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Étude de catalyseurs à base d’oxyde de titane et d’oxyde de vanadium sulfatés pour l’oxydation sélective du méthanol en diméthoxyméthane (DMM) / Sulfated vanadia-based and titania-based catalysts for selective oxidation of methanol to dimethoxymethane (DMM)Zhao, Hongying 28 June 2010 (has links)
Ce travail est en relation avec la thématique "Energies Propres". Le diméthoxyméthane estun composé adapté au stockage de l’hydrogène pour des applications mobiles, de par saforte teneur en hydrogène, sa très faible toxicité et son faible impact sur l'environnement.De ce fait, des catalyseurs mixtes, à base d’oxyde de vanadium et d’oxyde de titanesulfatés ont été préparés et testés dans la réaction d'oxydation sélective du méthanol enDMM, en vue de la production d'hydrogène. Les propriétés acides et redox de surface ontété corrélées aux performances catalytiques. Les mécanismes de réaction et l'identificationdes facteurs limitant l'activité et la sélectivité des catalyseurs ont été aussi étudiés. / This work is related to the subject “Clean Energy”. Dimethoxymethane (DMM) is asuitable H2 storage material for mobile application because of its high content of hydrogen,extremely low toxicity and environmentally benign. Therefore, sulfated vanadia-titania,sulfated binary vanadia-based and titania-based catalysts were prepared and evaluated inthe reaction of selective oxidation of methanol to DMM and further production ofhydrogen. The surface acidic and redox properties of the studied catalysts were correlatedto their catalytic performance. In addition, the reaction mechanisms and the identificationof factors limiting the activity and selectivity of catalysts were also studied.
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Production et caractérisation d'agrégats moléculaires protonés contenant un nombre donné de molécules d'eau auprès de dispositif DIAM / Production and characterization of protonated molecular clusters containing a given number of water molecules with the DIAM set-upBruny, Guillaume 03 December 2010 (has links)
La compréhension de l'irradiation à l'échelle du nanomètre dans les systèmes biomoléculaires nécessite l'observation de caractéristiques nouvelles auxquelles les développements techniques actuels nous permettent d'accéder. Ce travail se situe au coeur de la construction du nouveau dispositif DIAM Dispositif d’Irradiation d’Agrégats de Molécules biologiques développé à l’Institut de Physique Nucléaire de Lyon. Le développement d’une source d’agrégats associée à un spectromètre de masse à double focalisation a permis l’obtention des premiers faisceaux d’agrégats moléculaires protonés sélectionnés en masse. De plus, un système de détection innovant a été développé et validé dans des expériences de dissociations d’agrégats d’eau protonés par collision sur un gaz. Les résultats obtenus contribuent à la connaissance de la stabilité et de la structure des petits agrégats d’eau protonés et des agrégats mixtes d’eau et de pyridine protonés / Nanoscale characterization of irradiation in biomolecular systems requires observation of novel features which are now achievable with the recent technical progress. This work is a central part in the development of DIAM which is a new experimental set-up devoted to irradiation of biomolecular clusters at the Institut de Physique Nucléaire de Lyon. The development of the cluster source and of a double focusing mass spectrometer leads to the production of intense beams of mass selected protonated molecular clusters. Combined with this mass selected cluster beams an innovative detection technique is demonstrated in collision induced dissociation experiments. The results contribute to the knowledge of the stability and the structure of the small protonated water clusters and mixed clusters of water and pyridine
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Odstranění organického znečistění z vody s využitím UV záření. / Removing organic contamination from water, using UV radiation.Venská, Petra January 2017 (has links)
This diploma thesis focuses on possibilities of applications of UV radiation to remove pollutants from water. It summarizes sources of UV radiation and list their benefits and properties. The thesis characterizes so called advanced oxidation processes using UV light. Degradation pathways od pyridine and its derivatives especially halogenated pyridines are described. The photodegradability of pyridine and a rate of this reaction in model water is investigated in the experimental part. Also, the effect of concentration and dose of H2O2 is assessed. Gas chromatography was used to determinate concentrations of pyridine in samples.
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Synthesis of transition metal containing polymers and fabrication of photonic devices by self assembly methodMan, Ka-yan, Kitty., 文嘉欣. January 2004 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
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LASER-INDUCED THERMAL DECAY OF PYRIDINE AND CHLORIDE SURFACE-ENHANCED RAMAN SCATTERING AS A PROBE OF SILVER SURFACE-ACTIVE SITESSobocinski, Raymond Louis, 1962- January 1987 (has links)
The activation parameters for the temperature dependent irreversible loss of surface-enhanced Raman scattered (SERS) intensity from pyridine and chloride adsorbed at silver surfaces in an electrochemical environment have been determined. Laser-induced heating is introduced as a probe of the chemical nature of SERS-active sites. Surface temperatures are calculated from spectroscopic data. The activation energies associated with the destruction of SERS-active sites at a surface roughened by an illuminated oxidation-reduction cycle (ORC) are 12.8 ± 3.2 kcal/mole and 27.7 ± 3.1 kcal/mole for pyridine at two different types of sites on the Ag surface. Similarly, values for coadsorbed chloride are found to be 11.1 ± 2.4 kcal/mole and 24.5 ± 3.8 kcal/mole. An activation energy of 27.4 ± 1.9 kcal/mole is obtained for pyridine on a silver surface roughened by a nonilluminated ORC. Evidence for the desorption of pyridine and chloride is presented.
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Charting New Territory in Bis(imino)pyridine Coordination ChemistryJurca, Titel 17 July 2012 (has links)
This work was initially launched to study the synthesis of low-valent group 13 compounds bearing the bis(imino)pyridine ligand framework. Since its inception, this project has grown beyond the boundaries of group 13 to include low valent tin, silver, and rhenium. Alongside the reports of novel coordination compounds, we utilized computational chemistry to uncover unprecedented interactions which challenge conventional concepts of bonding. Synthesis, characterization, and complimentary computational studies are presented herein.
Chapter 1 presents a historical overview of the bis(imino)pyridine ligand as well as our synthetic methodology and characterization of new ligand variants we have contributed to the literature.
Chapter 2 presents the synthesis of a series of In(I) and In(III) bis(imino)pyridine complexes with varied sterics. Ligand-metal interaction and effect of ligand steric bulk on complex stability, as well as computational studies highlighting weak covalent interactions will be discussed.
Chapter 3 presents the synthesis of Ga(III) bis(imino)pyridine complexes. Reactivity with “GaI” synthon as well as varied-stoichiometry one-pot synthesis attempts to generate low valent Ga-bis(imino)pyridine complexes will be discussed.
Chapter 4 presents the synthesis of a series of Tl(I) bis(imino)pyridine complexes with varied sterics analogous to the approach taken with indium(I). Unprecedented weak ligand-metal as well as Tl-arene interactions will be discussed.
Chapter 5 presents the synthesis of a series of Sn(II) bis(imino)pyridine complexes with varied sterics and halide substituents. Preferential cation-anion pair formation and attempted reactivity will be discussed.
Chapter 6 presents the synthesis of a series of Ag(I) bis(imino)pyridine complexes with varied sterics. Resulting ligand-metal interactions as well as reactivity towards Lewis basic donor ligands will be discussed.
Chapter 7 presents the synthesis of first crystallographically authenticated examples of rhenium(I) pincer complexes utilizing the bis(imino)pyridine ligand.
Chapter 8 presents a general conclusion to the work.
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Synthèse et fonctionnalisation des furo[3,2-b]- et [2,3-c]pyridines par voie organométallique / Synthesis and functionalisation of furo [3,2-b]- et [2,3-c]pyridines by using an organometallic wayChartoire, Anthony 22 October 2010 (has links)
Le travail décrit dans ce mémoire concerne l'étude de la métallation régiosélective de deux bicycles fusionnés complexes : les furo[3,2-b]- et [2,3-c]pyridines. L'influence de la nature du système basique sur le cours de la réaction et sur la régiosélectivité de la lithiation a été étudiée avec différentes bases : n-BuLi, LTMP, LDA et [n-BuLi/LiDMAE]. D'un point de vue fondamental, cette étude nous a permis d'établir quelques règles pour la fonctionnalisation des hétérocycles complexes, ce qui nous a conduit à l'obtention efficace et rapide d'une vaste chimiothèque de furo[3,2-b]- et [2,3-c]pyridines polyfonctionnalisés et refonctionnalisables. Quelques composés préparés ont ainsi été mis en jeu dans des réactions de couplage catalysées par les métaux de transition (Pd, Ni). Les difficultés rencontrées au cours de ce travail nous ont permises de mettre en évidence une séquence de double fonctionnalisation des hétérocycles ?-déficients par une séquence "one-pot" combinant le piégeage d'un intermédiaire lithié par un électrophile et l'addition nucléophile d'une espèce réactive générée in-situ. Le développement de cette séquence nous a conduits à l'obtention directe de pyrazines, pyridines et furo[3,2-b]pyridines disubstituées / The work described in this PhD thesis concerns a regioselective metalation study of two fused heterocycles : the furo[3,2-b]- et [2,3-c]pyridines. The influence of the lithiated agent on the reaction course and on the selectivity of the lithiation has been studied with several bases : n-BuLi, LTMP, LDA and [n-BuLi/LiDMAE]. From a fundamental point of view, this study allowed us to establish some rules concerning the functionalisation of fused heterocycles, and then, a chemical library of polyfunctionalised furo[3,2-b]- and [2,3-c]pyridines has been designed. Some of the compounds obtained in this way were engaged in metallo-catalysed coupling reactions. The difficulties we met during this work allowed us to discover a double functionalisation sequence of ?-deficient heterocycles via a cascade process combining the trapping of lithiated intermediates and the nucleophilic addition of some in-situ released species. The development of this sequence afforded direct access to difunctionalised pyrazines, pyridines and furo[3,2-b]pyridines
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Regulation of Pyridine Nucleotide Metabolism in Saccharomyces cerevisiaeTing, Haung-yu 05 1900 (has links)
The levels of total nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), and their redox states were determined as the function of growth in S. cerevisiae. Cells growing in a medium containing 0.8% glucose exhibit two phases of exponential growth, utilizing glucose and ethanol, respectively. The NAD pool is 50% reduced during both stages of growth while the NADP pool is 67% reduced in glucose growth and 48% reduced in ethanol growth. The NAD/NADP ratio is constant during growth on glucose and a two-fold increase in the NAD/NADP ratio occurs upon exhaustion of glucose. The increased ratio is maintained during growth on ethanol. This alteration in the regulation of the relative levels of NAD and NADP may be due to a change in the regulation of NAD kinase and/or NADP phosphatase activities. These changes may be related to the redox state of the NADP pool.
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(Pyrazolylpyridine)- iron, cobalt and nickel complexes as carbon-carbon bond formation catalysts16 May 2011 (has links)
M.Sc. / 2-(Pyrazol-1-ylmethyl)pyridine ligands were synthesised by phase transfer alkylation of 2-picolyl hydrochloride with the appropriate pyrazole. These ligands were subsequently reacted with NiCl2, NiBr2, FeCl2 or CoCl2 to form the respective complexes. The substituents on the pyrazole included phenyl and tert-butyl groups as well as electron withdrawing CF3 groups. The substituents played an important role in the steric and electrophilic nature of the metals. A second ligand design is 2,6-bis(pyrazol-1-ylmethyl)pyridine and were prepared by phase transfer alkylation of 2,6-bis(chloromethyl)pyridine with two mole equivalents of the appropriate pyrazole. These ligands were reacted with NiCl2, NiBr2, FeCl2 or CoCl2 to form the respective complexes. A third ligand design is 2-(chloromethyl)- or 2-(bromomethyl)-6-(pyrazol-1-ylmethyl)pyridine and were prepared by the selective alkylation of 2,6-bis(chloromethyl)pyridine with one mole equivalent of the appropriate pyrazole. These ligands were also reacted with NiCl2, NiBr2, FeCl2 or CoCl2 to form the respective complexes. Characterisation of all compounds was done by a range of spectroscopic techniques as well as X-ray crystallography and elemental analysis. The data showed good fit to the proposed structures and in a few cases were confirmed by X-Ray crystallography. All complexes were tested as catalysts for ethylene and higher olefin oligomerisation and showed good activity. The production of alkenes were confirmed in toluene and hexane, however, due to the use of EtAlCl2 and toluene the oligomers were alkylated to form the Friedel-Crafts alkylation products. Similar alkylation was observed for the higher olefin reactions. In comparison, the same reactions in hexane resulted in only C4, C6 and C8 oligomers. When higher olefin reactions were also conducted in hexane, polymeric solids were observed.
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The effect of imidazo [1,2-a] pyridine amines on MCF-7 and MDA-MB-231 breast cancer cellsKurebwa, Taurai, Flloyd. January 2015 (has links)
A dissertation submitted to the Faculty of Health Sciences, University of
the Witwatersrand, Johannesburg, in fulfillment of the requirements for
the degree of Masters of Science in Medicine (Pharmacology)
Johannesburg,2015 / Breast cancer, is the most frequently diagnosed cancer in women and is associated with
high mortality rates in South Africa. There is a high prevalence of metastatic breast
cancer and triple negative tumours, which are associated with poor prognosis. In this
study, the response of two breast cancer cell lines, MCF-7 and MDA-MB-231, were
evaluated when treated with novel imidazo[1 ,2-a]pyridine amines.
The compounds were synthesized by the School of Chemistry of the University of the
Witwatersrand using the Groebke-Blackburn-Bienayme multicomponent reaction and
tested for purity by elemental analysis. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide) assay was used to determine the cytotoxic effects of test
compounds on breast cancer cells and the toxic effect of compounds on non-tumorigenic
unstimulated peripheral leukocytes. IC50 values of test compounds were calculated from
sigmoidal dose response curves. The morphology of cells exposed to test compounds
was assessed by fluorescent microscopy using Hoechst 33342, acridine orange and
ethidium bromide. The ability of test compounds to induce apoptosis was measured by a
colorimetric caspase-3 assay and a fluorometric Annexin-V-FITC assay.
Monodansylcadaverine was used to determine if autophagic vacuoles were formed after
exposure to test compounds.
Three imidazo[1,2-a]pyridine amines, JD88, JD253 and JD256, were more cytotoxic to
MCF-7 than to MDA-MB-231 cells. MCF-7 cells showed morphological features
associated with apoptosis, and proteolysis by caspase-3/7 was observed after MCF-7
cells were exposed to JD88 for two hours. Vacuole formation induced by these
compounds was not autophagic in since they did not co-localize with MDC florescent
clusters. This together with the exposure of phosphatidylserine to the outer surface of
MCF-7 cells suggests that apoptosis is induced in these cells. There was no evidence of
cytochrome c translocation to the cytoplasm, which indicates that the intrinsic pathway of
apoptosis is not activated. MDA-MB-231 cells treated with JD88, JD253 and JD256 were
large with multiple nuclei and decondensed chromatin, morphological features
associated with mitotic catastrophe. The cells also showed morphological features
associated with necrosis and apoptosis, which include loss of cell membrane integrity
and cell membrane blebbing respectively. MDA-MB-231 cells exposed to JD88 showed
marked exposure of phosphatidylserine and this was observed to a minor extent in cells
exposed to JD253 and JD256. Proteolysis by caspase-3/7 was activated in MDA-MB-231
cells exposed to JD88 as early as 2 hours after exposure.
In conclusion three compounds; JD88, JD253 and JD256 were able to induce apoptosis
in MCF-7 cells. These compounds were selectively toxic against MCF-7 cells compared
to MDA-MB-231 cells and JD256 in particular was less toxic to leukocytes, which may
translate to fewer serious adverse effects. Addition of a copper dioxygen complex to
these compounds increases activity against both breast cancer cells. JD88 in particular
has shown effective induction of apoptosis and this merits further investigation into its
potential as a lead compound in breast cancer therapy. / AC2016
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