Made available in DSpace on 2017-07-20T12:40:16Z (GMT). No. of bitstreams: 1 Alvaro Fontana.pdf: 7055530 bytes, checksum: 4a9069c1fa7120a7895a1587f1fe173e (MD5) Previous issue date: 2015-09-18 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / In this work were performed organic synthesis of the monomer derivatives of poly (p-phenylenevinylene) whose main interest was to obtain a monomer with an aromatic ring having attached two bromine atoms (this step not being performed), a cyano group, a side chain of six carbon atoms and a sulfonic group linked to the end of side chain. The syntheses were performed starting from the compound 2,5-dimethylphenol and adding the aromatic ring an iodine atom, made subsequently replacing the iodine atom by a cyano group, and the sequences of reactions by adding a side chain with six carbon atoms attached at its one end a sulfonic group. The characterization of the obtained compounds was performed by spectroscopy techniques, Infrared, nuclear magnetic resonance 1H and 13C and GC-MS. These analyzes showed that the structures of the proposed monomers were achieved almost entirely. Part of this doctoral work was performed in the laboratory of the Emeritus Professor Dr. Alan Maxwell Bond at Monash University, Melbourne - Australia, such as sandwich doctorate program. The study in Australia comprised learning and application of cyclic voltammetry technique ac coupled to Fourier transform in chemical reactions studying the kinetics of 1 and 2 electron transfer, in this case, taking as an example the molecule N,N,N',N'-Tetramethyl-p-phenylenediamine, TMPD. The molecular solvents used for the study of electron transfer in the molecule TMPD were acetone and acetonitrile, and the following ionic liquids: [BMPIPTFSI], [BMIM] [TFSI], [BMIm][BF4] and [BDMIM] [TF2N]. In all the results obtained it was found the process known as internal reference, where the first electron transfer reaction in the molecule, because it is faster, can be used to compare the values of the thermodynamic and kinetic parameters obtained in the first process with the parameter values obtained in the second electron transfer process in the same molecule. / Neste trabalho foram realizadas sínteses orgânicas de monômeros derivados de poli(p-fenilenovinileno) cujo principal interesse foi a obtenção de um monômero com um anel aromático tendo ligado a ele, dois átomos de bromo (não sendo realizada essa etapa), um grupamento ciano, uma cadeia lateral com seis átomos de carbono, e um grupamento sulfônico ligado a extremidade da cadeia lateral. As sínteses foram realizadas partindo-se do composto 2,5-dimetilfenol e adicionando-se ao anel aromático um átomo de iodo, posteriormente feita a troca do átomo de iodo por um grupo ciano e nas sequências das reações adicionando-se uma cadeia lateral com seis átomos de carbono oposta ao grupo ciano e ligado na extremidade da cadeia lateral um grupo sulfônico. A caracterização dos compostos foi realizada através das técnicas, infravermelho, ressonância magnética nuclear 1H, 13C e CG-MS. Essas análises evidenciaram que as estruturas dos monômeros propostos foram alcançadas em quase sua totalidade. Parte deste trabalho de doutoramento foi realizada no laboratório do professor Emeritus Dr. Alan Maxwell Bond na Monash University em Melbourne – Austrália, como doutorado sanduíche. O estudo feito na Austrália compreendeu a aprendizagem e aplicação da técnica de voltametria cíclica ac acoplada à transformada de Fourier, estudando-se a cinética de transferência de 1 e 2 elétrons, neste caso, utilizando-se como exemplo, a molécula N,N,N′,N′-Tetramethyl-p-phenylenediamine, TMPD. Os solventes moleculares utilizados para o estudo da transferência de elétrons nesta molécula foram acetona e acetonitrila e também os seguintes líquidos iônicos: [BMPIPTFSI], [BMIM][TFSI], [BMIm][BF4] e [BDMIM][TF2N]. Em todos os resultados obtidos constatou-se o processo chamado de referência interna, onde, a primeira reação de transferência de elétrons nesta molécula, por ser mais rápida, pode ser utilizada para comparar os valores dos parâmetros termodinâmicos e cinéticos obtidos no primeiro processo de transferência de elétrons com os valores dos parâmetros obtidos no segundo processo na mesma molécula.

Made available in DSpace on 2017-07-24T19:37:54Z (GMT). No. of bitstreams: 1 Alvaro Fontana.pdf: 7055530 bytes, checksum: 4a9069c1fa7120a7895a1587f1fe173e (MD5) Previous issue date: 2015-09-18 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / In this work were performed organic synthesis of the monomer derivatives of poly (p-phenylenevinylene) whose main interest was to obtain a monomer with an aromatic ring having attached two bromine atoms (this step not being performed), a cyano group, a side chain of six carbon atoms and a sulfonic group linked to the end of side chain. The syntheses were performed starting from the compound 2,5-dimethylphenol and adding the aromatic ring an iodine atom, made subsequently replacing the iodine atom by a cyano group, and the sequences of reactions by adding a side chain with six carbon atoms attached at its one end a sulfonic group. The characterization of the obtained compounds was performed by spectroscopy techniques, Infrared, nuclear magnetic resonance 1H and 13C and GC-MS. These analyzes showed that the structures of the proposed monomers were achieved almost entirely. Part of this doctoral work was performed in the laboratory of the Emeritus Professor Dr. Alan Maxwell Bond at Monash University, Melbourne - Australia, such as sandwich doctorate program. The study in Australia comprised learning and application of cyclic voltammetry technique ac coupled to Fourier transform in chemical reactions studying the kinetics of 1 and 2 electron transfer, in this case, taking as an example the molecule N,N,N',N'-Tetramethyl-p-phenylenediamine, TMPD. The molecular solvents used for the study of electron transfer in the molecule TMPD were acetone and acetonitrile, and the following ionic liquids: [BMPIPTFSI], [BMIM] [TFSI], [BMIm][BF4] and [BDMIM] [TF2N]. In all the results obtained it was found the process known as internal reference, where the first electron transfer reaction in the molecule, because it is faster, can be used to compare the values of the thermodynamic and kinetic parameters obtained in the first process with the parameter values obtained in the second electron transfer process in the same molecule. / Neste trabalho foram realizadas sínteses orgânicas de monômeros derivados de poli(p-fenilenovinileno) cujo principal interesse foi a obtenção de um monômero com um anel aromático tendo ligado a ele, dois átomos de bromo (não sendo realizada essa etapa), um grupamento ciano, uma cadeia lateral com seis átomos de carbono, e um grupamento sulfônico ligado a extremidade da cadeia lateral. As sínteses foram realizadas partindo-se do composto 2,5-dimetilfenol e adicionando-se ao anel aromático um átomo de iodo, posteriormente feita a troca do átomo de iodo por um grupo ciano e nas sequências das reações adicionando-se uma cadeia lateral com seis átomos de carbono oposta ao grupo ciano e ligado na extremidade da cadeia lateral um grupo sulfônico. A caracterização dos compostos foi realizada através das técnicas, infravermelho, ressonância magnética nuclear 1H, 13C e CG-MS. Essas análises evidenciaram que as estruturas dos monômeros propostos foram alcançadas em quase sua totalidade. Parte deste trabalho de doutoramento foi realizada no laboratório do professor Emeritus Dr. Alan Maxwell Bond na Monash University em Melbourne – Austrália, como doutorado sanduíche. O estudo feito na Austrália compreendeu a aprendizagem e aplicação da técnica de voltametria cíclica ac acoplada à transformada de Fourier, estudando-se a cinética de transferência de 1 e 2 elétrons, neste caso, utilizando-se como exemplo, a molécula N,N,N′,N′-Tetramethyl-p-phenylenediamine, TMPD. Os solventes moleculares utilizados para o estudo da transferência de elétrons nesta molécula foram acetona e acetonitrila e também os seguintes líquidos iônicos: [BMPIPTFSI], [BMIM][TFSI], [BMIm][BF4] e [BDMIM][TF2N]. Em todos os resultados obtidos constatou-se o processo chamado de referência interna, onde, a primeira reação de transferência de elétrons nesta molécula, por ser mais rápida, pode ser utilizada para comparar os valores dos parâmetros termodinâmicos e cinéticos obtidos no primeiro processo de transferência de elétrons com os valores dos parâmetros obtidos no segundo processo na mesma molécula.

Le photosystème II (PSII) est un complexe multi-protéique qui utilise l'énergie solaire pour oxyder l'eau et réduire des quinones. Le site catalytique d'oxydation de l'eau est localisé coté lumen du complexe, alors, que le site de réduction comprenant deux quinones (QA et QB) et un fer non-hémique est localisé sur le coté stromal du complexe membranaire. Dans cette thèse j'ai étudié les deux cotés accepteur et donneur d'électrons du PSII.QA•- et QB•- sont couplés magnétiquement au fer non-hémique donnant de faibles signaux RPE. Le fer non-hémique possède quatre ligands histidines et un ligand (bi)carbonate échangeable. Le formate peut échanger le ligand (bi)carbonate induisant un ralentissement dans le transfert d'électrons. Ici, je décris une modification du signal RPE de QB•- Fe2+ lorsque le formate est substitué au (bi)carbonate. J'ai aussi découvert un second signal RPE dû à la présence du formate à la place du (bi)carbonate lorsque QB est doublement réduit. De plus, j'ai trouvé que les signaux RPE natifs de QA•- Fe2+ et QB•- Fe2+ possèdent une signature intense encore jamais détectée. Tous les signaux RPE rapportés dans cette thèse devraient faciliter le titrage redox de QB par RPE. J'ai aussi observé que QB•- peut oxyder le fer non-hémique à l'obscurité en anaérobie. Cette observation implique qu'au moins dans une fraction des centres, le couple QB•-/QBH2 possède un potentiel redox plus haut que supposé. La quantification du nombre de centres où cette oxydation du fer se produit par le couple QB•-/QBH2 reste à faire. La réduction du PSII par le dithionite génère un signal modifié de QA•-Fe2+, un changement structural du PSII observé par électrophorèse. Cela peut indiquer la réduction d'un pont disulfure à l'intérieur du PSII. Concernant le site d’oxydation de l'eau, j'ai étudié la première étape de l'assemblage du site catalytique (Mn4Ca), en suivant l'oxydation du Mn2+ par RPE en bande X et haut champ. J'ai mis au point des conditions expérimentales permettant le piégeage du premier intermédiaire et j'ai aussi trouvé une incohérence avec des travaux publiés dans la littérature. J'ai aussi trouvé que le dithionite pouvait réduire le site catalytique Mn4Ca, en formant des états sur-réduits qui peuvent correspondre aux intermédiaires de l'assemblage du cluster Mn4Ca. / Photosystem II (PSII) uses light energy to oxidise water and reduce quinone. The water oxidation site is a Mn4Ca cluster located on the luminal side of the membrane protein complex, while the quinone reduction site is made up of two quinones (QA and QB) and a non-heme Fe2+ located on the stromal side of the membrane protein. In this thesis I worked on both oxidation and reduction functions of the enzyme. QA•- and QB•- are magnetically couple to the Fe2+ giving weak and complex EPR signals. The distorted octahedral Fe2+ has four histidines ligands and an exchangeable (bi)carbonate ligand. Formate can displace the exchangeable (bi)carbonate ligand, slowing electron transfer out of the PSII reaction centre. Here I report the formate-modified QB•- Fe2+ EPR signal, and this shows marked spectral changes and has a greatly enhanced intensity. I also discovered a second new EPR signal from formate-treated PSII that is attributed to formate-modified QA•- Fe2+ in the presence of a 2-electron reduced form of QB. In addition, I found that the native QA•- Fe2+ and QB•- Fe2+ EPR signals have a strong feature that had been previously missed because of overlapping signals (mainly the stable tyrosyl radical TyrD•). These previously unreported EPR signals should allow for the redox potential of this cofactor to be directly determined for the first time. I also observed that when QB•-Fe was formed; it was able to oxidise the iron slowly in the dark. This occurred in samples pumped to remove O2. This observation implies that at least in some centres, the QB•-/QBH2 couple has a higher potential then is often assumed and thus that the protein-bound semiquinone is thermodynamically less stable expected. It has yet to be determined if this represents a situation occurring in the majority of centres. Treatment of the system with dithionite generated a modified form of QA•-Fe2+ state and a change in the association of the proteins on gels. This indicates a redox induced modification of the protein, possibly structurally important cysteine bridge in PSII.On the water oxidation side of the enzyme, I studied the first step in the assembly of the Mn4Ca cluster looking at Mn2+ oxidation using kinetic EPR and high field EPR. Conditions were found for stabilising the first oxidised state and some discrepancies with the literature were observed. I also found that dithionite could be used to reduce the Mn4Ca, forming states that are formally equivalent to those that exist during the assembly of the enzyme.

The cytochrome P450 enzyme system is a multicomponent electron-transfer chain composed of a haem-containing monooxygenase cytochrome P450 (CYP) and one or more redox partners. Eukaryotic CYPs and their redox partner NADPH-dependent cytochrome P450 oxidoreductase (CPR) are involved in many biological processes. Each protein has one N- terminal membrane anchor domain for location within the endoplasmic reticulum (ER). In mammals, CYPs and CPR are especially abundant in liver cells, where they play important roles in the metabolism of steroids, fatty acids, and xenobiotic compounds including numerous drugs of pharmaceutical importance. Incorporation into lipid membranes is an important aspect of CYP and CPR function, influencing their kinetic properties and interactions. In this thesis, soluble nanometer-scale phospholipid bilayer membrane discs, "nanodiscs", were used as a reconstitution system to study the influence of lipid membrane composition on the activities of the abundant human CYP3A4 and human CPR. Both enzymes were expressed and purified from bacteria, and assembled into functionally active membrane-bound complexes in nanodiscs. Nanodisc assembly was assessed by a combination of native and denaturing gel electrophoresis, and a fluorimetric assay was developed to study CYP3A4 reaction kinetics using 7-benzyloxyquinoline as substrate. Kinetic properties were investigated with respect to different lipid membrane compositions: phosphatidyl choline; a synthetic lipid mixture resembling the ER; and natural lipids extracted from liver microsomes. Full activity of the CYP3A4 system, with electron transfer from NADPH via CPR, could only be reconstituted when both CYP3A4 and CPR were membrane-bound within the same nanodiscs. No activity was observed when CPR and CYP3A4 were each incorporated seperately into naodiscs then mixed together, or when soluble forms of CPR were mixed with pre-assembled CYP3A4-nanodiscs. Thus, assembly of the two proteins within the same membrane was shown to be essential for the function of the CPR-CYP3A4 electron transfer system. Comparison of the reaction kinetics in different membrane compositions revealed liver microsomal lipid to have an enhancing effect both on the activity of the assembled CPR-CYP3A4 nanodisc complex, and on the activity of CPR alone incorporated in nanodiscs, when compared either to the synthetic lipid mixture or to phosphatidyl choline alone. Thus, natural lipids appear to possess properties or include components important for the catalytic function of the CYP system, which are absent from synthetic lipid. Input of electrons, measured by NADPH consumption, exceeded product formation rate by the CPR-CYP3A4 complex in nanodiscs, indicating "leakage" in the electron flow, possibly due to uncoupling of the two enzymes. Uncoupling was shown to occur by developing a novel fluorimetric method using the dye MitSOX to detect superoxide production. The significance of this, and to what extent control of coupling could be a natural means of regulation of the CPR-CYP system, remains to be determined. Thus, phospholipid bilayer nanodiscs prove a powerful tool to enable detailed analysis of the reaction kinetics of membrane-reconstituted CPR-CYP systems, and to allow pertinent questions to be addressed concerning the integral significance of the membrane environment.

A eletroquímica direta de enzimas redox depende da distância entre os sítios redox da proteína e a superfície do eletrodo e também da eficiência na imobilização dessas enzimas na superfície eletródica. Dessa forma, a obtenção de enzimas mais hidrofóbicas possibilita a melhora na interação entre elas e a superfície de eletrodos sólidos, como os de carbono. Neste estudo, foi desenvolvida uma rota para a obtenção da glicose oxidase oligomerizada (Ol-GOx) com o objetivo de melhorar a interação entre a enzima e a superfície de fibras de carbono, uma vez que enzimas oligomerizadas contêm suas porções hidrofóbicas expostas.Para tanto, diferentes ácidos de Brønsted foram utilizados, sendo que a enzima obtida a partir da reação com o ácido trifluorometanosulfônico (TFMS) foi a que se manteve ativa cataliticamente. A Ol-GOx se mostrou um biocatalisador promissor devido a sua hidrofobicidade e seu tamanho, os quais permitiram uma imobilização mais eficiente em superfícies de carbono. Após a caracterização estrutural, concluiu-se que a Ol-GOx é formada por um oligômero composto por 10 unidades de GOx nativa com raio hidrodinâmico de aproximadamente 96 nm. Por voltametria cíclica estudou-se a transferência direta de elétrons (TDE) entre o cofator dinucleotídeo de flavina e adenina (FAD) e a superfície das fibras de carbono, sendo observado um aumento de 7 vezes nas correntes faradaicas em relação ao obtido para a GOx nativa. Além disso, as propriedades bioeletrocatalíticas foram melhoradas em 30% quando analisada a oxidação da glicose. Concluiu-se ainda que quanto maior a quantidade de folhas-β presente na estrutura proteica, maior a TDE observada entre a enzima e a superfície das fibras de carbono. / The direct electrochemistry of redox enzymes is dependent on the distance between the active centers of the protein and the electrode surface, and also on the efficiency in the immobilization of these enzymes on the electrodic surface. Thus, the synthesis of more hydrophobic enzymes could lead to better interaction between the redox enzymes and the solid electrode surfaces, such as carbon electrodes. In this study, it was proposed a chemical route to obtain oligomerized glucose oxidase (Ol-GOx), aiming to improve the interaction between the enzyme and the surface of carbon fibers, since oligomerized proteins have their hydrophobic chains exposed. After structural characterization, it was concluded that Ol-GOx is formed by 10 dimeric units of native GOx with a hydrodynamic radius corresponding to approximately 96 nm. By cyclic voltammetry, it was studied the direct electron transfer (DET) between the flavin adenine dinucleotide (FAD) cofactor and the surface of carbon fibers, where it was observed an increase of 7-fold in the faradaic currents in comparison to that observed for native GOx. Besides, bioelectrocatalytic properties are 30% improved, when analyzed the glucose oxidation by cyclic voltammetry. It was also concluded that the greater the β-sheet content in protein structure, the higher the DET observed between the enzyme and the carbon fibers surface.

De nos jours, les composés fluorés sont de plus en plus présents dans notre quotidien et gagnent tous les domaines d’application des sciences de la vie (industries pharmaceutique et agrochimique) mais également dans les matériaux. Cet engouement croissant s’explique de part les caractéristiques uniques que confèrent les motifs fluorés lorsqu’ils sont introduits sur une molécule. En outre, l’association du fluor avec des hétéroatomes, et notamment les chalcogènes, a permis d’apporter de nouvelles propriétés d’intérêt (lipophilie, conformation, stabilité métabolique). Ces deux dernières décennies ont vu la croissance exponentielle des développements autour des motifs OCF3, SCF3 et de leurs dérivés. Bien moins étudié que ses analogues, le groupement SeCF3 n’a pas connu le même essor en dépit des propriétés prometteuses. En effet, communément craint à cause de sa plus grande toxicité, peu de méthodes d’introduction de ce motif ont été décrites. Le sélénium est pourtant un oligoélément essentiel chez l’Homme et est particulièrement étudié en médecine pour ses propriétés anti-oxydantes. Ce manuscrit est dédié à l’introduction directe du groupement fluoroalkylsélénium SeRF sur divers substrats organiques à travers deux générations de réactifs et de leurs dérivés : les chlorures de fluoroalkylsélénium ClSeRF et les fluoroalkyltoluènesélénosulfonates TsSeRF. Si le premier a été impliqué dans dans diverses réactions électrophiles, l’émergence du second a permis de franchir les obstacles synthétiques rencontrés. De plus, en fonction des conditions opératoires, les réactifs TsSeRF peuvent introduire le motif fluoroalkylsélénié de manière électrophile, radicalaire ou nucléophilie. Cette versatilité s’avère être un outil synthétique de choix pour cette chimie. L’apport de ce réactif a contribué aux récents développements autour du motif SeCF3. Cependant, des efforts restent à fournir notamment afin d’apporter des données quant à la toxicité de ce motif lorsqu’il est introduit sur un composé organique. Celles ci ouvriraient alors le champ vers de potentielles applications / Nowadays, organofluorine compounds are widely used, with applications in all fields of life sciences (pharmaceuticals and agrochemicals) as well as materials. This growing interest is due to the unique properties induced by fluorinated motifs. In this context, the association of fluorine with heteroatoms such as chalcogens allows its properties of interest (lipophilicity, conformation, metabolic stability) to be modulated. The development of OCF3, SCF3 and their derivatives has significantly expanded during the past two decades. Despite its promising properties, the selenylated analog SeCF3 has been less studied. Indeed, selenium is well known to be more toxic. Thus, only few methodologies were reported in the literature. However, selenium is an essential trace element for humans and it is well studied in medicinal chemistry for its anti-oxidant properties. This manuscript is devoted to the direct introduction of the fluoroalkylselenylated moiety SeRF onto organic substrates through two generations of reagents: fluoroalkylselenyl chlorides, ClSeRF and fluoroalkyltolueneselenosulfonates, TsSeRF. On the one hand, the former was involved in various electrophilic reactions. On the other hand, the design and the synthesis of the latter allowed challenging transformations to be achieved. Moreover, depending on the conditions, TsSeRF derivatives appeared to be highly versatile since the fluorinated motif can be introduced as electrophile, radical or nucleophile. This unique behavior can be a useful synthetic tool in organofluorine chemistry. TsSeRF reagents are already well established in modern strategies for the introduction of fluoroalkylselenylated moieties. Nevertheless, efforts are still needed to shed some light on the toxicity of the SeRF-containing molecules. Such improvements will pave the way for future applications of this chemistry.

En utilisant les spectroscopies d'absorption UV-vis et d'émission stationnaire et résolue dans le temps (femto- et sub–nanoseconde, caméra à balayage de fente), nous avons étudié, au cours de cette thèse, les processus photophysiques au sein de différentes molécules et supramolécules. Les propriétés photophysiques de nouveaux complexes de Ru(II) polypyridine et de Ir(III) cyclométallé présentant un transfert d'énergie électronique réversible entre le noyau métallique et les chromophores organiques auxiliaires énergétiquement appariés (anthracène et pyrène) ont été analysées en détail. Les caractéristiques de la séparation de charge entre un donneur d'électron (OPV) et un accepteur (PB) à travers un pont d'oligoquinoline au sein de foldamères de longueurs croissantes ont été précisées dans une échelle de temps inférieure à la nanoseconde. De nouvelles sondes luminescentes à base de lanthanides ont été réalisées pour la détection en temps réel de l’ion Cu(I), leurs propriétés optiques étant modulées par effet «d’antenne» par le biais d'interactions cations-nuagePi. L'étude de sondes fluorescentes off-on en proche IR formées de colorantsBF2-AzaBODIPY fixés de manière covalente sur des nanoparticules (100 nm) polymériques a été réalisée, et étendue à de nouvelles sondes sensibles au pH émettant dans le proche IR. Des études de photoisomérisation ont été effectuées sur deux systèmes azobenzéniques capables de libérer/capturer des ions Ca(II) (azobenzène-éther«lasso», azobenzène-BAPTA) – l'impact de l'eau sur la photoisomérisation cis-trans d’hydroxychalcones a été mis en évidence dans CH3CN et H2O/CH3OH (v/v=1/1). / In the present work photophysical processes of different molecular and supramolecular systems were studied using steady-state and time-resolved femto- and sub-nanosecond (streak-camera detection) UV-vis absorption and emission spectroscopies. Detailed photophysical studies of novel Ru(II) polypyridine and cyclometalatedIr(III) complexes showing reversible electronic energy transfer between metallic core and auxiliary organic energetically-matched chromophores anthracene and pyrene, respectively were performed. Time-resolved characterization of charge separation between electron donor (OPV) and acceptor (PB) in the sub-nanosecond timescale through an oligoquinoline bridge in foldamers of increasing oligomeric length was carried out. Novel lanthanide-based luminescent probes were investigated for time-gated detection of Cu(I) ion, being modulated by an antenna effect through cation-pi interactions.The study on NIR fluorescent off-on probes, based on BF2-aza-BODIPY dyes, covalently attached to the surface of polystyrene 100 nm nanoparticles, along with related novel NIR pH-responsive fluorescence probes were conducted. Photoisomerization studies focused on azobenzene-based (azobenzene-lariat ether, azobenzene-BAPTA)Ca(II)-ion release/capture systems, while the impact of water on the cis−trans photoisomerizationof hydroxychalcones was studied in CH3CN and H2O/CH3OH (v/v=1/1).

Ce travail de thèse a été dédié à l’élaboration et l’étude de nouveaux matériaux hybrides obtenus par la fonctionnalisation de molécule-aimants (en anglais single-molecule magnets, SMMs) et de complexes à transfert d’électron. Le premier chapitre fait un état de l’art des deux classes de composés magnétiques utilisées dans ce travail : les molécule-aimants et les systèmes à transfert d’électrons. Une brève description des systèmes magnétiques hybrides présents dans la littérature est ensuite présentée dans le but d’illustrer les motivations qui ont conduit à ce travail. Le chapitre II décrit la fonctionnalisation des molécule-aimants de type [Mn12] dans le but d’obtenir des systèmes cristaux liquides hybrides. Deux approches ont été étudiées : (a) la fonctionnalisation des ligands périphériques avec des groupements fortement lipophiles (longues chaines alkyle) ou (b) le greffage de promoteurs mésogènes par l’intermédiaire d’espaceurs aliphatiques flexibles. Les chapitres III à V présentent les études sur des carrés moléculaires à ponts cyanure {Fe2Co2} qui montrent un transfert d’électron thermo- et photo-induit. Le chapitre III discute de la possibilité de moduler le processus de transfert d’électron de ces carrés moléculaires via le changement du contre anion. La fonctionnalisation du carré moléculaire {Fe2Co2} avec de chaines aliphatiques et son impact induit sur les propriétés physiques à l’état solide et en solutions sont décrits dans le chapitre IV. Le chapitre V discute de l’effet de la fonctionnalisation avec des groupements fortement électrodonneurs, tels que les groupements méthoxy, sur le processus de transfert d’électron des carrés moléculaires {Fe2Co2}. / The work presented in this thesis was focused on the design and investigation of novel hybrid materials via ligand functionalization of the single-molecule magnets (SMMs) and electron transfer complexes. Chapter I contains general information about these two classes of the magnetic systems. In order to illustrate the motivation behind our work, a brief review on previously reported soft hybrid magnetic systems, is presented. Chapter II is dedicated to the functionalization of [Mn12]-based SMMs towards hybrid liquid crystalline systems via two different approaches: (a) the functionalization of peripheral ligands with strongly lipophilic groups (long alkyl chains), or (b) the grafting of mesogenic promoters through flexible aliphatic spacers. Chapters III – V are focused on cyanido-bridged molecular {Fe2Co2} squares that exhibit thermally or photo-induced electron transfer. Thus, in Chapter III, the possibility to modulate the electron transfer properties in {Fe2Co2} molecular squares via the use of different counter-anion is discussed. The functionalization with long aliphatic chains and its influence over the properties of {Fe2Co2} molecular squares in solid state and solutions are discussed in Chapter IV. Finally, the effect of the ligand functionalization with strongly electron density donating groups (methoxy) over the electron transfer properties of {Fe2Co2} molecular squares is investigated in Chapter V.

<p>Denitrification is an anaerobic process performed by several soil bacteria as an alternative to aerobic respiration. A key-step in denitrification (the N-N-bond is made) is catalyzed by nitric oxide reductase (NOR); 2NO + 2e^- + 2H⁺ → N₂O + H₂O. NOR from <i>Paracoccus denitrificans</i> is a member of the heme copper oxidase superfamily (HCuOs), where the mitochondrial cytochrome c oxidase is the classical example. NOR is situated in the cytoplasmic membrane and can, as a side reaction, catalyze the reduction of oxygen to water.</p><p>NORs have properties that make them divergent members of the HCuOs; the reactions they catalyze are not electrogenic and they do not pump protons. They also have five strictly conserved glutamates in their catalytic subunit (NorB) that are not conserved in the ‘classical’ HCuOs. It has been asked whether the protons used in the reaction really come from the periplasm and if so how do the protons proceed through the protein into the catalytic site?</p><p>In order to find out whether the protons are taken from the periplasm or the cytoplasm and in order to pinpoint the proton-route in NorB, we studied electron- and proton transfer during a single- as well as multiple turnovers, using time resolved optical spectroscopy. Wild type NOR and several variants of the five conserved glutamates were investigated in their solubilised form or/and reconstituted into vesicles.</p><p>The results demonstrate that protons needed for the reaction indeed are taken from the periplasm and that all but one of the conserved glutamates are crucial for the oxidative phase of the reaction that is limited by proton uptake to the active site.</p><p>In this thesis it is proposed, using a model of NorB, that two of the glutamates are located at the entrance of the proton pathway which also contains two of the other glutamates close to the active site.</p>

<p>This thesis describes an interdisciplinary project, where the aim is to mimic the initial reactions in photosynthesis. In photosynthesis, the absorption of light is followed by the formation of charge-separated states. The energy stored in these charge-separated states is further used for the oxidation of water and reduction of carbon dioxide. In this thesis the photo-induced processes in a range of supramolecular complexes have been investigated with time resolved spectroscopic techniques. The complexes studied consist of three types of units; photosensitizers (P) capable of absorbing light, electron acceptors (A) that are easily reduced and electron donors (D) that are easily oxidised. Our results are important for the future design of artificial photosystems, where the goal is to produce hydrogen from light and water. </p><p>Two molecular triads with a D-P-A architecture are presented. In the first one, a photo-induced charge-separated state was formed in an unusually high yield (φ>90%). In the second triad, photo-irradiation led to the formation of an extremely long-lived charge-separated state (τ = 500 ms at 140K). This is also the first synthetically made triad containing a dinuclear manganese unit as electron donor.</p><p>Further, two sets of P-A dyads are presented. In both, the expected photo-induced reduction of the electron acceptor is diminished due to competing energy transfer to the triplet state of the acceptor.</p><p>Finally, a P-P-A complex containing two separate photosensitizers is described. The idea is to produce high-energy charge-separated states by using the energy from two photons.</p>