This thesis describes the oxidative addition reactions of sulfur, oxygen and nitrogen containing organic molecules into triosmium clusters. The products were formed by C-H, O-H, N-H and S-S bond cleavage. The direct reaction of dibenzyl disulfide, di(2-thienyl)disulfide and di-tertiary-butyl disulfide with cluster Os3(MeCN)2(CO)io yielded their respective unsymmetrical thiolato derivatives: Os3(u-SCH2Ph)2(CO)io , Os3(p-StBu)2(CO)i0 and Os3(u- SC4H3S2)2(CO)io in high yields with the cleavage of the S-S bond. Only dibenzyl disulfide gave a second cluster Os3(u-H)(S2CH2Ph)(CO)io , which retained the S-S bond. Thermal treatment of Os3(u-SCH2Ph)2(CO)io gave the symmetrical isomer in which both sulfur ligands bridged the same pair of osmium atoms. The interconversion of isomers of the unsymmetrical form of Os3(u-SCH2Ph)2(CO)io , related by inversion at sulfur, gave Ea = 61.5 2.0 kJ mol"1, determined by NMR methods. The direct reaction of 8-hydroxyquinoline with Os3(MeCN)2(CO)io employing various reaction conditions yielded both mono-, tri- and tetra-nuclear compounds: 0s(C9H6N0)2(C0)2 , 0s3(C9H6N0)2(C0)8 , Os3(u-H)(C9H6NO)(CO)9 and Os4(u- H)(C9H6N0)(C0)ii . Three isomers of complex 0s(C9H6N0)2(C0)2 were observed. Reactions between osmium carbonyl and phenols substituted with both electron- donating or accepting substituents always gave the dienone structures 0s3(u-H)2(u- 0C6H4X)(C0)9 (X = OH, F, OMe) in preference to the alternative aromatic form. The variable-temperature NMR spectra of Os3(u-H)2(u-OC6H40Me)(CO)9 show both the hydrides and the carbonyl ligands are mobile. Attempts to link clusters were only successful with hydroquinone which gave Os6(u-H)3(u-OC6H30)(CO)i9 . However with aminophenol, reaction was always preferred at the amine in preference to the hydroxyl group. Benzoquinone gave a unique cluster Os3(u-H)(u- OC6H5O)(CO)10 . Finally we have shown how the direct reaction of Os3(MeCN)2(CO)io with 4,4- dipyridyl disulfide yields the linked cluster OseCu-HMp-CsCsNXCOo leaving the S-S bond intact. The S-S cleavage occurs by treating Os6(p-H)2(n- C5H3NS2C5H3N)(CO)2o further with Os3(MeCN)2(CO)i0 to give Os9(u-H)2 (NC5fi3S)2(CO)3o . The initial reaction always takes place at the pyridine ligands followed by S-S cleavage. The reaction of 4-mercaptopyridine gave a linked cluster Os6(u-H)2(NC5H3S)(CO)2o . All these reactions were carried out at room temperature.

No description available.

Many metallporphyrins are catalysts for the oxidation of organic substrates using oxidants such as hydrogen peroxide or oxygen. They have been much studied, but the factors that influence their reaction with oxidant within the initial (-1 s) period arc poorly understood and have been studied in this work. The research used the stopped-flow technique to obtain the first direct measurement of the equilibrium constant K for the important complexation of hydrogen peroxide to tetrakis(pentafluorophenyl)porphyrin iron(1II) chloride Fe-1. In addition it provided direct measurement of rate constants for key steps in the mechanism. Specifically, a complex MeOH:Fem;H20 Z (388 om) is produced from the initial reaction in MeOH of Fe-l (404 !lm) with H2O2 (log K 2.39), then this undergoes 0 -0 bond cleavage, being quickly converted to FeIV=O (408 run) (kf 4.4 S-l). This species itself oxidizes (is reduced by) excess H2O2 (kr 54.3 M-IS"!) to regenerate the I MeOH:Fem:Hz0 2 complex, setting up an equilibrium between this complex and FeIV =0. As the proportion of DCM increases the value of log K falls. although in 3: 1 MeOH-DCM changes are small (log K 1.39, kc = 7 s-1, k, = 20 M-1s-1). In all cases after - 1 s decomposition (bleaching) is observed. Addition of an oxidizable substrate HNQ gives a MeOH:Felll:HNQ complex (log K 3.27 and 4.29 in MeOH and 3: 1 MeOH-DCM, respectively), but under the reaction conditions used (mM H,O, vs. μM HNQ) is displaced by H20 , to give MeOH:Few:H2O2 and the reaction proceeded as in the HNQ-free case. Finally, when oxidizable substrate HNQ was added to a preformed mixture of MeOH:Fe111:H2O2 and Fe1v=0. it had little effect and reaction kinetics (kf. kr) on the spectra. This was interpreted to mean that FelV =0 does not react with HNQ, and more speculatively, that the often-proposed Fe v =0 or por+o.Fe1V =0 may not be involved, at least under these conditions.

The selective aerobic oxidation of organic molecules has been highlighted as a fundamental and practical challenge for modem chemistry. The oxidation of alcohols is one such challenge. It is a key reaction in the synthesis of many compounds, however rarely implemented in an industrial setting. In the last 20 years Pd(II) complexes modulated with oxidatively stable ligands have emerged as a promising class of catalysts for the reaction. Such Pd(Il) ligated complexes utilise molecular oxygen as the sole oxidant producing benign by- products such as water. Although the work to date has been pioneering, a number of challenges still need to be addressed for the reaction be industrially viable; faster rates, catalyst separation and safe handling of O2, We sought to design new catalysts initially testing a range of anionic N, O-ligands for the homogeneous Pd(II) catalysed oxidation of 2-octanol. The optimal ligand from the screen was 8-hydroxyquinoline-2-sulfonic acid (HSA), producing a TOF highly competitive with the neocuproine ligand, the current literature benchmark. Further optimisation was undertaken altering reaction parameters such as temperature, catalyst loading, base additive and the introduction of a solvent. In addition to exploring such N,O-chelating ligands we also investigated NN-chelating ligands (phenanthroline-type ligands) of neocuproine and bathocuproine disulfonic acid. Such ligands have been well documented in the literature; hence we wanted to both compare our 8-hydroxyquinoline-2-sulfonic acid ligand, as well as probing the potential for further development of such phenanthroline derivatives. In addition to a traditional solvent screen an ionic liquid solvent was undertaken. It was concluded that a more non-coordinating solvent system produced optimal rates from the (I-ISA)Pd(OAc)2 catalyst system. The influence of a CO2 atmosphere on our catalytic systems was explored throughout the thesis (with the view to a future continuous flow CO2 system/as a means for catalyst separation and recycle). In the homogenous studies the catalyst was seemingly deactivating over prolonged reaction times, presumably via catalyst aggregation. Therefore we decided to investigate Pd(II) catalysts covalently tethered to silica supports. Synthesising numerous catalysts using different functionalities, it was demonstrated that a urea linkage was the optimum functionality for our study.

No description available.

La cellule lutte à chaque instant contre les perturbations afin de maintenir l'équilibre de son milieu intérieur, et permettre sa survie. L'apparition d'espèces oxydantes ou l'augmentation de la température sont autant de perturbations auxquelles la cellule doit faire face. Mon travail de thèse s'est articulé autour de la dynamique temporelle des stress oxydant et thermique en cellules vivantes. L’originalité de l’équipe où j’ai effectué ma thèse est de proposer une alternative aux photothérapies dynamiques en produisant directement, sans photosensibilisant, de l’oxygène singulet considéré comme l’agent cytotoxique principal. Cette façon de produire directement l’oxygène singulet permet non seulement d’adresser plus directement des questions de dosimétrie qui sont importantes en thérapie mais aussi d’identifier les macromolécules impliquées dans le stress oxydant. Dans une première partie je présenterai des études de cinétique photochimique qui ont permis de déterminer dans différents solvants et en cellule, le taux de production et la réactivité de l'oxygène singulet avec un partenaire spécifique. Dans une seconde partie, je présenterai mes travaux sur la dynamique temporelle de réponse au stress thermique en cellules vivantes. Le développement d’un modèle mathématique minimal de titration du stress thermique couplé à des expériences associant un facteur de transcription clef dans la régulation du stress, nous ont permis de mettre en évidence les contributions des principales réactions impliquées dans le mécanisme de réponse cellulaire au stress thermique. / The cell fight everytime against disturbances to maintain the balance of its internal environment and ensure its survival. The appearance of oxidative species or increasing the temperature are all major perturbations which the cell has to face. My thesis is structured around the temporal dynamics of oxidative and thermal stress in living cells. The originality of the team where I did my thesis, is to propose an alternative way to phototherapy dynamic in producing directly, without photosensitizer, singlet oxygen which is considered as the main cytotoxic agent. This way of producing singlet oxygen directly allows to address dosimetry issues that are important in therapy but also, to identify the macromolecules involved in oxidative stress more directly. In the first part ,I will present photochemical kinetic studies that have enable to determine in different solvents and in cells, the production rate and the reactivity of singlet oxygen with a specific partner. In the second part, I will present my work on the temporal dynamics of heat stress response in living cells. The development of a minimal mathematical model of titration of thermal stress coupled with experiments involving a key transcription factor in the regulation of stress, allowed us to identify the main reactions involved in the mechanism of cell response to heat shock.

Ce manuscrit détaille la découverte de nouveaux matériaux oxydes et oxysulfures. Dans un premier temps, il porte sur l’étude de composés hexagonaux RM2O4 et R2M3O7 modifiés topotactiquement par oxydation. Les deux composés métastables, YbFe2O4.5 et InFe2O4.5, montrent la conservation du caractère multicouche via un jeu de glissement des couches de fer et de terre rare et une réorganisation du sous-réseau anionique. Les structures modulées présentent une distribution unique de polyèdres FeOn (n = 4, 5 et 6). En revanche, le composé InGaFeO4.3 met en évidence la particularité des cations Ga3+ à bloquer le réarrangement structural. Les composés R2M3O7 (Yb2Fe3O7.5 et In2Ga2MnO7.12) contiennent les unités RM2O4 déjà décrites et, donc, présentent les mêmes phénomènes d’oxydation. Dans un second temps, l’étude se concentre sur la recherche de nouveaux oxysulfures de basse dimensionnalité, en s’inspirant notamment des composés Ba3VS3(VO3S) et La3SiS4(CuS3). Les phases inédites Ba10V6S7O18 et Ba10.67V3O6Fe8.67S17.33 ont été obtenues avec une charpente de basse dimension rendue possible par la présence de cations Ba2+ et d’entités V(O,S)4 qui jouent le rôle de séparateurs. La première phase ouvre la voie à de l’ingénierie du band gap à partir des différents types d’anions dont des soufres « isolés ». Les deux autres nouvelles phases Ba3(V,Cr)S3(VO3S) et La3Cu0.5 2δFe0.25+δSiS7 sont constituées de chaines ((Cr/V)3+S3 et (Fe2+/Cu+)S3 déficientes) séparées par des entités tétraédriques (VO3S et SiS4). Cette étude se termine sur la détermination structurale de Co7S8, un composé binaire du système Co-S, et la découverte de son comportement métallique non conventionnel. / This manuscript details the discovery of new oxide and oxysulfides materials. First, it focuses on the study of hexagonal compounds RM2O4 and R2M3O7 topotactically modified by oxidation. The two metastable compounds, YbFe2O4.5 and InFe2O4.5, show the conservation of the multilayer feature via a sliding of the iron’s and rare earth’ layer and a reorganization of the anionic sublattice. The modulated structures have a unique distribution of FeOn polyhedra (n = 4, 5 and 6). In contrast, the InGaFeO4.3 compound shows the particularity of Ga3+ cations to block the structural rearrangement. The R2M3O7 (Yb2Fe3O7.5 and In2Ga2MnO7.12) compounds have the RM2O4 units already discussed and, therefore, exhibit the same phenomenon of oxidation. Secondly, the study focuses on the research of new oxysulfides of lower dimension, by focusing on the compounds Ba3VS3(VO3S) and La3SiS4(CuS3). Two new structures Ba10V6S7O18 et Ba10.67V3O6Fe8.67S17.33 have been obtained with a low dimension framework made possible by the presence of Ba2+ cations and V(O,S)4 entities which are separators. The first phase opens the way to band gap engineering from the different types of anions including “isolated” sulfurs. The two other new phases Ba3(V,Cr)S3(VO3S) and La3Cu0.5 2δFe0.25+δSiS7 are made up of chains ((Cr/V)3+S3 and deficient (Fe2+/Cu+)S3) separated by tetrahedral entities (VO3S and SiS4).This study is conclude with the structural determination of Co7S8, a binary compound of Co-S system, and the discovery of it unconventional metallic behavior.

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Une étude de l’oxydation d’une poudre de nanoparticules de cuivre a été menée à 120 - 145°C sous des pressions partielles d’oxygène allant de 1 à 40 kPa. La réaction a été suivie par thermogravimétrie afin d’obtenir les données cinétiques. Des caractérisations chimiques, texturales et morphologiques de la poudre ont été réalisées à différents moments de la transformation. La cuprite (Cu2O) (produit unique) de la réaction croît d’une manière anisotrope et par développement externe autour de la particule initiale qui devient creuse. Une diminution de la surface spécifique et de la porosité de la poudre au cours de la transformation a été mise en évidence.Des tests cinétiques ont montré l’existence d’une étape limitante de croissance jusqu’à un taux de conversion de 0,7 à 140°C. Il a également été montré que pour P(O2) ≤ 4 kPa, les processus de germination et de croissance de l’oxyde interviennent simultanément pendant la réaction et que l’adsorption de l’oxygène est l’étape limitante. Pour P(O2) ≥ 20 kPa, la germination se fait instantanément au début de la transformation dont la vitesse est contrôlée par le processus de croissance, la diffusion du cuivre étant alors l’étape limitante. Deux modèles ont été construits et testés avec succès pour décrire la cinétique dans les deux gammes de P(O2) jusqu’à un taux de conversion donné. Pour expliquer le ralentissement observé au-delà de ce taux de conversion et pour P(O2) ≤ 4 kPa, le modèle a été couplé aux phénomènes de transfert de chaleur et de matière au sein des agglomérats. Ce couplage permet d’évaluer l’hypothèse d’un ralentissement de la réaction par la diffusion des molécules d’oxygène dans les pores de l’agglomérat. / The oxidation of copper nanoparticles at 120 – 145°C was investigated using TGA, DSC, XRD, SEM, TEM and nitrogen adsorption techniques (BET, BJH,..). Isothermal and isobaric studies of the oxidation reaction were carried out under various oxygen partial pressures 1 kPa – 40 kPa. The cuprous oxide (Cu2O) (the unique product of the reaction) grows in an anisotropic manner by outward diffusion of the copper. A considerable decrease of the specific surface area and the porosity of the powder during the transformation was highlighted.It was found that working under P(O2) ≤ 4 kPa leads to reaction where nucleation of Cu2O is in competition with its growth. The study of the dependency of the growth rate on the oxygen partial pressure has shown the adsorption of oxygen to be the rate-determining step. However, when the reaction is conducted under P(O2) ≥ 20 kPa, the nucleation occurs instantaneously in the early beginning of the reaction which will be governed by the growth process. Under these latter conditions of oxygen partial pressure the diffusion of copper ionized vacancies becomes the rate determining step. Hence, two kinetic models have been established to interpret the experimental curves in the two different oxygen partial pressure ranges. The expression of the extent of conversion was successfully confronted to the kinetic data up to an extent of conversion corresponding to the slowdown of the reaction. The kinetic model for P(O2) ≤ 4 kPa was coupled with mass and heat transfer within the porous agglomerate to verify if the diffusion of oxygen molecules in pores is in the origin of the reaction slowdown, this latter hypothesis was found not satisfactory.

Les objectifs de cette thèse sont d’une part d'étudier les effets d’un traitement thermique et de l’environnement physico-chimique sur la stabilité de 6 flavonoïdes de structure différente et sur l'évolution de leur activité anti-oxydante. Les conditions du traitement thermique ont été les suivantes : (i) chauffage dans des conditions isothermes durant 2h pour des températures allant de 30 à 130°C et (ii) chauffage dans des conditions non isothermes par microcalorimétrie (de 30 à 130°C, 4°C/ heure). Les flavonoïdes ont été solubilisés dans de l’eau. Nous avons constaté que les flavonoïdes glycosylés sont plus résistants que les flavonoïdes aglycones. Les énergies d'activation de dégradation calculées dépendent aussi de la structure du flavonoïde. Pour se dégrader, les flavonoïdes glycosylés ont besoin d’une énergie élevée par rapport à la forme aglycone. L’exposition à la lumière a été réalisée durant 15 jours avec et sans oxygène, le témoin de l’expérience étant un stockage à l’obscurité avec et sans oxygène. La dégradation des flavonoïdes est influencée par la présence de lumière et par la quantité d'oxygène. Les molécules ont une sensibilité différente en fonction de leur structure, le classement suivant est obtenu d’après : naringine, ériodictyol puis rutine, lutéoline, lutéoline 7-O-glucoside et enfin le mesquitol. En effet, la présence d'un groupe hydroxyle en position 3 et une double liaison C2-C3 diminue la stabilité des flavonoïdes. En outre, il a été observé que, malgré la dégradation totale de certains flavonoïdes par le traitement thermique et l’environnement physico-chimique, les solutions traitées conservent une activité anti-oxydante / The objectives of this thesis are to study the effects of a heat treatment and the physicochemical environment on the stability of 6 flavonoids of different structure and on the evolution of their antioxidant activity. The heat treatment conditions were as follows: (i) heating under isothermal conditions for 2 h at temperatures ranging from 30 to 130 ° C and (ii) heating under non-isothermal conditions by microcalorimetry (30 to 130 ° C, 4 ° C / hour). The flavonoids were solubilized in water. We found that the glycosylated flavonoids are more resistant than the aglyconic flavonoids. The calculated degradation activation energies also depend on the structure of the flavonoid. To degrade, glycosylated flavonoids require high energy relative to the aglycone form. Exposure to light was carried out for 15 days with and without oxygen, the experimental control being a dark storage with and without oxygen. The degradation of flavonoids is influenced by the presence of light and by the amount of oxygen. The molecules have a different sensitivity according to their structure, the following classification is obtained according to: naringine, ériodictyol then rutin, luteolin, luteolin 7-O-glucoside and finally the mesquitol. Indeed, the presence of a hydroxyl group at position 3 and a C2-C3 double bond reduces the stability of the flavonoids. Furthermore, it has been observed that, despite the total degradation of certain flavonoids by the heat treatment and the physical-chemical environment, the treated solutions retain an antioxidant activity