dithiol groups (0.51e, figure 5.4.5, a). Such data correlate well with the contraction of the sulfur sp 2 lone pairs upon oxidation. It in turn leads to the diminishing of the Pauli exchange repulsion, resulting in shorter S•••S contacts observed for S-exTTF •+ .

Figure 5 . 4 . 5 .

 545 Figure 5.4.5. Mulliken atomic charges computed for S-exTTF, S-exTTF •+ and 29 (a) and extracted from the different molecular fragments in passing from S-exTTF to S-exTTF •+ (left) and from S-exTTF •+ to S-exTTF 2+ (right) computed at the B3LYP-D3/6-31G** level in CH2Cl2 (b) Interestingly, the dithiol sulfur involved in the S•••S interaction for compound 29 presents a positive charge (+0.37e, figure 5.4.5) having a value which is closer to that found for S-exTTF •+ (+0.42e) than for S-exTTF (+0.29e). This outcome supports the experimental data for 29 and confirms the significant contribution of the charged mesomeric form in the neutral push-pull compound 29 (Scheme 5.4.1) and the contraction of the sulfur sp 2 lone pairs giving rise to short S•••S contacts.

Figure 5 . 4 . 6 .

 546 Figure 5.4.6. Summary of the structural evolution of S-exTTF (a) and exTTF' (b) upon oxidation calculated at the B3LYP-D3/6-31G** level in CH2Cl2. The thiomethyl groups have been omitted for clarity. A scheme of the aromatization achieved by the exTTF' 2+ dication species is also given

  of the oxidized states further highlights attractive character of 1,5 S•••S interactions, with good correlation between experimental and theoretical data. X-ray data of the oxidized [S-exTTF][PF6] . THF salt shows fully planarized molecule with remarkably short S•••S distance of 2.82-2.89 Å. Theoretical calculations on the B3LYP-D3/6-31G** level assign it to the contraction of sp 2 lone pair of the dithiole rings in the oxidized state. This further causes lower Pauli repulsion, leading to shorter S•••S contacts. Interestingly, push-pull intermediates 29 and 31 show similar S•••S distance, which suggests high contribution of the charged mesomeric form.

1 H

 1 NMR (300 MHz, CD3CN)  7.80 (HPh, m, 12H), 7.58 (HPh, m, 8H), 4.76 (HFc, s, 4H), 4.58 (HFc, s, 4H). 31 P NMR (122 MHz, CD3CN)  42.82. 1 H NMR (300 MHz, CD3OD) 7.95 (HPh, m, 8H), 7.83 (HPh, m, 4H), 7.69 (HPh, m, 8H), 4.82 (HFc, s, 4H), 4.70 (HFc, s, 4H). 31 P NMR (122 MHz, CD3OD)  48.21. 1 H NMR (300 MHz, CD3NO2): 7.92 (HPh, m, 8H), 7.78 (HPh, m, 4H), 7.60 (HPh, m, 8H), 4.81 (HFc, s, 4H), 4.69 (HFc, s, 4H). 31 P NMR (122 MHz, CD3NO2)  47.31.

  1 H NMR (methanol-d4) 5.97 (d, J = 6.2, 4H), 5.77 (d, J = 6.2 Hz, 4H), 2.88 (m, 2H), 2.27 (s, 6H), 1.39 (s, 6H),1.36 (s, 6H).

  1 H NMR (300 MHz, Methanol-d4) 7.39 (s, 4H), 5.92 (d, J = 5.7 Hz, 4H), 5.67 (d, J = 5.7 Hz, 4H), 2.93 (m, 2H), 2.30 (s, 6H), 1.42 (d, J = 6.9 Hz, 12H). Bis(chloro(p-cymene)ruthenium(II)) 6,11-dihydroxy-6,11-dihydrotetracene-5,12-bis(olate) 4 221 To a solution of dichloro(p-cymene)ruthenium (410 mg, 0.70 mmol) in anhydrous ethanol (20 mL), were added 6,11-dihydroxytetracene-5,12-dione (194.3 mg, 0.70 mmol) and sodium acetate (109.8 mg, 1.33 mmol). The solution was stirred at 80°C overnight and the suspension was filtered and the solid washed successively with: ethanol, water, acetone, diethyl ether and pentane to afford 4 as a dark green powder (445.2 mg, 80 %). Bis(triflate(p-cymene)ruthenium(II))6,11-dihydroxy-6,11-dihydrotetracene-5,12-bis(olate) Ru4 221

  1 H NMR (300 MHz, Methanol-d4) δ 8.72 (dd, J = 6.0, 3.3 Hz, 4H), 7.95 (dd, J = 6.1, 3.3 Hz, 4H), 6.03 (d, J = 6.1 Hz, 4H), 5.77 (d, J = 6.1 Hz, 4H), 3.04 (dt, J = 13.8, 6.9 Hz, 2H), 2.40 (s, 6H), 1.46 (d, J = 6.9 Hz, 12H).

1 H

 1 NMR (300 MHz, CDCl3) δ 8.65 (HαPy,d, J = 5.7 Hz, 8H), 7.55 (HPh, d, J = 8.4 Hz, 2H), 7.47 (HβPy d, J = 5.7 Hz, 2H), 7.38 (HPh, d, J = 8.4 Hz, 2H).

  To a suspension of TTF(PhPy)4 (40 mg, 0.049 mmol) in dry DMF (4 mL) was added large excess of iodomethane (120 uL, 278 mg, 1.96 mmol,). The mixture was stirred overnight until formation of clear intense red solution. After cooling down, Et2O was added and the resulting solid was filtered and dried to give dark powder. Anion exchange from SO4 2-to PF6 -was performed by adding a concentrated solution of potassium hexafluorophosphate in water and stirring for 2 hr. Resulting precipitate was centrifuged, washed with minimum methanol, Et2O and dried in vacuo to give 7 (TTF(PhPy-Me)4 ) as a dark powder(25 mg, 35 %).

1 H

 1 NMR (300 MHz, CDCl3) δ 2.86 (HSCH2, t, J = 7.2 Hz, 4 H), 1.65 (HCH2, m, 4H), 1.41 (HCH2, m, 4H), 1.29 (HCH2, m, 8H), 0.88 (HCH3, m, 6H).

1 H

 1 NMR (300 MHz, CDCl3) δ 5.73 (s, 1H), 2.81 (m, 4H), 2.25 (s, 3H), 1.65 (m, 4H), 1.44 -1.22 (m, 12H), 0.88 (m, 6H).

1 H

 1 NMR (300 MHz, CDCl3) δ 5.78 (s, 1H), 3.02 -2.65 (m, 4H), 2.29 (s, 3H), 1.86 -1.60 (m, 4H), 1.05 (t, J = 7.3 Hz, 6H).

1 H

 1 NMR (300 MHz, CDCl3) δ 8.12 (d, 4 J = 1.8 Hz, 2H), 8.07 (d, J = 8.1 Hz, 2H), 7.66 (dd, J = 1.8 Hz, J = 8.1 Hz, 2H).

  in the MW tube. To an argon degassed solution of 3,6-dibromo-9H-fluoren-9-one 22 (100 mg, 0.295 mmol) and3-ethynylpyridine (122 mg, 1.18 mmol, 4 equiv.) in diisopropylamine/toluene (v/v 1/1, 4 mL), Pd(PPh3)4 (68.3 mg, 0.059 mmol, 0.2 equiv.) and CuI (11.3 mg, 0.059 mmol, 0.2 equiv.) were added under argon. Tube was irradiated for 30 min at constant 250 W. The solvent was evaporated under vacuum. The residue was treated with water and extracted with dichloromethane (50 mL). The organic extracts were washed with water (3 x 50 mL) and dried over magnesium sulfate. The solvent was evaporated under vacuum. A chromatography column on silica gel was performed using mixture dichloromethane/petroleum ether (1/1). Compound was further purified by recrystallization with a mixture of dichloromethane/pentane. Compound 23 was obtained as yellow powder (85 mg, 75 %).1 H NMR (300 MHz, CDCl3) δ 8.80 (s, 1H), 8.59 (s, 1H), 7.84(d, J = 7.9 Hz, 1H), 7.74 -7.64 (m, 2H), 7.51 (d, J = 7.7 Hz, 1H), 7.37 -7.29 (m, 1H

Compound 25

 25 was obtained as red crystals(94 mg, 54 %). 1 H NMR (300 MHz, CDCl3) δ 8.82 (d, J = 1.8 Hz, 2H), 8.57 (dd, J = 4.9, J = 1.8 Hz, 2H), 8.06 (d, J = 1.6 Hz, 2H), 7.86 (ddd, J = 7.9, J = 1.8, J = 1.8 Hz, 2H), 7.76 (d, J = 8.2 Hz, 2H), 7.62 (dd, J = 8.2, J= 1.6 Hz, 2H), 7.31 (dd, J = 7.9, 4.9 Hz, 2H), 2.99 (m, 4H), 1.71 (m, 4H), 1.48 (m, 4H), 1.33 (m, 8H), 0.90 (t, J = 6.8 Hz, 6H). 13 C NMR (76 MHz, CDCl3) δ 152.

Compound 26

 26 was obtained as red crystals(84 mg, 75 %). 1 H NMR (300 MHz, CDCl3) δ 8.82 (d, J = 1.4 Hz, 1H), 8.57 (dd, J = 4.7, 1.4 Hz, 1H), 8.06 (d, J = 0.9 Hz, 1H), 7.86 (dt, J = 7.9, 1.8 Hz, 1H), 7.76 (d, J = 8.2 Hz, 1H), 7.62 (dd, J = 8.2, 1.6 Hz, 1H), 7.42 -7.30 (m, 1H), 3.13 -2.84 (m, 2H), 1.71 (dd, J = 15.0, 7.6 Hz, 4H), 1.48 (s, 4H), 1.38 -1.16 (m, 8H), 0.90 (t, J = 6.8 Hz, 6H). 13 C NMR (76 MHz, CDCl3) δ 149.

Compound 27

 27 was obtained as red crystals (132 mg, 46 %).

  of dimethyl (4,5-bis(methylthio)-1,3-dithiol-2-yl)phosphonate 18 (276 mg, 0.90 mmol) in anhydrous tetrahydrofuran (10 mL) at -78°C, was added slowly n-butyl lithium (570 µL, 0.90 mmol, 1.6 M). The solution was stirred at -78°C for 1 h 30 and a suspension of benzo[1,2-b:4,5-b']dithiophene-4,8dione (100 mg, 0.45 mmol) in anhydrous tetrahydrofuran at -78°C was added via cannula. The mixture was stirred 1 h at -78°C and overnight at room temperature. The solvent was removed under vacuum.

1 H

 1 NMR (300 MHz, CDCl3) δ 7.95 (d, J = 5.4 Hz, 1H), 7.87 (d, J = 5.4 Hz, 1H), 7.78 (d, J = 5.4 Hz, 1H), 7.43 (d, J = 5.4 Hz, 1H), 2.62 (s, 3H), 2.60 (s, 3H). 13 C NMR (76 MHz, CDCl3) δ 173.

  of dimethyl (4,5-bis(methylthio)-1,3-dithiol-2-yl)phosphonate 18(145,72 mg, 3.75 mmol) in anhydrous tetrahydrofuran (10 mL) at -78°C, was added slowly n-butyl lithium(2.35 mL, 3.75 mmol, 1.6 M). The solution was stirred at -78°C for 1 h and a suspension of benzo[1,2-b:4,5-b']dithiophene-4,8dione 29 (300 mg, 0.75 mmol) in anhydrous tetrahydrofuran at -78°C was added via cannula. The mixture was stirred 1 h at -78°C and overnight at room temperature. The solvent was removed under vacuum. The residue was treated with water and extracted with dichloromethane. The organic extracts were washed with water, and dried over magnesium sulphate. The solvent was removed under vacuum. A chromatography column on alumina was performed using mixture EP/dichloromethane 75/25 with constant 1% thiethylamine as eluent. The compound 30 or S-exTTF was isolated as a red powder (of dimethyl (4,5-bis(hexylthio)-1,3-dithiol-2-yl)phosphonate 16 (970 mg, 2.18 mmol) in anhydrous tetrahydrofuran (10 mL) at -78°C, was added slowly n-butyl lithium(1.4 mL, 2.18 mmol, 1.6 M). The solution was stirred at -78°C for 1 h 30 and a suspension of benzo[1,2-b:4,5-b']dithiophene-4,8dione (400 mg, 1.81 mmol) in anhydrous tetrahydrofuran at -78°C was added via cannula. The mixture was stirred 1 h at -78°C and overnight at room temperature. The solvent was removed under vacuum.

  Finally, a new aromatic scaffold S-exTTF (benzo[1,2-b:4,5-b'] dithiophene) is explored as an alternative system to the well-established π-extended tetrathiafulvalene (exTTF). A combined experimental and theoretical study is proposed to characterize the specific structural and electronic properties of this new compound. Introduction of additional 1,5 S•••S non-covalent interactions allowed to assert further control over the conformation and planarity of the molecule in both neutral and oxidized states. The single crystal X-Ray diffraction analysis of the oxidized [S-exTTF][PF6] . THF salt, grown by electrocrystallization, shows a fully planarized molecule with remarkably short S•••S distance of 2.82-2.89 Å. Theoretical calculations on the B3LYP-D3/6-31G** level assign this conformation to the contraction of S sp 2 lone pair of the dithiole rings in the oxidized state. This further causes lower Pauli repulsion, leading to shorter S•••S contacts. Accordingly, it is worth noting that push-pull intermediates 29 and 31 show similar very short S•••S distances, which suggests a high contribution of the charged mesomeric form.

  S•••S interactions is demonstrated by a combined experimental and theoretical approach.

	Abbreviations
	2D	two-dimensional
	3D	three-dimensional
	CV	cyclic voltammetry
	D	diffusion coefficient
	DCTNF	9-dicyanomethylen-2,4,7-trinitrofluoren
	DFT	density functional theory
	DMF	dimethylformamide
	DMSO	dimethyl sulfoxide
	DOSY	diffusion-ordered spectroscopy
	dppf	[1,1'-bis(diphenylphosphino)ferrocene]
	DTF	dithiafulvalene
	Equiv.	equivalent
	ESI	electrospray ionization
	exTTF	π-extended tetrathiafulvalene
	GC	glassy carbon
	HRMS	high resolution mass spectrometry
	HWE	horner wadsworth reaction reaction
	IR	infra-red
	M	mol.l -1
	MALDI	matrix-assisted laser desorption/ionisation
	MS	mass spectrometry
	NMR	nuclear magnetic resonance
	PC61BM	phenyl-c61-butyric acid methyl ester
	Pddppf	[1,1'-bis(diphenylphosphino)ferrocenepaladium (ii) triflate
	Ph	phenyl
	Ppm	parts per million
	Py	pyridine
	rH	hydrodynamique radius
	rt	room temperature
	Ru1	bis(triflate (p-cymene)rhuthenium(ii))oxalato-1,4-bis(olate)
	Ru2	bis(triflate(p-cymene)ruthenium(ii))	5,8-dioxo-5,8-dihydronaphthalene-1,4-
		bis(olate)
	Ru3	bis(chloro(p-cymene)ruthenium(ii))	6,11-dihydroxy-6,11-dihydrotetracene-
		5,12-bis(olate)
	Ru4	bis(triflate(p-cymene)ruthenium(ii))6,11-dihydroxy-6,11-dihydrotetracene-
		5,12-bis(olate)
	SEC	spectroelectrochemistry
	TDAE	tetrakis(dimethylamino)ethylene
	Tf	triflate
	TFA	trifluoroacetic acid
	THF	tetrahydrofuran
	TLC	thin layer chromatography
	TLCV	thin layer cyclic voltammetry
	TTF	tetrathiafulvalene
	UV	ultraviolet
	XRD	x-ray diffraction
	δ	chemical shift, ppm

Table 1 .

 1 Non-covalent interactions in supramolecular chemistry.

	-ion	100-350	Sodium chloride
	Ion-dipole	50-200	Crown ether -Na +
	Dipole-dipole	5-50	Acetone
	Hydrogen bond	4-120	DNA
	Cation-π	5-80	К + in benzene
	π-π	0-50	Benzene and graphite
	Van der Waals	≤5	Alkyl chains
			Inclusion compounds in
	Hydrophobic	Depending on the solvent	cyclodextrines, self-
			organization of proteins

H NMR (CDCl3)  5.57(d, J = 6.4, 4H), 5.33 (d, J = 6.4 Hz, 4H),

2.88 (m, 2H), 2.22 (s, 6H), 1.33 (s, 6H),1.29 (s, 6H).

H NMR (300 MHz, CDCl3)  6.95 (s, 4H), 5.49 (d, J = 6.0 Hz, 4H), 5.23 (d, J = 6.0 Hz, 4H),

2.86 (m, 2H), 2.22 (s, 6H), 1.31 (d, J = 6.9 Hz, 12H).

H-NMR (400 MHz, CDCl3) 8.50 (d, J = 8.1 Hz, 4H), 7.72 (d, J = 8.1 Hz, 4H), 5.68 (d, J = 5.4, 4H), 5.33 (d, J = 5.4 Hz, 4H), 3.06 (sept., J = 3.0 Hz,

2H), 2.42 (s, 6H), 1.57 (d, J = 6.9 Hz, 12H).

H NMR (300 MHz, CDCl3) δ 8.67(d, J = 6.2 Hz,

2HαPy), 7.63(d, J = 8.6 Hz, 2HPh), 7.51 (d, J = 8.6 Hz, 2HPh), 7.47 (d, J = 6.2 Hz, 2HβPy).

H NMR (300 MHz, MeOD) δ 8.40 (d, J = 6.7 Hz, 16H), 7.62 (d, J = 6.7 Hz, 16H), 7.49 (d, J = 8.5 Hz, 16H), 7.28 (s, 8H), 7.23 (s, 8H), 7.17 (d, J = 8.5 Hz, 16H), 5.88 (d, J = 6.0 Hz, 16H), 5.65 (d, J = 6.0 Hz, 16H),

2.87 (m, 4H), 2.16 (s, 24H), 1.37(d, J = 6.9 Hz, 48H).1 H NMR (300 MHz, MeOD/MeNO2 50/50) δ 8.39(d, J = 6.6 Hz, 16H), 7.57 (d, J = 6.6 Hz, 16H), 7.47 (d, J = 8.0 Hz, 16H), 7.22 (ovelap, 32H), 5.83 (m, 16H), 5.61 (d, J = 6.5 Hz, 16H), 2.89 (m, 8H), 2.16 (s, 24H), 1.37 (d, J = 6.9 Hz, 48H). 1 H DOSY NMR (MeOD/MeNO2 50/50) D = 3.16 x 10 -10 m²s -1 . HRMS-ESI-FTICR: m/z calculated: [Ru8TTF2, 5OTf -]3 + : 1671.4091; [Ru8TTF2, 4OTf -]4 + 1216.3187; m/z found: [Ru8TTF2, 5OTf -]3 + : 1671.4093, [Ru8TTF2, 4OTf -]4 + : 1216.3185.

H NMR (300 MHz, CDCl3-d) δ

2.85 (dd, J = 7.6, 6.9 Hz, 4H), 1.70 (h, J = 7.3 Hz, 4H), 1.03 (t, J = 7.3 Hz, 6H).

H NMR (300 MHz, CDCl3) δ 4.74 (d, J = 5.4 Hz, 1H), 3.88 (d, J = 10.6 Hz, 6H),

2.81 (m, 4H), 1.66 (m, 4H), 1.51 -1.14 (m, 12H), 0.89 (t, J = 6.8 Hz, 6H).

H NMR (300 MHz, DMSO-d6) δ 11.64 (t, J =

2.0 Hz, 1H), 9.40 (d, J = 2.0 Hz, 2H).

H NMR (300 MHz, CDCl3) δ 5.97 (s,

2H), 5.03 (d, J = 3.9 Hz, 1H), 3.89 (d, J = 10.5 Hz, 6H). 31 P NMR (122 МHz, CDCl3): 19.99.

H NMR (300 MHz, CDCl3) δ 7.67(d, J = 1.4 Hz,

2H), 7.55 (d, J = 7.9 Hz, 2H), 7.49 (dd, J = 7.9, J = 1.4 Hz, 2H).

H NMR (300 MHz, MeOD) δ 8.04 (d, 8H), 7.74 (s, 4H), 7.47 (d, J =

2.0 Hz, 8H), 7.40 -7.28 (m, 8H), 5.95 (d, J = 4.5 Hz, 8H), 5.78 (d, J = 4.4 Hz, 8H), 3.23 -2.94 (m, 8H), 2.91 -2.81 (m, 4H), 2.23 (s, 12H), 1.82 -1.67 (m, 8H), 1.59 -1.45 (m, 8H), 1.43 -1.31 (m, 40H), 0.94 (t, J = 6.5, 2.6 Hz, 12H). FTICR-HRMS (m/z), [[Ru14L2] 4+ -2TfO -] 2+ : found: 1409.1616, calculated 1409,1663.

H NMR (300 MHz, MeOD) δ 8.04 (d, J = 6.7 Hz, 8H), 7.71 (d, J = 1.5 Hz, 4H), 7.47 (d, J = 6.7 Hz, 8H), 7.36 -7.26 (m, 8H), 5.95 (d, J = 6.2 Hz, 8H), 5.78 (d, J = 6.2 Hz, 8H), 3.17-2.92 (m, 8H),

2.86 (p, J = 6.9 Hz, 4H), 2.24 (s, 12H), 1.77 (hd, J = 7.1, 1.8 Hz, 8H), 1.39 (d, J = 6.9 Hz, 24H),1.11 (t, J = 7.3 Hz, 12H).

H NMR (300 MHz, CDCl3) δ 7.61(d, J = 5.4 Hz,

2H), 7.39(d, J = 5.4 Hz, 2H), 2.61 (s, 12H).[START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (76 MHz, CDCl3) δ 136.[START_REF] Young | Structural design principles for self-assembled coordination polygons and polyhedra[END_REF] 133.76, 127.74, 127.65, 124.99, 124.22, 116.43, calculated 575.8459.

H NMR (300 MHz, CDCl3) δ 8.00(d, J = 5.4 Hz, 1H), 7.93 (d, J = 5.4 Hz, 1H), 7.81 (d, J = 5.4 Hz, 1H), 7.45 (d, J = 5.3 Hz, 1H), 3.01 (t, J = 7.3 Hz, 4H), 1.72 (p, J = 7.3 Hz, 4H), 1.48 (d, J = 7.6 Hz, 4H), 1.38 -1.27 (m, 8H), 0.97 -0.83 (t, J = 6.4 Hz,6H).[START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR(76 MHz, CDCl3) δ 173.31, 149.24, 144.84, 140.43, 137.17, 134.12, 131.91, 131.70, 131.48, 126.10, 125.16, 123.74, 113.24, 37.05, 31.32,

29.75, 29.71, 28.24, 22.55, 14.04. EI-HRMS: found: 538.8510, calculated 538.8740.

Dimethyl (1,3-dithiol-2-yl)phosphonate 20

A chromatography column on a silica gel was performed using ethyl acetate/petroleum ether (1/1) as eluent. The compound 20 was isolated as a colorless oil (1.41 g, 80 %).

Self-assembly AA9

Self-assembly АА9 was obtained as a red powder (9,23 mg, 82%). Crystals suitable for x-ray analysis were obtained by liquid diffusion in NMR tube with acetone/MTBE system.

Dimethyl (4,5-bis(propylthio)-1,3-dithiol-2-yl)phosphonate 17

A chromatography column on a silica gel was performed using ethyl acetate/petroleum ether (1/1) as eluent. The compound 17 was isolated as a brown oil (3,08 g, 78.6 %). 1 H NMR (300 MHz, CDCl3) δ 4.71 (d, J = 5.5 Hz, 1H), 3.88 (d, J = 10.6 Hz, 6H), 2.98 -2.62 (m, 4H), 1.85 -1.58 (m, 5H), 1.01 (t, J = 7. 3 Hz, 7H).

Dimethyl (4,5-bis(methylthio)-1,3-dithiol-2-yl)phosphonate 18

A chromatography column on a silica gel was performed using ethyl acetate/petroleum ether (1/1) as eluent. The compound 18 was isolated as a yellow oil, which solidified in the freezer (4.14 g, 69 %). 1 H NMR (300 MHz, CDCl3) δ 4.73 (d, J = 5.6 Hz, 1H), 3.88 (d, J = 10.6 Hz, 6H), 2.41 (s, 6H).

1,3-dithiol-2-ylium tetrafluoroborate 19

Compound 19 was obtained as a white powder after precipitating with diethyl ether and used without purification (1.71 g, 87 %).

Self-assemblies based on the dithiafulvalene fragment

Self-Assembly AA3

A mixture of ligand 25 (10.00 mg, 14.2 µmol) and Pd(BF4)2(CH3CN)4 (3.16 mg, 7.10 µmol) in DMSO (0.5 mL) was heated at 50°C for 5 min until complete dissolution. Then, ethyl acetate was added and resulting suspension was centrifuged. The residue was washed with diethyl ether and dried under vacuum to give AA3 as a dark red solid (10.5 mg, 80 %). Crystals suitable for analysis were obtained by slow diffusion of ethyl acetate in DMSO (gas-liquid). 1 H NMR (300 MHz, DMSO) δ 9.17 (d, J = 6.7 Hz, 2H), 8.43 (d, J = 8.1 Hz, 1H), 8.23 (s, 1H), 7.98 -7.70 (m, 3H), 3.06 (t, J = 7.0 Hz, 2H), 1.69 -1.52 (m, 2H), 1.40 (s, 2H), 1.32 -1.16 (m, 4H), 0.83 (t, J = 6. 7 Hz, 3H). FTICR-HRMS: found for [[Pd2L4] 4+ , 4BArF --3BArF -] 3+ : 1293.2362, calculated: 1293.2350.

General protocol for self-assemblies АА4-6

A stoichiometric mixture of ligand 25-28 (7.01 mg, 0.01 mol) and Pddppf 1 (9.57 mg, 0.01 mol) in CH2Cl2 (1 mL) was stirred at room temperature for 2 hr at room temperature. Then, Et2O was added, resulting suspension was centrifuged and dried under vacuum to give self-assembly AA4-6 respectively.

Self-assembly AA4

Self-assembly АА4 was obtained as a red powder (14.25 mg, 86%). Crystals suitable for analysis were obtained by slow liquid diffusion CH2Cl2/MTBE in a NMR tube. 1 H NMR (300 MHz, CD2Cl2) ) δ 8. 64 (dd, J = 6.6, 3.0 Hz, 8H), 8.04 -7.82 (m, 20H), 7.77 -7.57 (m, 28H), 7.51 (dd, J = 8.2, 1.6 Hz, 4H), 7.10 (d, J = 5.4 Hz, 8H), 4.83 (d, J = 1.9 Hz, 8H), 4.65 (s, 8H), 2.96 (t, J = 7.3 Hz, 8H), 1.68 (p, J = 7.3 Hz, 8H), 1.43 (p, J = 7.2, 6.6 Hz, 8H), 1.29 (dd, J = 7.3, 3.9 Hz, 16H), 0.86 (t, J = 7.8, 7.0 Hz, 12H). [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (126 MHz, CDCl3) δ 150. 06, 144.93, 137.79, 136.21, 134.89, 134.15, 134.05, 132.84, 130.76, 129.79, 129.70, 127.78, 127.50, 127.04, 123.96, 122.43, 122.33, 119.77, 118.64, 117.22, 99.73, 85.66, 76.83, 76.77, 76.73, 75.35, 75.29, 70.10, 70.06, 69.58, 69.54, 36.55, 31.14, 29.59, 28.02, 22.38, 13.63. FTICR-HRMS (m/z), [[Pd2L2] 4+ -2TfO -] 2+ : found: 1510.1598, calculated 1510.1660.

Self-assembly AA5

Self-assembly АА5 was obtained as a red powder (11.5 mg, 86%). Crystals suitable for analysis were obtained by slow liquid diffusion CH2Cl2/MTBE in a NMR tube. 1 H NMR (300 MHz, CDCl3) δ 8. 74 (dd, J = 6.6, 3.1 Hz, 8H), 7.97 -7.85 (m, 20H), 7.64 (t, J = 6.4 Hz, 28H), 7.46 (dd, J = 8.3, 1.6 Hz, 4H), 7.07 (d, J = 5.7 Hz, 8H)

Self-assembly AA6

Self-assembly АА6 was obtained as a red powder (15.10 mg, 89%). 1 H NMR (499 MHz, CD2Cl2) δ 8.86 (s, 4H), 8.71 (s, 4H), 8.31 (s, 4H), 8.18 -8.07 (m, 8H), 7.97 (dd, J = 12.9, 7.6 Hz, 8H), 7.91 (s, 4H), 7.71 (dd, J = 15.6, 7.7 Hz, 20H), 7.64 (d, J = 8.0 Hz, 4H), 7.52 (dd, J = 20.9, 8.2 Hz, 8H), 7.12 (t, J = 6.9 Hz, 4H), 4.92 (s, 4H), 4.79 (s, 4H), 4.56 (s, 4H), 4.31 (s, 4H)

Self-assembly AA7

Self-assembly АА7 was obtained as a red powder (12.15 mg, 91%). 1 H NMR (300 MHz, CD2Cl2) δ 8.86 (s, 4H), 8.65 (s, 4H), 8.30 (s, 4H), 8.11 (t, J = 10.2 Hz, 8H), 7.95 (d, J = 27.4 Hz, 16H), 7.71 (bs, 20H), 7.63 (d, J = 8.1 Hz, 4H), 7.53 (d, J = 8.4 Hz, 8H), 7.19 -7.03 (m, 4H), 4.94 (s, 4H), 4.77 (s, 5H), 4.57 (s, 7H), 4.33 (s, 4H), 2.95 (t, J = 7.2 Hz, 8H), 1.72 (q, J = 7.2 Hz, 8H), 1.04 (t, J = 7. 3 Hz, 12H). FTICR-HRMS (m/z), [[Pd2L2] 4+ -2TfO -] 2+ : found: 1427.0420, calculated 1426,0779.

General protocol for self-assemblies АА8-12

A stoichiometric mixture of ligand 26 or 28 (0,01 mol) and corresponding acceptor Ru1, Ru3 or Ru4 (0.01 mol) in 2 ml methanol were stirred at 50 0 С overnight solution. Then, Et2O was added, resulting suspension was centrifuged and dried under vacuum to give self-assembly AA8-12 respectively.

Self-assembly AA8

Self-assembly АА8 was obtained as a red powder (9,55 mg, 86%). Crystals suitable for x-ray analysis were obtained by liquid diffusion in NMR tube with acetone/MTBE system.

Self-assembly AA10

Self-assembly АА10 was obtained as a dark-green powder (9,69 mg, 83%). Crystals suitable for x-ray analysis were obtained by liquid diffusion in NMR tube with acetone/MTBE system. 1 H NMR (499 MHz, MeOD) δ 8. 44 (dd, J = 11.3, 6.2 Hz, 8H), 7.45 -7.40 (m, 4H), 7.40 -7.34 (m, 8H), 7.30 (d, J = 5.7 Hz, 4H), 7.26 -7.21 (m, 2H), 7.11 (d, J = 7.9 Hz, 2H), 7.03 (d, J = 7.9 Hz, 2H), 6.90 (s, 2H), 6.58 (d, J = 8.0 Hz, 2H), 5.93 (t, J = 6.7 Hz, 4H), 5.88 (t, J = 5.1 Hz, 4H), 5. 73 -5.68 (m, 4H), 5.65 (dd, J = 6.1, 2.6 Hz, 4H), 2.85 (tdd, J = 36.2, 13.6, 6.7 Hz, 8H), 2.31 (d, J = 7.6 Hz, 4H), 2.20 (s, 6H), 2.12 (s, 6H), 1.56 (p, J = 7.7 Hz, 4H), 1.40 (dd, J = 6.9, 4.4 Hz, 12H), 1.36 (dd, J = 7.0, 5.0 Hz, 12H), 1.27 (dd, J = 9.8, 5.1 Hz, 8H), 1.11 (dd, J = 23.9, 7.6 Hz, 8H), 0.84 (t, J = 6.9 Hz, 12H), 0.61 (d, J = 8.2 Hz, 6H), 0.42 (t, J = 7. 3 Hz, 6H). FTICR-HRMS (m/z), [[Ru14L2] 4+ -2TfO -] 2+ : found: 1509.3691, calculated 1509,1976.

Self-assembly AA11

Self-assembly АА11 was obtained as a dark-green powder (9,58 mg, 82%). Crystals suitable for x-ray analysis were obtained by liquid diffusion in NMR tube with acetone/diisopropyl ether system. 1 H NMR (499 MHz, MeOD) δ 8. 44 -8.41 (m, 4H), 8.38 -8.34 (m, 4H), 7.47 -7.40 (m, 4H) 5.96 (dd, J = 10.5, 6.1 Hz, 4H), 5.89 (dd, J = 6.1, 4.6 Hz, 4H), 5.77 -5.70 (m, 4H), 5.69 -5.62 (m, 4H), 3.06 -2.92 (m, 4H), 2.87 (dt, J = 14.0, 7.2 Hz, 4H), 2.50 (t, J = 7.4 Hz, 4H), 2.24 (s, 6H), 2.12 (s, 6H), 1.65 (ddt, J = 19.7, 14.1, 7.1 Hz, 4H), 1.43 (dd, J = 7.0, 4.8 Hz, 12H), 1.36 (dd, J = 6.9, 5.2 Hz, 12H), 1.04 (t, J = 7.3 Hz, 6H), 0.86 (t, J = 7.3 Hz, 6H).

Self-assembly AA12

Self-assembly АА12 was obtained as a dark-green powder (9.53 mg, 76%). 5.96 -5.87 (m, 8H), 5.76 -5.66 (m, 8H), 2.98 (dt, J = 9.4, 6.8 Hz, 4H), 2.82 (ddt, J = 40.4, 13.7, 7.3 Hz, 4H), 2.09 (s, 6H), 1.59 -1.51 (m, 6H), 1.40 -1.31 (m, 12H), 1.26 -1.20 (m, 6H), 1.12 (t, J = 7.0 Hz, 6H). FTICR-HRMS (m/z), [[Ru14L2] 4+ -2TfO -] 2+ : found: 1609.7412, calculated 1609,2289.

Self-assembly AA13

Self-assembly АА13 was obtained as a dark-green powder (9.21 mg, 79%).

Self-assembly АА14

Ligand exTTF-TEG (100 mg, 0.075 mmol) and PdCl2(CH3CN)2 (39 mg, 0.150 mmol, 2 equiv.) were heated in DMSO (10 mL) for 1 h. Then, the solution was cooled to room temperature and EtOAc was added. The resulting precipitate was centrifuged and washed 3 times with EtOAc, and dried under vacuum to give AA14 Pd12(LTEG)6 (103 mg, 82%) as a dark red solid. 1 H NMR (300 MHz, CDCl3) δ 8.72 (s(br), 48H), 7.04 (72H, m), 4.23 (s(br), 48H), 3.90 (s(br), 48H), 3.74 -3.55 (m, 192H), 3.37 (s, 72H); [START_REF] Pan | Chiral metal-organic cages/containers (MOCs): From structural and stereochemical design to applications[END_REF] C NMR (300 МHz, CDCl3) δ 154. 16, 147.24, 141.42, 128.25, 127.53, 126.04, 125.05, 124.17, 123.89, 112.66, 71.96, 70.92, 70.71, 70.60, 69.71, 69.33, 59. Electrocrystallization allows to obtain single crystals of the oxidized compound for further applications, in our case -for x-ray diffraction analysis. Main principle is based on the slow oxidation or reduction of the electro-active molecule and generation of corresponding charge particle. The later than crystalize with counter-ions, present in solution in order to maintain conductivity.

Experiment is conducted using the standard U-shaped electrochemical cell, with compartments separated with a glass filter in order to prevent mixing and contamination while maintaining conductivity. On order to prevent impurities, cell is washed with a H2SO4/H2O2 mixture, followed by methanol, water, acetone and drying in the oven.

Pt wire with 1mm diameter and approximately ~2 cm length is used, which is also cleaned by an electrolysis in 1М H2SO4 and then washed with water and acetone. In order to obtain crystals of sufficient quality such parameters as concentration of the compound and supporting electrolyte, solvent, temperature and current density can be adjusted.