• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 24
  • 14
  • 6
  • 5
  • 2
  • 1
  • 1
  • Tagged with
  • 59
  • 16
  • 14
  • 14
  • 10
  • 8
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Citrato de rodio (II): síntese, caracterização, adsorção em nanopartículas de maguemita e preparação de fluidos magnéticos / Rhodium(II) citrate: synthesis, characterization, adsorption on maghemita nanoparticles, and preparation magnetic fluids

Nunes, Eloiza da Silva 10 March 2010 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-08-22T11:23:26Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação_Eloiza da Silva Nunes.pdf: 2557684 bytes, checksum: 485672a5e5df50e25a70cde5803fbfb4 (MD5) / Made available in DSpace on 2014-08-22T11:23:26Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação_Eloiza da Silva Nunes.pdf: 2557684 bytes, checksum: 485672a5e5df50e25a70cde5803fbfb4 (MD5) Previous issue date: 2010-03-10 / In this work are described the synthesis and characterization of dinuclear rhodium(II) citrate, adsorption study in maghemite nanoparticles, and preparation of nanoparticles-modified based magnetic fluids. Rhodium(II) citrate has significant antitumor activity being promissory to cancer chemotherapy. Due to the existence of free functional groups in its molecular structure this complex has capacity to functionalize iron oxide nanoparticles to produce drug-particles formulations. The modified nanoparticles show features of biocompatibility suitable to use the system in medical applications. Rhodium(II) citrate was synthesized by an exchange reaction of trifluoroacetate ligands from the precursor rhodium(II) trifluoroacetate by citrate ligands. The products were characterized by C and H elemental and thermogravimetric analysis, mass spectrometry, and infrared, UV/visible and 13C nuclear magnetic resonance spectroscopy. The results are consistent with the formation of dinuclear structure characteristic for rhodium(II) carboxylates. Changing the synthesis conditions were obtained products with stoichiometries [Rh2(H2cit)2(H2O)4] and [Rh2(H2cit)4(H2O)2]. The results and compounds solubility observations suggest that the first one occur as a coordination polymer. The second one showed composition e solubility behavior consistent with the formation of monomeric units. Maghemite nanoparticles with size mean between 5 and 7 nm were obtained through alkaline coprecipitation of Fe2+ and Fe3+ ions with further oxidation with oxygen gas. The solids were characterized by X-ray difratometry and the Scherrer relation was use to calculate the crystallite size mean. Adsorption experimental data were adjusted to Langmuir model and linear coefficients obtained, R2, were greater than 0,99. Functionalized nanoparticles were dispersed into water producing a stable colloid. Dispersion s characterization was performed by absorbance, zeta potential, and hydrodynamic diameter measurements. Surface properties and colloidal behavior of functionalized nanoparticles are much affected by adsorbed species. The colloidal stability of the magnetic fluids is dependent on the adsorbed amounts of rhodium(II) citrate and pH. When the adsorbed amount of rhodium(II) citrate is next to saturation, the magnetic fluids are stable in pH over 3 and show hydrodynamic diameter around 60 nm. Fluids colloidal stability is preserved against physiologic saline solution, PBS buffer, and fetal bovine serum over a period of 30 days. / Neste trabalho estão descritos a síntese e a caracterização do complexo dimérico citrato de ródio(II), estudo de sua adsorção em nanopartículas de maghemita e a preparação de fluidos magnéticos á base de nanopartículas modificadas com o complexo. O citrato de ródio (II) apresenta significante atividade antitumor sendo promissor para aplicação na quimioterapia do câncer. Devido à existência de grupos funcionais livres em sua estrutura molecular esse complexo possui capacidade de funcionalizar nanopartículas de óxidos de ferro para produzir formulações droga-partícula. As nanopartículas modificadas apresentam características de biocompatibilidade adequadas para utilização do sistema em aplicações médicas. O citrato de ródio(II) foi sintetizado via reação de troca de ligantes trifluoroacetato do precursor trifluoroacetato de ródio(II) por citrato. Os produtos foram caracterizados por análise elementar de C e H e termogravimétrica, espectrometria de massas e espectroscopia nas regiões do UV/visível e infravermelho e ressonância magnética nuclear de 13C. Os resultados são consistentes com a formação da estrutura dimérica. Variando-se as condições de síntese pode-se obter produtos com estequiometrias [Rh2(H2cit)2(H2O)4] e [Rh2(H2cit)4(H2O)2]. Os resultados somados às observações sobre a solubilidade dos compostos sugerem que o primeiro ocorre como um polímero de coordenação. O segundo composto apresentou características de composição e solubilidade coerente com a formação de unidades dimetálicas monoméricas. Foram obtidas nanopartículas de maghemita com diâmetros entre 5 e 7 nm através do método de coprecipitação de íons Fe2+ e Fe3+ em meio alcalino com posterior oxidação com oxigênio gasoso. Os sólidos foram caracterizados por difratometria de raios-X e o diâmetro de cristalito calculado pela equação de Scherrer. Os dados experimentais de adsorção de citrato de ródio(II) em maghemita foram ajustados ao modelo de Langmuir sendo obtido coeficiente de regressão linear, R2, maior que 0,99. As nanopartículas funcionalizadas foram dispersas em água obtendo-se um colóide estável. As dispersões foram caracterizadas por medidas de absorvância, potencial zeta e de diâmetro hidrodinâmico. As propriedades de superfície bem como o comportamento coloidal das nanopartículas funcionalizadas são influenciadas pelas espécies adsorvidas. A estabilidade coloidal dos sóis obtidos é dependente das quantidades de citrato de ródio(II) adsorvida e do pH. Quando a quantidade de citrato de ródio adsorvida é próxima da capacidade de adsorção, os fluidos magnéticos obtidos apresentam estáveis em pH acima de 3 com diâmetros hidrodinâmicos próximos de 60 nm. A estabilidade coloidal dos fluidos obtidos é preservada frente a soluções de soro fisiológico, tampão PBS e soro fetal bovino por períodos superiores a 30 dias.
42

Investigação comparativa da liberação controlada de CO e NO por carboxilatos trinucleares de rutênio contendo ligantes pi-receptor e sigma-doador / Comparative investigation of the controlled release of CO and NO by ruthenium trinuclear carboxylates containing pi-receptor ligands and sigma-donor

Silva, Camila Fontes Neves da 23 February 2015 (has links)
Neste trabalho foram realizadas as sínteses e caracterizações dos precursores (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6, (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 e dos complexos inéditos (5) [Ru3O(CH3COO)6(4-acpy)2(CO)], (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)], (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6, (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. Os complexos foram caracterizados por espectroscopia na região do UV-Vis e do infravermelho, espectroscopia de ressonância magnética nuclear (RMN), voltametria cíclica e análise elementar. Por meio dos resultados obtidos nas técnicas de caracterização, foi possível confirmar a estrutura proposta inicialmente para os complexos e também para os precursores. Além disso, também foi possível observar a influência dos ligantes, -receptor e -doador na estrutura dos mesmos. Por meio da técnica de espectroscopia de infravermelho analisou-se principalmente estiramentos dos ligantes CO nos complexos 5 e 6 e do NO nos complexos 7 e 8. Nos estudos de RMN observou-se as características diamagnéticas dos complexos 5 e 6, e no caso dos complexos 7 e 8 foi possível confirmar que há uma forte interação entre o elétron desemparelhado na unidade [Ru3O]+ e do ligante NO0. Os ensaios eletroquímicos de voltametria cíclica mostraram a influência dos ligantes CO e NO na comunicação eletrônica da unidade [Ru3O].Os complexos com ligantes CO e NO foram irradiados com laser em 377 nm e 660 nm em soluções de acetonitrila e tampão fosfato pH 7,4. Estas irradiações foram acompanhadas por espectroscopia na região do UV-visível. No caso dos complexos 5 e 6, o aumento da banda na região de 900 nm indicou a formação do complexo, [Ru3O(CH3COO)6(L)2(S)], após a liberação do ligante monóxido de carbono (CO). A liberação de CO ocorreu predominantemente com irradiação em 377 nm na região do ultravioleta em pH fisiológico (solução aquosa de tampão fosfato, pH=7,4) e também em solução de acetonitrila. Para os complexos com ligantes NO, o perfil espectral obtido após fotólise indicou a formação de um complexo oxidado sem a coordenação do NO, [Ru3O(CH3COO)6(L)2(S)]+. / In this study it was performed the synthesis and characterization of the precursors (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6 (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 and the unpublished complexes (5) [Ru3O(CH3COO)6(4-acpy)2(CO)] (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)] (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6 (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. The complexes were characterized by UV-Vis and infrared spectroscopy, nuclear magnetic resonance (NMR), cyclic voltametry, and elemental analysis. By means of the results obtained from the characterization, it was possible to confirm the initially proposed structure for both complexes and precursors. Furthermore, it was also possible to observe the influence of ligands, - receptor and the -donor in the structure of the complexes. By infrared spectroscopy it was verified primarily stretches of the CO and NO ligands in complexes 5,6 and 7,8 respectively. In NMR it was observed the diamagnetic character of complexes 5 and 6, and in the case of complexes 7 and 8 it was confirmed that there is a strong interaction between the unpaired electron in the [Ru3O]+ unit and the NO0 ligand. The cyclic voltammograms showed the influence of the CO and NO ligands on the electronic communication of the [Ru3O] unit. Complexes with ligands CO and NO were irradiated with laser at 377 nm and 660 nm in solutions of acetonitrile and phosphate buffer pH 7.4. The photolysis were accompanied by spectroscopy in the UV-visible region. In the case of complexes 5 and 6, the increase of the band in the region of 900 nm indicated the formation of the complex, [Ru3O(CH3COO)6(L)2(S)]+ produced after release of carbon monoxide (CO). The release of CO occurs predominantly with irradiation at 377 nm in the ultraviolet region at physiological pH (aqueous phosphate buffer solution, pH = 7.4) and in acetonitrile solution. For complexes with NO ligands, the spectral profile obtained after photolysis indicated the formation of an oxidized complex without coordination of NO, the [Ru3O(CH3COO)6(L)2(S)] + molecule.
43

Phosphane and Phosphite Silver(I) Complexes: Synthesis, Reaction Chemistry and their Use as CVD Precursors

Djiele Ngameni, Patrice 03 February 2005 (has links) (PDF)
Silver(I) complexes of type LnAgX (X = organic ligand, such as carboxylates, dicarboxylates, Schiff-base; L = Lewis-bases, e. g. PnBu3, P(OMe)3, P(OEt)3; n = 1, 2, 3) have been synthesized and characterized with respect to their suitability for the Chemical Vapour Deposition (CVD) of silver thin films. For some of these compounds single crystal could be obtained. Their solid-state structure was determined by single crystal X-ray diffraction. The volatility, thermal stability, and gas phase decomposition mechanism of selected compounds were studied using temperature-programmed and in-situ mass spectrometry. CVD experiments were performed according to the results of the gas phase analysis. Silver films could be grown by using a cold-wall CVD reactor. The morphology of the latter films was determined. / Silber(I) Komplexe LnAgX (X = organische Ligand, Z. B. Carboxylate, Dicarboxylate, Schiff Base; L = Lewis-Base, Z. B. PnBu3, P(OMe)3, P(OEt)3; n = 1, 2, 3) wurden Bezug auf ihre Eignung für die chemische Gasphasenabscheidung von Silberfilmen synthetisiert und charakterisiert. Von einigen dieser Verbindung konnten Einkristalle erhalten werden. Der Bau dieser Verbindungen wurde mittels Röntgeneinkristallographie ermittelt. Ausgewählten Verbindungen wurden mit Temperatur-programmierter und in-situ Massenspektrometrie analysiert. Gasphasenabscheidungs- mechanismen für einige Prekursoren sind vorgestellt. CVD-Abscheidungsexperimente wurden entsprechend den Ergebnissen der Gasphaseanalyse durchgeführt. Silber Schichten konnten mit einen Kaltwand CVD-Reaktor erzeugt werden, deren Oberflächenmorphologie wurde untersucht.
44

Carboxylates in the rhizosphere of canola, wheat, lupins and pulses : their role in P acquisition from sparingly soluble forms

Pearse, Stuart James January 2006 (has links)
[Truncated abstract] Native Australian soils contain very low amounts of phosphorus. The soils of southwestern Australia are ancient and highly weathered. Consequently, the availability of phosphorus in these soils is too low for cropping purposes, so the application of P is necessary to maintain productivity. When P is applied to soil, typically as soluble superphosphate, it tends to be transformed to increasingly less soluble forms over time. Sparingly soluble forms of soil P are relatively inaccessible to Triticum aestivum; however, many grain legumes have a higher P-acquisition efficiency, allowing them to access pools of soil P that T. aestivum cannot. The P-acquisition efficiency of some grain legumes has been attributed in part to their ability to release large quantities of carboxylates, coupled with the development of cluster roots for species such as Lupinus albus. There are a number of unexplained observations in terms of the P-acquisition efficiency of grain legume species and the way that those species respond to P fertilisation. This PhD project aimed to study carboxylate release from a range of crop species, and investigate its role in variation among species for acquisition of phosphorus from sparingly soluble forms (chapter 1). ... L. albus (chapter 5). There was considerable variation in P acquisition among accessions. The variation cannot be attributed to differences in carboxylate release, cluster-root development or whole root system rhizosphere extract pH as measured in this study. We hypothesise that the variation might be attributed to differences in the ratio of release of protons and other cations localised around cluster roots. In conclusion studies of carboxylate exudation and sparingly soluble forms should use more than a single form if the aim is to draw generalised conclusions on P-uptake efficiency from sparingly soluble forms. Comparative studies of a range of species are a useful tool for enhancing our understanding of root physiology. While the benefit of carboxylates for providing access to poorly soluble P has been demonstrated, questions remain as to potential other roles for carboxylates, particularly in species that do not form cluster roots. Variation in P uptake among accessions of L. albus is present, and more work on proton release and ion balance of root clusters is necessary to understand intraspecific variation.
45

Investigação comparativa da liberação controlada de CO e NO por carboxilatos trinucleares de rutênio contendo ligantes pi-receptor e sigma-doador / Comparative investigation of the controlled release of CO and NO by ruthenium trinuclear carboxylates containing pi-receptor ligands and sigma-donor

Camila Fontes Neves da Silva 23 February 2015 (has links)
Neste trabalho foram realizadas as sínteses e caracterizações dos precursores (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6, (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 e dos complexos inéditos (5) [Ru3O(CH3COO)6(4-acpy)2(CO)], (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)], (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6, (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. Os complexos foram caracterizados por espectroscopia na região do UV-Vis e do infravermelho, espectroscopia de ressonância magnética nuclear (RMN), voltametria cíclica e análise elementar. Por meio dos resultados obtidos nas técnicas de caracterização, foi possível confirmar a estrutura proposta inicialmente para os complexos e também para os precursores. Além disso, também foi possível observar a influência dos ligantes, -receptor e -doador na estrutura dos mesmos. Por meio da técnica de espectroscopia de infravermelho analisou-se principalmente estiramentos dos ligantes CO nos complexos 5 e 6 e do NO nos complexos 7 e 8. Nos estudos de RMN observou-se as características diamagnéticas dos complexos 5 e 6, e no caso dos complexos 7 e 8 foi possível confirmar que há uma forte interação entre o elétron desemparelhado na unidade [Ru3O]+ e do ligante NO0. Os ensaios eletroquímicos de voltametria cíclica mostraram a influência dos ligantes CO e NO na comunicação eletrônica da unidade [Ru3O].Os complexos com ligantes CO e NO foram irradiados com laser em 377 nm e 660 nm em soluções de acetonitrila e tampão fosfato pH 7,4. Estas irradiações foram acompanhadas por espectroscopia na região do UV-visível. No caso dos complexos 5 e 6, o aumento da banda na região de 900 nm indicou a formação do complexo, [Ru3O(CH3COO)6(L)2(S)], após a liberação do ligante monóxido de carbono (CO). A liberação de CO ocorreu predominantemente com irradiação em 377 nm na região do ultravioleta em pH fisiológico (solução aquosa de tampão fosfato, pH=7,4) e também em solução de acetonitrila. Para os complexos com ligantes NO, o perfil espectral obtido após fotólise indicou a formação de um complexo oxidado sem a coordenação do NO, [Ru3O(CH3COO)6(L)2(S)]+. / In this study it was performed the synthesis and characterization of the precursors (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6 (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 and the unpublished complexes (5) [Ru3O(CH3COO)6(4-acpy)2(CO)] (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)] (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6 (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. The complexes were characterized by UV-Vis and infrared spectroscopy, nuclear magnetic resonance (NMR), cyclic voltametry, and elemental analysis. By means of the results obtained from the characterization, it was possible to confirm the initially proposed structure for both complexes and precursors. Furthermore, it was also possible to observe the influence of ligands, - receptor and the -donor in the structure of the complexes. By infrared spectroscopy it was verified primarily stretches of the CO and NO ligands in complexes 5,6 and 7,8 respectively. In NMR it was observed the diamagnetic character of complexes 5 and 6, and in the case of complexes 7 and 8 it was confirmed that there is a strong interaction between the unpaired electron in the [Ru3O]+ unit and the NO0 ligand. The cyclic voltammograms showed the influence of the CO and NO ligands on the electronic communication of the [Ru3O] unit. Complexes with ligands CO and NO were irradiated with laser at 377 nm and 660 nm in solutions of acetonitrile and phosphate buffer pH 7.4. The photolysis were accompanied by spectroscopy in the UV-visible region. In the case of complexes 5 and 6, the increase of the band in the region of 900 nm indicated the formation of the complex, [Ru3O(CH3COO)6(L)2(S)]+ produced after release of carbon monoxide (CO). The release of CO occurs predominantly with irradiation at 377 nm in the ultraviolet region at physiological pH (aqueous phosphate buffer solution, pH = 7.4) and in acetonitrile solution. For complexes with NO ligands, the spectral profile obtained after photolysis indicated the formation of an oxidized complex without coordination of NO, the [Ru3O(CH3COO)6(L)2(S)] + molecule.
46

Investigations Of Graphene And Open-Framework Metal Carboxylates

Ghosh, Anupama 09 1900 (has links) (PDF)
The thesis contains two parts. Part 1 describes the investigations on graphene and contains five sections. Section 1, gives a brief overview of graphene and other nanocarbons. The other four sections deal with various aspects of single-layer and few-layer graphene such as functionalization and solubilization, surface properties and gas adsorption, molecular charge transfer interaction and some properties and applications. Section 2 describes covalent and noncovalent functionalization and solubilization of few-layer graphene samples prepared by different methods as well as of single-walled carbon nanotubes (SWNTs). It includes covalent functionalization of graphene with organometallic reagents, noncovalent functionalization of graphene and SWNTs with surfactants as well as large aromatic molecules, and exfoliation of few-layer graphene by a water-soluble coronene carboxylate. Section 3 deals with surface properties and gas adsorption (mainly H2 and CO2) of few-layer graphenes. It is found that graphene samples with high surface area can adsorb even more than 3 wt% of H2 at high pressure which makes it promising material for gas-storage applications. Section 4 describes the molecular charge-transfer interaction of single and few-layered graphenes and SWNTs with different electron-donor and -acceptor molecules probed by both ITC measurements and Raman spectroscopy. Electron–acceptor molecules interact more strongly with graphene and SWNTs than the -donor molecules and nature of interaction of metallic SWNTs are different than the as-prepared ones. A Raman study of the interaction of single-layer graphene, prepared by micromechanical cleavage as well as chemical route, with an electron donor molecule such as tetrathiofulvalene (TTF) and an electron acceptor molecule such as tetracyanoethylene (TCNE) is examined. In Section 5, some properties and applications of graphene are discussed. These include fluorescence quenching phenomena observed with few-layer graphene samples on two fluorescent molecules such as coronene and perylene derivatives. Fabrication of a sensing device as well as of FETs prepared from doped and undoped few-layer and single-layer graphene samples forms part of this section. Part 2 of the thesis includes a brief introduction of hybrid open-framework material and synthesis, characterization and crystal structure of various open-framework metal carboxylates, starting with different transition and main group metals. The carboxylic acids used to form these frameworks vary such as simple aliphatic amino acids such as beta-alanine and aspartic acid or simple aliphatic hydroxyl carboxylic acid such as malic acid in its chiral and achiral forms or five-membered heterocyclic aromatic acid, such as imidazole dicarboxylic acid.
47

Phosphane and Phosphite Silver(I) Complexes: Synthesis, Reaction Chemistry and their Use as CVD Precursors

Djiele Ngameni, Patrice 27 January 2005 (has links)
Silver(I) complexes of type LnAgX (X = organic ligand, such as carboxylates, dicarboxylates, Schiff-base; L = Lewis-bases, e. g. PnBu3, P(OMe)3, P(OEt)3; n = 1, 2, 3) have been synthesized and characterized with respect to their suitability for the Chemical Vapour Deposition (CVD) of silver thin films. For some of these compounds single crystal could be obtained. Their solid-state structure was determined by single crystal X-ray diffraction. The volatility, thermal stability, and gas phase decomposition mechanism of selected compounds were studied using temperature-programmed and in-situ mass spectrometry. CVD experiments were performed according to the results of the gas phase analysis. Silver films could be grown by using a cold-wall CVD reactor. The morphology of the latter films was determined. / Silber(I) Komplexe LnAgX (X = organische Ligand, Z. B. Carboxylate, Dicarboxylate, Schiff Base; L = Lewis-Base, Z. B. PnBu3, P(OMe)3, P(OEt)3; n = 1, 2, 3) wurden Bezug auf ihre Eignung für die chemische Gasphasenabscheidung von Silberfilmen synthetisiert und charakterisiert. Von einigen dieser Verbindung konnten Einkristalle erhalten werden. Der Bau dieser Verbindungen wurde mittels Röntgeneinkristallographie ermittelt. Ausgewählten Verbindungen wurden mit Temperatur-programmierter und in-situ Massenspektrometrie analysiert. Gasphasenabscheidungs- mechanismen für einige Prekursoren sind vorgestellt. CVD-Abscheidungsexperimente wurden entsprechend den Ergebnissen der Gasphaseanalyse durchgeführt. Silber Schichten konnten mit einen Kaltwand CVD-Reaktor erzeugt werden, deren Oberflächenmorphologie wurde untersucht.
48

Nucleophilic ring-opening of Methyl 1- Nitrocyclopropanecarboxylates

Lifchits, Olga January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
49

Cristallochimie de nouveaux polymères de coordination chiraux poreux à corps central fluorène pour la séparation et la catalyse énantiosélective : synthèses, structures cristallines et réactivité / Cristallochemistry of new chiral coordination polymers with fluorene core for enantioselective separation and catalysis : synthesis, crystal structures and reactivity

Robin, Julien 16 December 2013 (has links)
Ce travail porte sur la cristallochimie de polymères de coordination poreux, ou Metal-Organic Frameworks (MOFs), pour la séparation et la catalyse énantiosélective. Les molécules chirales sont d'une importance capitale et jouent un rôle important dans la reconnaissance moléculaire. Il est donc nécessaire de pouvoir synthétiser un seul énantiomère ou de pouvoir séparer un mélange. La particularité des polymères de coordination à bénéficier d'une partie organique est la possibilité d'introduire des fragments chiraux dans la structure-même des matériaux. Nous avons décidé d'introduire la chiralité dans les MOFs par utilisation de ligands carboxylates originaux chiraux à cœur fluorène. Le premier chapitre de ce mémoire est consacré à l'étude bibliographique des MOFs avec une description des concepts de cette chimie qui permet de comprendre la stratégie mise en place dans cette étude. Le deuxième chapitre décrit la stratégie de synthèse des ligands ainsi que leurs caractérisations. Les trois chapitres suivants décrivent la synthèse, les structures cristallines et les caractérisations physico-chimiques de séries de MOFs regroupés par métal utilisé pour leur élaboration (Zn, Cd et Cu). Ces trois chapitres exposent les problématiques généralement rencontrées avec les MOFs, comme la perte de porosité par interpénétration des réseaux, et les stratégies mises en place pour les contourner, comme l'augmentation de la taille et de la fonctionnalité des ligands utilisés. Enfin la réactivité thermique et chimique des MOFs a été investiguée par diffraction des rayons X par la poudre afin de comprendre les mécanismes réactionnels et la création éventuelle de sites acides en vue d'applications en catalyse. Les techniques expérimentales sont détaillées dans le dernier chapitre de ce mémoire. Enfin un récapitulatif de cette étude est présenté afin de conclure sur la stratégie exposée dans ce mémoire et les perspectives offertes par cette étude. / This work deals with crystallochemistry of new porous coordination polymers or Metal-Organic Frameworks (MOFs) for enantioselective separation and catalysis. Chiral molecules are of a key role in molecular recognition as a consequence the ability to synthesize only one enantiomer or to separate a mixture is priority for chemistry. The particularity of coordination polymers to possess an organic part gives the possibility to introduce chiral fragments in the material structure. We decided to introduce chirality on MOFs by using originals chiral carboxylates ligands with fluorene core. The first chapter is devoted to the bibliographic study of porous coordination polymers. The second chapter describes the ligands synthesis strategy and characterizations. The next three chapters group the crystal structures and physicochemical characterizations of coordination polymers according to the metal used for their preparation (Zn, Cd et Cu). These three chapters explore also the general issues related to MOFs as the loss of porosity consequent to frameworks interpenetration, and strategies implemented to circumvent, such as increasing the size and functionality of the ligands used. Finally the thermal and chemical reactivity of MOFS has been investigated by powder X rays diffraction in order to understand reactions mechanisms and eventually the creation of acid sites for catalytic applications. The experimental technics are detailed in the last chapter. Finally a summary of this work closes this thesis showing the future perspectives of this work.
50

Nucleophilic ring-opening of Methyl 1- Nitrocyclopropanecarboxylates

Lifchits, Olga January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Page generated in 0.0671 seconds