Chlorine solid-state nuclear magnetic resonance (SSNMR) is an ideal site specific probe of chloride-containing solids as SSNMR tensor properties are sensitive to the local chlorine environment. In this thesis, the development and use of chlorine SSNMR as a method to characterize a wide variety of chemical environments was explored. Ultrahigh field, and multi-field studies were essential to overcome the difficulties associated with the collection of chlorine SSNMR spectra. Benchmark chemical shift (CS) and electric field gradient (EFG) tensor data were collected for organic chloride systems, including several amino acid hydrochlorides. These experiments demonstrated the sensitivity of chlorine SSNMR to slight changes in chemical environment. Quantum chemical calculations were used to complement experimental data, with the gauge-including projector augmented wave DFT (GIPAW-DFT) method shown to yield better agreement than B3LYP or RHF methods. The GIPAW-DFT method was found to slightly, but systematically, overestimate the chlorine quadrupolar coupling constant and the CS tensor span. Other organic chlorides examined by chlorine SSMR included a known ion receptor, meso-octamethylcalix[4]pyrrole. This compound was found to have a very small quadrupole interaction (QI), but significant chemical shift anisotropy (CSA). GIPAW-DFT calculations were also utilized and, in combination with the experimental results, used to identify the solvate structure of the material analyzed by NMR. Chlorine SSNMR was further used to study different solvate structures and polymorphism. The technique was an effective means to distinguish different room temperature polymorphs of benzidine hydrochloride, despite the similarities of the chloride environments. In the case of magnesium chloride, chlorine SSNMR was sensitive to the level of hydration and through the use of GIPAW-DFT calculations, the identity of an unknown hydrate was determined. An analysis of several group thirteen chlorides demonstrated that chlorine SSNMR was also capable of characterizing the chlorine environment in cases where the QI is large, despite the resulting broad line widths. In these systems GIPAW-DFT calculations also yielded excellent agreement with experimental values. Throughout this research, chlorine SSNMR has been shown to be a useful and effective means to study both organic and inorganic chlorides, with computational methods proving to be an important complement to experimental data.

I have examined three different topological forms of a material modifier. The modifier is silicone and the three topological forms are cyclic, linear tethers and networked siloxane bonds in the form of a nanoparticulate. Often silicones, or siloxanes, are added to a material because of its unique properties that are related to its inorganic or inorganic-organic hybrid character. This dissertation addresses either the synthesis of silicones for material modification or the effect of the adding silicones to a variety of substrates and polymeric systems. Chapters 2 and 3 present research focused on the first topological form, cyclic PDMS. The synthesis of cyclic polymers is very important to the synthesis and subsequent characterization of cyclic containing multi-component materials. Cyclic PDMS is formed via ring-chain depolymerization and bimolecular coupling and the unique issues associated with the formation, purification and analysis of cyclic polymer topologies. The goal of the work described in these chapters was to find a straightforward high-yield route to form large cycles of PDMS in a relatively high purity. Chapter 4 focuses on the modification of the next topological form, linear polymers as tethers for surface modification and presents a novel concept for surface-modifying compounds; the incorporation of an ionic-reactive functionality into PDMS is presented. The idea being its ionic character will increase affinity for the surface, surface coverage and levelness, while the subsequent reactive fixation will permanently modify the surface to improve retention and fastness. The use of such chemistry has not been applied for surface modification protocols. Chapters 5, 6 and 7 discuss the characterization of systems with the third topological form incorporated. They include differences in the viscoelastic behavior of PVAc/silica nanocomposites and the neat PVAc matrix, relating those differences to polymer dynamics and structure as determined by several solid-state NMR experiments. The latter two chapters pertain to PVAc/silica nanocomposites with PDMS surface treatments. Specifically, evaluating how polymer dynamics and structure changes particularly at the interfaceinterphase with various PDMS surface treatments having different topologies at the surface.

This thesis combines synthetic studies for isotopic enrichment with solid-state characterisation techniques to investigate two classes of microporous materials: zeolites and metal-organic frameworks (MOFs). These materials have a wide range of successful applications, from industrial catalysis to medicine, resulting in the increasing need for both a complete understanding of their unique structural features and synthetic methods to target new frameworks. Nuclear magnetic resonance (NMR) spectroscopy, thanks to its sensitivity to the local, atomic-scale, environment and its element specificity, is applied, in combination with powder X-ray diffraction (PXRD), electron microscopy, N2 adsorption and mass spectrometry, to the study of these materials. Oxygen atoms play a crucial role in the structure and chemistry of zeolites and MOFs, making 17O NMR an excellent tool for chemical and structural investigations. However, the low natural abundance of this isotope (0.037%) and the cost of 17O-enriched reactants require the development of atom-efficient synthetic processes for isotopic enrichment. In the first part of this work, the unconventional assembly-disassembly-organisation-reassembly (ADOR) method is applied to the Ge-doped UTL framework and optimised in reduced-volume conditions for economic enrichment to obtain 17O- and 29Si-enriched UTL-derived zeolites. In situ and ex situ solid-state characterisation studies show that isotopic enrichment not only enables a more detailed spectroscopic investigation, but also provides new insights into the mechanism of the ADOR process and its sensitivity to experimental conditions. In the second part of this work, dry gel conversion synthesis and a novel steaming procedure are studied as cost-effective 17O-enrichment pathways for Al, Ga and Sc mixed-metal terephthalate MOFs. 17O solid-state NMR spectroscopy, in combination with PXRD and electron microscopy, is employed to investigate cation disorder and 17O NMR spectra are shown to be sensitive to substitution of metal centers and conformational changes upon interaction with guest molecules.

Cette thèse porte sur l’étude structurale de fluorures et d'oxyfluorures, en combinant la RMN du solide, la diffraction des rayons X et les calculs PAW/GIPAW des paramètres RMN. La première partie est consacrée à l’étude des cinq composés du binaire KF-YF3. Des corrélations linéaires entre valeurs expérimentales de déplacements chimiques isotropes et de constantes d’écran isotropes calculées ont été établies pour 19F, 89Y et 39K, à partir des attributions des raies RMN aux sites cristallographiques. Ces corrélations conduisent à des accords satisfaisants. Dans le cas de 19F et 89Y, le lien entre paramètres RMN et environnement a été établie. Les paramètres RMN calculés de 39K permettent des reconstructions satisfaisantes des spectres complexes.La deuxième partie est dédiée à l’étude des deux phases ordonnées de LaOF. Les optimisations et les calculs de valence de liaison montrant que les positions atomiques de F et O devaient être inversées dans ces deux phases, leurs structures ont été réaffinées. L’accord entre paramètres RMN expérimentaux et calculés de 19F et 139La valide nos modèles structuraux. Enfin les composés MO2F (M = Nb, Ta), isotypes et désordonnés vu que les atomes de O et F occupent le même site anionique, ont été étudiés. Il est montré que la synthèse en milieu aqueux conduit à des composés hydroxylés lacunaires dont les compositions ont été déterminées en combinant RMN 19F, DRX sur poudre et ATG. La synthèse en phase solide permet d’obtenir ces composés purs. Les calculs DFT ont été réalisés sur des supermailles 3 × 3 × 3 en respectant l'ordre -M-O-M-O-M-F-. Le bon accord entre paramètres RMN de 19F expérimentaux et calculés valide les modèles proposé. / This thesis focuses on the structural study of fluorides and oxyfluorides by combining solid state NMR, X-ray diffraction and PAW/GIPAW calculations of NMR parameters. The first part is devoted to the study of compounds of the KF-YF3 binary system. Linear correlation between experimental isotropic chemical shift (delta iso) and calculated isotropic shielding (sigma iso) values have been established, for 19F, 89Y and 39K, from assignments of NMR lines to crystallographic sites. These correlations lead to satisfactory agreements. In the case of 19F and 89Y, the link between NMR parameters and environment has been established. The calculated 39K NMR parameters allow satisfying reconstructions of the experimental complex spectra. The second part is dedicated to the study of the two ordered phases of LaOF. The optimizations and bond valence calculations showing that the atomic positions of F and O should be interchanged in both the phases, their structures have been refined. The agreement between experimental and calculated NMR parameters of 19F and 139La validates our structural models. Finally, the isotypic and disordered MO2F (M = Nb, Ta) compounds, since the O and F atoms occupy the same anionic site, have been studied. It is shown that the aqueous solution synthesis leads to hydroxylated and lacunary compounds, whose formulations have been determined by combining 19F NMR, XRD and TGA. The solid state synthesis enables to obtain pure compounds. DFT calculations were carried out on optimized 3 × 3 × 3 supercells that respect the partial order -M-O-M-O-M-F-. The good agreement between experimental and calculated NMR parameters of 19F validates the proposed model.

Le développement de matériaux biocompatibles permettant la vectorisation de principes actifs est particulièrement souhaitable dans le cadre de la réparation osseuse liée à certaines pathologies. Dans la première partie de ce mémoire, nous décrivons la synthèse et la caractérisation de verres de phosphates de calcium dopés avec du gallium qui est un agent inhibiteur de la résorption osseuse. Les modifications du réseau phosphate sont étudiées par RMN du 31P et les différents environnements locaux du Ga3+ sont mis en évidence par RMN du 71Ga en utilisant des conditions expérimentales spécifiques (très haut champ magnétique de 20T et rotation de l’échantillon ultra-rapide). Le comportement en solution de ces verres a été étudié par RMN et par ICP-AES. Les résultats obtenus indiquent qu’ils sont soumis à une dissolution quasi-congruente et que l’ajout de Ga3+ augmente leur durabilité chimique. La seconde partie de ce travail est dédiée à l’étude d’un verre bioactif utilisé en chirurgie réparatrice osseuse : le Bioglass® 45S5 (système SiO2-CaO-Na2O-P2O5). L’utilisation d’expériences RMN de double résonance a permis d’apporter des éléments de réponse sur le type d’association entre les groupements phosphates et le réseau silicate. Après immersion de ce verre dans un fluide physiologique simulé (SBF), un suivi quantitatif des espèces, initiales et formées à la surface du verre, a été réalisé par RMN. Les résultats obtenus par RMN et par d’autres techniques de caractérisation montrent que l’hydroxyapatite carbonatée se formant en surface du verre présente de grandes similitudes avec les apatites biologiques. / The development of biocompatible materials allowing the local delivery of specific drugs is of high interest to repair pathological bone defects. The first part of this manuscript describes the synthesis and the characterisation of calcium phosphates glasses doped with gallium, which is a bone resorption inhibitor. The nature of the phosphate network is probed by 31P NMR and the Ga3+ local environments are studied 71Ga NMR at very high magnetic field (20T) and ultra-fast spinning frequency. The leaching behaviour of these glasses is investigated by NMR and ICP-AES. The obtained results indicate that the glass dissolution is nearly congruent and that Ga3+ doping improves the chemical durability. The second part of this work is dedicated to the study of the Bioglass® 45S5 which is a bioactive glass (SiO2-CaO-Na2O-P2O5 glassy system) used in bone repair surgery. Double-resonance NMR experiments are used to obtain information about the association between the phosphate units and the silicate network. NMR analyses are also used to characterize quantitatively the various species formed at the glass surface after immersion into a simulated body fluid for varying periods. Results obtained from NMR and other characterization methods revealed that the carbonated hydroxyapatite formed at glass surface shows strong similarities with biological apatites.

Recentemente, grande interesse tem sido demonstrado por cerâmicas transparentes dopadas com íons terras raras trivalentes, como meios ativos para lasers na região espectral do infravermelho próximo. Em particular, cerâmicas dopadas com altas concentrações de Nd3+ e Yb3+ são muito estudadas pela possibilidade de gerar emissão laser de alta potência em torno de 1,0 mm. Embora a cerâmica transparente de titanato zirconato de chumbo e lantânio (PLZT), com composição La/ Zr/Ti = 9/65/35, seja originalmente reconhecida por suas propriedades ferroelétricas e eletro-ópticas, a mesma também apresenta características interessantes como matriz hospedeira de íons oticamente ativos. Recentemente, de Camargo et al. realizaram vários estudos espectroscópicos que comprovam a potencialidade laser de amostras dopadas com Yb3+, Er3+, Tm3+ e em especial Nd3+. Apesar de a cerâmica PLZT:Nd ser a mais promissora, se comparada a líder de mercado YAG:Nd (sistema ítrio-alumínio garnet dopado com neodímio), ainda não foi possível obter ação laser da primeira, devido à presença de fases espúrias (imperceptíveis a olho nu), que comprometem a qualidade óptica do material, especialmente para concentrações de dopagem maiores que 1,0% peso de Nd2O3. Uma vez que a qualidade estrutural tem implicação direta na qualidade óptica/espectroscópica de materiais ópticos, faz-se necessário estender os estudos visando otimizar a obtenção de amostras transparentes com mais altos níveis de dopagem. Neste trabalho apresenta-se um método alternativo para a dopagem da matriz PLZT com os íons TR = Nd3+ e Yb3+, e utiliza-se de várias técnicas (DR-X, DTA-TG, FT-IR, Raman, RMN e Luminescência), para caracterizar os compostos precursores e/ou produtos. O novo método baseia-se na obtenção prévia de óxidos precursores dopados, seguida da utilização destes para o preparo das cerâmicas PLZT:TR. As caracterizações foram conduzidas em função da concentração de dopantes (0,1 4,0% peso TR2O3), comparativamente ao método de dopagem convencional utilizado nos trabalhos anteriores. A espectroscopia de ressonância magnética nuclear em sólidos em 207Pb, mostrou-se uma ferramenta bastante útil na elucidação de questões estruturais desses sistemas tão complexos. Como os íons paramagnéticos Nd3+ e Yb3+ não podem ser diretamente acessados por RMN, a estratégia para caracterizar suas distribuições espaciais foi investigar suas respectivas mímicas diamagnéticas Y3+ e Sc3+ (núcleos 45Sc e 89Y). Resultados de DR-X apresentam menor formação de fase secundária nas amostras preparadas via método alternativo, sendo identificado as fases secundárias como (La,Nd)2(Zr,Ti)2O7 (estrutura do tipo pirocloro), ZrO2 em fase parcialmente monoclínica e cúbica e ZrO2 em fase cúbica, das amostras dopadas com Nd3+, Y3+ e Yb3+, respectivamente. De acordo com os resultados de DR-X, experimentos de RMN permitiram melhor avaliação quanto a inserção do íon dopante a medida que há formação de fase secundária e mostraram que a inserção dos íons dopantes é homogênea, bem como resultados de luminescência, com o limite de solubilidade do íon dopante sempre menor do que o necessário para que seja observado supressão da luminescência dos íons emissores. / In recent years, there has been a great interest for rare-earth (RE) doped transparent ceramics as near-infrared laser active media. Particularly, Nd3+ and Yb3+-doped ceramics are of special interest due to the possibility of generating high power emissions at around 1.0 mm. Even though lead lanthanum zirconate titanate (PLZT) ceramics, with composition La/Zr/Ti = 9/65/35, are mostly known by their ferroelectric and electro-optic properties, recent works by de Camargo et al. have also indicated their potentiality as laser active media. In this regard, the most promising system is PLZT:Nd (as compared to YAG:Nd - neodymium-doped yttrium aluminium garnet), however, laser action of the former has not yet been possible, the reason lying in the presence of secondary phases (invisible to the naked eye) that compromise the optical quality of the ceramics, especially for samples with concentration higher than 1.0 wt% Nd2O3. Since the structural quality of samples has a direct implication on their spectroscopic and optical qualities, the goals pursued in this work are to present means to obtain highly transparent samples with higher incorporation of dopants, as well as to understand some fundamental questions regarding the microstructure of PLZT:RE ceramics. Thus, an alternative method, based on the obtainment of RE-doped precursor oxides, is presented for the synthesis of PLZT:RE and several techniques (XRD, DTA-TG, FT-IR, Raman, NMR and Luminescence) are used to characterize the samples, as a function of doping concentration (0,1 4,0 wt% RE2O3). These studies are done in comparison to the conventional method used in previous works. Solid state NMR spectroscopy of 207Pb proved to be a very useful tool for the understanding of these complex systems. Because Nd3+ and Yb3+ are paramagnetic and thus inaccessible by NMR, the strategy used for the characterization of their spatial distribution was to study samples doped with their respective diamagnetic mimics Sc3+ and Y3+ (45Sc and 89Y nuclei). XRD results have shown formation of less secondary phase for samples prepared by alternative method, being identified as secondary phase pyrochlore structure (La,Nd)2(Zr,Ti)2O7, partially monoclinic/cubic ZrO2 and cubic ZrO2 of the samples doped with Nd3+, Y3+ and Yb3+ respectively. NMR measurements allowed to make proposals about dopant ion insertion while secondary phase is formed and showed homogeneous distribution of dopant into the matrix, aswell luminescence measurements with maximum dopant solubility being less than enough to show any suppression of luminescence.

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No. of bitstreams: 2 Dissertação - Diego Alves Rodrigues - 2014.pdf: 3563553 bytes, checksum: 740d277eef5f559b08bdd1742e750f6e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-09-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The commercialization of drugs most often occurs through their solid forms, and the caracteriscas of drugs should be kept throughout the process of production and storage. Upon this fact the characterization studies of the drugs in the solid state are in constant growth. NMR solid state high resolution can provide important complementary information current techniques, through the changes of the chemical shifts.The objective of this study is the characterization of the drug efavirenz (EVZ) and oseltamivir by the technique of nuclear magnetic resonance both in solution and solid state data together with the theoretical computations. Efavirenz drug was characterized by X diffraction (XRD), nuclear magnetic resonance in solution (1H NMR and 13C {1H}) and solid (CPMAS NMR and 13C CPTOSS e15N), and the use of theoretical calculations in solution GIAO using the model for unambiguous assignment of NMR signals. The same techniques of structural characterization and theoretical calculations were used in drug Oseltamivir, reeking the technique of X diffraction (XRD), and this drug hitherto considered amorphous.The experimental data obtained by NMR analyzes were consistent with the structure of drug efavirenz and oseltamivir; and the results of theoretical calculations were tabulated, a work of statistical analysis is performed in order to correlate the experimental data with the theoretical data, the analysis of the standard deviation (SD), mean deviation (MD), linear coefficient (R) . Notably, the theoretical values of the chemical shifts of 1H and 13C NMR in solution, obtained at the level of theory DFT/B3LYP, allowed for the drugs in question a considerable correlation with experimental values and permitted to associate a low computational cost of a good precision results.Thus using NMR experiments in solution 1D and 2D allies the results of computational theoretical calculations was possible the elucidation and assignment of all NMR signals of 1H and 13C of both drugs. efined experiments 1D solid state NMR (CP / TOSS and 13C CP / MASS de15N) allowed identification of these atoms in the solid state. Combined with theoretical calculations GIPAW provided valuable information on the molecules within the asymmetric unit of each drug. / A comercialização de medicamentos na maioria das vezes ocorre mediante suas formas sólidas, sendo que as caracteriscas dos fármacos devem ser conservadas durante todo processo de produção e estocagem. Mediante este fato os estudos de caracterização dos fármacos em estado sólido estão em constante crescimento. A RMN em estado sólido de alta resolução pode fornecer informações complementares importantes as atuais técnicas, através das mudanças dos deslocamentos químicos. O objetivo deste presente estudo é a caracterização dos fármacos Efavirenz (EVZ) e Oseltamivir pela técnica de ressonância magnética nuclear tanto em solução como em estado sólido aliado aos dados teóricos de cálculos computacionais. O fármaco Efavirenz foi caracterizado por Difratometria de raios X (DRX), ressonância magnética nuclear em solução (RMN de 1H e 13C{1H}) e de sólidos (RMN CPMAS e CPTOSS de 13C e15N), além do uso de cálculos teóricos em solução utilizando o modelo GIAO para uma atribuição inequívoca dos sinais de RMN. As mesmas técnicas de caracterização estrutural e cálculos teóricos foram utilizadas no fármaco Oseltamivir, rescendendo a técnica de Difratometria de raios X (DRX), sendo este fármaco até então considerado amorfo. Os dados obtidos pelas análises experimentais de RMN foram coerentes com a estrutura dos fármacos Efavirenz e Oseltamivir; e os resultados dos cálculos teóricos foram dispostos em tabelas, sendo realizado um trabalho de análises estatísticas de forma a correlacionar os dados experimentais com os dados teóricos, pela análise do desvio padrão (SD), desvio médio (MD), coeficiente linear (R). Notavelmente os valores teóricos dos deslocamentos químicos de RMN 1H e 13C em solução, obtidos com o nível de teoria DFT/B3LYP, possibilitaram para os fármacos em questão uma correlação considerável com os valores experimentais e permitiram associar um baixo custo computacional a uma boa precisão dos resultados obtidos. Desta forma utilizando experimentos de RMN em solução 1D e 2D aliados aos resultados dos cálculos teóricos computacionais foi possível a elucidação e atribuição de todos os sinais de RMN de 1H e 13C de ambos os fármacos. Experimentos refinados de RMN em estado sólido 1D (CP/TOSS de 13C e CP/MASS de15N) possibilitaram a identificação destes átomos em estado sólido. Aliados a cálculos teóricos GIPAW forneceram valiosas informações sobre as moléculas dentro da unidade assimétrica de cada fármaco.

Les transporteurs à ATP binding cassette (ABC) peuvent transporter une grande variété de substrats utilisant l'ATP-Mg2+ comme source d'énergie. Ces transporteurs sont présents dans toutes les formes de vie et sont impliqués dans la résistance aux médicaments, comprenant les anticancéreux et les antibiotiques. Mes travaux de thèse se concentrent sur le transporteur BmrA (130 kDa) de Bacillus subtilis utilisé en tant que système modèle et homologue de la P-glycoprotéine humaine impliquée dans la multirésistance aux anticancéreux. Dans ces travaux nous montrons que la reconstitution de cette protéine dans les lipides de Bacillus subtilis répond aux deux exigences centrales pour RMN: haut rapport signal sur bruit et la stabilité de l'échantillon sur une période de plusieurs années. Les spectres obtenus indiquent une protéine bien repliée et une préparation très homogène, comme en témoignent les lignes de résonance étroites et la dispersion du signal typique de la distribution de structure secondaire attendue de la protéine membranaire. Nous avons adapté la méthode GRecon utilisée dans les études de microscopie électronique pour la reconstitution des protéines membranaires pour la RMN à l'état solide. Nous avons suivi en détail la reconstitution du transporteur ABC BmrA par dialyse comme référence, et établi des conditions optimales de reconstitution en utilisant un gradient combiné de saccharose / cyclodextrine / lipide caractérisant GRecon. Les spectres RMN de l‘échantillon reconstitué par GRecon sont très similaire à ceux obtenus précédemment sur des échantillons reconstitués par dialyse. La préparation d'échantillons par GRecon présente un gain de temps de près d'un ordre de grandeur. Afin d'étudier les états ouvert vers l'intérieur (inward-facing IF) et ouvert vers l'extérieur (outward-facing OF) du transporteur, nous avons développé un protocole reproductible et quantitatif induisant l'état OF. Nous avons enregistré des spectres bidimensionnels RMN à l'état solide avec différents temps de mélange (20 et 200 ms) afin de suivre les changements des déplacements chimiques et d'identifier les résidus par des corrélations séquentielles. L'apparition très apparente de nouveaux signaux concomitants à la grande amplitude des perturbations de déplacement chimique (CSP) met en évidence l'importante flexibilité et les changements conformationnels de la protéine en présence d'ATP: Mg2+. Afin d'identifier les résidus apparaissant dans les spectres, nous avons utilisé le remplacement paramagnétique du co-facteur Mg2+ par du Mn2+. Cette méthode a révélé que les acides aminés apparaissant dans les spectres sont situés à proximité du site de liaison de l'ATP. En outre, les mesures EPR ont confirmé l'état fermé de la protéine en identifiant la distance correspondant à 1,8 nm entre deux atomes de Mn2+. Nous avons étudié les différences conformationnelles entre l'état IF et OF de BmrA. L'observation de nombreux CSP, ainsi que l'apparition de nouveaux signaux sont observés pour un mutant ne pouvant pas hydrolyser l'ATP, indiquant que l'hydrolyse n'est pas nécessaire pour la transition IF à OF dans BmrA. Nous avons également analysé le mécanisme lié au motif X-loop décrit comme étant impliqué dans la communication entre deux domaines de la protéine. Nous avons observé pour une protéine mutante dans laquelle le transport est aboli mais qui reste ATPase active, une transition incomplète puisque seul un sous-ensemble de CSPs est observé, ainsi qu'un manque de rigidification. Ces mesures suggèrent que la flexibilité semble être le point central dans la transmission des changements conformationnels nécessaires de la partie motrice à la partie d'exportation de molécules. Ces observations montrent que ce système serait semblable à un moteur tournant à plein régime qui ne serait pas connecté de manière rigide à un arbre de transmission le reliant au système de transport / ATP binding cassette (ABC) transporters can translocate a variety of molecules by coupling drug/lipid efflux with an ATP-Mg2+ fuelled engine. They are found in all forms of life and they are involved in a number of drug resistances including anti-cancer drugs and antibiotics. My studies focus on the drug exporter BmrA (130 kDa) from Bacillus subtilis as a model system and homologue of the human P-glycoprotein that is involved in multidrug resistance in cancer. We show that the reconstitution of this protein in lipids from Bacillus subtilis at a lipid-protein ratio of 0.5 m/m allows an optimal protein insertion into lipid bilayer as well as it complies with the two central NMR requirements: high signal-to-noise in the spectra and sample stability over a time period of years. The obtained spectra point to a well-folded protein and a highly homogenous preparation, as witnessed by the narrow resonance lines and the signal dispersion typical of the expected secondary structure distribution of the membrane protein. In the same time, we adapted the GRecon method used in electron microscopy studies for membrane protein reconstitution to the needs of solid-state NMR sample preparation. We followed in detail the reconstitution of the ABC transporter BmrA by dialysis as a reference, and established optimal reconstitution conditions using the combined sucrose/cyclodextrin/lipid gradient characterizing GRecon. NMR spectra recorded on a sample produced by GRecon showed a highly similar fingerprint as those recorded previously on samples reconstituted by dialysis. GRecon sample preparation presents a gain in time of nearly an order of magnitude for reconstitution. In order to study the inward-facing (IF) and the outward-facing (OF) state of the transporter, we developed a reproducible and quantitative protocol of ATP:Mg2+:VO43- addition inducing the OF state. We used selectively labelled samples obtained by the addition of natural abundance residues in the bacterial medium in order to reduce the number of signals in the spectra of this large protein. We recorded solid-state NMR two-dimensional spectra with different mixing times (20 and 200 ms) in order to follow chemical shift changes and identify residues by sequential correlations. The very noticeable apparition of new signals concomitant with the large amplitude of chemical shift perturbations (CSPs) highlight the important flexibility and conformational changes of the protein in presence of ATP:Mg2+:VO43- substrate. In order to identify the residues appearing in the spectra, we use paramagnetic replacement by Mn2+ of the Mg2+ acting as a co-factor in the active site. The paramagnetic relaxation enhancements caused the Mn2+ revealed that the amino acids appearing in the spectra are located in proximity to the ATP binding pocket. Besides, EPR measurements confirmed the closed state of the protein by identifying the corresponding 1.8 nm distances between two Mn2+. We investigate on the conformational differences identified between the IF and OF state in the ABC transporter BmrA reconstituted in its natural lipids. The observation of numerous CSPs, as well as the apparition new signals are observed for a hydrolysis-incompetent mutant on addition of ATP, indicating that hydrolysis is not required for the IF to OF transition in BmrA. We also analyze the mechanistic of the X-loop motif described to be involved in the communication between two domains of the protein. We observe for a mutant protein in which transport is abolished, but which remains ATPase active, an incomplete transition since only a subset of CSPs is observed, as well as lack of rigidification. This suggests that the change in dynamics might be central for transmitting the relevant conformational changes to the part of the protein driving transport, concomitant of an engine which is turning an input shaft, but which fails to connect in a rigid manner, trough adequate gears, with the output shaft driving the pump

Les matériaux céramiques à base de bore dans le système quaternaire Si-B-C-N présentent des propriétés de grand intérêt grâce aux liaisons covalentes et à la faible mobilité des éléments bore et silicium dans leurs phases nitrure et carbure, ce qui amène une grande fiabilité mécanique et une bonne stabilité thermique. Ces dernières années, la voie « polymères précéramiques » est devenue la plus intéressante pour la préparation des ce type de céramiques avancées. En utilisant la thermolyse de polymères, une large variété de céramiques dérivées de polymères précéramiques peut être produite à partir de précurseurs moléculaires, en contrôlant la structure de l'unité monomérique, la polymérisation et la procédure de thermolyse. Notamment la thermolyse directe des polymères est une voie compatible avec plusieurs types de techniques de mise en forme, entre autres l'infiltration ou le filage, qui offrent la possibilité de réaliser structures et objets avec des formes complexes avec une approche simple et à faible coût. La première génération de fibres SiBCN a été obtenue à partir du polymère de type [B(C2H4SiCH3NCH3)3]n. Celle-ci présentait de bonnes propriétés mécaniques et une bonne stabilité thermique. Ce manuscrit présente une étude sur le développement de ce type de polymères, en particulier l'optimisation du filage et de la qualité de fibres à travers la modification des voies de synthèse et des traitements de thermolyse. De plus, une élaboration de nouveaux précurseurs moléculaires est développée afin de produire une nouvelle génération de fibres SiBCN / Boron-based ceramic materials in the quaternary Si-B-C-N system are of great interest because of their covalent bonding and the poor mobility of boron and silicon elements in their respective nitride and carbide which both provide mechanical reliability and high temperature stability. In recent years, the PDCs route became of increasing interest for the preparation of such advanced ceramics. Using the general polymer thermolysis route, a large variety of net-shaped polymerderived ceramics can be built up from molecular units and shaped by controlling the structure of the molecular units as well as the polymerization and thermolysis procedures. Interestingly, the direct polymer thermolysis route makes polymers compatible with many shaping techniques such as infiltration or melt-spinning offering the opportunity to realize complex shapes/structures in a simple and cost-efficient way.The first generation of such fibers obtained from a polymer type [B(C2H4SiCH3NCH3)3]n showed good mechanical properties and thermal stability. This document is about the development of such a polymer in order to optimize spinnability and fibers quality throught synthesis modification and thermolysis treatments. Moreover, design of new preceramic polymers is investigate to produce a new generation of SiBCN fibers

Chlorine solid-state nuclear magnetic resonance (SSNMR) is an ideal site specific probe of chloride-containing solids as SSNMR tensor properties are sensitive to the local chlorine environment. In this thesis, the development and use of chlorine SSNMR as a method to characterize a wide variety of chemical environments was explored. Ultrahigh field, and multi-field studies were essential to overcome the difficulties associated with the collection of chlorine SSNMR spectra. Benchmark chemical shift (CS) and electric field gradient (EFG) tensor data were collected for organic chloride systems, including several amino acid hydrochlorides. These experiments demonstrated the sensitivity of chlorine SSNMR to slight changes in chemical environment. Quantum chemical calculations were used to complement experimental data, with the gauge-including projector augmented wave DFT (GIPAW-DFT) method shown to yield better agreement than B3LYP or RHF methods. The GIPAW-DFT method was found to slightly, but systematically, overestimate the chlorine quadrupolar coupling constant and the CS tensor span. Other organic chlorides examined by chlorine SSMR included a known ion receptor, meso-octamethylcalix[4]pyrrole. This compound was found to have a very small quadrupole interaction (QI), but significant chemical shift anisotropy (CSA). GIPAW-DFT calculations were also utilized and, in combination with the experimental results, used to identify the solvate structure of the material analyzed by NMR. Chlorine SSNMR was further used to study different solvate structures and polymorphism. The technique was an effective means to distinguish different room temperature polymorphs of benzidine hydrochloride, despite the similarities of the chloride environments. In the case of magnesium chloride, chlorine SSNMR was sensitive to the level of hydration and through the use of GIPAW-DFT calculations, the identity of an unknown hydrate was determined. An analysis of several group thirteen chlorides demonstrated that chlorine SSNMR was also capable of characterizing the chlorine environment in cases where the QI is large, despite the resulting broad line widths. In these systems GIPAW-DFT calculations also yielded excellent agreement with experimental values. Throughout this research, chlorine SSNMR has been shown to be a useful and effective means to study both organic and inorganic chlorides, with computational methods proving to be an important complement to experimental data.