The electrochemic's behaviour of the bile acids (cholic, glycocholic, deoxycholic, ursodeoxycholic and lithocholic acid) was studied on the meniscus-modified silver solid amalgam electrode (m-AgSAE) by differential pulse voltammery. Bile acids provide in the solution of the Britton - Robinson buffer and methanol (9:1) in the pH range 3.0 to 12.0 a cathodal signal in the high negative potentials: cholic acid, deoxycholic acid, ursodeoxycholic acid and lithocholic acid about −1400 mV and glycocholic acid, which alone is the conjugate with glycine, about −1500 mV. Cholic acid, glycocholic acid, deoxycholic acid and ursodeoxycholic acid provide the highest peaks to pH 5.0, approximately in their pKa values. Lithocholic acid provides peaks from pH 7.0. It was demonstrated by the cyclic voltammetry that the electrochemical behavior is influenced by the adsorption of the bile acids to the electrode; presumed reaction at the working electrode - a reduction of a proton of a carboxylic group, is controlled by the diffusion and the process is quasireversible. Utilization of the electrochemical reduction of bile acids for the voltammetric determination does not seem very suitable. It has been proven that the presence of the methanol deteriorates the measuring results for glycocholic acid. In the presence of...

This work studies various electrical properties of polymer layers of polyaniline, polythiophenes and poly(((benzothiadiazol)4,7-di(thien-2-yl)-5,6-difluoro-2,1,3-benzothiadiazol). Goal of this work is to determine electrical and photoelectrical properties as are electric conductivity, mobility of the free charge carriers, work function of the electrons and diffusion length of excitons. Conductivity was obtained through current and voltage contacts, mobility was measured by CELIV method (charge extraction by linearly increasing voltage). To determine work function a Kelvin probe was built and utilized. Diffusion length of excitons was determined from photovoltage spectrum formed by illuminating space charge region of the polymer.Space charge region on surface of the polymer can arise spontaneously or by laying suitable contact electrode. Powered by TCPDF (www.tcpdf.org)

In der vorliegenden Dissertation geht es um die Synthese und Charakterisierung chiraler, redoxaktiver (Raumtemperatur-)Ionischer Flüssigkeiten basierend auf Ferrocen und der natürlich vorkommenden Aminosäure S-Prolin. Diese Baueinheiten sind entweder über eine Ether- oder über eine Esterverbrückung verknüpft. Auch der Anionenaustausch vom I– - zum CF3SO3– - sowie (CF3SO2)2N– -Salz (kurz NTf2–) wird dargelegt und der Einfluss des Anions auf den Schmelzpunkt der Verbindungen untersucht und diskutiert. Die Redoxaktivität wird durch das im Ferrocen enthaltene Fe II eingebracht, das reversibel zu Fe III oxidiert werden kann. Aufgrund des Pyrrolidin-Rings sind die dargestellten Verbindungen stets chiral und bilden nach der Quaternisierung mit Halogenalkanen Diastereomere, soweit die Alkylkette größer als Methyl ist. Das Diastereomerenverhältnis wurde mittels 1H-NMR-Spektroskopie und in einem Fall anhand von Röntgenpulverdiffraktogrammen durch Rietveld-Verfeinerung analysiert. Die Verbindungen wurden thermisch anhand simultaner thermischer Analysenund Tieftemperaturversuchen untersucht, die belegen, dass die Synthese von insgesamt sechs neuen Raumtemperatur-Ionischen Flüssigkeiten gelang. Davon basiert eine Verbindung, (1S2S)- und (1R2S)-2-[(Ferrocenylcarbonyl)oxy]methylen-N-methyl-N-pentylpyrrolidin-1-iumiodid, auf I– und fünf Verbindungen enthalten NTf2– als Gegenion. Das Diastereomerengemisch der Verbindungen (1S2S)- und (1R2S)-N-Butyl-2-[(ferrocenylcarbonyl)oxy]methylen-N-methylpyrrolidin-1-ium NTf2– besitzt den größten Flüssigkeitsbereich von -25 bis +263 °C und auch die höchste Zersetzungstemperatur aller hier dargestellten Verbindungen. Insgesamt werden in dieser Arbeit elf Einkristallstrukturanalysen vorgestellt, wobei es sich um drei Verbindungen des Typs FcCH2N(CH3)2(CnH2n+1)I (Fc = Ferrocenyl, n = 1,2,3), Ferrocenmonocarbonsäurechlorid, zwei ether- sowie fünf esterverbrückte Verbindungen handelt. Mikrokristalline Proben wurden mittels Röntgenpulverdiffraktometrie charakterisiert. Ergänzende Analysen wurden mittels UV-Vis- und IR-Spektroskopie sowie Massenspektrometrie und Elementaranalyse durchgeführt. Ein wichtiger Aspekt bei Ferrocenverbindungen ist das Redoxpotential, welches mittels Cyclovoltammetrie bestimmt wurde. Hierbei liegt das Formalpotential des Fe II /Fe III -Redoxpaars der etherverbrückten Verbindungen bei +0,05 V und bei den esterverbrückten Verbindungen unabhängig vom Anion bei +0,28 V vs. Ferrocen/Ferrocenium in Acetonitril. Bei den iodidhaltigen Verbindungen zeigt das I– -Ion ebenfalls eine Redoxaktivität bei E(0,f,Fc) = -0,18 V und 0,22V. Die Diffusionskoeffizienten der esterverbrückten Triflat- und NTf2– -Verbindungen liegen in der Größenordnung von 7·10−6 cm2/s und die heterogenen Geschwindigkeitskonstanten bei 0,01 cm/s. / The present dissertation deals with the synthesis and characterization of chiral, redoxactive room temperature ionic liquids (RTILs) based on ferrocene and the naturally occurring amino acid S-proline. These building blocks are coupled either via an ether- or an ester-bridge. The anion exchange from I– to CF3SO3– and (CF3SO2)2N– salts (abbreviated as NTf2–) is presented. The influence of the anion on the melting point of the compound is investigated and discussed. The redox activity is introduced into the molecule via the Fe II -containing ferrocenyl groups, which can be oxidized reversibly to Fe III . The synthesized compounds based on the pyrrolidine ring are chiral. After quaternization with alkyl halides, they form diastereomers in case of alkyl chains longer than methyl. The ratio of the different diastereomers was analyzed by 1H NMR spectroscopy and, in one case, by Rietveld refinement of the X-ray powder diffraction pattern. The thermal behavior of the compounds was studied by simultaneous thermal analysis and low temperature experiments. The results show the successful synthesis of six new RTILs. One of them is based on iodide ((1S2S)- and (1R2S)-2-[(ferrocenylcarbonyl)oxy]methylene-N-methyl- N-pentylpyrrolidine-1-ium iodide) and six RTILs contain NTf2– as counter ion. The diastereomeric mixture of compounds (1S2S)- and (1R2S)-N-butyl-2-[(ferrocenylcarbonyl)oxy]methylene-N-methylpyrrolidine-1-ium NTf2– exhibits the widest liquid range from -25 to +263 °C and the highest decomposition temperature of all compounds presented herein. Eleven single crystal structure analyses are presented. Three of them belong to compounds FcCH2N(CH3)2(CnH2n+1)I (with Fc = ferrocenyl and n = 1,2,3), then ferrocene monocarboxylic acid chloride, two of ether- as well as five ester-bridged compounds. Microcrystalline samples were characterized by X-ray powder diffractometry. Supplementary analyses by UV/Vis and IR spectroscopy as well as mass spectrometry and elemental analyses have been carried out. An important feature of ferrocene containing compounds is their redox potential which is determined with cyclic voltammetry. The formal potential of the Fe II /Fe III redox couple in the ether-bridged compounds is at +0.05 V and in the ester-bridged compounds independent from the type of anion at +0.28 V vs. ferro- cene/ferrocenium in acetonitrile. The I– anion shows as well redox activity with formal potentials at E(0,f,Fc) = -0.18 V and 0.22 V. The diffusion coefficients of the ester-bridged triflate and NTf2– compounds are in the order of 7·10−6 cm2/s, the heterogeneous rate constants in the order of 0.01 cm/s.

Considerando a relevância dos trabalhos onde se utiliza eletrodos quimicamente modificados e o pequeno número de estudos envolvendo cocaína e seus interferentes (cafeína, teobromina e lidocaína), por técnicas eletroquímicas ou piezelétricas, este estudo tem como objetivo o desenvolvimento de eletrodos de ouro e platina quimicamente modificados com compostos da classe das cucurbiturilas (CB[5], CB[6] e CB[7]) para a detecção de cocaína. A técnica de microbalança de cristal de quartzo foi empregada a fim de se estudar cocaína padrão e seus interferentes, em fase gasosa. Os eletrodos de ouro foram quimicamente modificados com cucurbiturilas e o modificador CB[6] apresentou os melhores resultados. Medidas por voltametria cíclica foram realizadas utilizando-se um potenciostato Autolab III acoplado a um computador, com eletrodo de ouro e platina atuando como eletrodo de trabalho, Ag/AgCl como eletrodo de referência e eletrodo espiral de platina como eletrodo auxiliar, com velocidade de varredura de 0,1 V.s-1 (100 mV.s-1). Os parâmetros voltamétricos foram otimizados para tornar as análises mais rápidas e sensíveis sem perda de qualidade ou intensidade do sinal voltamétrico. O eletrodo de platina quimicamente modificado com filme de cucurbit[6]urila apresentou aumento da corrente de pico catódica quando estudado frente à cocaína, teobromina e lidocaína. Análises com eletrodo de platina sem modificador químico apresentaram limite de detecção de 4,14.10-6 mol.L-1 e limite de quantificação de 1,38.10-5 mol.L-1 , para a cocaína, e na presença do modificador químico CB[6] apresentou limite de detecção de 1,36.10-6 mol.L-1 e limite de quantificação de 4,54.10-6 mol.L-1 . Eletrodos de ouro com ou sem a presença de modificadores químicos não apresentaram sinal para nenhum analito. / Considering the importance of chemically modified electrodes and the small amount of the cocaine study and their interfering (caffeine, theobromine and lidocaine) using electrochemical and piezoelectric techniques, this study aims to investigate the development of the gold and platinum electrodes chemically modified by cucurbiturils (CB[5], CB[6] and, CB[7]) in order to detect cocaine. The Quartz Crystal Microbalance technique was employed in order to study in gas phase the standard samples of cocaine and their interfering. Gold electrode was chemically modified with cucurbiturils films and the CB[6] modifier showed the best results. The cyclic voltammetric measurements were performed using a Autolab III potentiostat coupled to a computer, being gold and platinum as the working electrode, Ag/AgCl as the reference electrode and platinum wire as counter electrode, using a scan rate of 0,1 V.s-1 (100 mV.s-1). The voltammetric parameters were optimized in order to make the analysis faster and more sensitive without loss of intensity and quality of the voltammetric signal. The platinum electrode modified by cucurbit[6]uril film showed an increase of cathodic current peak when electrode was exposed to cocaine, theobromine and lidocaine. Analysis employed platinum working electrode without chemical modifier showed a detection limit of 4.14 . 10-6 mol.L-1 and quantification limit of 1.38 . 10-5 mol.L-1 for cocaine and with chemical modifier CB[6] showed a detection limit of 1.36 . 10-6 mol.L-1 and quantification limit of 4.54 . 10-6 mol.L-1 . Gold electrodes with or without chemical modifiers showed no response for any analyte.

Made available in DSpace on 2017-07-24T19:37:58Z (GMT). No. of bitstreams: 1 Introducao.pdf: 4076807 bytes, checksum: 48a9024758e4ef8be57c1dc1d440a82c (MD5) Previous issue date: 2008-03-13 / In this work was developed a methodology for incorporation of platinum particles to carbon black matrices called Eeonomers (Kp0; Kp20 and Kpy20). The characterization of modified materials Kp0/Pt; Kp20/Pt and Kpy20/Pt was performed by SEM / EDX; XRD; TEM and Cyclic Voltammetry (VC). Measures of the SEM coupled to EDX showed that the platinum particles were homogeneous distributed in the carbon matrix. Meanwhile, the average size of nanoparticles were estimated between 3 and 7 nm through calculations with the application of the Scherrer’s equation and were confirmed by MET measurements. The VC confirmed the incorporation of particles by the increase of faradaics current in negative and positive extremes of the potencial scan range assigned to the generation of oxygen and hydrogen due to the presence of platinum incorporated to the modified materials. These modified materials were used in the production of electrodes and were applied in electroanalysis used for determination of dopamine and for oxidation of methanol. The electrodes modified with platinum (EPC/Kp0/Pt, EPC/Kp20/Pt e EPC/Kpy20/Pt) showed no effects of electrooxidation for dopamine, as was expected and therefore, did not justify a modification of the material due to the high cost of platinum. Nevertheless, the electrodes of Kp0/Pt and Kp20/Pt were efficient in electrooxidation of methanol in all concentrations and can be used to replace the smooth platinum, since it increased the number of available active sites even in smaller concentrations investigated. This surface area of available platinum in the modified electrodes was calculated by the difference of integrals of the first and second cycles during the process of cyclical scanning in measures of CO adsorbed considering a load of platinum smooth at 484 μ C.cm2. Key words: Carbon black, Eeonomers, carbon paste electrodes, Cyclic Voltammetry / Neste trabalho desenvolveu-se uma metodologia para incorporação de partículas de platina a matrizes de negro de fumo denominadas de Eeonômeros (Kp0; Kp20 e Kpy20). A caracterização dos materiais modificados Kp0/Pt; Kp20/Pt e Kpy20/Pt foi realizada por MEV/EDX; DRX; MET e Voltametria Cíclica (VC). As medidas de MEV acopladas a EDX mostraram que as partículas de platina estavam distribuídas de forma homogênea na matriz orgânica. Já os tamanhos médios das nanopartículas foram estimados entre 3 e 7 nm através de cálculos com a aplicação da equação de Scherrer e confirmados pelas medidas de MET. A VC confirmou a incorporação das partículas pelo aumento das correntes faradaicas nos extremos negativos e positivos devido à geração de oxigênio e hidrogênio atribuídos à presença da platina incorporada aos materiais modificados. Estes materiais modificados foram utilizados na produção de eletrodos e aplicados em eletroanálise através da técnica de VC e utilizados para determinação da dopamina e oxidação do metanol. Os eletrodos modificados com platina (EPC/Kp0/Pt, EPC/Kp20/Pt e EPC/Kpy20/Pt) não apresentaram efeitos de eletrooxidação para a dopamina como era esperado e, portanto não justificaram a modificação do material devido ao alto custo da platina. Entretanto, os eletrodos de EPC/Kp0/Pt e EPC/Kp20/Pt mostraram-se eficientes na eletrooxidação do metanol em todas as concentrações e podem ser utilizados em substituição à platina lisa, pois, aumentaram o número de sítios ativos disponíveis mesmo nas menores concentrações investigadas. Esta área superficial de platina disponível nos eletrodos modificados foi calculada pela diferença das integrais do primeiro e segundo ciclos durante processo de varredura cíclica nas medidas de CO adsorvido considerando-se uma carga de platina lisa de 484μC.cm2.

Made available in DSpace on 2017-07-24T19:37:59Z (GMT). No. of bitstreams: 1 VagnerSantos.pdf: 4155066 bytes, checksum: ae50f41570dc02ffdf10ee8ee6a584a7 (MD5) Previous issue date: 2009-03-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work describes the preparation of platinum nanoparticles using the inorganic polymer 3-n-propylpyridine sylsesquioxane chloride (SiPy+Cl-) as nanoreator and stabilizer. The system comprising the metallic nanoparticle and the SiPy+Cl- (called hybrid Pt-SiPy+Cl-) was obtained by chemical reduction of H2PtCl6 in the presence of SiPy+Cl-, using formic acid as reducing agent. The formation of platinum nanoparticles was monitored by UV-vis spectroscopy by measuring the decrease in the intensity of the band in ca. 375 nm attributed to the electronic absorption of PtCl6 -2 ions. The average size of the nanoparticles was determined by transmission electron microscopy (TEM) and is between 3 and 40 nm. The hybrid Pt-SiPy+Cl- was used as a polycation in the preparation of layer-by-layer (LbL) films on FTO substrate (tin oxide doped with fluorine), alone, or being alternated with polyanion polyvinylsulphonic acid (PVS). Measurements of cyclic voltammetry obtained from prepared films confirmed the incorporation of metallic platinum in the polymer SiPy+Cl-, as can be seen by the adsorption and desorption of hydrogen in potential regions characteristics for platinum. The electrodes containing LbL films of Pt-SiPy+Cl-/PVS and PVS/Pt-SiPy+Cl- were tested as catalyst for dopamine (DA) oxidation at different concentrations (1.0x10-6 mol L-1 to 2.17x10-3 mol L-1). The film containing 12 LbL bilayers of PVS/Pt-SiPy+Clpresented the greater homogeneity in the distribution of material on substrate, as determined by atomic force microscopy (AFM). The former also has the better response for the electrochemical determination of DA in concentrations lower than 1.0x10-5 mol L-1 (greater sensitivity) when compared to electrodes made of: a LbL film containing only the hybrid, a platinum plate and a FTO plate. Moreover, the limit of detection (LOD) for DA using the LbL film containing 12 bilayers of PVS/Pt-SiPy+Cl- was in the order of 1.0x10-5 mol L-1, while the other electrodes showed higher values. These results indicate that the application of this electrode formed by LbL films illustrate a new material for DA electrochemical detection, generating the possibility of replacing the conventional platinum electrodes. Moreover, in the future, there is the possibility of the application of this LbL film electrode as a sensor for in vivo DA detection. / Este trabalho descreve a preparação de nanopartículas de platina utilizando o polímero inorgânico cloreto de 3-n-propilpiridínio silsesquioxano (SiPy+Cl-) como nanoreator e estabilizante. O sistema composto pela nanopartícula metálica e o SiPy+Cl- (chamado de híbrido Pt-SiPy+Cl-) foi obtido via redução química do H2PtCl6 na presença de SiPy+Cl-, usando ácido fórmico como agente redutor. A formação das nanopartículas de platina foi monitorada por espectroscopia de UVvis medindo-se o decréscimo da intensidade da banda de 375 nm atribuída à absorção eletrônica dos íons PtCl6 -2. O tamanho médio das nanopartículas foi determinado por medidas de microscopia eletrônica de transmissão (MET) e estão entre 3 e 40 nm. O híbrido Pt-SiPy+Cl- foi utilizado como um policátion na preparação de filmes automontados sobre substrato FTO (óxido de estanho dopado com flúor) por meio da técnica Layer-by-Layer (LbL), sozinho, ou sendo alternado com o poliânion ácido polivinilsulfônico (PVS). Medidas de voltametria cíclica obtidas a partir dos filmes preparados confirmaram a incorporação de platina metálica no interior do polímero SiPy+Cl-, já que se pode observar o processo de adsorção e dessorção do hidrogênio em regiões de potencial características da platina. Os eletrodos formados com filmes automontados de Pt-SiPy+Cl-/PVS e PVS/Pt-SiPy+Cl- foram testados como catalisador para a oxidação da dopamina (DA) em diferentes concentrações (1,0x10-6 mol.L-1 a 2,17x10-3 mol.L-1). O filme LbL contendo 12 bicamadas de PVS/Pt-SiPy+Cl- foi o que apresentou uma melhor homogeneidade na distribuição do material sobre o substrato, conforme determinado por medidas de microscopia de força atômica (AFM). Este último, também foi o que apresentou uma melhor reposta eletroquímica na eterminação de DA em concentrações abaixo de 1,0x10-5 molL-1 (maior sensibilidade) em relação aos eletrodos constituídos por: um filme LbL formado apenas com o híbrido, uma placa de platina e uma placa de FTO. Além disso, o limite de detecção (LOD) para a DA utilizando o filme LbL contendo 12 bicamadas de PVS/Pt-SiPy+Cl- foi da ordem de 1,0x10-5 mol L-1, enquanto que os demais eletrodos apresentaram valores maiores. Estes resultados indicam que a aplicação desse eletrodo, formado por filmes LbL, mostram um novo material para detecção eletroquímica da DA criando a possibilidade de substituir os eletrodos convencionais de platina. Além da possibilidade, no futuro, da aplicação dos eletrodos LbL nas detecções de dopamina in vivo.

Filmes de óxidos de molibdênio, com ou sem a inclusão de metais, foram eletroquimicamente depositados sobre eletrodos de carbono vítreo em solução de Mo(VI) com pH ajustado em 2,5 ou 3,0. Estes filmes foram caracterizados por Soft X-ray Spectroscopy (SXS), X-ray Diffraction (XRD) e Rutherford Backscattering Spectroscopy (RBS). A coordenação local dos sítios de Mo foram analizadas. As configurações estruturais locais do Mo foram avaliadas quando diferentes números de ciclos de potencial foram empregados na modificação dá superfície do eletrodo. Alguns metais (Pt, Pd, Rh e Cu) foram codepositados com as espécies de Mo e seu efeito nos materiais obtidos foi investigado. O grau de ocupação do orbital 4d do Mo foi examinado como um indicador da existência de interações entre o Mo e o metal codepositado. A incorporação de Pt no filme de óxidos na superfície de um eletrodo de ouro foi caracterizada por espectroscopia PIXE. O eletrodo modificado por óxidos de molibdênio foi estudado em faixas de potencial positivas frente à oxidação de nitrito (NO2-) e de óxido nítrico (NO). A relação entre a porosidade do filme e a presença de água em seus interstícios foi examinada e a capacidade de retenção de NO e NO2 foi também investigada. O eletrodo modificado foi usado como um sensor amperométrico em um sistema de injeção em fluxo (FIA) e o método foi empregado na determinação de nitrito em amostras de lingüiça. A oxidação de H2O2 foi investigada em superfície recoberta por filme de óxidos de Mo com Pt codepositada. O efeito do pH, do potencial e do tempo de pré-redução do filme de Pt e MoOx foi discutida. O comportamento eletroquímico dos filmes codepositados de Rh, Pd, Pt ou Cu e MoOx foi caracterizados comparativamente pela redução do iodato e pela oxidação do nitrito e do etanol nestes substratos. H4MogO26 foi empregado para preparar filmes contendo molibdênio e sua resposta eletroquímica foi comparada com as obtidas com o filme depositado por procedimento usual. O filme de óxidos de molibdênio foi usado com sucesso na imobilização de um complexos de Ru(III) na superfície de carbono vítreo. / Molybdenum oxide films with and without metal inclusion were electrochemically deposited on glassy carbon electrodes from Mo(VI) solutions at pH 2.5 or pH 3.0. These films were characterized by Soft X-ray Spectroscopy (SXS), X-ray Diffraction (XRD) and Rutherford Backscattering Spectroscopy (RBS). The local coordination of Mo sites was analyzed. The Mo local structure configurations were evaluated when different number of potential cycles were employed in the modification of the electrode surface. Some metaIs (Pt, Pd, Rh and Cu) were codeposited with the Mo species and their effect on the obtained material was investigated. The occupancy leveI of the 4d orbital of Mo was examined as an indicator of interactions between Mo and codeposited metals. The incorporation of Pt in the oxide film at a gold electrode surface was characterized by PlXE spectroscopy. The electrode modified by molybdenum oxides was studied at positive potential ranges for the oxidation of nitrite (NO2-) and nitric oxide (NO). The relationship between the porosity of the film and its water content was exarnined and the entrapment of NO and NO2 was also investigated. The modified electrode was used as an amperometric sensor in a flow injection configuration and the method was employed in the deterrnination of nitrite in sausage samples. The oxidation of H2O2 was investigated at surfaces covered by the Mo filrn with codeposited Pt. The effect of pH and potential and time of pre-reduction on the response of the film with Pt was discussed. The electrochemical behaviour of codeposited films of Rh, Pd, Pt or Cu and Mo MoOx was characterized comparatively for the reduction of iodate and the oxidation of nitrite and ethanol. 4MogO26 was also employed to prepare films containing molybdenum and their electrochemical responses were compared with those obtained by using the film electrodeposited by the usual procedure. The molybdenum oxide film was successfully used for the immobilization of Ru(III) complex at glassy carbon surfaces.

Ce travail porte sur les complexes des métaux de transitions pour la catalyse de la réduction des protons en hydrogène. La nature de l’espèce catalytiquement active mise en jeu lors du processus de réduction a été étudiée par voltampérométrie cyclique afin de comprendre le rôle et le mode d’action de ces complexes. Le premier chapitre introduit le contexte et les principaux objectifs de ce travail. Le deuxième chapitre propose une étude électochimique de complexes de cobalt et de nickel à ligands bis(glyoxime) et clathrochélates en phase homogène. Leur comportement en présence d’acide et en condition réductrice est décrit et un mécanisme réactionnel associé est proposé. L’influence des ligands de la sphère de coordination sur le comportement électrochimique de ces complexes a été rationalisé par le biais de substitution des groupements présents sur les ligands bis(glyoxime) et clathrochélates. Le troisième chapitre aborde le rôle de pré-catalyseur que peuvent tenir ces complexes en condition d’électrolyse réductrice et en milieu acide. L’électrosynthèse de nanoparticules catalytiques à partir de ces complexes a mis en évidence le rôle majeur des ligands bis(glyoxime) et clathrochélates dans ce phénomène d’électrodéposition. Ces résultats montrent que ces ligands peuvent être utilisés pour contrôler la nature et l’activité de nanoparticules catalytiques pour la réduction des protons en dihydrogène. Le quatrième chapitre vise à immobiliser les complexes de cobalt à ligand clathrochélate au sein de réseaux de coordination afin d’optimiser leur activité catalytique. Malgré la faible solubilité et l’encombrement stérique de ces complexes, des synthèses en conditions très douces ont abouti à la formation de réseaux mono et bi-dimensionels à base d’ions cadmium(II). / My PhD thesis goal was to investigate on the catalytic properties of first row transition metal complexes for the hydrogen evolving reaction (HER). The underlying question in the field concerning the catalytic species of metal complexes for the HER was then, whether it is homogeneous or heterogeneous catalysis. My work concerns the synthesis and characterization of oximato based cobalt and nickel complexes and their electrochemical behavior in presence of acids.In the first chapter, I give a general introduction on the search for catalytic molecular systems for the production of hydrogen. I also give an overview of my approach tackling the problem of homogeneous and heterogeneous catalysis. In the second chapter I discuss on the electrochemical study of cobalt and nickel complexes containing bis(glyoxime) ligands and clathrochelates complexes in homogeneous phase. Their electrochemical behavior under reductive conditions in presence of acids is described. The absence of molecular based catalysis is discussed and a mechanistic pathway for the consumption of protons and electrons is proposed. The influence of the ligands in the coordination sphere has been rationalized through substitutions of the chemical groups on the bis(glyoxime) and clathrochelates ligands. The third chapter concerns the generation of catalytic material from the molecular precursors in acidic reductive conditions. Electrochemically modified glassy carbon electrodes were characterized by TEM and evidenced the formation nanoparticles containing the initial metal ions (either cobalt of nickel). Our results show that the chemical nature of the ligands can be used in order to control the nature and reactivity patterns of these catalytically active nanoparticles for proton reduction into hydrogen.In the forth chapter, I give the preliminary results on the immobilization the cobalt clathrochelates complexes inside coordination networks in order to improve their catalytic activity. Despite the weak solubility and the bulk of these complexes, mild conditions synthesis have led to mono and bi-dimensional networks based on cadmium (II) ions.To conclude I emphasize on the different ways that can be followed to further pursue this quest for catalytic materials for the HER starting with molecular based complexes as precursors.

Le mode d’action des traitements médicaux fait généralement intervenir des interactions entre une (des) molécule(s) et une (des) cible(s) protéique(s) de l’organisme. Au sein de notre équipe, le choix s’est porté vers l’APN, protéine connue depuis les années 2000, pour être impliquée dans les processus d’angiogenèse i.e. la formation de nouveaux vaisseaux sanguins à partir de vaisseaux préexistants, et de migration cellulaire. Compte tenu de la pertinence thérapeutique des fonctions de l’APN et de leur validation lors d’études in vivo, la conception de voies de synthèse simples et efficaces menant à l’inhibiteur le plus puissant et sélectif de l’APN est devenu un des objectifs premier du laboratoire : 3 voies de synthèses sont décrites. Par ailleurs, notre laboratoire s’est intéressé à une nouvelle classe de composés comportant un groupement ferrocényle. En effet, les composés organométalliques suscitent un intérêt grandissant dans le développement de thérapies anticancéreuse ou encore les maladies tropicales. Ses possibilités réactionnelles étendues combinées à ses remarquables propriétés électrochimiques donnent lieu à des molécules nouvelles aux propriétés biologiques étonnantes. Ayant développé la molécule la plus puissante vis-à-vis de l’APN, ses impressionnantes propriétés inhibitrices peuvent être exaltées en créant des molécules à activité duale : inhibitrice de l’APN et cytotoxique vis-à-vis des cellules tumorales. La synthèse de ces composés hybrides ainsi que l’évaluation de leurs effets envers deux cibles, l’APN (porcine et d’Escherichia coli) et les cellules HT1080 (cellules de type fibrosarcome exprimant fortement l’APN), sont décrites dans cette thèse. / APN/CD13, a zinc dependent metallo-peptidase ectoenzyme widespread in human tissues is emerging as a new target in cancer therapy. Indeed several studies indicate that APN/CD13 plays an active role in angiogenesis and tumor metastasis. We already prepared a series of (±)-1,4-disubstituted-7-amino-benzocyclohepten-6-ones and discovered the extraordinary inhibitory power of the 1-bromo-4-phenyl derivative (Ki = 60 pM) on mammalian APN/CD13. As recent crystallographic works in collaboration with the Paul Scherrer Institut have revealed that only the (S) enantiomer was efficiently binded to the enzyme active site, we recently developed a new synthetic pathway to prepare this optically pure molecule in benzo-oxepine series. In parallel we prepare analogs equipped with at least one ferrocenyl moiety of potential intrinsic additional cytotoxicity.

L’hydrogène est la solution potentielle pour réussir la transition énergétique d’un système actuel basé en grande partie sur les combustibles fossiles vers un système non émetteur de gaz toxiques et respectueux de l’environnement. Cependant, le stockage de l’hydrogène est un grand défi qui freine son application pratique dans les différents domaines. Les hydrures métalliques permettent de stocker une grande quantité d’hydrogène de façon réversible dans de bonnes conditions (Température, pression, sécurité…) comparée aux autres modes de stockage (gazeux et liquide). En plus, ces mêmes matériaux sont utilisés comme électrode négative dans les batteries Nickel-Métal Hydrure.Dans la première partie de cette thèse, les alliages Ti-Fe ont été synthétisés parmécanosynthèse pour différents temps de broyage et différents rapports massiquesbilles/poudre. Afin d’optimiser les paramètres d’élaboration, ces alliages ont été caractérisés par différentes techniques telles que la diffraction des rayons X, la microscopie électronique à balayage, la chronopotentiométrie, la chronoampérométrie et la voltamétrie cyclique.Dans une seconde partie, les alliages TiFe+4%MWNTs, TiFe0.95-xMx, TiFe0.90M0.10 etTiFe0.90Mn0.05V0.05 (x=0.05, 0.15) (M : Mn ou V) ont été élaborés selon les paramètres optimaux déterminés précédemment. L’influence de l’additif Nanotubes de Carbone à multiparois (MWNTs), de la substitution partielle du Fe par Mn et/ou V et de l’excès de Titane sur les propriétés structurales, morphologiques et électrochimiques telles que l’activation, la capacité de décharge électrochimique, la réversibilité, la tenue au cyclage, le coefficient de diffusion ont ensuite été étudiés. Les propriétés redox des électrodes, le potentiel de Nernst et la densité du courant d’échange, ont été déterminés, en se basant sur la première loi de Sternet le modèle théorique de Bulter -Volmer.Les résultats électrochimiques obtenus montrent que l’alliage TiFe+4 wt.% MWNTs présente les meilleures performances : une activation rapide (au 1er cycle) et une meilleure capacité maximale de décharge (266 mAh g-1) avec une réversibilité qui reste inchangée. / Hydrogen is the potential solution to make a success of the energy transition of a current system basically based on fossil fuels towards a system friendly to environment. However, the storage of hydrogen is a big challenge that hinders its practical application in different areas.. Metal hydrides can store a large amount of hydrogen reversibly under good conditions (temperature, pressure, safety ...) compared to other storage modes (gaseous and liquid). In addition, these same materials are used as negative electrode in Nickel-Metal Hydride batteriesIn the first part of this thesis, Ti-Fe alloys were synthesized using mechanical alloying (MA) under argon atmosphere at room temperature, with different ball to powder weight ratio and at different milling times. In order to determine the optimal parameters of the elaboration the metallic composite were investigated using different techniques such as X-ray diffraction, scanning electron microscopy (EDS support), chronopotentiometry, chronoamperometry and cyclic voltammetry,In the second part, the metallic compounds, TiFe+4%MWNTs, TiFe0.95-xMx, TiFe0.90M0.10 and TiFe0.90Mn0.05V0.05 (x=0.05, 0.15) (M : Mn or V), which are used as the negative electrode material for Ni-MH secondary batteries, were synthesized by mechanical alloying according to optimal parameters, previously determined.The effect of MWNT addition, the Mn and/or V partial substitution for Fe and the excess of titanium on the structural, morphological and electrochemical parameters such as activation, electrochemical discharge capacity, reversibility, cycle life time and hydrogen diffusion coefficient were investigated.The redox properties of the electrodes such as the Nernst potential and the exchange current density were studied based on Stern’s first law and the theoretical model of Bulter-Volmer.The electrochemical properties of studied samples show the best performance for TiFe+4% MWNTs alloy. Indeed, this alloy presents a rapid activation (1st cycle) and a best discharge capacity (266 mAhg-1) with a reversibility remaining unchanged