Mustafa Bulut

Makoto Handa

Catherine Hirel

Dominique Luneau

Emel Önal

MOLECULAR MAGNETIC MATERIALS BASED ON PORPHYRIN MACROCYCLES JURY

Keywords: Porphyrin, molecular magnetic material, nitroxide free radical, EPR, synthesis

The preparation of Molecule-Based Magnets is based on the assembling carriers of magnetic moment. These may be the metal ions only with diamagnetic linkers or the metal ions connected through open-shell organic molecule. The building of novel Molecule-Based Magnets architectures following the metal-radical approach relies on the design of innovative open-shell organic molecular blocks. In this regard, we focus our strategy on the synthesis of porphyrins incorporating free radicals. Indeed, porphyrins compounds are -conjugated systems which should favor spin delocalization and the transmission of the magnetic interactions on the overall macrocycle and further over the all architecture.

Due to their excellent stability in a wide variety of chemical environments, and their abilities to coordinate with transition metal we focus our attention on nitroxide radicals. In this dissertation a series of porpyrin macrocycles were synthesized, bearing tBuNO, nitronyl and imino nitroxide covalently linked to the skeleton. Characterization was done by UV-Vis, Mass and EPR spectroscopy.

Moreover during this work some interesting synthetic intermediates were obtained with good yield and characterize for the first time. This was the case for meso-tetrakis(4-formylphenyl)porphyrin and its corresponding metallated derivatives by Cu(II) and Mn(II). Some novel promising tetrapyrrolic macrocycle precursors bearing nitronyl and imino nitroxides free radicals as 2-(3,4dicyanophenyl)-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl, 2-(3,4dicyanophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and 2-(4-benzaldehyde)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl. To the best of our knowledge, these compounds represent the first example of nitronyl and imino nitroxide substituted porphyrin derivatives that have been unambiguously characterized by spectroscopic techniques.

Anahtar Kelimeler: Porfirin, moleküler manyetik malzeme, nitroksit serbest radikal, EPR, sentez.

scientific matters, for your rigor in editing the manuscripts that we coauthored, and for the enthusiasm with which you helped me pursue my future career steps.

A large group of extraordinary people collaborated to make my doctoral studies a truly enlightening experience. Throughout the years, the Prof Dominique

Luneau and the Prof. Vefa Ahsen groups have been a diverse and stimulating community and it has been a privilege to be part of them.

I would like to thank the other members of my committee, Prof. Makoto Handa, Prof. Mustafa Bulut and Prof. Vefa Ahsen I am indebted to Guillaume Pilet and Prof. Luneau for the critical help for refining the crystal structures of this Dissertation, for giving a chance to the most hopeless crystals and for their friendship.

I would like to thank Dr. Yusuf Yerli and Lhoussain Khrouz for their help with all EPR measurements.

I express my profound thanks to the French Embassy in Ankara for having given me an opportunity to carry out my doctoral work by PHD co-tutelle fellowship.

Finally, I am grateful to my parents and my best friends for always believing in me and for their unconditional support. then p-chloranil, reflux. Hydrolysis: CH2Cl2 /TFA/water (10:1:1), room temp.

3.26:

Synthesis of 5-formyl porphyrin with organosulfur reagent method.

3.27: a)Synthesis of mono or diformyl porphyrin by Vilsmeier Formylation Method, b) Mechanism of Vilsmeier Formylation reaction.

3.28:

Acetal protected formyl group method.

3.29: FT-IR spectrum of tetra formyl porphyrin ATPP.

3.30:

The UV-Vis spectrum of tetra formyl porphyrin ATPP 1.10 -6 M in CHCl3.

3.31:

1 H NMR spectrum of tetra formyl porphyrin ATPP in CDCl3.

3.32: HR-ESI Mass spectrum of tetra formyl porphyrin ATPP.

3.33:

Condensation and oxidation reactions.

3.34:

The UV-Vis spectrum of Nitronyl nitroxide substituted porphyrin (2)

1.10 -6 M in CHCl3.

3.35:

Reconvertion of imino nitroxide to nitronyl nitroxide.

3.36:

Synthesis of imino nitroxide substituted porphyrin 3.

3.37

Synthetic strategy for imino nitroxide radical substituted porphyrin.

3.38:

FT-IR spectrum of imino nitroxides 10 and 11.

3.39:

Proposed fragmentation mechanism of nitronyl nitroxide 9.

3.40:

Proposed fragmentation mechanism of imino nitroxide 10.

3.41:

ESI mass spectrum of imino nitroxide 10.

3.42:

The UV-Vis spectrum of imino nitroxide substituted porphyrin (IMIP) 1.10 -6 M in CHCl3.

3.43: Synthesis of AB3BrP.

3.44:

Synthesis of molecule 4.

3.45:

Synthesis of AB3AP.

3.46:

IR spectra of AB3BrP and AB3AP.

3.47: MALDI-MS spectrum of AB3AP porphyrin.

3.48:

1 HNM spectrum of AB3AP porphyrin obtained in CDCl3.

3.49:

Synthesis of molecule 5 and 6.

3.50

Synthesis of metallated porphyrins.

3.51: MALDI-MS spectra of ATPPCu(II) and TBrPPCu(II). 4.17: Molecular structure of ATPPCu(II).

4.18:

Molecular structure of ATPPCu(II).

4.19:

Molecular structure of 1.

4.20:

Molecular structure of 2.

4.21:

Molecular structure of 3.

4.22:

Molecular structure of 4.

4.23:

Molecular structure of 6.

xviii

LIST of TABLES

2.2:

Nuclear spin values for some common element.

3.1:

Solvent studies for solubility problem of porphyrin.

3.2:

Temperature studies for synthesis of in Diethyl ether.

3.3:

Different equivalent studies of n-BuLi for synthesis of tBuNOP in Diethyl ether.

3.4:

Uv-Vis spectra data of TBrPP and tBuNO substituted porphyrins fraction A and B in CHCl3.

3.5:

Different reaction conditions for ATPP.

3.6:

Acidic conditions for synthesis of 8.

3.7:

UV-Vis spectrum of ATPP and molecule 2 1.10-6 M in CHCl3.

3.8:

Uv-Vis spectra data of ATPP and IMIP in CHCl3.

3.9: Uv-Vis spectra data of AB3BrP and Molecule 4 in CHCl3.

3.10:

The UV-Vis spectra data of AB3A, Molecule 5 and 6 radical 1.10 -6 M in CHCl3.

3.11:

The UV-Vis spectra data of TBrPP, TBrPPCu(II), TBrPPMn(III), ATPP, ATPPCu(II) and ATPPMn(III) 1.10 -6 M in CHCl3.

INTRODUCTION 1.The outline of the thesis

The intention of the thesis was construction of novel bricks for molecular magnets in solid state. All the dedicated efforts were focused on synthesis, structural and magnetic studies of porphyrin macrocycles including different spin carriers at the periphery, preferentially nitroxide free radicals and also metal ions. The biggest challenge was building organic spin carrying ligands such as tBuNO, nitronyl and imino nitroxide free radicals on targeted porphyrin derivatives with multi step synthesis work. This principally essential work based on radical-radical interaction approach;

In solid state, crystal phase very important for magnetic behaviour and for organic compounds design of solid state structure is not easy because of crystal packing based on weak bonds like hydrogen bond or Wan Der Waals interactions.

Porphyrin macrocycles were great choice because of their highly polarizableconjugated system that will favor the spin delocalization all over the molecule skeleton favoring the spin coupling between the radical-radical and the metal-radical interaction. As a spin carriers tBuNO nitroxide, imino nitroxide and nitronyl nitroxide free radicals were chosen because of their high stability, solubility, exhibiting structural versatility and multifunctionality among the building blocks in literature. According the radical-radical interaction approach it was necessary to combining of spin carrier nitroxide stable free radical on highly polarizableconjugated porphyrin system. For this aim the biggest challenge was synthesis of meso-tetrakis(4-formylpenyl)porphyrin which was the key intermediated molecule for creation of nitronyl and imino nitroxide substituted porphyrins. To compare the contribution of different number nitroxide radicals on porphyrin macrocyle for the high spin magnetic material, it was necessary to start to synthesis tetra radicals( targeted molecules 1, 2, 3) which is the maximum number for meso-pistion on porphyrin macrocyle and also mono radical substituted porphyrins ( molecule 4, 5, 6)

which will help to understand the spin contribution to magnetic behaviour.

In addition, obtaining well-resolved ESR spectra with isotropic proton hyperfine structure were necessary to understand of the type of the radicals if they are tBuNO, nitronyl or imino nitroxide free radicals and also to control the number of the radical on the porphyrin macrocyles.

Using crystal engineering as a tool to prove structural characterization, it was challenging to obtain single crystals X-ray structures of maximum number of molecules. Good magneto-structural correlation was necessary in order to find an explanation for the different magnetic behaviors. This had to be done by correlating solution ESR data and the bulk magnetic susceptibility data with the crystal structures.

BIBLIOGRAPHY

Porphyrins

General Background

Porphyrins are a large class of deeply colored compounds that is one of the most exiting stimulating and rewarding research are for scientists in the files of chemistry, physics, biology and medicine. They owe their bright colors to intense absorptions in the near ultraviolet and visible regions. Porphyrins have been described as "the pigments of life" because they perform a variety of fundamental biological functions that lie at the very core of life as we understand it [START_REF] Milgrom | The Colours of Life: An Introduction to the Chemistry of Porphyrins and Related Compounds[END_REF]. The word porphyrin is actually derived from the Greek word for purple, porphura.

The best-known natural porphyrin is probably the heme cofactor (iron porphyrin), which is responsible for O 2 -transport and storage (as hemoglobin and Although far from complete, this introduction aims to highlight the diversity of the available meso-porphyrin ligands and the principal advances in the field over the past decades. It is hoped that this chapter will provide a useful underpinning for the research work reported by the author in the ensuing chapters of this Dissertation and it will allow the readers to obtain a glimpse into the meso-porphyrin chemistry that remains to be explored.

meso-Substituted Porphyrins

Synthesis of porphyrins involves the arrangement of diverse susbtituents in specific patterns about the periphery of the macrocycle. synthetic control over the molecular entities attached at the porphyrin periphery enables porphyrins to be designed and tailored for specific applications. The -substituted porphyrins closely resemble naturally occuring porphyrins. The meso-substituted porphyrins have no direct biological counterparts but have found wide application in material chemistry.

The popularity of meso-susbtituted porphyrins comes from their easy synthesis. Oneflask synthetic methods can be used to prepare a meso-substituted porphyrin from an aldehyde and pyrrole. The wide availability and ease of manipulation of aldehydes enables diverse porphyrins to construct without extensive multistep synthesis of precursors. The substituents at the meso-positions can include alkyl, aryl, heterocyclic or organometalic groups, as well as other porphyrins. In particul mesosubstituted tetraarylporphyrins provide versatil building blocks for creating 3-D architectures that incorporate porphyrins. The challenge of creating more refine structures leaded to development of variaty of methods for meso-substitution. the best known synthetic methods for meso-substituted porphyrins were summarized below.

P. Rothemund Method

Meso-substituted porphins have been synthesized by the method, using pyrrole and one of the following aldehydes: formaldehyde, acetaldehyde , propionaldehyde, nbutyraldehyde, benzaldehyde and a-furaldehyde in methanol, pyridine, one-flask reaction in slead vessel in 1935-1936. In most of his work, careful examination of each reaction product showed the presence of a second porphyrinic substance at the 10-20 % level which was isalated by chromatography and shown to be chlorin. The chlorin can be converted by oxidation to the corresponding porphyrin [START_REF] Aronoff | The porphyrin-like products of the reaction of pyrrole with benzaldehyde[END_REF]- [4]. In a summary for fetures of Ruthemund method reactions were at high concentartion and high temeperature in a sealed vessel in an absense of an added oxidant [START_REF] Rothemund | Formation of porphyrins from pyrrole and aldehydes[END_REF], [START_REF] Rothemund | A New Porphyrin Synthesis[END_REF].

Lindsey Method

A one-step synthesis of porphyrins has been investigated where aldehyde, pyrrole, acid catalyst, and oxidant are present simultaneously. Also the room-temperature synthesis of meso-porphyrins has been investigated at aldehyde and pyrrole, using the two-step process of acid-catalyzed condensation followed by quinone [START_REF] Maccrum | Investigation of a Synthesis of meso-Porphyrins Employing High Concentration Conditions and an Electron Transport Chain for Aerobic Oxidation[END_REF], [START_REF] Lindsey | Synthetic Routes to meso-Patterned Porphyrins[END_REF]. For the comparison of One-flask synthetic methods for preparing porphyrins some generalisation can be conserned wieved in Table 2.1. Following wonderful explanation in the Porphyrin Handbook [START_REF] Kadish | Synthesis and Organic Chemistry[END_REF] one can have genaral picture of the conditions employed in different methods. From Table 2.1 it is clear that the Rothemund method does not have any avantages.

The Adler method is prevailing method for synthesizing porphyrins for preparative scale from stable aldehydes. The limitaion of this method ; refluxing propionic acid condition is can be very strong condition for not stable aldehydes, many 2,6-disusbtituted aryl aldehydes, some aliphatic aldehydes and some of aldehydes do not crystalize from propionic acid. But also quick and easy crystalisation leaded 20 % reaction yield makes this method attractive.

The Lindsey method has the strongest reaction conditions but brodest scope of application. The yields are gerally higher than Adler method. The best part of the method is very sensitive aldehydes can be used in this method. the disavantage of the method is for the reaction from 0.01M to 0.1M requries and removal of large amount of solvent. During this dissertation work chiefly Adler method was used.

Literature Survey of Nitroxides Directly Substituted to

Porphyrin

In the area of purely organic materials, radicals are still under active investigation. Among the radicals Nitroxides are the most well-known class of stable radicals. The molecular skeleton of these stable neutral free radicals has two importants features i) the good stabilization of the spin and ii) the modulation and Kamachi et al [START_REF] Kamachi | Synthesis of New Polymers Containing Porphyrins in Their Side Chains: Radical Polymerizations of 5-[ 4-(Acryloyloxy) phenyl] -10,15,2Otriphenylporphyrin and 5-[ 4-(Met hacryloyloxy)phenyl] -10,15,20-trip henylporphyrin[END_REF]reported polymers of acrylate and methacrylate containing paramagnetic piperadinyloxyl and verdazyl side chain groups on porphyrin rings to demonstrate a magnetic ordering of the paramagnetic species through an exchange interaction of unpaired electrons is possible in the polymers. For this reason they used stable macrocycle porphyrins as a spin carrier konjuge system. A polymer effect on the magnetic ordering was found in those systems, but the exchange interactions between these organic radicals were too weak for the polymers to function as magnetic materials.

The coordination chemistry approach is essential in the file of molecular-based magnets. Shultz prepared free radical substituted Zn porphyrins for construction of coordination polymers. The phenylnitroxide radical is attached to the meso-position of three porphyrins: directly through a single bond ; through an ethenyl group and through an ethynyl group to investigate conjugative effectiveness of the fragment that links the porphyrin because the aryl group is critical for sufficient spin-spin communication. Functionalized porphyrins are now relatively easily accessible and well studied compounds. Especially, their ease of functionalization is of particular interest as it has been clearly demonstrated that tailoring the nature of the substituent or the central metallic ion allows fine-tuning the properties of these metalloligands.

Particularly, since the 1990s, many attempts have been reported in order to build up open coordination frameworks based on linkers derived from porphyrins. Thank to porphyrin chemistry richness, there are numerous work extensively explored for their numerous applications in molecular devices and molecular magnets is one of the promising area. Although many works in this field, researches in the literature for molecular magnetic materials shows the lack of new molecular building blocks and the sufficiency of the metal-radical approach. in this situation our study proposes the synthesis of porphyrins decorated with free nitroxide radicals as a novel building blocks which may be used for the building of molecule-based magnets (MBM) or in single-molecule magnets (SMM).

Nitroxide Free Radicals

Stable Radicals

There are many scientific work in chemistry of systems containing stable organic radicals because many kinds of radicals are stable enough to isolate, can be stored without any special technique and can be used effectively. They have one less bond than expected based on simple valency considerations. They are highly reactive that dimerization, hydrogen abstraction, disproportionation reaction can occur with little to no activation barrier. Many radicals exist with unpaired electrons that have sufficiently long lifetimes to be observed by conventional spectroscopic methods and some of them can be isolated as pure compounds, and a few of these are even unreactive to air and water. In chemistry there are many areas that use advantage of specific combination of open-shell configuration and chemical stability.

For example, stable radicals have been used for a long time to obtain structural, dynamic, and reactivity information using electron paramagnetic resonance (EPR) spectroscopy and spin labelling [START_REF] Berliner | Spin Labelling: Theory and Applications[END_REF] and spin trapping [START_REF] Perkins | Spin Trapping[END_REF]- [START_REF] Bowry | Kinetics of Nitroxide Radical Trapping. 2. Structural Effects[END_REF]. More recently EPR imaging [START_REF] Zweier | Electron paramagnetic resonance measurements of free radicals in the intact beating heart: a technique for detection and characterization of free radicals in whole biological tissues[END_REF] is very useful technique to get definite information from the systems that include stable radicals. Magnetism and conductivity are another technological area that many efforts aimed for developing new materials with relevant properties and stable radicals are excellent building blocks simply by virtue of having unpaired electrons [START_REF] Rajca | Organic Diradicais and Poiyradicais: From Spin Coupling to Magnetism?[END_REF], [START_REF] Rawson | Thiazyl radicals: old materials for new molecular devices[END_REF].

Another good reason to work with stable radical is their rich chemistry which is much more selective and controllable nature than the reactivity of reactive radicals.

They are widely used as (co)catalysts for the oxidation of alcohols to carbonyl compounds [START_REF] Zimmer | Oxidation with potassium nitrosodisulfanate(Fremy's radical). The Teuber reaction[END_REF]- [START_REF] Sheldon | Green, Catalytic Oxidations of Alcohols[END_REF]. Their transition metal coordination chemistry is an active area of interest to inorganic chemists for three decades [START_REF] Kaim | The transition metal coordination chemistry of anion radicals[END_REF]- [START_REF] Chaudhuri | Progress in Inorganic Chemistry[END_REF] Radical reactions are implicated in a huge range of biological processes, and stable radicals are often key players from simple inorganic radicals such as NO and O2 to tyrosyl [START_REF] Stubbe | Protein Radicals in Enzyme Catalysis[END_REF], [START_REF] Stubbe | Radicals with a controlled lifestyle[END_REF] based radicals. Triphenylmethyl discovery was the beginning of organic free radical chemistry [START_REF] Gomberg | An instance of trivalent carbon: triphenyl-methyl[END_REF] phenalenyl [START_REF] Stubbe | Radicals with a controlled lifestyle[END_REF] and Phenoxyls [START_REF] Rajca | P oly(arylmethyl) quartet triradicals and quintet tetraradicals[END_REF]- [START_REF] Rajca | A Polyarylmethyl Quintet Tetraradical[END_REF] are still venerable stable radicals in class of hdyrocarbon-based radicals.

Nitroxides

A considerably portion of spin density of many stable radicals on nitrogen and/or oxygen. Simple inorganic radicals such as O2, NO, and NO2 can be viewed as prototypes of the many different organomain group radicals [START_REF] Hicks | What's new in stable radical chemistry?[END_REF]. Among stable radicals Nitroxide chemistry has a long and rich history, and there are many derivatives which are stable with respect to air, water, dimerization, and other radical-involving reactions. The versatility of these radicals is further enhanced by the fact that a fairly diverse range of organic chemistry can be carried out on remote sites of molecules carrying a nitroxide group without affecting the radical site itself.

In coordination chemistry studies aimed at synthesizing new magnetic materials, metal-radical interaction must not result in diamagnetic compounds and it is generally achieved by control of redox potential through appropriate chosen susbtituents. for this aim among the bridging ligands, such as nitronyl-(2a) and imino-(2b) nitroxides [START_REF] Ullmann | Unsaturated Cyclopropanes. III Synthesis and Properties of Alkylidenecyclopropanes and Spiropentanes[END_REF]- [START_REF] Ullmann | Stable Free Radicals. VIII. New Imino, Amidino, and Carbamoyl Nitroxides[END_REF] and polynitroxides, where nitroxyl groups are msubstituents of a phenyl ring (2e) are particularly attractive [START_REF] Calder | Nitroxide Radicals. V. N,N'-Di-t-butyl-m-phenylenebinitroxidea, S table Triplet[END_REF]- [START_REF] Inoue | Spontaneous Magnetization in a 2:3 Complex Formed by 3,4',5-Tris(N-oxy-tertbuty1amino) biphenyl and Manganese(II)-bis(hexafluoroacety1acetonate[END_REF]. They all possess several oxyl groups and unsaturated structures allowing correlation of the unpaired spin density over the different coordination sites. Toward molecular magnets, they are the keystone of the metal-radical approach [START_REF] Caneschi | Progress in Inorganic Chemistry[END_REF], [START_REF] Caneschi | Toward Molecular Magnets: The Metal-Radical Approach[END_REF], [START_REF] Miller | Magnetism: Molecules to Materials II[END_REF]. To control the intermolecular exchange interactions and the resultant magnetic behavior of the compounds, one should be able to arrange molecules in a predictable fashion. Therefore, much interest in the field of organic-based magnetic materials was focused on studying the magneto-structural correlations and finding the way to adjust them.

The oxygen atom of the nitroxide group exhibits weak basicity; therefore, it demonstrates coordinating ability with respect to transition metal ions, which allows assembling metal ions and nitroxide radicals in low dimensional materials in order to obtain bulk magnets [START_REF] Caneschi | Magnetic Materials Formed by Metal Ions and Nitroxides[END_REF]- [START_REF] Caneschi | Structure and Magnetic Properties of Two Bis(nitrony1 nitroxide) Adducts of Bis(hexafluoroacetylacetonato)manganese(II). Molecular Orbital Interpretation of the Coupling in Manganese-Nitroxide Complexes[END_REF]. Iwamura has described tert-butyl nitroxide radicals functionalized pyridines and imidazoles (Figure 2.13), which were used for the preparation of a number of metal complexes [START_REF] Kitano | Exchange Interaction in Metal-Radical Systems: Chloro(meso-tetraphenyl porphyri nato)chromium(III)'s and (Hexafluoroacetylacetonato)manganese(II) Ligated with 3-and 4-(N-Oxy-N-tert-butylamino)pyridines[END_REF], [START_REF] Ishimaru | Regiospecificity in the Exchange Coupling of the Spins of Copper(II) Ion Coordinated with the Ring Nitrogen Atoms and N-tert-Butylaminoxyl Radical Attached as a Substituent on the Pyridine and N-Phenylimidazole Rings[END_REF].

Figure 2. 13:Some tert-butyl nitroxide radicals.

Nitronyl Nitroxide

The first report of a nitronyl nitroxide appared in 1968 and most of these free radicals have been described by Ullman and co-workers [START_REF] Osiecki | Studies of Free Radicals. I. a-Nitronyl Nitroxides, a New Class of Stable Radicals[END_REF]. The fundamental aspects of their electronic structure are well-established [START_REF] Perkins | Spin Trapping[END_REF]. These radicals incorporate the necessary features for stability (e.g., no -hydrogens) typical for nitroxides, and can thus be made with a wide variety of R groups. The stability of nitronyl nitroxides generally rivals the most stable examples of nitroxides. The spin distribution is symmetrically disposed about the two NO groups and is only slightly affected by the substituent R. In rich nitronyl niroxide chemistry history, the versatility of these radicals was further enhanced by Rey has developed the synthesis of pyrimidinyl nitronyl nitroxides [START_REF] Brough | A versatile synthesis of new pyrimidinyl nitronyl nitroxides[END_REF], [START_REF] Brough | Pyrimidinyl Nitronyl Nitroxides[END_REF] whose electronic structures are generally quite similar to those of the more familiar imidazolinebased nitronyl nitroxides. The reaction yield vary widely depending on the susbtitutent R. In addition, the preparation of bulk quantities of nitroxides is limited by the avability of the starting bis(hyrdroxylamino) compound. Although this chemical is commercialy available as the sulfate, it very often contains inorganic salts and it is expensive. The bis(hydroxylamino) derivative BHA is prepared by reduction of 2,3-dimethyl-2,3dinitrobuthane; it is surprisingly volatile and removal of the solvents causes loss of most of the product. Better yields can be obtained by using the free base, the synthetic pathway is reported by different scientist with different optimization of the reaction [START_REF] Hirel | Nitronyl and Imino Nitroxides: Improvement of Ullman's Procedure and Report on a New Efficient Synthetic Route[END_REF], [START_REF] Shimono | Preparation and Characterization of New Chiral Nitronyl Nitroxides Bearing a Stereogenic Center in the Imidazolyl Framework[END_REF].

The nitronyl nitroxides must be kept in the dark and at low temperature with this way they are stable for months. The stability of the nitroxides has been accounted for by the presence of inactive groups attached to the nitrogen atom. Thus the Tempo and Proxyl radicals bear methyl groups on the -carbon atoms; the presence of a hydrogen atom would lead to disproportionation to the corresponding hydroxylamine and nitrone. In the case of the nitronyl nitroxide radicals, the nitronyl group confers the required inactivity. It is also likely that the conjugation of the two NO groups contributes to observed stability of these free radicals.

In coordination chemistry the most importance part of these radicals is having two equivalent donor sites on radical. Their powerful characterization by EPR spectra exhibit identical hyperfine couplings for two equivalent nitrogen atoms.

Nitronyl nitroxide and imino nitroxide they both bear several oxyl groups and unsaturated structures allowing correlation of the unpaired spin density over the different coordination sites.

Since magnetism is a bulk property spin carrying ligands, such as nitronyl-(NIT) and imino-(IMI) nitroxides, are particularly attractive [START_REF] Luneau | N-Bonded Copper(I1)-Imino Nitroxide Complexes Exhibiting Large Ferromagnetic Interactions[END_REF], [START_REF] Oshio | Assembly of imino nitroxides with Ag(I) and Cu(I) ions[END_REF] As chemical structure point of view, in the nitronyl nitroxides the sites of coordination are less hindered than in nitroxides. Furthermore, modification of coordination ability can be diversified by crowding.

From the magnetic point of view, due to their bridging properties and wellestablished antiferromagnetic coupling, most nitronyl nitroxide-metal complexes exhibit ferromagnetic-alternating chains [START_REF] Fegy | 1D Manganese(II) Derivatives of an Imidazole-Substituted Nitronyl Nitroxide. An Approach toward Molecular Magnetic Materials of High Dimensionality[END_REF], [START_REF] Caneschi | Structure and Magnetic Properties of Ferrimagnetic Chains Formed by Manganese(II) and Nitronyl Nitroxides[END_REF]- [START_REF] Caneschi | Magnetic Coupling in Zero-and One-Dimensional Magnetic Systems Formed by Nickel(II) and Nitronyl Nitroxides. Magnetic Phase Transition of a Ferrimagnetic Chain[END_REF] the discrete [Mn(II)(hfac)2NITPh]6 ring shown in Figure 2.17 [START_REF] Caneschi | Preparation, Crystal Structure, and Magnetic Properties of an Oligonuclear Complex with 12 Coupled Spins and an S = 12 Ground State[END_REF] a good example for discrite high spin molecules as ferrimagnetic rings. Note that free radicals, thanks to direct coordination of spin density rich donor atoms to metal ions, are well suited for giving large exchange interactions and very robust high-spin ground states. Despite the large S value, the compound behaves as a paramagnet throughout the temperature range.

Figure 2.17: Molecular structure of the cyclic [Mn(hfac)2NNPh]6 complex.

Imino Nitroxides

Imino nitroxides are similar with nitronyl nitroxides since both have one unpaired electron delocalized on two coordination sites but their coordination properties are different. Generally they have higher stability compared to the corresponding nitronyls [START_REF] Gronowitz | On the two isomeric tris(perchlorothienyl)methyl radicals[END_REF].

EPR spectroscopy, neutron diffraction, and computational studies indicate that spin on the nitroxide nitrogen is substantially larger than on the imino nitrogen, though the latter nitrogen does possess substantial spin density [START_REF] Stroh | Synthesis, structure and properties of benzoic acids bearing para-or meta-imino nitroxides or ortho-nitronyl nitroxide radical centres[END_REF], [START_REF] Zheludev | An imino nitroxide free radical: experimental and theoretical spin density and electronic structure[END_REF].

Coordination through the oxyl fragment leads antiferromagnetic interactions like for nitronyl nitroxides but some rare-earth ions and axial coordination to Cu(II) results ferromagnetic coupling with selected metal ions (Cu, Ni and Co) [START_REF] Luneau | N-Bonded Copper(I1)-Imino Nitroxide Complexes Exhibiting Large Ferromagnetic Interactions[END_REF], [START_REF] Luneau | Ferromagnetic Behavior of Nickel(II)-Imino Nitroxide Derivatives[END_REF]. The first high-spin molecule (S = 5/2) including imino nitroxides is a copper complex [START_REF] Luneau | N-Bonded Copper(I1)-Imino Nitroxide Complexes Exhibiting Large Ferromagnetic Interactions[END_REF] (Figure 2.18). It was reported that for the first time that copper-imino nitroxide interactions were ferromagnetic and large. Coupling of the two terminal metal ions through the imino nitrogen of the free radical is large (J > +200 cm 1 ) and the central ion is also ferromagnetically coupled weakly (J = +10 cm 1 ). It was a good example for to show that imino nitroxides can be used for designing high-spin species. As conclusion we can say that nitronyl and imino nitroxides are the cornerstones of the metal-radical approach toward molecular magnets [START_REF] Caneschi | Progress in Inorganic Chemistry[END_REF], [START_REF] Caneschi | Toward Molecular Magnets: The Metal-Radical Approach[END_REF].

Essential of Magnetism

Magnetism

Magnets play a crucial role in a modern life; as we know, a vast number of devices are employed in the electromagnetic industry. In ancient times human beings experienced magnetic phenomena by utilizing natural iron minerals, especially magnetite. It was not until modern times that magnetic phenomena were appreciated from the standpoint of electromagnetics, to which many physicists such as Oersted and Faraday made a great contribution. In particular, Ampère explained magnetic materials in 1822, based on a small circular electric current. This was the first explanation of a molecular magnet. Furthermore, Ampère's circuital law introduced the concept of a magnetic moment or magnetic dipoles, similar to electric dipoles. The true understanding of the origin of magnetism, however, has come with quantum mechanics, newly born in the twentieth century. Before the birth of quantum mechanics vast amounts of data concerning the magnetic properties of materials were accumulated, and a thoroughly logical classification was achieved by observing the response of every material to a magnetic field. These experiments were undertaken using magnetic balances invented by Gouy and Faraday. The principle of magnetic measurement is depicted in Figure 2.19, in which the balance measures the force exerted on the materials in a magnetic field. In general, all materials are classified into two categories, diamagnetic and paramagnetic substances, depending on the directions of the force. The former tend to exclude the magnetic field from their interior, thus being expelled effect in the experiments of Figure 2.19. On the other hand, some materials are attracted by the magnetic field. This difference between diamagnetic and paramagnetic substances is caused by the absence or presence of the magnetic moments that some materials possess in atoms, ions, or molecules. Curie made a notable contribution to experiments, and was honored with Curie' s law (1895). Our understanding of magnetism was further extended by Weiss, leading to antiferromagnetism and ferromagnetism, which imply different magnetic interactions of magnetic moments with antiparallel and parallel configurations. These characteristics are involved in the Curie -Weiss law.

Macroscopic electromagnetic phenomena are depicted in

There are five main magnetic states of matter [START_REF] Kettle | Physical Inorganic Chemistry -A Coordination ChemistryApproach[END_REF]. In a diamagnetic material all of the electron spins are paired and so the overall net spin is zero. This results in a weak repulsion to an applied magnetic field. All atomic and molecular compounds exhibit diamagnetic behavior to some extent. A paramagnetic material has an attraction to an applied magnetic field due to interaction of the external field with one or more unpaired electrons within the material. The interaction between paramagnetic atoms or molecules with their surrounding neighbors gives rise to the bulk magnetic properties of the material (Figure 2.20). In the case of paramagnetism each unpaired electron has no effect on any other electrons in its neighbors and so the spins are in random directions. The spins can be easily changed to a uniform direction by application of an external magnetic field. Ferromagnetism occurs when adjacent spins are aligned parallel and in the same direction, which results in a large net magnetic moment, even with no applied field. Antiferromagnetism occurs when the spins are parallel but face in opposite directions, which leads to a cancelling of the spins and hence a zero magnetic moment. A special case of antiferromagnetic behavior results in the last main class, ferrimagnetism. Here the spins are still aligned in an antiparallel arrangement, but the spins in each direction are of different magnitudes and so the substance has an overall magnetic moment. Where M is the magnetization (magnetic moment per unit volume) and H is the magnetic field strength. is dimensionless. The molar susceptibility [ M] of a paramagnetic substance is proportional to the thermodynamic temperature [T], i.e.

M= C/T (2.2)

where C is the Curie constant, which is given by,

C = NA 2 g 2 S (S+1)/ 3KB or C = 0.125 g 2 S(S+1) cm 3 K /mol -1 (2.3)
where NA is Avogadro's number, KB is Boltzmann constant, is a constant unit called the Bohr magneton (BM). The Curie constant provides the convenient check of the spin concentration of the sample (C = 0.375 emu K/mol for S = ½). A modification of the Curie law, which takes into account the interactions among the individual magnetic moments, is the Curie-Weiss law. It states that,

M= C/(T -) (2.4)
where is the Weiss constant in temperature units, a characteristic of the material. It relates the total dipole-dipole exchange interactions [J] of magnetically active centers with all its magnetic neighbors z (nearest, next nearest, etc.).

= [2S( S +1) / 3 ] zi Ji (2.5)
When the spins coupled in a parallel manner is enhanced i.e. > 0

[ferromagnetic], and when the spins are coupled in antiparallel manner is

suppressed i.e. < 0 [antiferromagnetic]. M= NA 2g2 S (S+1)/ 3KB (T-) (2.6)
In substances with interacting magnetic moments and where the orbital contribution to the magnetic moment is significant, the molar susceptibility is given by,

M= NA 2g2 J (J+1)/ 3KB (T-) (2.7)
Here the resultant total angular momentum [J] is given by, If the substance is diamagnetic containing only spin-paired electrons the magnetic response opposes the applied field and is small and negative. In a paramagnetic substance, i.e. one that contains unpaired electrons the normally randomized spin moments aligns with the external magnetic field. Here the density of the magnetic lines of force within the sample is intensified giving small but positive , independent of the magnetic field intensity, and decreases with increase in temperature. In a ferromagnetic substance, the spins are spontaneously parallel to one another in microscopic domains leading to a permanent magnetization. The application of a magnetic field causes the domains to point along the field even when the field is removed. The is large and positive, dependent on the magnetic field, temperature, and the history of the sample. The related phenomenon, antiferromagnetism occurs when neighboring, equal spin moments couple in an antiparallel fashion, leading to a lowering of the magnetization, while ferrimagnetism occurs when unequal spin moments couple in a way to leave a net magnetization.

J(J+1) = L(L+1) + S(S+1) (2.
Ferro-, antiferro-, and ferrimagnetic materials often show a hysteresis, which is an irreversibility of the magnetic behavior as the applied magnetic field is changed (see Figure 2.22). Although ferromagnets, below Tc exhibit long-range ordering of spins, a sample may still not behave like a magnet, unless this ordering occurs within "domains". The domain themselves are randomly oriented and cancel each other out, however application of magnetic field will magnetize the sample. When the field is turned off, the magnetization curve shows hysteresis and the sample retains some magnetization. The amount of magnetization the sample retains at zero driving field is called remanence. It must be driven back to zero by a field in the opposite direction; the amount of reverse driving field required to demagnetize it is called coercivity. If an alternating magnetic field is applied to the material, its magnetization will trace out a loop called hysteresis loop. The area of the hysteresis loop is related to the amount of energy dissipation upon reversal of the field. It is important to emphasize that highly magnetic behavior is not a property of an isolated molecule. It is a cooperative solid-state (bulk) property. This can be achieved through strong intermolecular interactions in 3-D space. The magnetic susceptibility can be measured using Faraday-type balance or Super conducting quantum interference device -SQUID susceptometer down to liquid helium temperature.

Today the greatest challenge in the field of magnetic materials research remains in the design and synthesis of ferromagnets. Many strategies have currently been followed towards molecular magnets, 1) the pure organic approach with spin carrying molecules, 2) the organic-inorganic hybrid approach and 3) the single molecular magnets (SMMs).

Organic Magnets

Atoms in organic molecules are held together with covalent bonds consisting of electron pairs with anti-parallel electron spins. Typical organic materials are diamagnetic for this reason. There are, however, exceptional species, so-called free radicals, which carry an unpaired electron. Most radicals are very reactive and mainly play a role as intermediates in chemical transformation. Fortunately, stable radicals do exist, and these species enable the investigation of possible electron spinspin interactions in organic magnetic materials. In the area of molecular magnetism, purely organic materials based on radicals are still under active investigation.

Therefore, magnets with multiple properties can be synthesized (i.e. plastic magnets). These molecular compounds will have no presence of metal ions, but rather rely solely on electron spins residing only in the s and p orbitals. They must also maintain long range order of spins in at least two dimensions to produce The unpaired electron is delocalized mainly between nitrogen and oxygen and between both N-O groups, it is stabilized by protecting the radical center with geminal dimethyl groups. These methyl groups also prevent NIT from becoming dinitrone [START_REF] Ullmann | Studies of Stable Free Radicals. X.' Nitronyl Nitroxide Monoradicals and Biradicals as Possible Small Molecule Spin Labels[END_REF], [START_REF] Osiecki | Studies of Free Radicals. I. a-Nitronyl Nitroxides, a New Class of Stable Radicals[END_REF]. Nitroxide radicals have an inherently stable electronic configuration and can be further stabilized by conjugation with electrons of aromatic systems and/or by shielding with bulky substituents. The SOMOs of the mononitroxides (NO) are localized mainly on the N-O moiety and the unpaired electron mainly resides there. The general strategy for designing nitroxide containing magnetic materials has been to prepare molecules with large intermolecular spin polarizations, and to minimize the intermolecular overlap integrals between the SOMOs of adjacent radical centers, and the vacant or doubly occupied molecular orbital of neighboring molecules. Each radical unit has its merits and demerits.

Amongst the radicals units mentioned above NIT, IN, NO, VZ are stable spin carrying units at ambient conditions. Many molecules have been synthesized based on NIT, IN, NO radicals due to their synthesis, purification and characterization advantages in presence of oxygen [START_REF] Ullmann | Studies of Stable Free Radicals. X.' Nitronyl Nitroxide Monoradicals and Biradicals as Possible Small Molecule Spin Labels[END_REF], [START_REF] Osiecki | Studies of Free Radicals. I. a-Nitronyl Nitroxides, a New Class of Stable Radicals[END_REF].

The first pure organic based magnet was reported in 1991 by Kinoshita and

Single Molecule Magnets

A Single Molecule Magnet (SMM) consists of a central large spin metal-oxo core, which is surrounded by organic ligands to form a discrete molecular species. It has the characteristic property that the molecule retains its spin orientation even in the absence of an external magnetic field. If the molecule possesses a large spin ground state (S) as well as an Ising type magnetic anisotropy (D<0) then this gives rise to an energy barrier that lies between the 'spin-up' and 'spin down' configurations as shown in Figure 2.26 [START_REF] Aromi | Synthesis of 3d Metallic Single-Molecule Magnets, Structure and Bonding[END_REF]. This is the result of Zero Field Splitting (ZFS) of the ground state caused by spin-orbit coupling of the ground and excited states, which splits the Ms levels in the absence of an applied field [START_REF] Kahn | Molecular Magnetism[END_REF].

This energy barrier will therefore oppose the re-orientation of the magnetization, and so if the height of the barrier is large in comparison to the available thermal energy, the resulting relaxation of the magnetization will be slow [START_REF] Aromi | Synthesis of 3d Metallic Single-Molecule Magnets, Structure and Bonding[END_REF], [START_REF] Murrie | Molecular magnetism[END_REF]. The relaxation rate can be investigated by ac magnetic susceptibility measurements. Ac measurements are used to examine the dynamic susceptibility (Equation 1) of a sample by applying an oscillating magnetic field. The dynamic susceptibility is a complex quantity with real (dispersion) and imaginary (absorption) components that are dependent on the angular frequency ( = 2 ) of the ac field.

c (w) = c ¢(w) -ic ¢¢(w) (2.10)
The relaxation process follows an Arrhenius law for a thermal activation process to overcome the energy barrier with exp( / ) 0 t =t DE kT (2.11) where t = (w)-1 . So from an Arrhenius plot of ln( ) versus (1/T) the energy barrier (_E) can be determined from the gradient of the line. As the ac magnetic field frequency becomes close to the relaxation rate of the molecules the observed inphase susceptibility ( ) reduces. Therefore the out-ofphase component ( ) will increase. For measurements where there is only one relaxation process operating, a graph of against temperature will show a peak at the temperature where w = (t )-1.

If the switching frequency of the applied field is increased, the peak should be shifted to a higher temperature [START_REF] Long | Molecular Cluster Magnets, Chemistry of Nanostructured Materials[END_REF]. This effect is demonstrated in the data obtained for the The steps in the loops are due to quantum tunnelling of the magnetisation [START_REF] Thomas | Macroscopic quantum tunnelling of magnetization in a single cristal of nanomagnets[END_REF].

The initial proposal for the application of SMMs was for high density data storage with each molecule representing one bit, however this now appears less likely due to the technological limitations for addressing individual molecules and in obtaining functionality at non-cryogenic temperatures. More promising future applications of SMMs include quantum computing, MRI contrast agents and magnetic refrigeration [START_REF] Murrie | Molecular magnetism[END_REF], [START_REF] Long | Molecular Cluster Magnets, Chemistry of Nanostructured Materials[END_REF].

Aspects of EPR spectroscopy 2.4.1. Introduction

Electron Paramagnetic Resonance (EPR) also call Electron Spin Resonance (ESR) results from microwave-induced transitions between the magnetic energy levels of atoms or molecule, with unpaired electron, in an applied magnetic field.

The magnetic properties are determined by the electron magnetic moment.

Nucleus magnetic moment is significantly smaller than the electron magnetic moment; therefore the latter basically defines the magnetic properties of the matter.

Electron magnetic properties in atoms appear due to their motion around the nucleus (orbital magnetic momentum) and intrinsic orbital angular momentum of the electron, or spin. [START_REF] Ingram | Hyperfine Splitting in Paramagnetic Resonance[END_REF]- [START_REF] Bales | Electron Paramagnetic Resonance Line Shifts and Line Shape Changes Due to Spin Exchange between Nitroxide Free Radicals in Liquids. 3. Extension to Five Hyperfine Lines. Additional Line Shifts Due to Re-encounters[END_REF]. Atoms and molecules possess different magnetic properties, depending on their electronic structure. As we have seen earler (section 2.2.4) materials consisting of molecules with nonzero magnetic moments are called paramagnetic. Examples of paramagnetic materials are some gases (O2, NO), alkali metals, various salts of the rare-earth metals, etc.

In the majority of biological and chemical systems the orbital magnetic momentum of paramagnetic particles is negligible. Therefore, the paramagnetic properties of a sample could be attributed to the total spin S of the molecule. In a magnetic field [H], the corresponding 2S + 1 degenrated MS energy sub-levels are splitted, corresponding to the different projections of the total spin S in direction of the vector of the applied magnetic field:

E (MS) = g MS H (2.12)
According to the selection rule [START_REF] Ingram | Hyperfine Splitting in Paramagnetic Resonance[END_REF]- [START_REF] Wertz | Electron Spin Resonance, Elementary Theory and Practical Applications[END_REF] two values of MS are allowed for a system consisting of one unpaired electron S =½ : Ms can take the values +½ and -½, which will be separated in a magnetic field by an energy interval ( E) of g H. In EPR the resonance absorption is the microwave energy that causes a transition from the lower energy Ms=-1/2 to the higher energy state Ms=+1/2. The micro-wave frequency required for this transition is commonly in the range of 9-19 GHz(Xband).

The splitting of the energy levels in an applied field is called the Zeeman

E = h = g H (2.14)
where g is the g-factor (unit less), e is the electron magnetic moment or Bohr magneton (eh/4 me = 9.2740 x 10-24 J/T), and Ms is the magnetic quantum number.

The free electron ge value is 2.002319304386, for most of the organic radicals generally g value is 2.01, but varies depending on the electron configuration especially for transition metal ions.

Figure 2.29: Splitting of Zeeman levels in a magnetic field for a system with one unpared electron.

The position of a line in the EPR spectra is characterized by the magnitude of g factor: g = h /( H), where H is the magnetic field, at which the resonance condition is met. For a free electron g = 2.00232. Most of organic radicals, among which nitroxide radicals, show similar values of g (2.003 -2.007). In solution the g factor is isotropic, while in solid state it is anisotropic and becomes orientation dependent:

g 2 = gxx 2 Ix 2 + gyy 2 Iy 2 + gzz 2 Iz 2 (2.15)
where IX, Iy, Iz are the direction cosine between the direction H and the principle gaxes. Among the other factors, which cause anisotropy of the g factor and lead to serious deviations from the spin value of 2.00232, is the influence of anisotropic electric fields, surrounding the atoms, splitting of Zeeman levels in zero magnetic field, etc. Typically significant differences of the magnitude of the g-factor from a free electron value are observed in the presence of strong spin-orbital interactions (as in the case of transition metals). For paramagnetic species in dilute liquid solution of low viscosity the system is apparently isotropic, due to the free molecular rotation. In such systems all the g axes gx = gy = gz are equal to the applied magnetic field H.

Consequently, g factor is independent from the field direction and to be regarded as an effective value averaged over all orientations: giso = (gxx +gyy +gzz)/3 (2.16)

In solid-state powder or frozen solution due to anisotropic nature of the paramagnetic site three main components can be seen for a (rhombic case) or in axial case, two anisotropic g values, (g and g ) are required to describe the ESR spectrum. Since the paramagnetic crystallites have more g (gx and gy) aligned than g (gz), the most intense absorption will correspond to g (see Figure 2.28). In reality, often one finds that due to the overlapping features it is generally difficult to obtain the g and g values. Figure 2. 30: The g and some g axes in a crystallite with three fold and higher axis.

Hyperfine Coupling (hfc)

In addition to the interaction of an electron with the magnetic field (Zeeman effect), it should be taken into account its interaction with the neighboring atoms that have an intrinsic nuclear spin. The magnetic interaction between an unpaired electron magnetic moment (spin) and nuclear magnetic moment (nuclei with non-zero nuclear spin, I 0) I is called hyperfine coupling A. This gives spectrum with multiline that is call the hyperfine structure. If there was the Zeeman effect only then all spectra would consist of a single line and this would be of little interest to chemists.

However, the most useful chemical information that can be derived from EPR spectra comes from the hyperfine structure.

The number of the lines depends on the magnetic nucleus number. Examples of the nucleus with non-zero nuclear spin are: 1 H, 13 C, 14 N, 15 As an example, let us consider the hyperfine interaction with the nitrogen nuclei of the NO paramagnetic molecule. 14 The general Hamiltonian describing the Zeeman and hyperfine interactions is given by,

H = ( • g • ) + • A • Î (2.17)
Any observed hyperfine interaction theoretically consists of two terms i) isotropic and ii) anisotropic. The total hyperfine value of a system can be expressed by the following equation

A = aiso + Adip (2.18)
The aiso value also called Fermi contact term can be explained by the following quantum mechanical equation, aiso = 8 ge egn n (0) (2.19) Where (0) = (0) 2 is the unpaired electron density at the nucleus, gn the nuclear g-factor, n is the nuclear magneton (5.0507866 * 10 -27 J T -1 ). Equation 2.20 measures the magnetic interaction energy (in joules) between the electron and nucleus. The A term arises due to the interaction between the electron and nuclear dipoles, and is time-averaged to zero in liquid solution due to the random molecular motions. The observed isotropic hyperfine value in liquid solution is exclusively due to the Fermi contact term, EFC. aiso = [ Axx + Ayy + Azz ] / 3 (2.20)

In solid or frozen rigid systems, it is precisely the dipole-dipole interaction between the electron and nuclear dipoles that gives anisotropic component of hyperfine coupling. The magnitude of the A component, like the g component, is dependent of orientation. The Hamiltonian describing the anisotropic interaction takes the following form,

H = ( • g • ) + ( z • Azz • Îz + x • Axx • Îx + y • Ayy • Îy ) (2.21)
Thus we can obtain the principle hyperfine values Axx, Ayy, and Azz for each directional cosines for all three directions or the Azz = A and Axx = Ayy = A in case of axial symmetry. Most often g axis and the A axis are collinear.

EPR Spectra of Nitronyl and Imino Nitroxide

Nitronyl nitroxide and imino nitroxide monoradicals exhibit very distinct EPR hyperfine structure. In the case of nitronyl nitroxide, the spectrum recorded in dilute ( 10 -4 M) and oxygen free DMSO solution at room temperature exhibits a clear isotropic five line pattern with giso = 2.0065 [START_REF] Maccrum | Investigation of a Synthesis of meso-Porphyrins Employing High Concentration Conditions and an Electron Transport Chain for Aerobic Oxidation[END_REF]. The five lines spectra originate from the interaction of the unpaired electron with the two equivalent nitrogen nuclei of the imidazolyl moiety. The relative intensity of each line follows the typical 1:2:3:2:1 ratio, as shown in Figure 2.33 [START_REF] Baumgarten | EPR of Free Radicals in Solids[END_REF]- [START_REF] Stryer | A Spin-labeled hapten[END_REF]. The best fitting of the EPR curve was obtained assuming Lorentzian/Gaussian linewidth ratio = 0.66. and has giso = 2.0058(3).

Exchange Interactions (J)

The simulated isotropic solution state EPR spectrum of a mono-( 14 N = 2), bi- The number of lines for a polyradical depends of the ratio between the intramolecular exchange interaction (J) and the hyperfine constant (AN). This is illustrated in Figure 2.35 for a binitroxide radical (NO)2 with two equivalent nitrogens [I =1] . For a two-spin system (S1, S2) the total spin Hamiltonian is given by,

(
H= g H (S1z + S2z) + A( 1Î1 + 2Î2) -2J 1. 2 (2.22)
When the exchange interaction between the two spins is zero (J = 0), the radical are independent and the spectrum looks like a mononitroxide showing three lines with hyperfine constant (AN) of equal intensity but with double intensity compare to the monoradical. When the exchange interaction is much larger than the hyperfine interaction it shows five lines with intensity close to 1:2:3:2:1 ratio.

Importantly the spectral width is the same as for the monoradical but the spacing between the five lines is half those between the three lines of the corresponding monoradical (AN/2). Intermediate cases like J < AN or J = 2aN changes the total spectral width higher than for the respective monoradical, with a number of additional lines with different intensities. When the exchange interaction between the two radicals is large the J value increases, in other words the energy gap between the singlet and triplet state increases. However, when the exchange is weak the singlet and the triplet states are almost degenerate. There also exists an electronspinelectronspin contact interaction analogous to the Fermi contact interaction that is the mechanism of isotropic hyperfine interaction. However, the magnitude of this term is very small. To the extent it is present, it contributes to J.

Ground State Spin Multiplicity

RESULTS and DISCUSSION

Introduction

The main goal of the thesis was the construction of novel bricks for molecular magnets. All our efforts were dedicated to synthesize, characterize and study the magnetic properties of porphyrin macrocycles including different kind of spin carriers covalently attached to its backbone; preferentially N-tert-butyl-N-oxyamino, nitronyl and imino and nitroxide free radicals. One of the most challenging aspects of our work was to design a multi-step synthesis pathway that lead, from desirable starting material to the targeted compounds.

Porphyrin macrocycles were chosen because of their highly polarizableconjugated system that should favor the spin delocalization all over the molecule skeleton.

Free-radicals were introduced on the meso position of tetraphenylporphyrins (TPP), one of the most common simple symmetric porphyrin derivatives. Thus, no isomer will be present which will promote crystallization of such a structure and its characterization by X-ray diffraction.

As a spin carrier N-tert-butyl-N-oxyamino (tBuNO), nitronyl (NIT) and imino (IMI) nitroxide free radicals were preferred because they are well-known as among the most stable class of radicals with respect to air, water, dimerization and other radical-involving reactions. They are generally well soluble in most organic solvents but moreover they can be quite easily incorporated on many molecules without affecting the radical site.

Considering all these parameters, three targeted molecules based on tetrakis phenylporphyrin macrocycle decorated by four radicals have been designed: one with N-tert-butyl-N-oxyamino radicals (1), a second with nitronyl nitroxide radicals

(2) and the third one with imino nitroxide radicals (3) as represented in the Figure 3.1 below.

In the following text, the abbreviation mono-, di-, tri-or tetra-radical will be use indicating of the number of radicals present in the macrocycle. To achieve the molecule 1, some difficulties have to be envisaged: i) Control of the low temperature is important to prevent the easy decomposition of n-Buthyllithium reagent.

ii) n-Buthyllithium is a very active reagent therefore the protection of the inner nitrogens by Zn metal may be necessary.

iii) Control of multi-site reaction is always a challenge. On TBrPP that contain four brome atoms, the halogen-lithium exchanges followed by the nucleophilic attack by 2-methy-2-nitrosopropane have to be done in four position at the same time. It could be difficult to avoid the formation of mono, di or tri tBuNO porphyrin derivatives.

-nitronyl and imino nitroxide radical

The synthesis of nitronyl and imino nitroxide result on the condensation of 2,3bis(hydroxylamino)-2,3-dimethylbutane with an aldehyde followed by oxidation of the condensation product with NaIO4 or PbO2. Following this pathway, formyl group have to be introduce on tetraphenylporphyrin to obtain meso-tetrakis(4-formylphenyl)porphyrin (ATPP).

Popularly, the formyl group may be introduced on the para position of the phenyl substituent by regioselective bromine-lithium exchange mechanism starting from the bromo-containing tetraphenylporphyrin. However, to the best of our knowledge, along this method only the mono-and the di-(4-formyl)-tetraphenylporphyrin are known; [START_REF] Wennerstrom | meso-Tetra(meso-tetraporphyrinyl)porphyrin, a macrocycle with five covalently linked porphyrin units[END_REF], [START_REF] Hammel | Coupling between Polypyridineruthenium(II) and Methylviologen Moieties in n-Conjugated Hybrid Systems[END_REF]. Nonetheless, no synthesis and characterization of mesotetrakis(4-formylphenyl)porphyrin has been reported to date which may be ascribe to the difficulty to have a stoichiometric control of the introduction of formyl group in a multi-site reactivity reaction (Figure 3.5). Regarding the synthetic pathway of 1 and ATPP, both of them have the same starting molecule TBrTPP. The use of the same synthon, described in good yield in literature, is a real advantage. Considering that the control of the the halogen-lithium exchange multi-site reaction may be difficult, a protecting route -call acetal routewas also envisaged to by-pass this step. But the synthesis of the meso-tetrakis(4-(4,4-Dimethyl-2,6-dioxan-1-yl)phenyl)porphyrin was never described previously, so it has been necessary to find some good conditions of synthesis to obtain this molecules with good yield. Another reaction pathway that we envisaged was first to synthetized the imino nitroxide susbtituted benzaldehyde then IMIP radical [START_REF] Calvin | Tetraphenylchlorin[END_REF] porphyrin by condensation with pyrol; by this way the the porphyrin macrocycle would be the last step and the four imino nitroxide incorporated on one poprhyrin simultnously.

Considering that obtaining multi radical substituted porphyrin is a "complicatenot easy" task, we also synthesized porphyrin macrocycle bearing only one radical moiety. The synthetic pathway of mono tBuNO(4), mono NIT(5) and mono IMI [START_REF] Rothemund | A New Porphyrin Synthesis[END_REF] nitroxide is described in Figure 3.6. Apart from the simplication of the synthesis these molecules are interesting because they allow comparing the effect of radicals on porphyrin macrocycles. In this manuscript, the presentation of our results will be articulated around three parts:

3.2. The synthesis of paramagnetic porphyrins will be described. The advantages and disadvantages of all synthetic pathways will be discussed. The characterization of molecules obtained throughout the thesis was done by the usual technique tools (NMR, IR, UV, MASS spectroscopy).

3.3. EPR spectroscopy investigations were achieved for the paramagnetic compounds to determine the radical group type (tBuNO, NIT/IMI) but also to determine the number of spin present on the molecule. Radical-Radical interactions will be explored. metallation of porphyrins by paramagnetic transition metals as M=Cu(II) and Mn(II) will be discussed. Like this, the resulting spin number of the molecules will increase.

3.4. In the last part, the results will be summarised by conclusion section. Following Adler method [START_REF] Gradillas | Novel synthesis of 5,10,15,20-tetraarylporphyrins using high-valent transition metal salts[END_REF], [START_REF] Mathevet | Interpenetrated 3D Polymeric Metal-Radical Networks Built from a Tetranitroxide Radical and Bis(hexafluoroacethylacetonato) Manganese(II)[END_REF], meso-tetrakis(4-bromophenyl)porphyrin was obtained from condensation of 4-bromobenzaldehyde with pyrrole in reflux propionic acid. The reaction was completed in a short time; 30 min. The compound was obtained in the form of purple crystals after cooling the reaction mixture slowly down to room temperature. After purification on silica gel column with DCM:

Synthesis of Radical Substituted Porphyrins

Hexane (1:1) as eluent, TBrPP was obtained as a purple compound in 25% yield. The FT-IR spectrum of TBrPP shows the characteristic intense peaks of porphyrin macrocycle [START_REF] Craven | Infrared Absorption Spectra of Porphyrins[END_REF], [START_REF] Alben | Infrared Spectroscopy of Porphyrins[END_REF]. The C-H vibration at 2958 cm -1 corresponds to the aromatic protons. The peak at 964 cm -1 belongs to porphyrin ring vibration. The vibration at 794 cm -1 is characteristic of pyrrole ring bending whereas the one at 726 cm -1 of pyrrole vibration. The NH vibration of the porphyrin free base was observed at 3300 cm -1 peak and also at 730 cm -1 is for NH bending. Especially for porphyrin macrocyle, peaks at 1472 cm -1 and 1382 cm -1 are characteristics and correspond to C=N and =C-N vibration respectively. The 1 H NMR spectrum of TBrPP in CDCl3 exhibits a singlet at -2.94 ppm assigned to the 2 NH inner protons of the porphyrin. The aromatic region presents two doublets and a singlet due to the meso-phenyl proton and the -pyrrolic protons respectively. The doublet at 7.83 ppm is attributed to the 8 orto-CHAr protons of meso-phenyl group whereas the doublet at 7.98 ppm is attributed to the 8 meta-CHAr protons. Meanwhile, the -pyrrolic protons appears at 8.76 ppm.

Characterization of TBrPP

Molecule 1 3.2.2.1. Synthesis Work on Molecule 1

Porphyrins substituted by N-tert-butyl-N-oxyamino (tBuNO) radical were previously reported exclusively by Shultz and al with the aim to include them in coordination polymers. One [START_REF] Shultz | Synthesis and Characterization of Phenylnitroxide-Substituted Zinc(II) Porphyrins[END_REF] or two [START_REF] Shultz | Electron Spin-Spin Exchange Coupling Mediated by the Porphyrin System[END_REF] tBuNO radical were introduced in the meso position of the porphyrins as shown on Figure 3.12. The synthesis involved four steps of difficult reaction which are based on a Pdcatalyzed coupling reaction of iodo or bromoporphyrin with the appropriate TBSprotected phenylnitroxide, alkene, or alkyne boronate and followed by a Fluoridepromoted TBS deprotection and PbO2 oxidation. In Figure 3.13 we present as an example the Zn(II)-porphyrin substituted by a single tBuNO. To the best of our knowledge, there is no other work on meso-porphyrin substituted by the N-tert-butyl-N-oxyamino radical. From which we can concluded that direct covalent attachement of stable nitroxide radical on the meso-position of the porphyrin is a challenging task. Unfortunately at the end of the reaction a green product was handling as a side product which was ascribed to chorin macrocycle [START_REF] Mojzisova | Photosensitizing properties of chlorins in solution and in membrane-mimicking systems[END_REF]. EPR spectroscopy was used to check wether or not the porphyrin was substituted by radicals and how many (Table 2). It resulted that in THF no radical were fixed on porphyrin macrocycle while in diethylether up to two radical were introduced. Therefore THF was discarded and diethylether previlegied despite low solubility. For THF as well as for diethyether we found the results were not dependent of the concentration (Table 3 -mono and -di 3 150 eqv.

-mono and -di Zn(II) metallated TBrPP was also try as starting material. Zn could be indeed a good protecting group of the the two core nitrogens of the porphyrin against the very reactive n-Buthyllithium. However, as the reaction is quenched by 5% HClsol this leads to the partial demetallation of the porphyrin due to the acidic condition. As a result; it gives a mixture of metallated and free base tBuNO porphyrin derivatives that result in lower yield of the reaction. Keeping the porphyrin in acidic condition for more than 10 min, to try to achieve the complete demetallation of all porphyrin derivatives and get higher yield, was not successful as it results in the decomposition of many products.

Characterization Work

Upon chromatography on silica gel, we evidenced many fractions (more than 8), not totally separated. All fractions correspond to compounds that contain porphyrin macrocyles as may be conclude from their UV-vis spectra that show the characteristic Soret peak (~420 nm) as seen above for TBrPP. However, among the all fractions there were only two (A and B) that could be identified by EPR spectroscopy as bearing radicals. Accordingly, fractions A contain mono tBuNO radical and fraction B contains di tBuNO radical (See Figure 56 in the section 3.3.) It is clearly seen from Table 3.5, that there is no significant shifted of the absorption band due to the incorporated radical moieties. But it is noticeable that there is a change of the intensity of the Q bands. The bands at 648 nm or 646 nm for mono-tBuNO and di-tBuNO (see Figure 32

Mass spectroscopy

Mass spectroscopy is one of the usefull and popular tool for the characterization of molecular structure and of quite an easy acces. Depending of the mass spectroscopy experiment conditions (ionisation, presence of matrix) molecular ion peak of tetra tBuNO could be observed. The best result was obtained without matrix, radicals were detected as the M + specie. In the presence of DHB as matrix a m/z= 88 fragment corresponding to the addition of the tBuNHO was observed. The Mass spectra exhibit molecular ion peak of di tBuNO porphyrin with the BHA matrix and tetra tBuNO porphyrin molecular ion peak without matrix (See Figure 3.17 and 3.18 bellow).

Concluding remarks

The radical moities on porphyrin could be proven by EPR spectroscopy(see section 2.4.3). But for these porphyrins although working on different mass spectroscopy method like MALDI spectroscopy using different matrix DHB, ANTRA or without matrix and ESI mass spectroscopy, we could not obtaine their molecular ion peak on spectra.

On the other hand, even there is no EPR signals of some fractions, according to the mass spectroscopy results they contain porphyrin bearing radical(see Figure 3.17, 3.18). We are optimistic to isolate our targeting molecule tetra tBuNO porphyrin and works in this direction are on going.

Except the two reports by Shultz et al. there is no literature on N-tert-butyl-Noxyamino radical covalently link to porphyrin. When we consider these two reports, it is clear that the reaction conditions are not easy, giving radical in small amount.

The oxidation step was done in a glovebox in 0.2 mM toluene directly in EPR quartz tube containing an excess of PdO2. All the EPR studies have been carried out with this limited quartz tube amount.

In conclusion, according to EPR result we can synthesize and characterized mono-and di-N-tert-butyl-N-oxyamino substituted free base porphyrin (tBuNO porphyrin).

Molecule 2 3.2.3.1. Synthesis Work on Molecule 2

The general synthesis of nitronyl nitroxyde free radicals is based on condensation of 2,3-bis(hydroxyamino)-2,3-dimethylbutane (BHA) with an aldehyde and followed by oxidation step with NaIO4 or PbO2.

In our work to obtain porphyrins substituted by nitronyl nitroxide (2 and 5) we used meso-tetrakis(4-formylphenyl)porphyrin (ATPP) as the aldehyde for condensation with BHA.

2,3-bis(hydroxyamino)-2,3-dimethylbutane (BHA)

The main precursor of Ullman's route [START_REF] Osiecki | Studies of Free Radicals. I. a-Nitronyl Nitroxides, a New Class of Stable Radicals[END_REF] 2,3-bis(hydroxyamino)-2,3dimethylbutane (BHA) has difficult reproducibility and questionable purity with low yield. Dr. Hirel [START_REF] Hirel | Nitronyl and Imino Nitroxides: Improvement of Ullman's Procedure and Report on a New Efficient Synthetic Route[END_REF] reported new route for the free base BHA in a very pure form and up to 60% yield. It is based on using the classical reduction process with zinc in ammonium chloride buffered solution of the dinitro analogue and fallowed by purification of Zn contant with continuous extraction with chloroform from sodium carbonate and sodium chloride solution in water. Rajca [START_REF] Rajca | Alternate calix[END_REF], [START_REF] Shimono | Preparation and Characterization of New Chiral Nitronyl Nitroxides Bearing a Stereogenic Center in the Imidazolyl Framework[END_REF] used Aluminum foil shreds / HgCl2 solution for the reduction in THF/ water at -7 o C. The purification was based on washing with ether and the yield was % 79 maximum.

The purity of the free base is important for the success and the yield of the condensation reaction. This is especially acute in the case of our porphyrin substituted with aldehydes for which the yield is low and the condensation a difficult step. This can takes long time with reflux during more than 1 day. In our study we used Hirel's and Rajca's methods explained above and pure free base BHA was obtained with % 40 yield maximum.

meso-tetrakis(4-formylphenyl)porphyrin (ATPP)

The synthetic sequence towards porphyrin substituted with four nitronyl nitroxide (NITP, 2) is based on meso-tetrakis(4-formylphenyl)porphyrin (ATPP) as the key building block (Figure 3.20) As for the synthesis of tBuNO substituted porphyrin we choose also here a bromo-lithium exchange reaction followed this time by reaction with with N,N'-dimethylformamide (DMF). This has long been known in organic syntheses as a desirable method for the preparation of aldehydes [START_REF] Ulrich | A simple synthesis of metallocene aldehydes from lithiometallocenes and N,Ndimethylformamide: Ferrocene and ruthenocene aldehydes and 1,1dialdehydes[END_REF]. The In conclusion of this study, only the porphyrins containing one or two dithian-2-yl residues in a 5,15 orientation were stable, the tri-and tetra substituted porphyrins were increasingly unstable especially towards traces of acid. The latter had to be stored under an atmosphere of argon at -20 °C. The instability of these compounds result from the increased steric strain in such systems [START_REF] Senge | Synthesis, Reactivity and Structural Chemistry of 5,10,15,20-Tetraalkylporphyrins[END_REF] and the reactivity of the dithian-2-yl residues. Considering the literature work on meso-formylation methods, the major limitations of the described methods are that only mono or di-aldehyde were obtained. And in some case the instability of tri-and tetra-intermediate syntons was mentioned limiting the synthetic possibilities.

Up to date, there is not a good description of synthesis of meso-tetrakis(4formylphenyl)porphyrin (ATPP) in literature. We choose to prepare it via the Bouveault reaction, a regioselective bromine-lithium exchange mechanism quench by N,N'-dimethylformamide (DMF) to introduce the formyl groups, a well-known organic syntheses for the preparation of aldehydes [START_REF] Ulrich | A simple synthesis of metallocene aldehydes from lithiometallocenes and N,Ndimethylformamide: Ferrocene and ruthenocene aldehydes and 1,1dialdehydes[END_REF] When we look over the reaction conditions and reagents based on organometallic synthesis, one has to be very careful with the parameters of the reactions; low temperature should be kept during the reaction because organometallic reagents can be easily decomposed when the temperature rise up. As organometallic compound are highly reactive, contaminants such as water, alcohols and oxygen must be avoided. Consequently, all the solvents have to be very dry and pure. Also, the reaction has to be worked under absolute dry nitrogen atmosphere. All the reaction vessels were dried in oven during 24h before the usage. All the solvents and liquid reagent bottles were purchase with molecular sieve. meso-tetrakis(4-formylphenyl)porphyrin ATPP was prepared from mesotetrakis(4-bromophenyl)porphyrin (TBrPP) derivative in diethylether by using nbuthylithium and dry DMF at low temperature. For hydrolysis a %5 HCl solution was used.

-As pointed above, controlling the low temperature was crucial due to the easy decomposition of n-Buthyllithium reagent. However, the decrease of the temperature lowers the solubility of the porphyrin in diethylether solution. That is why we used more dilute solution for better solubility.

-To increase the yield of ATPP and to avoid the formation of mono and di formyl derivative, different equivalent of n-Buthyllithium in 2.5M solution in Hexane, from 6.25 equiv to 32 equiv, were tested. The excess of equiv of n-buLi did not change anything to the reaction.

The different conditions are summarized in table 3.5 the optimized conditions were -50 o C and 6,25 equiv per mol of meso-tetrakis(4-bromophenyl)porphyrin (TBrPP). Like this, n-BuLi was stable during the reaction time and TBrPP was well soluble. Utilizing this optimized conditions, only tri-and tetra-formyl porphyrin were obtained in 40% and 30% yield respectively. -The scrambling of the mixture was performed on silica gel by three column chromatography one after the other 1)DCM, 2) Diethyl ether/ DCM 1:9, 3) Diethyl ether/DCM 1:5, 1:3,1:2 .

-According to literature, and especially the article of Shultz Zn(II) was used to protect the porphyrin nitrogens core against the very reactive n-Buthyllithium, but the quenching of the reaction by a 5% HCI solution lead to the demetallation of the obtained porphyrin due to the acidic condition, as a result a mixture of metallated (ZnATPP) and free base formyl porphyrin (ATPP) derivatives were obtained, lowering the yield of the reaction and increasing the problem of purification by column chromatography due to the raise of products.

According to these parameters we take into account also the possibility to introduce the formyl function not directly on a pre-formed porphyrin macrocyle but on an adequate precursor, like benzaldehyde derivative.

With this intention, we also explored a synthetic method base on acetal Dimethyl-2,6-dioxan-1-yl )benzaldehyde 7 with 80% yield. [START_REF] Balakumar | A New Route to meso-Formyl Porphyrins[END_REF], [START_REF] Eckert | Fullerene-Oligophenylenevinylene Hybrids: Synthesis, Electronic Properties, and Incorporation in Photovoltaic Devices[END_REF], [START_REF] Grosu | Synthesis and stereochemistry of some new 1,3-dioxane derivatives of 1,4benzenedicarbaldehyde[END_REF] All the spectroscopic results were consistent with literature.

To synthesis the macrocycle porphyrin, the classical Adler method [START_REF] Adler | A Simplified Synthesis for meso Tetraphenylporphin[END_REF], [START_REF] Kadish | Synthesis and Organic Chemistry[END_REF] consisting on the cross-condensation of pyrrole and aldehyde 7 in refluxing propionic acid was tested, but this method failed and the meso-tetrakis(4-(4,4-Dimethyl-2,6-dioxan-1-yl-)phenylporphyrin 8 was never obtained in these conditions. Boron trifluoride etherate (BF3.OEt2) CNPh The FT-IR spectrum of ATPP shows the characteristic intense peaks of porphyrin macrocycle [START_REF] Craven | Infrared Absorption Spectra of Porphyrins[END_REF]. At 2932 cm -1 C-H vibration corresponding to the aromatic protons, at 1694 cm -1 C=O intense peaks correspond to aldehyde vibration.

Characterization Work of ATPP

The porphyrin ring vibration was at 966 cm -1 , also the peak at 804 cm -1 is characteristic for pyrrole ring bending and at 1170 cm -1 is for pyrrole ring vibration.

NH vibration was observed at 3322 cm -1 and NH bending vibration at 730 cm -1 .

Especially for the porphyrin macrocyle, the vibration C=N at 1472 cm -1 and the =C-N vibration at 1382 cm -1 are characteristics. The electronic absorption spectrum of the ATPP is dominated by a very strong Soret band located at 420 nm which is characteristic for porphyrin macrocyles. Four Q bands located in the spectral range of 517-647 which are typical of free base porphyrins according to the D2h symmetry [START_REF] Dorough | Spectra of the Metalloderivatives of , , -Tetraphenylporphine[END_REF]. The EPR results are a first and trustful characterization work for radical substituted porphyrins. The EPR spectroscopy measurements in solution will be discussed in section 3.3.

Characterization Work for NITP

Molecule 3 3.2.4.1. Synthesis work on Molecule 3

For the synthesis of Imino nitroxide substituted porphyrin (3), two different methods were used; one is based on the conversion of nitronyl nitroxide to imino derivative by the well known over oxidation reaction with NaNO2. A second method was also tried, based on the cross condensation of 4-(4,4-Dimethyl-2,6-dioxan-1yl)benzaldehyde [START_REF] Adler | A Simplified Synthesis for meso Tetraphenylporphin[END_REF] precursor by the Adler synthetic pathway.

Method 1: Conversion of NITP to IMINP

According to Ullman [START_REF] Ullmann | Stable Free Radicals. VIII. New Imino, Amidino, and Carbamoyl Nitroxides[END_REF] when nitronyl nitroxides are heating in the presence of triphenylphosphine in benzene or treated with nitrous acid, imino nitroxides are obtained in high yields. It is possible to reconvert to the starting nitronyl nitroxides with m-chloroperbenzoic acid. According to EPR results nitronyl nitroxide moieties were fully converted to imino nitroxide derivative successfully. EPR measurements will be discussed in section 3.3. The non-protected formyl derivative [START_REF] Kamachi | Synthesis of New Polymers Containing Porphyrins in Their Side Chains: Radical Polymerizations of 5-[ 4-(Acryloyloxy) phenyl] -10,15,2Otriphenylporphyrin and 5-[ 4-(Met hacryloyloxy)phenyl] -10,15,20-trip henylporphyrin[END_REF] was recovered by reacting the raw mixture of ( 9) and ( 10) by trifluoroacetic acid (TFA). The reaction was carried out on the raw mixture of ( 9) and ( 10 Syntheses of 3 in different acidic condition were attempted but unfortunately we could not succeed up to now. According to IR spectra, the carbonyl stretch C=O of aromatic aldehyde was obtained at 1716 cm -1 as expected, but is not easy to differ H-C=O stretch (2830-2695 cm -1 ) of aldehyde from aromatic C-H stretch (2870-2960 cm -1 ). The electronic absorption spectrum of imino nitroxide radical substituted porphyrin IMIP shows remarkable spectral change. Characteristic Q band exhibit more red-shifted to 428 nm and B bands also red-shifted to 522,559,599 and 654 nm.

Method 2: Protecting group pathway

Characterization Work of Precursors

Molecule 4

As seen above and as may be expected the incorporation of four nitroxide on the porphyrin is difficult and complicated. In a tentative of simplification and with the objective to test the synthetical approach we decided to work on the porphyrin substituted a single nitroxide radical. The starting precursor of the mono nitroxide substituted porphyrin was the 5-(4-bromophenyl)-10-15-20-tripehylporphyrin (AB 3 BrP) which was synthesized by routine Adler method using 1 eqv. of 4-bromobenzaldehyde and 10 eqv. of benzaldehyde to avoid formation of di-and tri-meso-4-bromophenyl porphyrin derivatives. Inseparable AB 3 BrP porphyrin and unsubstituted meso-tetraphenyl porphyrin TPP were used together for further reactions.

Synthesis of AB 3 BrP

Halogen Lithium Exchange Reaction and Oxidation

Mono meso-N-tert-butyl-N-oxyamino substituted prophyrin 4 was prepared from AB 3 Br according to the same method as described for molecule 1 (Figure 3.14)

which is based on Lithium-halogen exchange reaction at low temperature. According to Table 3.9 there is no significant shift of the absorption band due to introduction of N-tert-butyl-N-oxyamino radical moiety. The results are consistent with the UV-Vis spectroscopic work for molecule 1 explained before in section 3.2.2. The electronic absorption spectrum of 5 and 6, shows striking spectral changes.

Characterization Work

Condensation-Oxidation

For molecule 5 and 6 the B and Q bands exhibit a red-shift. These significant red shifts can be referred to the contribition of nitronyl and imino nitroxide moities on the porphyrin macrocyle.

Metal insertion to Porphyrin Macrocycles

To our best knowledge, up to today there were only three reported work 124-126 that mentioned the utilization of ATPP but without any experimental and characterization part as well no report for metallo-derivative of ATPP.

In this study, after an easy metallation process of ATPP, ATPPCu(II) and ATPPMn(III) were full characterized for the first time as well as TBrPPCu(II) and

TBrPPMn(II).

Mn(II) porphyrins are generally air-sensitive, giving rise to Mn(III)compounds. According to the electronic absorption spectra of TBrPPMn and ATPPMn (see Table 3.12), a strong Soret band (B band) located at 479 nm is present that correspond to Mn(III)-compounds which are described in literature [START_REF] Silva | Cyclohexane hydroxylation by iodosylbenzene and iodobenzene diacetate catalyzed by a new -octahalogenated Mn-porphyrin complex: The effect of meso-3-pyridyl substituents[END_REF]. In case of Mn(II)-complex Q band have to be located at 434-442 nm [START_REF] Stute | Molecular Structure, UV/Vis Spectra, and Cyclic Voltammograms of Mn(II), Co(II), and Zn(II) 5,10,15,20-Tetraphenyl-21-oxaporphyrins[END_REF], [START_REF] Mut | Spectroelectrochemical Characterization of Solvent-Related Changes in Axial Ligation of Manganese(II) and -(III) Tetraphenylporphyrins[END_REF]. From all works were described above, one can conclude that among many meso-position formylation methods Butyllithium/DMF formylation is the best way to get tetra formyl porphyrin. Microwave irradiation makes possible metallation of porphyrin macrocyle in short time with perfect yield. In our work we could synthesized ATPP, ATPPCu(II) and ATPPMn(III) and also full characterization work was done for the first time.

EPR Work on Nitroxide Substituted Porphyrins

EPR Spectroscopy of Nitroxides

Nitroxide monoradicals exhibit very distinct EPR resonance envelopes.

For the mono N-tert-butyl-N-oxyamino (tBuNO) the EPR spectrum exhibits a triplet hyperfine structure with an intensity distribution in the ratio of 1:1:1, due to the interaction of the unpaired electron with the one nitrogen atom ( 14 N, I = 1) in isotropic media, characteristic of a tBuNO nitroxide radicals system(see Figure 3.53). EPR spectrum di-tBuNO radical represents a quintet hyperfine structure (2nI+1=5)with an intensity distribution in the ratio of 1:2:3:2:1, due to the interaction of the unpaired electron with the two equivalent nitrogen atoms ( 14 N, I = 1) in isotropic media for di-tBuNO radicals.

In the case of mono nitronyl(NIT) the EPR spectrum represents a quintet hyperfine structure with an intensity distribution in the ratio of 1:2:3:2:1, due to the interaction of the unpaired electron with the two equivalent nitrogen atoms ( 14 N, I = 1) in isotropic media(see Figure 3.55). In our study the X-band measurements of chloroform solution of N-tert-butyl-N-oxyamino (tBuNO), nitronyl(NIT) and imino(IMI) nitroxide radicals were carried at ambient temperature in chloroform solution. The spectra were simulated with the values of g, aN (isotropic hyperfine coupling constant in gauss) and linewidth extracted from the solution spectrum, using Jeol IsoSimu and Winsim computer programs [START_REF] Duling | Simulation of Multiple Isotropic Spin-Trap EPR Spectra[END_REF]. According to our many EPR experiments most hyperfine couplings correspond to mono (2nI+1=3 lines) and di (2nI+1=5 lines) tBuNOP porphyrin radical.

EPR Study for Targeted Molecule 1

Nevertheless, three-line profile is typical of isolated nitroxide moieties in solution, therefore low temperature (helium temperature) study should be done to observe the anisotropic coupling between the nitroxides. According to the EPR solution spectra of nitronyl nitroxide susbtituted porphyrins, the hyperfine structure corresponds to the mono (2nI+1= 5 lines) nitroxide radical. As there are not references for this kind of molecules, we can not conclude that the molecule obtained during the synthesis of molecule 3 bears one radical, or four radicals without interactions. Further studies are ongoing in this direction.

EPR Study for Targeted Molecule 2

EPR Study for Targeted Molecule 3

Precursors for targeted molecule 3

Conclusion

Result 1

Mono-tBuNOP, mono-NITP and mono-IMIP were obtained successfully and characterized without any doubt concerning the structure. Although we used the same synthetic pathway to obtained 1 (tetra-tBuNOP), 2 (tetra-NITP) and 3 (tetra-IMIP) the reactions was not so easy. Probably due to the multi-site reaction that complicated the lithium-halogen exchange mechanism, some more studies have to be done to clarify the relationship because the different spectroscopic characterization and the ESR results.

Result 6

Contrary to the reported literature work, we demonstrated it is disadvantageous to use Zn(II) protected porphyrin, and that the inner nitrogens were not involve in the halogen-lithium exchange reaction.

EXPERIMENTAL SECTION

General

Absorption and fluorescence spectra were recorded by using a Shimadzu 2101 UV-Visible spectrophotometer and a Varian Cary Eclipse spectrofluorometer, respectively. IR spectra were recorded between 4000 and 600 cm -1 using a Perkin Elmer Spectrum 100 FT-IR spectrometer with an attenuated total reflection (ATR) accessory featuring a zinc selenide (ZnSe) crystal.

meso-tetrakis-[4-(N-tert-buthyl-N-oxyamino)phenyl]porphyrin (Molecule 1)

Step 1: 200 mg (0.2 mmol) meso-tetrakis(4-bromophenyl)porphyrin TBrPP was purged nitrogen(g) then vacuum for many times. Then 50 mL of dry diethylether was added by syreng under nitrogen(g) at room temperature and continued bubling with nitrogen(g). Then the purple solution was placed in an acetone-liquide nitrogen bath(-78 o C) for 10 min. Then 2.5 mL of n-buthyllithium solution was added by syreng under nitrogen(g). The green mixture was warmed slowly at room temperature over 1 h.

Step 2: 0.522 g (3 mmol) of 2-methy-2-nitrosopropane(dimer) was placed in a 50 mL of schlenk and 10 mL of dry diethylether was added under nitrogen(g). After two minutes the color of mixture converted to blue which is the color of monomer 2methyl-2-nitrosopropane. Blue solution was added to the green solution at -78 o C under nitrogen(g). After one hour the color of mixture was converted to red/brown.

Then the reaction mixture was allowed to room temperature and stirred over night.

The reaction was monitored with TLC system DCM/Hexane 1:1. 20 mL of saturated aqua ammonium chloride solution was added to the reaction mixture. Then the organic phase extracted with diethyl ether and dried with Na2SO4, without purification the compound was used for the next Step 3.

Step 3: meso-tetrakis[4-(N-tert-buthyl-N-hydroxyamino)phenyl]porphyrin was dissolved in 40 mL of CHCl3. 1,5 g NaIO4 was dissolved in 40 ml of water. Then NaIO4 solution was added to the first mixture and stirred very strongly for 10 min.

The reaction was monitored with TLC then stirred for more1 hr . The green mixture was extracted with DCM for many times. Organic phase was combined and dried over NaSO4, filtered and solvent was evaporated. The chromatography work was done with DCM then second chromatography work was done with n-heptane/EtOAc eluent system (9:1, 4:1, 1:1). After evaporation of the solvent, TLC (n-heptane/DCM 2:1) was performed to identify the radicals formed. The spots were identified as mixture of more then 8 radicals and non radical porphyrins. Only mono and di Step 1: 0,03 g (0,04 mmol) meso-tetrakis(4-formylphenyl)porphyrin ATPP was dissolved in 40 mL of methanol then 0.06 g(0.016 mmol) 2,3-bis(hydroxylamine)-2,3-dimethylbutane (BHA) was added and reaction mixture was refluxed over night and protected from light. Then the reaction mixture was cooled to room temperature, and methanol was evaporated. Because of instability of the molecule, the purple residue was used for last oxidation step without purification and characterization.

Step 2: The purple residue was dissolved in 30 mL of DCM and 15 mL of distillated water was added to the solution. After addition of some drops of concentrated NaHCO3 solution, the reaction mixture was stirred for 5 min. Step 1: 0,064 g (0,08 mmol) meso-tetrakis(4-formylphenyl)porphyrin ATPP was dissolved in 40 mL of methanol then 0.06 g(0.016 mmol) 2,3-bis(hydroxylamine)-2,3-dimethylbutane BHA was added and reaction mixture was refluxed over night and protected from light. Then the reaction mixture was cooled to room temperature and methanol was evaporated.

Step 2: The purple residue was dissolved in 40 mL of DCM and 15 mL of distillated water was added to the solution. After addition of some drops of concentrated NaHCO3 solution, the reaction mixture was stirred for 5 min. NaIO4 solution (0.25 g 1.2 mmol, 4 eqv) was added slowly to the reaction mixture and the color of solution converted to red/purple color immediately. After stirring for 5 min the mixture was extracted with DCM, dried over Na2SO4 and solvent was evaporated.

Step 3: The crude product from step 2 was dissolved in 20 mL of DCM then 20 mL NaNO2 (0.03 g) solution was added and the reaction mixture was placed in icebath, stirred for 5 min. Then 10 mL 0,25 M HCl solution was added drop by drop, the color was converted to green. The reaction mixture was extracted with DCM and washed with water many times. The color was converted purple again. After drying with Na2SO4 the solvent was evaporated to dryness. with this method all nitronyl nitroxide radicals were converted to imino nitroxide porphyrins. After evaporation of the solvent, TLC (n-heptane/DCM 2:1) was performed to identify the radicals formed. The spots were identified as mixture of mono imino radical porphyrin which were characterised by EPR spectroscopy. UV-visible : , nm, CHCl3: 428; 522; 559; 599; 654. EPR: c = 10 -6 , 298 K, = 9.408191 GHz, 6.406 mW, CHCl3: 7 lines, giso=2.0067, aN1 = 9.17, aN2 = 4.33. Step 1: 200 mg (0.2 mmol) 5-(4-bromophenyl)-10,15,20-triphenyl porphyrin AB 3 BrP was purged nitrogen(g) then vacuum for many times. Then 50 mL of dry diethylether was added by syreng under nitrogen(g) at room temperature and continued bubling with nitrogen(g). Then the purple solution was placed in an acetone-liquide nitrogen bath(-78 o C) for 10 min. Then 2.5 mL of n-buthyllithium solution was added by syreng under nitrogen(g). The green mixture was warmed slowly at room temperature over 1 h.

Step 2: 0.522 g (3 mmol) of 2-methy-2-nitrosopropane(dimer) was placed in a 50 mL of schlenk and 10 mL of dry diethylether was added under nitrogen(g). After two minutes the color of mixture converted to blue which is the color of monomer 2methyl-2-nitrosopropane. Blue solution was added to the green solution at -78 o C under nitrogen(g). After one hour the color of mixture was converted to red/brown.

Then the reaction mixture was allowed to room temperature and stirred over night.

The reaction was monitored with TLC system DCM/Hexane 1:1. 20 mL of saturated aqua ammonium chloride solution was added to the reaction mixture. Then the organic phase extracted with diethyl ether and dried with Na2SO4, without purification the compound was used for the next Step 3. Step 1: 0.01 g (0.015 mmol) 5-(4-formylphenyl)-10,15,20-triphenylporphyrin (AB 3 AP) was dissolved in 20 mL of methanol then 0.01 g (0.016 mmol, 1.5 eqv.) 2,3-bis(hydroxylamine)-2,3-dimethylbutane was added and reaction mixture was refluxed over night and protected from light. Then the reaction mixture was cooled to room temperature and methanol was evaporated.

Step 2: The purple residue was dissolved in 20 mL of DCM and 15 mL of distillated water was added to the solution. After addition of some drops of concentrated NaHCO3 solution, the reaction mixture was stirred for 5 min. NaIO4 solution (0.0125 g 0.6 mmol, 2 eqv) was added slowly to the reaction mixture and the color of solution converted to red/purple color immediately. After stirring for 5 min the mixture was extracted with DCM, dried over NaSO4 and solvent was evaporated.

Step 3: 0.01 g of crude mixture from step 2 was dissoleved in 20 mL of DCM then 20 mL NaNO2 (0.03 g) solution was added and the reaction mixture was placed in ice-bath, stirred for 5 min. Then 10 mL 0.25 M HCl solution was added drop by drop, the color was converted to green. The reaction mixture was extracted with DCM and washed with water many times. The color was converted purple again.

After drying with NaSO4 the solvent was evaporated to dryness. Imino nitroxide substituted porphyrin were characterised with EPR spectroscopy. UV-visible : , nm,

  manyetik moment ta y c lar n n birle tiricili ine dayanmaktad r. Bunlar diyamanyetik ba lay c metal iyonlar veya aktif organic moleküller boyunca ba lanm metal iyonlar d r. Metal-radical yakla m olarak bilinen son yakla m molekül bazl manyetler için özellikle etkili oldu u kan tlanm t r. Yeni molekül bazl manyetlerin yap m yeni tip organic moleküllerin dizayn na dayanan metal-radikal yakla ma dayanmaktad r. Bu ba lamda çal mam zdaki stratejimizi serbest radikaller içeren porfirin sentezleri üzerine odaklad k. Nitekim porfirin bile ikleri spin delokalizasyonunu sa lamas beklenen ve manyetik etkile imin makromolekül boyunca ve tüm yap üzerinde iletimini sa lamas beklenen pi-konjuge sistemlerdir.Çok geni çe itli kimyasal çevreler içindeki mükemmel kararl l klar ve geçi metalleri ile koordina olabilmeleri nedeni ile ilgimizi nitroksit radilleri üzerine toplad k. Bu tez çal mas nda bir seri üzerinde kovalent ba larla ba l tBuNO, nitronil ve imino nitroksit radikalleri içeren porfirin makroyap lar sentezledik. Karakterizasyon çal malar UV-Vis, kütle ve EPR spektroskopisi ile yap ld . Dahas bu çal ma boyunca baz ilginç sentetik ara ürünler iyi verimlerle elde edildi ve ilk kez karakterizasyonlar yap ld . Bu olgu meso-tetrakis(4formilfenil)porfirin ve onun Cu(II) ve Mn(II) metal türevleri sentezi durumda ve baz yeni ümit verici tetrapirolik makrohalka olan üzerlerinde nitronil ve imino nitroksit serbest radikaller ta yan ba lang ç maddeleri olan 2-(3,4-disiyanofenil)-4,4,5,5tetrametilimidazolin-3-oksit-1-oksil, 2-(3,4-disiyanofenil)-4,4,5,5tetrametilimidazolin-1-oksil ve 2-(4-benzaldehit)-4, 4, 5, 5-tetrametilimidazolin-1oksil dir. Bildi imiz kadar yla, bu bile ikler nitronil ve nitroksit süsbstitüe porfirin türevlerinin aç k bir ekilde spektroskopik tekniklerle karakterize edilmi ilk örneklerini temsil etmektedirler.

3. 3 . 4 .

 34 Abbreviations and Acronyms

xvi 3 . 52 :

 352 MALDI-MS spectra of ATPPMn(III) and TBrPPMn(III). 3.53: a) Molecular structure of nitroxide, b) stick diagrame, c) resulting EPR signals of mono tBuNO nitroxide moities. 3.54: General EPR solution spectrum of di-tBuNO radicals. 3.55: a) Molecular structure of nitroxide, b) stick diagrame, c)resulting EPR signals of interaction between the unpaired electron and the 14 N nucleus for nitronyl nitroxide moities. 3.56: a) Molecular structure of nitroxide, b) stick diagrame, c)resulting EPR signals of mono imino nitroxide moities. 3.57: EPR solution spectra of a) mono tBuNOP (4.028 mW, 60 dB,1G, 1 scan), b) di tBuNOP (4.027 mW, 60 dB,1G, 1 scan) radical porphyrins at c = 1×10 -6 M in CHCl3. 3.58: EPR solution spectrum of nitroxide substituted radical porphyrin at c = 1×10 -6 M in CHCl3 (2.03 mW, 60 dB,1G, 1 scan).

3 . 59 EPR spectrum of precursors 9 ,

 3599 10 and 11 at c = 1×10 -6 M in CHCl3 3.60: EPR solution spectra of imino radical porphyrin at c = 1×10 -6 M in CHCl3 (6.399 mW, 60 dB,1G, 1 scan).

3 . 61 EPR solution spectra of a) mono tBuNO substituted porphyrin 4 ( 6 .

 36146 399 mW, 60 dB,1G, 1 scan), b) mono imino nitroxide substituted porphyrin 6 (6.399 mW, 60 dB,1G, 1 scan) at c = 1×10 -6 M in CHCl3. 3.62 a)mono tBuNO, b) nitronyl(NIT), c) imino(IMI) nitroxide radical substituted porphyrins. 3.63: a,b) Nitronyl(9,10), c) imino(11) nitroxide mono radical synthons. 3.64: Molecular structure of a) ATPP, b) ATPPCu(II), c) ATPPMn(III).

  myoglobin), electron transport (as cytochromes b and c), O 2 activation and utilisation (cytochrome P 450 and cytochrome oxidase) and sensing (as the NO-sensor soluble guanylate cyclase, the O 2 sensor, and the CO sensor)[1].

Figure 2 .

 2 Figure 2.1: a)The hemoglobin a, b) hemoglobin b.

Figure 2 . 2 :

 22 Figure 2.2: Positions of the a) C , b) C , c) Cm of free base porphyrin.

Figure 2 . 3 :

 23 Figure 2.3: P. Rothemund method.

Figure 2 . 4 :

 24 Figure 2.4: Adler method.

Figure 2 . 5 :

 25 Figure 2.5: Lindsey method.

  control of electronic structure by N-O group with one unpaired electron in a * orbital equally shared by the nitrogen and oxygen atoms. Thus nitroxides are one of the best ligands have potential in many different research area. In porphyrin chemistry nthere are limited reports describing the synthesis and properties of porphyrin-bound nitroxides since the attaching nitroxide radical directly to porphyrin macrocyle is still challenging synthetic point of view.

Figure 2 . 6 :

 26 Figure 2.6: Phenyl nitroxide substituted porphyrins.

Figure 2 . 7 :Figure 2 . 8 :

 2728 Figure 2.7: Isoindoline nitroxide substituted porphyrin.

Figure 2 . 9 :

 29 Figure 2. 9:Copper(II), nickel(II) porphyrin/nitroxide model system.

Figure 2 . 10 :

 210 Figure 2.10:Porphyrins containing a) mono, b) diisoindolin nitroxide moities.

Figure 2 .

 2 Figure 2.11: a)Triphenylmethyl, b)phenalenyl, c)phenoxyls.

Figure 2 . 12 :

 212 Figure 2. 12: Examples of nitroxide ligands a)nitronyl b) imino c) 3-imidazolinyl d)aminoxyls e) aromatic polyaminoxyl.

Figure 2 .

 2 Figure 2. 14: a)Pyrimidinyl nitronyl, b)benzannelated nitroxide.

Figure 2 . 15 :

 215 Figure 2. 15: Synthesis of nitronyl nitroxide.

  , Luneau has described a set of ligands based on functionalization of imidazole and benzimidazole[71]-[74] (Figure 2. 16).

Figure 2 . 16 :

 216 Figure 2. 16: Structure of a)imidazole, b)benzimidazol nitroxide.

Figure 2 . 18 :

 218 Figure 2. 18: Molecular structure of first high spin molecule involving Cu(II) and imino nitroxides ferromagnetically coupled. As conclusion we can say that nitronyl and imino nitroxides are the

Figure 2 .

 2 [START_REF] Knight | Free Radicals, Antioxidants, Aging and Disease[END_REF], in which a bar magnet and a circuital current in a wire are physically equivalent.

Figure 2 . 19 :

 219 Figure 2.19: Magnetic fields due to a) bar magnet, b) circuital current.

Figure 2 . 20 :

 220 Figure 2.20: The arrangement of spins for a) paramagnet, b)antiferromagnet, c)ferrimagnet, d) ferromagnet.

7 )A

 7 typical plot of the effective magnetic moment [ eff] as a function of temperature [T] is shown for an ideal paramagnet, ferromagnet, ferrimagnet, and antiferromagnet in Figure 2.20. For the substance that shows bulk ferromagnetism, a transition occurs at a temperature known as Curie temperature [Tc], leading to a phase in which there is long range parallel ordering of spins. Below this temperature M rises abruptly to a very high value.

Figure 2 . 21 :

 221 Figure 2.21: Temperature dependence of the effective magnetic moment ( eff) in magnetic materials.

Figure 2 . 22 :

 222 Figure 2.22: Hysteresis curve of a ferromagnetically ordered material with memory.

  ferromagnetic behavior. Many spin carrying units are in active use toward building organic based magnets. Examples are, Nitronylnitroxides (NIT), Iminonitroxides (IMI), tButyl-Nitroxides (NO), Verdazyl radicals (VZ), Carbenes, Nitrenes, Phenoxides (ArO), Ketyl radicals, Triphenylmethyl radical (TPM) (Figure 2.23).

Figure 2 . 23 :

 223 Figure 2.23: Some common organic radical units.

Figure 2 .

 2 Figure 2.24: Ullman's reaction.

coworkers 84 (

 84 . i.e. the -Phase of p-nitrophenyl nitronylnitroxide (PNN) with Tc = 0.65 K, exhibiting low magnetic anisotropy and small coercive forces. This discovery evoked the successive rapid development and discovery of other ferromagnets. Most of them are based on nitroxide radicals. After PNN an elegant example was provided by Rassat and his coworkers3 in 1993, namely 1,3,5,7-tetramethyl-2,6-diazaadamantane-N,N´-dioxyl with Tc = 1.48 K. This compound was expected to possess intermolecular ferromagnetic interactions from the orthogonality of the two N-O groups of the biradical, and owing to the favorable 3-D network of NO chains for an intermolecular ferromagnetic interactions. Later in 1995, thiaverdazyl based organic magnet was reported with Tc = 0.67 K4. The dithiadiazolyl radical has also displayed properties smaller than expected for a ferromagnet, but has one of the highest Tc = 36 K so far reported [85]. (Figure 2.25).

Figure 2 . 25 :

 225 Figure 2.25: Pure organic based magnets obtained from NIT, NO, VZ and dithiadiazolyl radicals.

Figure 2 .

 2 Figure 2.26: The ZFS of the Ms levels for an S = 10 system with energy barrier _ E between the ms = -10 and ms = +10 states.The dark red arrow shows a shortcut through the barrier via Quantum Tunneling of the Magnetisation.

  first SMM [Mn12O12(MeCO2)16(H2O)4].2MeCO2H.4H2O, which is shown in Figure 2.27.

Figure 2 . 27 :

 227 Figure 2.27: The frequency dependent peaks seen in the ac susceptibility measurements for the SMM [Mn12O12(MeCO2)16(H2O)4].2MeCO2H.4H2O.

Figure 2 . 28 :

 228 Figure 2. 28: Magnetisation versus field hysteresis loops observed for the SMM [Mn12O12(MeCO2)16(H2O)4].2MeCO2H.4H2O.

  effect. Because the electron has a magnetic moment , it acts like a compass in a magnetic field H. It will have a state of lowest energy where the electron moment is aligned along the local magnetic field (Ms = -½) and a state with highest energy where is aligned against magnetic field (Ms = +½). From quantum mechanics the derived basic equation for ESR is as follows E = Ms ge e H = ±½ ge e H(2.13)

  For rhombic systems due to the lower symmetry of the crystallite the observed g values in different directions (X, Y, and Z) are no longer equal, gxx , gyy gzz. For an axial systems the solid-state anisotropic g values are [gz = g and gx = gy = g ].

Figure 2 .

 2 Figure 2.31: Energy-level scheme illustrating origins of hfc in EPR spectra of NO paramagnetic molecule.

Figure 2 . 32 :

 232 Figure 2.32: Pascal's triangle.

Figure 2 . 33 :

 233 Figure 2. 33: EPR spectra of mono a) nitronyl, b)imino nitroxide free radical.

  14 N = 4) and tri nitronylnitroxide ( 14 N = 6) radicals are given in Figure2.34. For a mono nitronyl nitroxide radical (NIT), we have to considere the interaction of electron spin with only two equivalent nitrogen nuclei 14 N [I = 1], and as seen above this yields, in solution, five lines pattern with intensity distribution 1:2:3:2:1 which contains only information about the nitrogen hyperfine constant AN (I). A more resolved spectrum that shows additionaly the hyperfine interaction with neighboring hydrogen (AH) can be obtained by using argon bubbled solution of concentration c 10 -4 M and low modulation frequency (II). This kind of spectrum gives rich information about the structural environement of the unpaired electron as well the spin density of the different carbons attached to hydrogens, in other words spin polarization pathways. For a bi-nitronyl nitroxide radical, when the intramolecular exchange interaction (J) between the two radical units exceeds the hyperfine constant (AN), we have to consider the interaction of one unpaired electron with four equivalent nitrogen nuclei 14 N (I = 1). This gives in solution nine lines with intensity ratios close to 1:4:10:16:19:16:10:4.1.(III). The integrated intensity of the signal is 2.66 times that of a monoradical, which provides information about the spin concentration. For a tri-nitronyl nitroxide radical, whith J >> AN, the interaction of the electron spin with now six equivalent nitrogens 14 N (I = 1) affords a thirteen line pattern (IV) with the intensity ratio close to 1:6:21:56:96:132:141:132:96:56:21:6:1.

Figure 2 . 34 :

 234 Figure 2.34: Simulated solution state ESR spectrum of the ms = ±1 transition of I) monoNITradical -poorly resolved [AN = 7.4 G; BPP = 1.5 G; L/G = 0.33], II) monoNITradical -well resolved [AN = 7.4 G; 12 H = 0.21G; 2 H = 0.51 G; BPP = 0.18 G; L/G = 0.33]in the limit of J >> AN, III, IV) diNITradicals.

Figure 2 . 35 :

 235 Figure 2.35: Hyperfine coupling of a two spin system having coupling with nuclear spin (I =1) with different J values.

For

  fast electron exchange (i.e., strong coupling) the ground state of the biradical will be either a singlet or a triplet. The ground state of a biradical can be explored by plotting the double integrated signal intensities of the ms = ±1 transitions or the ms = ±2 transitions (forbidden transition -the selection rule ms = ±1 is no longer valid at lower fields; this signal appears exactly at half field of the ms = ±1 transition, also called half field transition) versus inverse temperatures (down to liquid helium temperature). In order to establish the pure intramolecular spin ground state, it is necessary to use lower concentrated solutions [c 10 -3 M] to avoid intermolecular contacts between the molecules. Usually, peak-to-peak signal intensities or better double integrated ms = ±2 transition signal intensities ( ESR) are plotted as a function of inverse temperature. The saturation of the signal can be easily avoided by using lower microwave power. It can be monitored by plotting the observed signal intensities with respect to the square root of the microwave power.For a species having triplet ground state or triplet-singlet nearly degenerate states the signal intensity follows Curie law [ ESR = C/T]. The difference between the singlettriplet ( ES-T) energy levels is equal to 2J and its magnitude and sign can be estimated by fitting the curve of the product of ms = ±2 signal intensity and the temperature ( ESR × T) versus temperature using the Bleany-Bower equation [101]. = [2NAg 2 2 /3kBT ][1+( )exp(-2J/KBT)] -1(2.23)

Figure 3 . 1 :

 31 Figure 3.1: Targeted radical porphyrins.

Figure 3 . 2 : 1 Figure 3 . 3 :

 32133 Figure 3. 2: General synthetic patways for tBuNO tetra radical 1, NITP tetra radical 2 and IMIP tetra radical 3 porphyrins.

Figure 3 . 4 :

 34 Figure 3.4: Synthesis of nitronyl nitroxide.

Figure3. 5 :

 5 Figure3. 5: Synthetic pathways for ATPP, NITP porphyrin 2 and IMIP porphyrin 3.

Figure 3 . 6 :

 36 Figure 3. 6: Mono tBuNO(4), mono NIT(5) and mono IMI(6) nitroxide susbtituted porphyrins synthetic strategies.

Figure 3 . 7 :

 37 Figure 3.7: Synthesis of TBrPP.

Figure 3 . 8 :

 38 Figure 3. 8: FT-IR spectrum of TBrPP.

Figure 3 . 9 :

 39 Figure 3.9: MALDI mass spectrum of TBrPP.

Figure 3 . 10 :

 310 Figure 3.10: Uv-Vis spectrum of TBrPP in CHCl3.

Figure 3 .

 3 Figure 3.11: 1 H NMR spectrum of TBrPP in CDCl3.

Figure 3 . 12 :

 312 Figure 3.12: Mono and di tBuNO radical substituted porphyrins reported by Shultz.

Figure 3 . 13 :

 313 Figure 3.13: Synthesis of mono tBuNO substituted porphyrin.

Figure 3 . 14 :

 314 Figure 3.14: Synthesis work on tetra-tBuNO radical porphyrin.

Figure 3 . 15 :

 315 Figure 3.15: The UV-Vis spectrum of fraction A mono tBuNO substituted free porphyrin 1.10 -6 M in CHCl3.

Figure 3 .

 3 Figure 3.16: The UV-Vis spectrum of fraction B di tBuNO substituted free porphyrin 1.10 -6 M in CHCl3.

Figure 3 .

 3 Figure 3.17: MALDI-MS spectrum of tBuNO porphyrin experiment with DHB matrix.

Figure 3 .

 3 Figure 3.18: MALDI-MS spectrum of tBuNO porphyrin experiment without DHB matrix.

Figure 3 . 19 :

 319 Figure 3.19: Hirel route for BHA synthesis.

Figure 3 . 20 :

 320 Figure 3.20: Chandru's purification method.

target NITP tetra radical 2

 2 was prepared by subsequent condensation reaction of BHA with ATPP by reflux for one day in DCM/ MeOH solvents to afford condensed molecule TPPNOH. The oxidation reaction of TPPNOH was performed in phase transfer solution (CHCl3 / H2O) with NaIO4 solution as oxidant to give radical as dark purple powder.

Figure 3 . 21 :Figure 3 . 22 :

 321322 Figure 3.21: Synthesis of NITP tetra radical 2 and the key building block ATPP. Reagents and conditions: i) n-Bulithium /diethyl ether / DMF / -78 o C, ii) 2,3-Dimethyl-2,3-bis (hydroxylamino) butane (BHA) / MeOH / DCM / reflux, Overnight, iii) NaIO4 / CHCl3 / H2O.

Figure 3 . 23 :

 323 Figure 3.23: Synthesis of ABAB formyl porphyrin. Reagent and conditions: i) Tollyldipyrromethane/4-bromobenzaldehyde/DMSO/90 o C/NH4Cl/9h., ii)diethyl ether/-15 o C/n-butyllithium, 2,5 eqv./2h./DMF, 15 eqv., 30 min/ diluted HCl.

Figure 3 . 24 :

 324 Figure 3.24: Synthesis of 5-formyl, 5,15-diformyl and 5,10-diformyl porphyrin. Reagent and conditions: i) CH2Cl2 / InCl3/ DDQ,1.50 eqv./MeOH and TEA., ,ii)THF/methanol (3:1)/NaBH4(excess)/CH2Cl2 /InCl3 /DDQ/TEA. Hydrolysis: CH2Cl2 /TFA/water (10:1:1), room temp. stirring 2.5 h.

Figure 3 . 25 :

 325 Figure 3.25: Synthesis of 5-formylphenyl porphyrin. Reagent and conditions:i) Pyrrole, BF3•Et2O, CHCl3 (containing 0.75% EtOH), room temp. then p-chloranil, reflux. Hydrolysis: CH2Cl2 /TFA/water (10:1:1), room temp.

Figure 3 . 26 :Figure 3 .

 3263 Figure 3. 26: Synthesis of 5-formyl porphyrin with organosulfur reagent method.Reagent and conditions: i) 1,3-dithiane/n-buLi/TMEDA(N,N,N,Ntetramethylethylenediamine) then H2O/DDQ, ii)DDQ/BF3. Et2O.

protection; 4 -

 4 bromobenzaldehyde was protected by 2,2-dimethylpropane-1,3-diol in toluene catalyzed by p-TsOH to give 1-Bromo-4-(4,4-dimethyl-2,6-dioxan-1yl)benzene in 90% yield, follow by the formylation of the protected product by halogen-lithium exchange reaction (2 eqv. of n-BuLi, THF, -78 o C) giving 4-(4,4-

Figure 3 . 28 :

 328 Figure 3.28: Acetal protected formyl group method.

Figure 3 .

 3 Figure 3.29: FT-IR spectrum of tetra formyl porphyrin ATPP.

Figure 3 .

 3 Figure 3.30: The UV-Vis spectrum of tetra formyl porphyrin ATPP 1.10 -6 M in CHCl3.

Figure 3 .

 3 Figure 3.31: 1 H NMR spectrum of tetra formyl porphyrin ATPP in CDCl3.

Figure 3 . 16 3Figure 3 . 33 :

 316333 Figure 3.32: HR-ESI Mass spectrum of tetra formyl porphyrin ATPP.

Figure 3 .

 3 Figure 3.34: The UV-Vis spectrum of Nitronyl nitroxide substituted porphyrin (2) 1.10 -6 M in CHCl3.

Figure 3 . 35 :Figure 3 . 36 :

 335336 Figure 3.35: Reconvertion of imino nitroxide to nitronyl nitroxide.

  Another synthetic way was to introduce the radical on the precurseur to get a mixture of predominant nitronyl nitroxide radical 2-[4-(4,4-dimethyl-2,6-dioxan-1yl)benzene]-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (9) with some imino nitroxide derivative 2-(4,4-dimethyl-2,6-dioxan-1-yl)benzene]-4,4,5,5tetramethylimidazoline-1-oxyl (10) as described in Figure 3.37.

  ) taking into account that acidic conditions change the nitronyl nitroxide in imino nitroxyde as mention earlier. Accordingly and as expected, only the orange imino derivative was obtained by this way due to treatment by trifluoroacetic acid and further reoxidation by air here in the excellent yield of 98%.. It should be notified that although, 2-(4-benzaldehyde)-4,4,5,5tetramethylimidazoline-3-Oxide-1-oxyl (11) has already been mentioned there were no previous details of the synthesis and lack of EPR spectrometry work which is fundamental characterization tool for radicals[START_REF] Smith | Electrospray mass spectrometry of stable iminyl nitroxide and nitronyl nitroxide free radicals[END_REF].

Figure 3 . 37 :

 337 Figure 3.37: Synthetic strategy for imino nitroxide radical substituted porphyrin.

Figure 3 .

 3 Figure 3.38: 1: FT-IR spectrum of imino nitroxides 10 and 11.

Figure 3 . 39 :

 339 Figure 3. 39: Proposed fragmentation mechanism of nitronyl nitroxide 9.

Figure 3 . 40 :

 340 Figure 3. 40: Proposed fragmentation mechanism of imino nitroxide 10.

Figure 3 . 40 3. 2 . 4 . 5 .

 340245 Figure 3. 41: ESI mass spectrum of imino nitroxide 10.

Figure 3 . 43 :

 343 Figure 3.43: Synthesis of AB 3 BrP.

Figure 3 . 44 :

 344 Figure 3.44: Synthesis of molecule 4.

Figure 3 .

 3 Figure 3.47: MALDI-MS spectrum of AB 3 AP porphyrin.

Figure 3 .

 3 Figure 3.48: 1 HNM spectrum of AB 3 AP porphyrin obtained in CDCl3.

Figure 3 . 49 :

 349 Figure 3.49: Synthesis of molecule 5 and 6.

Figure 3 . 51 :Figure 3 . 52 :

 351352 Figure 3.51: MALDI-MS spectra of a)ATPPCu(II), b) TBrPPCu(II).

Figure 3 .

 3 Figure 3.53: a) Molecular structure of nitroxide, b) stick diagrame, c) resulting EPR signals of mono tBuNO nitroxide moities.

Figure 3 . 54 :

 354 Figure 3.54: General EPR solution spectrum of di-tBuNO radicals.

Figure 3 .

 3 Figure 3.55: a) Molecular structure of nitroxide, b) stick diagrame, c)resulting EPR signals of interaction between the unpaired electron and the 14 N nucleus for nitronyl nitroxide moities.

Figure 3 .

 3 Figure 3.56: a) Molecular structure of nitroxide, b) stick diagrame, c)resulting EPR signals of mono imino nitroxide moities.

Figure 3 . 57 :

 357 Figure 3.57: EPR solution spectra of a) mono tBuNOP (4.028 mW, 60 dB,1G, 1 scan), b) di tBuNOP (4.027 mW, 60 dB,1G, 1 scan) radical porphyrins at c = 1×10 -6 M in CHCl3.

Figure 3 . 58 :

 358 Figure 3.58: EPR solution spectrum of nitroxide substituted radical porphyrin at c = 1×10 -6 M in CHCl3 (2.03 mW, 60 dB,1G, 1 scan).

Figure 3 . 59 :

 359 Figure 3.59: EPR spectrum of precursors 9, 10, 11 at c = 1×10 -6 M in CHCl3.

Figure 3 . 60 :

 360 Figure 3.60: EPR solution spectra of imino radical porphyrin at c = 1×10 -6 M in CHCl3 (6.399 mW, 60 dB,1G, 1 scan).

Figure 3 . 3 . 3 . 5 . 6 Figure 3 . 61 :

 33356361 Figure 3.30 shows the typical seven lines well-resolved EPR spectrum corresponding to a mono imino nitroxide susbtituted porphyrin structure. One should consider that a seven-line profile is typical of an isolated imino nitroxide moieties in solution, but to observe the anisotropic coupling of the corresponding different number of imino nitroxides and to investigate the spin-spin interactions in case of the presence of multi radicals, low temperature (helium temperature) study should be done with freeze-pump-thaw cycles to avoid oxygen effect on spin interactions.

Figure 3 .

 3 Figure 3.62: a)mono tBuNO, b) nitronyl(NIT), c) imino(IMI) nitroxide radical substituted porphyrins.

Figure 3 . 4 5 For

 345 Figure 3.63: a,b) Nitronyl(9,10), c) imino(11) nitroxide mono radical synthons.

Figure 3 . 64 :

 364 Figure 3.64: Molecular structure of a) ATPP, b) ATPPCu(II), c) ATPPMn(III).

  1 H and13 C NMR spectra were recorded on a Varian 500 MHz spectrometer (with the deuterated solvents as the lock and tetramethylsilane as the internal reference). Mass spectra were acquired in linear modes with an average of 50 shots on a Bruker Daltonics Microflex mass spectrometer (Bremen, Germany) equipped with a nitrogen UV-Laser operating at 337 nm. MALDI MS spectra were obtained using 2,5-dihydroxybenzoic acid as the MALDI matrix. ESI MS analyzer was a Bruker Daltonics MicrOTOF mass spectrometer equipped with orthogonal electrospray ionization (ESI) source. The instrument was operated in positive or negative ion mode using a range of m/z 50-3000. The instrument was calibrated with caffeine, Met Arg Phe Ala acetate (MRFA), and Ultramark 1621 (all from Aldrich) in the mass range 195 1822 amu.The X-band EPR measurements were carried at ambient temperature on chloroform solution of tBuNO, nitronyl and imino nitroxide radicals. Column chromatographies were carried out on silica gel Merck-60 (43-63 mesh) and TLC on aluminum sheets precoated with silica gel 60F254 (Merck).2,3-dimethyl-2,3-dinitrobutane 40.8 g(1 mol) NaOH in 170 mL distilated water was put in a 1000 ml of flask.The solution was placed in an ice-bath, then 90 mL(1 mol) of 2-nitropropane was added and stirred for 1h vigorously. 28 mL(0.54 mol) of bromine was added drop by drop and stirred for 1h. Then the temperature rised to room temperature. 320 mL of ethanol was added and refluxed for 3 hr. When heating was stopped white precipitate occoured immediately. 250 mL of wate and ice was added. After filtration white precipitate was washed with water. 95 g 2,3-dimethyl-2,3-dinitrobutane was obtained. Yield %54.

Figure 4 . 1 :

 41 Figure 4.1: Molecular structure of 2,3-dimethyl-2,3-dinitrobutane.

Figure 4 . 2 :

 42 Figure 4.2: Molecular structure of BHA.

Figure 4 . 3 :

 43 Figure 4.3: Molecular structure of 1-Bromo-4-(4,4-dimethyl-2,6-dioxan-1yl)benzene.

Figure 4 . 4 :Figure 4 . 5 :

 4445 Figure 4.4: Molecular structure of molecule 7.

Figure 4 . 6 :

 46 Figure 4.6: Molecular structure of molecule 10.

Figure 4 . 7 :

 47 Figure 4.7: Molecular structure of molecule 11.

Figure 4 . 8 :

 48 Figure 4.8: Molecular structure of monoacetal.

Figure 4 . 9 :

 49 Figure 4.9: Molecular structure of AcetDPM.

Figure 4 . 10 :

 410 Figure 4.10: Molecular structure of AB 3 BrP.

Figure 4 . 12 :

 412 Figure 4.12: Molecular structure of TBrPPZn.

Figure 4 . 13 :

 413 Figure 4.13: Molecular structure of TBrPPCu.

Figure 4 . 14 :

 414 Figure 4.14: Molecular structure of TBrPPMn.

Figure 4 . 15 :

 415 Figure 4.15: Molecular structure of AB 3 AP.

Figure 4 . 17 :

 417 Figure 4.17: Molecular structure of ATPPCu(II).

Figure 4 . 18 :

 418 Figure 4.18: Molecular structure of ATPPMn(III).

  radicals could be identified by EPR studies.UV-visible : , nm, CHCl3, mono tBuNOP: 420; 519; 555; 594; 659. di tBuNOP: 418; 512, 544, 586, 646. ESR : c = 10 -6 , 298 K, = 9.404158 GHz, 6.421 mW, CHCl3. mono tBuNOP : 3 lines, giso=2.0062, aN = 7.38. c = 10 -6 , 298 K, = 9.404158 GHz, 6.421 mW, CHCl3. di tBuNOP: 5 lines, giso=2.0063, aN = 7.36.

Figure 4 . 19 :

 419 Figure 4.19: Molecular structure of 1.

  30 mL of NaIO4 solution (0.25 g 1.2 mmol, 4 eqv) was added slowly to the reaction mixture and the color of solution converted to red/purple color immediately. After stirring for 5 min the mixture was extracted with DCM, dried over Na2SO4 and the residue was chromatographed on silica with a mixture (1:2) Ethyl acetate and Hexane. After evaporation of the solvent, TLC (-heptane/DCM 2:1) was performed to identify the radicals formed. The spots were identified as mixture of not only nitronyl and imino radicals but also non radical porphyrins. Only mono nitronyl nitroxide radical could be identified by EPR studies.UV-visible : , nm, CHCl3: 427; 519; 558; 599; 625.EPR : c = 10 -6 , 298 K, = 9.408191 GHz, 6.406 mW, CHCl3: 5 lines giso=2.0063, aN = 7.39

Figure 4 . 20 :

 420 Figure 4.20: Molecular structure of 2.

Figure 4 . 21 :

 421 Figure 4.21: Molecular structure of 3.

Step 3 : 5 -Figure 4 . 22 :

 35422 Figure 4.22: Molecular structure of 4.

Figure 4 . 23 :

 423 Figure 4.23: Molecular structure of 6.

Figure B1. 2 :

 2 Figure B1.2: IR spectrum of 2,3-bis(hydroxyamino)-2,3-dimethylbutane (BHA).

Figure B1. 3 : 1 H

 31 Figure B1.3: 1 H NMR spectrum of 2,3-bis(hydroxyamino)-2,3-dimethylbutane (BHA) in D2O.

Figure B1. 5 : 1 H

 51 Figure B1.5: 1 H NMR spectrum of 1-Bromo-4-(4,4-dimethyl-2,6-dioxan-1yl) benzaldehyde in CDCl3.

Figure B1. 6 :

 6 Figure B1.6: EPR spectrum of 9 at c = 1×10 -6 M in CHCl3 4.028 mW, 60 dB,1G, 1 scan.

Figure B1. 7 :

 7 Figure B1.7: EPR spectrum of (Iminacet) at c = 1×10 -6 M in CHCl3 4.028 mW, 60 dB,1G, 1 scan.

Figure B1. 8 :

 8 Figure B1.8: EPR spectrum of 11 at c = 1×10 -6 M in CHCl3 4.028 mW, 60 dB,1G, 1 scan.

Figure B1. 9 :

 9 Figure B1.9: IR spectrum of meso-tetra(4-bromophenyl)porphyrin (TBrPP).

Figure B1. 10 :

 10 Figure B1.10: UV-Vis spectrum of meso-tetra(4-bromophenyl)porphyrin (TBrPP) in CHCl3.

Figure B1. 11 :

 11 Figure B1.11: ESI-MS spectrum of meso-tetra(4-bromophenyl)porphyrin (TBrPP).

Figure B1. 12 : 1 H

 121 Figure B1.12: 1 H NMR spectrum of meso-tetra(4-bromophenyl)porphyrin (TBrPP) in CDCl3.

Figure B1. 13 :

 13 Figure B1.13: 13 C NMR spectrum of meso-tetra(4-bromophenyl)porphyrin (TBrPP) in CDCl3.

Figure B1. 14 :

 14 Figure B1.14: IR spectrum of meso-tetra(p-bromophenyl)porphyrinato Zn(II) (TBrPPZn).

Figure B. 1 .

 1 Figure B.1.15: UV-Vis spectrum of meso-tetra(p-bromophenyl)porphyrinato Zn(II) (TBrPPZn) in CHCl3.

Figure B1. 16 :

 16 Figure B1.16: ESI-MS spectrum of meso-tetra(p-bromophenyl)porphyrinato Zn(II) (TBrPPZn).

Figure B. 1 . 17 : 1 H

 1171 Figure B.1.17: 1 H NMR spectrum of meso-tetra(p-bromophenyl)porphyrinato Zn(II) (TBrPPZn).

Figure B. 1 .

 1 Figure B.1.18: 13 C NMR spectrum of meso-tetra(p-bromophenyl)porphyrinato Zn(II), (TBrPPZn).

Figure B1. 19 :

 19 Figure B1.19: MALDI-MS spectrum of meso-tetra(p-bromophenyl)porphyrinatoCu(II), (TBrPPCu).

Figure B1. 20 :

 20 Figure B1.20: UV-Vis spectrum of meso-tetra(p-bromophenyl)porphyrinato Cu(II) (TBrPPCu) in CHCl3.

Figure B1. 21 :

 21 Figure B1.21: MALDI-MS spectrum of meso-tetra(p-bromophenyl)porphyrinatoMn(III), (TBrPPMn).

Figure B1. 22 :

 22 Figure B1.22: UV-Vis spectrum of meso-tetra(p-bromophenyl)porphyrinato Mn(III), (TBrPPMn).

Figure B1. 23 :

 23 Figure B1.23: UV-Vis spectrum of 5-(4-formylphenyl)-10,15,20-triphenylporphyrin (AB3AP) in CHCl3.

Figure B1. 24 :

 24 Figure B1.24: MALDI-MS spectrum of 5-(4-formylphenyl)-10,15,20triphenylporphyrin (AB3AP).

Figure B1. 25 : 1 H

 251 Figure B1.25: 1 H NMR spectrum of 5-(4-formylphenyl)-10,15,20triphenylporphyrin (AB3AP) in CDCl3.

Figure B1. 26 :

 26 Figure B1.26: MALDI-MS spectrum of meso-tetra(4-formlyphenyl)porphyrin (ATPP).

-

Figure B1. 27 : 1 H

 271 Figure B1.27: 1 H NMR spectrum of meso-tetra(4-formlyphenyl)porphyrin (ATPP) in CDCl3.

Figure B1. 28 :

 28 Figure B1.28: UV-Vis spectrum of meso-tetra(4-formlyphenyl)porphyrin (ATPP) in CHCl3.

Figure B1. 29 :

 29 Figure B1.29: IR spectrum of meso-tetra(4-formlyphenyl)porphyrin (ATPP).

Figure B1. 30 :

 30 Figure B1.30: UV-Vis spectrum of meso-tetra(4-formylphenyl)porphyrinato Cu(II), ATPPCu(II).

FigureB1. 31 :

 31 FigureB1.31: MALDI-MS spectrum of meso-tetra(4-formylphenyl)porphyrinatoCu(II), ATPPCu(II).

Figure B1. 32 :

 32 Figure B1.32: UV-Vis spectrum of meso-tetra(4-formylphenyl)porphyrinatoMn(III) in CHCl3.

Figure B1. 33 :

 33 Figure B1.33: UV-Vis spectrum of meso-tetra(4-formylphenyl)porphyrinatoMn(III) in CHCl3.

Table 2 .

 2

1: Porphyrin synthetic methods.

  .2).Low temperature is crucial to avoid decomposition of n-Buthyllithium reagent as well as to control the number of nBu-Li equivalent to be introduced (see Table3.2). For bromo-lithium exchange it is habitual to work at -78 o C. Due to solubilty problem in diethylether, higher temperatures were tested to carry out the reaction.

	However, the best results were obtained at -78 o C and with 10 equiv of n-BuLi for
	synthesis of tBuNO radical porphyrin.
	Tablo 3. 2: Temperature studies for synthesis of in Diethyl ether.
	entry Temp. ( o C) Radical number
	1	-78	-mono and -di
	2	-50	-mono and -di
	3	-25	-mono and -di
	4	0	-no radical
	Tablo 3. 3: Different equivalent studies of n-BuLi for synthesis of tBuNOP
		in Diethyl ether.
	Entry n-BuLi (mol/ eqv) Radical number
	1	6.25 eqv.	-mono and -di
	2	10 eqv.
	Tablo 3. 1: Solvent studies for solubility problem of porphyrin.
	entry Solvent (mL)		Radical
				number
	1	Diethyl ether, 25 mL -mono and -di
	2	Diethyl ether, 50 mL	-mono and -di
	3	THF, 25 mL		-no radical

  , 33) increase dramatically.

	Tablo 3. 4: Uv-Vis spectra data of TBrPP and tBuNO substituted porphyrins fraction
		A and B in CHCl3.
	Compound	Q band max	Soret(B) bands max
	TBrPP	418	512, 547, 588, 644
	fraction -A	420	514, 544, 590, 648
	fraction-B	418	512, 544, 586, 646

  Tablo 3. 5: different reaction conditions for ATPP.

	Solvent (mL)	Temp. ( o C)	n-BuLi (mol/
			equiv)
	Diethyl ether, 25 mL	-78	6.25 eqv.
	Diethyl ether, 50 mL	-78	6.25 eqv.
	Diethyl ether, 50 mL	-50	6.25 eqv.
	Diethyl ether, 50 mL	-50	10 eqv.
	Diethyl ether, 50 mL	-50	25 eqv.
	Diethyl ether, 50 mL	-50	32 eqv.

  Tablo 3. 8: Uv-Vis spectra data of ATPP and IMIP in CHCl3.

	Compound	Q band max	Soret(B) bands max
	ATPP	420	517, 552, 592, 647
	IMIP	428	522, 559, 599, 654

  Tablo 3.9: Uv-Vis spectra data of AB 3 BrP and Molecule 4 in CHCl3.

	Entry	B band max (nm)	Q bands max (nm)
	AB 3 BrP	418	522, 556, 596, 652
	Molecule 4	420	522, 556, 596, 654

  Then the resulting emulsion was extracted with chloroform, dried with Na2SO4 and evaporated to dryness at 45 o C. 0.07 g AB3A free poprhyrin was separated by coloumn chromatography diethyl ether/ DCM 1:9. At the end of the reaction TPP was taken back without reacting. Yield % 35.

	8.79 (d, 2H, CHfpyrrole), 8.78 (s, 2H, CHgpyrrole), 10.31(s, H, COH). UV-visible : ,
	nm, CHCl3, 419; 516; 550; 591; 648. Mass (MALDI-MS, m/z) : 643.310 [M+H] + ,
	(C46H30N4O).

1 H NMR : (ppm), CDCl3, -2.84 (s, 2H, NH), 7.66 (m, 15H, CHAr-phenyl), 7.66 (d, 2H, CHa-phenyl), 8.13 (d, 2H, CHbphenyl), 8.21(d, 2H, CHc-pyrrole), 8.32(d, 2H, CHd-pyrrole), 8.71 (d, 2H, CHepyrrole),

  Figure B1.4: 1 H NMR spectrum of 1-Bromo-4-(4,4-dimethyl-2,6-dioxan-1yl) benzene in CDCl3.

	7.508	7.416			5.363	3.764	3.670	1.297	0.814
		2.24	2.00			1.00		2.41	2.13	3.44	3.25
			10.032	7.916	7.705	5.458			3.785	3.699	1.300	0.825
									10000
									50000
									0
			0.98		2.02	2.00	1.00		2.08 2.12	3.27	3.18
			10.0				5.0
	ppm (t1)

ACKNOWLEDGEMENTS

I am grateful to my advisor, Prof. Dominique Luneau and Dr. Catherine HIREL for their support and encouragement during the journey described in this doctoral Dissertation. Thank you, for your guidance through scientific and non-

LIST of FIGURES

Characterization Work of AB 3 AP

According to traditional preparative procedures to generate metalloporphyrins, free base porphyrin is generally reacted with a large excess of metal salt or metal carbonyl in high boiling solvents.

To obtained ATPPMn(III) [START_REF] Lahaye | Design and synthesis of manganese porphyrins with tailored lipophilicity: Investigation of redox properties and superoxide dismutase activity[END_REF], [START_REF] Borovkov | Convenient Method for Efficient Iron and Manganese Ion Insertion into Various Porphyrins under Mild Conditions[END_REF] Mn(OAc)2 was chosen as metal source and CHCl3/MeOH as solvent system that present the advantage of being easy removable from reaction media. ATPPCu(II) and TBrPPCu(II) were obtained by MW irradiation in short time (30 min) with 70-90 % yield from ATPP. Dry DMF was chosen as efficient conducting solvent, its high polarity (6.4) and dielectric constant (37.7) which makes it MW active solvent. Secondly, Cu(OAc)2.H2O was highly soluble of in DMF.

Appendix B: Spectra