Les matériaux magnétiques à base moléculaire sont généralement faiblement colorés. Une étude en parallèle des propriétés optiques et magnétiques est alors envisageable. Nous avons étudié la complémentarité entre propriétés magnétiques et optiques dans les composés à base de Mn2+ et Cu2+. L'intéraction entre les électrons célibataires des ions métalliques est du type échange à travers un ligand pontant organique. Les systèmes Mn2+Cu2+ étudiés présentent des topologies différentes : de la molécule isolée au système infini. Nos études ont permis de mettre en évidence l'exaltation des bandes d'absorption de l'ion Mn2+ acitvées par un mécanisme d'échange. A partir des variations thermiques des bandes d'absorption de l'ion Mn2+ nous avons déterminé la valeur de la constante d'interaction entre les ions métalliques dans l'état électronique fondamental du système, valeur qui est en bon accord avec celle déterminée par les mesures magnétiques. De plus les mesures optiques, contrairement aux mesures magnétiques, nous ont également permis d'évaluer la valeur constante d'interaction lorsque un ion Mn2+ est dans un état électronique excité.

A new type of organometallic polymer networks with a covalent structure of cross-linked substituted polyacetylenes containing Cu2+ or Pd2+ ions (5 to 17 wt%) has been developed. The metal ions were complexed in the networks predominantly with two N-salicylideneaniline ligands covalently bound to two different network monomeric units. Due to the chosen method of complexation, the metal ions have actively participated (as knots of the network) in the formation of cross-linked architecture of the products. For the preparation of organometallic networks two independent methods were used: (i) the direct polymerization of organometallic monomers and (ii) the two-stage method using postpolymerization introduction of metal ions into polyacetylene polymers containing covalently bound N-salicylideneaniline proligands. The starting low-molecular-weight blocks used for the network synthesis were new substances prepared within the framework of the diploma thesis, namely monomers of the mono- and diethynylated N-salicylideneanilines type and diethynylated organometallic monomers in which two molecules of a monoethynylated N-salicylideneaniline complexed one Mt2+ ion. The ethynylated monomers were polymerized to organometallic networks or precursors of these networks via chain-growth coordination polymerization,...

Aujourd'hui, avec l'augmentation de la population, la consommation de médicaments et de produits phytosanitaires dans l'agriculture a considérablement augmenté. Cela devient inquiétant car une grande partie de ces molécules, rejetée dans l'environnement, ne sont pas bien éliminées par les stations d'épuration (lorsqu'elles existent). En trop grande quantité, ces produits deviennent des poisons pour tous les organismes vivants, y compris l’Homme.Des méthodes analytiques classiques pour la mesure de ces produits chimiques existent déjà (méthodes séparatives classiques telles que la chromatographie en phase gazeuse, la chromatographie liquide à haute performance, éventuellement couplée à la spectrométrie de masse, etc.). Cependant, même si elles sont extrêmement précises et fiables, ces techniques sont difficiles à appliquer pour la surveillance sur site et sont généralement coûteuses. Pour cette raison, ma thèse se concentre sur de nouvelles approches analytiques pour détecter de petites molécules en milieu aqueux, telles que ces polluants. Dans une première partie de mon travail, j’ai développé un immunocapteur basé sur une complexation compétitive originale et sur une transduction électrochimique (ampérométrique), pour la détection du diclofénac, un anti - inflammatoire non stéroïdien généralement utilisé pour réduire l’inflammation et soulager la douleur. L'électrode de travail a été fonctionnalisée par deux sels de diazonium, l'un utilisé comme sonde moléculaire (un dérivé du diclofénac couplé à une arylamine) et l'autre comme sonde redox (une quinone) également couplée à une arylamine, capable de transduire l'association haptène-anticorps par une variation de son électroactivité ; en particulier, la transduction a été conçue pour délivrer une augmentation de courant lors de la détection du diclofénac (soit une détection « signal-on »). J’ai montré une limite de détection d’environ 20 fM dans l'eau du robinet, ce qui rend ce type de capteur très compétitif. Dans la suite de mon travail, j'ai conservé la même approche de transduction originale (immunoreconnaissance compétitive) mais appliquée à un transistor à effet de champ organique à grille électrolytique (EGOFET) dont le semiconducteur est le poly (N-alkyldiketopyrrolo-pyrrole dithiénylthiéno [3,2-b ] thiophène) (DPP-DTT) et dont l'électrode de grille a été fonctionnalisée par électrogreffage d'un sel de diazonium fonctionnel capable de lier un anticorps spécifique de l'acide 2,4-dichlorophénoxyacétique (2,4-D), un herbicide courant. Le design de la sonde moléculaire a été rationalisée par modélisation moléculaire afin d’optimiser la capture de l’anticorps en surface de grille. Dans la dernière partie de mon travail, je propose une approche qui met à profit à la fois le couplage capacitif de l'EGOFET mais aussi sa sensibilité aux charges électrostatiques accumulées en surface de grille. J'ai immobilisé en surface de grille un peptide court (Gly-Gly-His) connu pur avoir une forte affinité envers les ions cuivre Cu2+. Le peptide a été immobilisé par électro-oxydation directe de l'amine primaire du premier fragment glycine. J’ai démontré que les dispositifs EGOFET, modifiés par GGH, peuvent transduire la complexation de Cu2+ par des variations significatives de leurs caractéristiques de sortie et de transfert, en particulier par un décalage de la tension de seuil (VTh). / Today, with the increase of population, the consumption of drugs and of chemicals in agriculture has dramatically increased. It becomes a worrisome issue because a large amount of these molecules, excreted to the environment, are not well eliminated by water-treatment plants (when they exist) and are therefore released without control into the ecosystem. In too large quantities, these drugs are poisons for living organisms, including humans. Classical analytical methods for the measurement of these chemicals already exist (classical separative methods such as gas chromatography, high-performance liquid chromatography, possibly coupled with mass spectrometry, etc). However, even if extremely precise and reliable, these techniques are difficult to apply for on-site monitoring and are usually costly. For this reason, my thesis focuses on novel analytical approaches to detect small organic molecules such as these pollutants. In a first part of my work, I developped an original immunosensor based on a competitive complexation and on an electrochemical (amperometric) transduction, for detection of diclofenac, which is a non – steroidal anti – inflammatory drug generally employed to protect patients from inflammation and relieve pain. The working electrode was electrografted with two functional diazonium salts, one as molecular probe (a diclofenac derivative coupled with an arylamine) and the other as redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The transduction was designed to deliver a current increase upon detection of diclofenac (“signal-on” detection). The detection limit is ca. 20 fM in tap water, which is competitive compared to other label-free immunosensors. In the following part of my thesis, I kept the same original transduction approach (competitive immunoassay) but applied to an Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) based on poly(N-alkyldiketopyrrolo-pyrrole dithienylthieno[3,2-b]thiophene) as organic semiconductor whose gate electrode was functionalized by electrografting a functional diazonium salt capable to bind an antibody specific to 2,4-dichlorophenoxyacetic acid (2,4-D), an herbicide well-known to be a soil and water pollutant. Molecular docking computations were performed to design the functional diazonium salt to rationalize the antibody capture on the gate surface. In the last part of my work, I propose an approach which takes profit not only of the capacitive coupling of the EGOFET but also on its sensitivity to electrostatic charges accumulated on the gate surface. To illustrate this in the field of sensors, I used a short peptide (Gly-Gly-His), known to selectively bind copper ions Cu2+. The peptide was immobilized by direct electrooxidation of the primary amine of the first glycine moiety. I demonstrated that GGH-modified EGOFETs can transduce Cu2+ complexation through significant changes of their output and transfer characteristics, in particular their threshold voltage (VTh).

La molécule de méthane possède la liaison C-H la plus forte parmi les hydrocarbures (BDE = 104 kcal mol-1) : son oxydation en conditions douces représente un challenge d'importance. La Méthane Monoxygénase particulaire (pMMO) est une enzyme à cuivre qui catalyse l'oxydation du méthane (CH4) en méthanol (CH3OH). Le site actif de l'enzyme est composé d'atomes de cuivre séparés par 2.6 Å. Des recherches récentes suggèrent qu'un cluster Cu2 III,II/O2 à valence mixte soit un intermédiaire-clé du cycle catalytique. L'objectif de ce travail vise à la synthèse et caractérisation de nouveaux complexes dinucléaires à valence mixte de type bis(µ-oxo)Cu2 III,II ou (µ-OH, µ-O)Cu2 III,II. Deux familles de motifs coordinants ont été mises en oeuvre, polypyridyle ou polyamide ; les deux sites sont assemblés par des ponts courts et rigides, phenoxo, naphthyridine ou alkoxo. De nouveaux complexes ont été caractérisés par électrochimie, spectroscopies UV-visible et RPE, et par des calculs théoriques. Un dispositif original de cryo-spectroélectrochimie UV-vis-NIR a été développé en parallèle de cette étude : il permet l'identification spectroscopique d'intermédiaires transitoires, réputés très instables à température ambiante. De nouveaux composés à valence mixte, Cu2 III,II(μ-OH, μ-O) et Cu2 III,IIbis(μ-OH) ont été identifiés. Ces résultats élargissent le champ des données de cette famille d'intermédiaires instables limitée jusqu'ici à un seul exemple. / Methane has the strongest C-H bond of any hydrocarbon (BDE = 104 kcal mol-1); its oxidation under mild conditions remains a great challenge. The particulate Methane Monooxygenase (pMMO) is a copper enzyme that oxides methane (CH4) to methanol (CH3OH). In the active site of the enzyme, two copper ions are located at a short distance (2.6 Å). Recent researches have suggested a mixed-valent Cu2III,II/O2 cluster as a key intermediate in the catalytic cycle. The main objective of this work was the synthesis and characterization of new mixed-valent CuIIICuII bis(μ-oxo) and (μ-OH, μ-O) dinuclear complexes. For this purpose we designed promising symmetrical and unsymmetrical complexes based on specific and distinct scaffolds for each side of the structure. Two families of coordination pattern have been used, polypyridyle or polyamide; the two sites are shortly and rigidly bridged by phenoxo, alkoxo or naphthyridine linkers. New complexes have been characterized by electrochemistry, UV-vis and EPR spectroscopies, and by theoretical calculations. A new cryo-UV-Vis-NIR spectroelectrochemical set up, developed in parallel during this work, has allowed the spectroscopic identification of these transient intermediate species, known to be unstable at room temperature. New mixed-valence Cu2 III,II(μ-OH, μ-O) and Cu2 III,IIbis(μ-OH) complexes have been characterized. These results expand the recent knowledge on the only mixed valent CuIII(μ-OH)CuII species described so far.

Thermoelectric (TE) materials directly convert heat energy into electrical energy. The conversion efficiency of the TE devices depends on the performance of the materials. The conversion efficiency of available thermoelectric materials and devices is low. Therefore, the development of new materials for improving thermoelectric device performance is a highly essential. As the performance of the TE materials depends on TE figure of merit [zT=S2P T ] which consist of three material properties such as Seebeck coefficient (S), electrical resistivity ( ) and thermal conductivity ( ). Thermoelectric figure of merit can be improved by either increase of power factor or decreasing of thermal conductivity or by both. In the present thesis, Cu based chalcogenide compounds are chosen for the study of thermoelectric properties because of their complex crystal structure, which leads to lower values of thermal conductivity. Also, the power factor of these materials can be tuned by the partial substitution doping. In the present thesis, Cu based chalcogenide compounds quaternary chalcogenide compound (Cu2ZnSnSe4), ternary compounds (Cu2SnSe3 and Cu2GeSe3) and tetrahedrite materials (Cu12Sb4S13) have been prepared by solid state synthesis. The prepared compounds are characterized by XRD for the phase identification, Raman Spectroscopy used as complementary technique for XRD, SEM for surface morphology and EPMA for the phase purity and elemental composition analysis respectively. For the evaluation of zT, thermoelectric properties of all the samples have been studied by measuring Seebeck coefficient, resistivity and thermal diffusivity. In the chapter 1, a brief introduction about thermoelectricity and its effects is discussed. Thermoelectric materials parameters such as electrical resistivity, Seebeck coefficient and thermal conductivity for different class of materials are mentioned. The selection of thermoelectric materials and the motivation for choosing the Cu based chalcogenide compounds for thermoelectric applications are discussed. In chapter 2, the details of the experiments carried out for Cu based chalcogenide compounds are presented. In chapter 3, the effect on thermoelectric properties by the cation substitution on quaternary chalcogenide compound Cu2+xZnSn1 xSe4 (0, 0.025, 0.05, 0.075, 0.1, 0.125, and 0.15) is studied. The electrical resistivity of all the samples decreases with an increase in Cu content except for Cu21ZnSn09Se4, most likely due to a higher content of the ZnSe. All the samples showed positive Seebeck coefficients indicating that holes are the majority charge carriers. The thermal conductivity of doped samples was higher as compared to Cu2ZnSnSe4 and this may be due to the larger electronic contribution and the presence of the ZnSe phase in the doped samples. The maximum zT = 0.23 at 673 K is obtained for Cu205ZnSn095Se4. In chapter 4, the effect of multi{substitution of Cu21ZnSn1 xInxSe4 (0, 0.05, 0.075, and 0.1) on transport properties were studied. The Rietveld powder X-ray diffraction data accompanied by electron probe microanalysis (EPMA) and Raman spectra of all the samples con firmed the formation of a tetragonal kesterite structure. The electrical resistivity of all the samples exhibits metallic-like behavior. The positive values of the Seebeck coefficient and the Hall coefficient reveal that holes are the majority charge carriers. The co-doping of copper and indium leads to a significant increase of the electrical resistivity and the Seebeck coefficient as a function of temperature above 650 K. The thermal conductivity of all the samples decreases with increasing temperature. Lattice thermal conductivity is not significantly modified as the doping content may infer negligible mass fluctuation scattering for copper zinc and indium tin substitution. Even though, the power factors (S2 ) of indium-doped samples Cu21ZnSn1 xInxSe4 (x=0.05, 0.075) are almost the same, the maximum zT=0.45 at 773 K was obtained for Cu21Zn09Sn0925In0075Se4 due to its smaller value of thermal conductivity. In chapter 5, thermoelectric properties of Zn doped ternary compounds Cu2ZnxSn1 xSe3 (x = 0, 0.025, 0.05, 0.075) were studied. The undoped com\pound showed a monoclinic crystal structure as a major phase, while the doped compounds showed a cubic crystal structure confirmed by powder XRD (X-Ray Diffraction). The electrical resistivity decreased up to the samples with Zn content x=0.05 in Cu2ZnxSn1 xSe3, and slightly increased in the sample Cu2Zn0075Sn0925Se3 . This behavior is consistent with the changes in the carrier concentration confirmed by room temperature Hall coefficient data. Temperature dependent electrical resistivity of all samples showed heavily doped semiconductor behavior. All the samples exhibit positive Seebeck coefficient (S) and Hall coefficient indicating that the majority of the carriers are holes. A linear increase in Seebeck coefficient with increase in temperature indicates the degenerate semiconductor behavior. The total thermal conductivity of the doped samples increased with a higher amount of doping, due to the increase in the carrier contribution. The total and lattice thermal conductivity of all samples decreased with increasing of temperature, which points toward the dominance of phonon scattering at high temperatures. The maximum zT = 0.34 at 723 K is obtained for the sample Cu2SnSe3 due to a low thermal conductivity compared to the doped samples. In chapter 6, thermoelectric properties of Cu2Ge1 xInxSe3 (x = 0, 0.05, 0.1, 0.15) compounds is studied. The powder X-ray diffraction pattern of the undoped sample revealed an orthorhombic phase. The increase in doping content led to the appearance of additional peaks related to cubic and tetragonal phases along with the orthorhombic phase. This may be due to the substitutional disorder created by indium doping. The electrical resistivity ( ) systematically decreased with an increase in doping content, but increased with the temperature indicating a heavily doped semiconductor behavior. A positive Seebeck coefficient (S) of all samples in the entire temperature range reveal holes as predominant charge carriers. Positive Hall coefficient data for the compounds Cu2Ge1 xInxSe3 (x= 0, 0.1) at room temperature (RT) con rm the sign of Seebeck coefficient. The trend of as a function of doping content for the samples Cu2Ge1 xInxSe3 with x = 0 and 0.1 agrees with the measured charge carrier density calculated from Hall data. The total thermal conductivity increased with rising doping content, attributed to an increase in carrier thermal conductivity. The thermal conductivity decreases with increasing temperature, which indicates the dominance of Umklapp phonon scattering at elevated temperatures. The maximum thermoelectric figure of merit (zT) = 0.23 at 723 K was obtained for Cu2In01Ge09Se3. In chapter 7, thermoelectric properties of Cu12 xMn1 xSb4S13 (x = 0, 0.5, 1.0, 1.5, 2.0) samples were studied. The Rietveld powder XRD pattern and Electron Probe Micro Analysis revealed that all the Mn substituted samples showed a single tetrahedrite phase. The electrical resistivity increased with increasing Mn due to substitution of Mn2+ on the Cu1+ site. The positive Seebeck coefficient for all samples indicates that the dominant carriers are holes. Even though the thermal conductivity decreased as a function of increasing Mn, the thermoelectric figure of merit (zT) decreased, because the decrease of the power factor is stronger than the decrease of the thermal conductivity. The maximum zT = 0.76 at 623 K is obtained for Cu12Sb4S13. In chapter 8, the summary and conclusion of the present work is presented.