• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 83
  • 13
  • 5
  • 5
  • 4
  • 4
  • 2
  • 1
  • 1
  • Tagged with
  • 143
  • 143
  • 143
  • 45
  • 31
  • 29
  • 28
  • 27
  • 26
  • 26
  • 26
  • 24
  • 21
  • 16
  • 16
  • 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.
81

Engineering the Biophysical and Biochemical Properties of Polymerized Hemoglobin as a Red Blood Cell Substitute via Various Strategies

Gu, Xiangming January 2022 (has links)
No description available.
82

Gas Adsorption Applications of Porous Metal-Organic Frameworks

Ma, Shengqian 29 April 2008 (has links)
No description available.
83

Magnesium Sulfonyldibenzoates: Synthesis, Structure, Phase Transformation and Microscopic Studies

Lucas, Kaitlyn D. January 2013 (has links)
No description available.
84

Metal-Organic Frameworks for Post-Combustion Carbon Capture - A Life Cycle Assessment

Gu, Xiangming 24 August 2018 (has links)
No description available.
85

Fundamental Investigations of Hazardous Gas Uptake and Binding in Metal-Organic Frameworks and Polyurethane Films

Grissom, Tyler Glenn 19 June 2019 (has links)
The advancements of chemists, engineers, and material scientists has yielded an enormous and diverse library of high-performance materials with varying chemical and physical properties that can be used in a wide array of applications. A molecular-level understanding of the nature of gas–surface interactions is critical to the development of next generation materials for applications such as gas storage and separation, chemical sensing, catalysis, energy conversion, and protective coatings. Quartz crystal microbalance (QCM) and in situ infrared (IR) spectroscopic techniques were employed to probe how topological features of a material as well as structural differences of the analytes affect gas sorption. Detailed studies of the interactions of three categories of molecules: aromatic hydrocarbons, triatomic ambient gases, and chemical warfare agents, with metal-organic frameworks (MOFs) and polyurethane coatings were conducted to build structure–property relationships for the nature and energetics of gas sorption within each material. Differences in the molecular structure of the guest compounds were found to greatly influence how, and to what extent each molecule interacts with the MOF or polyurethane film. Specifically, IR studies revealed that transport of aromatic compounds within the zirconium-based MOF, UiO-66 was limited by steric restrictions as molecules passed through small triangular apertures within the pore environment of the MOF. In contrast, the smaller triatomic molecules, CO2, SO2, and NO2, were able to pass freely through the MOF apertures and instead reversibly adsorbed inside the MOF cavities. Specifically, SO2 and NO2 were observed to preferentially bind to undercoordinated zirconium sites located on the MOF nodes. In addition, uptake of CO2, SO2, and NO2 was also aided by dispersion forces within the confined pore environments and by hydrogen bond formation with μ3 OH groups of the MOFs. Dimethyl chlorophosphate (DMCP), a nerve agent simulant that contains several electronegative moieties, was also found to strongly adsorb to undercoordinated zirconium; however, unlike in the aromatic and triatomic molecule systems, DMCP remained permanently bound to the MOFs, even at high temperatures. Finally, QCM studies of mustard gas simulant uptake into polyurethane films of varying hard:soft segment compositions revealed that dipole-dipole and dipole-induced dipole interactions were responsible for favorable absorption conditions. Furthermore, the ratio of hard and soft segment components of the polyurethane had a minor impact on simulant adsorption. Higher hard-segment content resulted in a more crystalline film that reduced simulant uptake, whereas the rubbery, high soft segment polyurethane allowed for greater vapor absorption. Ultimately, molecular-level insight into how the chemical identity of a guest molecule impacts the mechanism and energetics of vapor sorption into both MOFs and polymeric films can be extended to other relevant systems and may help identify how specific characteristics of each material, such as size, shape, and chemical functionality impact their potential use in targeted applications. / Doctor of Philosophy / The nature in which specific gases interact with materials will largely dictate how the material can be utilized. By understanding where and how strongly gas molecules interact with a material, scientists and engineers can rationally design new and improved systems for targeted applications. In the research described in this thesis, we examined how the chemical structure of three different groups of compounds, which have relevance in many industrial, environmental, and defense-related applications, affected the type and strength of interaction between the gas and material of interest. From these studies, we have identified how key properties and features within the examined materials such as size, shape, and chemical composition, lead to significant differences in how vapor molecules interacted with the materials. For example, benzene, toluene, and xylene, which are incredibly important chemicals in industry, were found to be restricted by narrow passageways as they moved through materials with small pores. In contrast, small gases present in the environment from combustion exhaust such as CO₂, SO₂, and NO₂ were able to freely traverse through the passageways, and instead weakly interacted with specific chemical groups inside the cavities of the material. On the same material however, a third class of compounds, organophosphorus-containing chemical warfare agent mimics, irreversibly reacted with chemical groups of the surface, and remained bound even after exposure to high temperatures. Ultimately, the work presented in this thesis is aimed at providing key fundamental insights about specific classes of materials on how, and how strongly they interact with targeted hazardous vapors, which can be utilized by synthetic chemists to design next generation materials.
86

Interfacial Energy Transfer in Small Hydrocarbon Collisions with Organic Surfaces and the Decomposition of Chemical Warfare Agent Simulants within Metal-Organic Frameworks

Wang, Guanyu 09 May 2019 (has links)
A molecular-level understanding of gas-surface energy exchange and reaction mechanisms will aid in the prediction of the environmental fate of pollutants and enable advances toward catalysts for the decomposition of toxic compounds. To this end, molecular beam scattering experiments performed in an ultra-high vacuum environment have provided key insights into the initial collision and outcome of critical interfacial processes on model systems. Results from these surface science experiments show that, upon gas-surface collisions, energy transfer depends, in subtle ways, on both the properties of the gas molecules and surfaces. Specifically, model organic surfaces, comprised of long-chain methyl- and hydroxyl-terminated self-assembled monolayers (SAMs) have been employed to test how an interfacial hydrogen bonding network may affect the ability of a gas-phase compound to thermally accommodate (typically, the first step in a reaction) with the surfaces. Results indeed show that small organic compounds transfer less energy to the interconnected hydroxyl-terminated SAM (OH-SAM) than to the organic surface with methyl groups at the interface. However, the dynamics also appear to depend on the polarizability of the impinging gas-phase molecule. The π electrons in the double bond of ethene (C2H4) and the triple bond in ethyne (C2H2) appear to act as hydrogen bond acceptors when the molecules collide with the OH-SAM. The molecular beam scattering studies have demonstrated that these weak attractive forces facilitate energy transfer. A positive correlation between energy transfer and solubilities for analogous solute-solvent combinations was observed for the CH3-SAM (TD fractions: C2H6 > C2H4 > C2H2), but not for the OH-SAM (TD fractions: C2H6 > C2H2 > C2H4). The extent of energy transfer between ethane, ethene, and ethyne and the CH3-SAM appears to be determined by the degrees of freedom or rigidity of the impinging compound, while gas-surface attractive forces play a more decisive role in controlling the scattering dynamics at the OH-SAM. Beyond fundamental studies of energy transfer, this thesis provides detailed surface-science-based studies of the mechanisms involved in the uptake and decomposition of chemical warfare agent (CWA) simulants on or within metal-organic frameworks (MOFs). The work presented here represents the first such study reported in with traditional surface-science based methods have been applied to the study of MOF chemistry. The mechanism and kinetics of interactions between dimethyl methylphosphonate (DMMP) or dimethyl chlorophosphate (DMCP), key CWA simulants, and Zr6-based metal-organic frameworks (MOFs) have been investigated with in situ infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD), and DFT calculations. DMMP and DMCP were found to adsorb molecularly (physisorption) to the MOFs through the formation of hydrogen bonds between the phosphoryl oxygen and the free hydroxyl groups associated with Zr6 nodes or dangling -COH groups on the surface of crystallites. Unlike UiO-66, the infrared spectra for UiO-67 and MOF-808, recorded during DMMP exposure, suggest that uptake occurs through both physisorption and chemisorption. The XPS spectra of MOF-808 zirconium 3d electrons reveal a charge redistribution following exposure to DMMP. Besides, the analysis of the phosphorus 2p electrons following exposure and thermal annealing to 600 K indicates that two types of stable phosphorus-containing species exist within the MOF. DFT calculations (performed by Professor Troya at Virginia Tech), were used to guide the IR band assignments and to help interpret the XPS features, suggest that uptake is driven by nucleophilic addition of a surface OH group to DMMP with subsequent elimination of a methoxy substituent to form strongly bound methyl methylphosphonic acid (MMPA). With similar IR features of MOF-808 upon DMCP exposure, the reaction pathway of DMCP in Zr6-MOFs may be similar to that for DMMP, but with the final product being methyl chlorophosphonic acid (elimination of the chlorine) or MMPA (elimination of a methoxy group). The rates of product formation upon DMMP exposure of the MOFs suggest that there are two distinct uptake processes. The rate constants for these processes were found to differ by approximately an order of magnitude. However, the rates of molecular uptake were found to be nearly identical to the rates of reaction, which strongly suggests that the reaction rates are diffusion limited. Overall, and perhaps most importantly, this research has demonstrated that the final products inhibit further reactions within the MOFs. The strongly bound products could not be thermally driven from the MOFs prior to the decomposition of the MOFs themselves. Therefore, new materials are needed before the ultimate goal of creating a catalyst for the air-based destruction of traditional chemical nerve agents is realized. / Doctor of Philosophy / A molecular-level understanding of gas-surface energy exchange and reaction mechanisms will aid in the prediction of the environmental fate of pollutants and enable advances toward catalysts for the decomposition of toxic compounds. Our gas-surface scattering experiments performed in an ultra-high vacuum environment have provided key insights into the outcome of critical interfacial processes on model systems. Results show that energy transfer upon gas-surface collisions depends on both the properties of the gas molecules and surfaces. Due to the formation of interfacial hydrogen bonding network in hydroxyl-terminated surface, the small organic compounds transfer less energy to it than to the organic surface with methyl groups at the interface. The dynamics also appear to depend on the properties of the impinging gas-phase molecule. The π electrons in the double bond of ethene and the triple bond in ethyne act as hydrogen bond acceptors when the molecules collide with the hydroxyl-terminated surface. The attractive forces facilitate energy transfer. A positive correlation between energy transfer and solubilities for analogous solute-solvent combinations was observed for the methyl-terminated surface, but not for the hydroxyl-terminated surface. The extent of energy transfer between ethane, ethene, and ethyne and the methyl-terminated surface appears to be determined by the degrees of freedom or rigidity of the gas, while gas-surface attractive forces play a more decisive role in controlling the scattering dynamics at the hydroxyl-terminated surface. Furthermore, this thesis provides detailed surface-science-based studies of the mechanisms involved in the uptake and decomposition of chemical warfare agent (CWA) simulants on or within metal-organic frameworks (MOFs). Dimethyl methylphosphonate (DMMP) and dimethyl chlorophosphate (DMCP), key CWA simulants, physisorbed to the MOFs through the formation of hydrogen bonds between the phosphoryl oxygen and the free hydroxyl groups associated with inorganic nodes or dangling -COH groups on the surface of crystallites. The infrared spectra for UiO-67 and MOF-808 suggest that uptake occurs through both physisorption and chemisorption. The XPS spectra of MOF-808 zirconium 3d electrons reveal a charge redistribution following exposure to DMMP. Besides, the analysis of the phosphorus 2p electrons following exposure and thermal annealing to 600 K indicates that two types of stable phosphorus-containing species exist within the MOF. DFT calculations suggest that uptake is driven by nucleophilic addition of a surface OH group to DMMP with subsequent elimination of a methoxy substituent to form strongly bound methyl methylphosphonic acid (MMPA). With similar IR features of MOF-808 upon DMCP exposure, the reaction pathway of DMCP in MOFs may be similar to that for DMMP, but with the final product being methyl chlorophosphonic acid (elimination of the chlorine) or MMPA (elimination of a methoxy group). The rates of product formation suggest that there are two distinct uptake processes. The rate constants for these processes were found to be nearly identical to the rates of physisorption, which suggests that the reaction rates are diffusion limited. Overall, this research has demonstrated that the final products inhibit further reactions within the MOFs. The strongly bound products could not be thermally driven from the MOFs prior to the decomposition of the MOFs themselves. Therefore, new materials are needed before the ultimate goal of creating a catalyst for the air-based destruction of traditional chemical nerve agents is realized.
87

Développement de MOFs fonctionnels sur support solide : application à la photochimie. / Development of functional MOFs on solid support : application to photochemistry.

Genesio, Guillaume 19 November 2018 (has links)
Les travaux présentés dans ce manuscrit s’inscrivent dans le cadre général de la conversion et du stockage de l’énergie lumineuse. Dans ce domaine, l’utilisation de MOFs (Metal-Organic Frameworks) polyfonctionnels n’en est qu’à ses débuts et ils sont principalement utilisés sous forme de poudre cristalline. Or le développement de ces MOFs sur un support solide est essentiel dans l’obtention d’un objet technologiquement avancé répondant à des critères industriels. Les travaux réalisés lors de ce projet ont donc porté sur la croissance contrôlée de matériaux hybrides polyfonctionnels de type MOF sur une surface conductrice transparente TCO (Transparent Conductive Oxide). Les différentes fonctionnalités ont été introduites au sein du MOF par intégration d’une partie photosensible et d’une unité catalytique.A partir de systèmes de MOFs modèles à base de zirconium, il a été possible de produire des systèmes polyfonctionnels par modifications directement pendant la synthèse et/ou post synthèse. Le contrôle de la croissance, en maîtrisant les conditions expérimentales lors de la synthèse solvothermale directe in situ, nous a permis d’obtenir une couche de cristaux monodisperses solidement attachés aux supports TCO. Des efforts importants ont également été dédiés à la compréhension des mécanismes de croissance des MOF sur support TCO. Des essais de photodégradation du bleu de méthylène (polluant organique) ont permis de valider le potentiel photochimique de nos dispositifs.La méthodologie développée pour le contrôle de la croissance des MOFs à base de zirconium a été transposée avec succès à des analogues à base de titane, démontrant la portabilité de la stratégie vers d’autres types de MOFs. Ces derniers ont été utilisés en photo-réduction du CO2 lors d’essais préliminaires (collaboration avec le Collège de France) conduisant sélectivement à l’obtention de formiate. / This work is focused on the development of a functionalization method of TCO transparent conductive surfaces (Transparent Conductive Oxide) by hybrid multifunctional materials, Metal-Organic Frameworks (MOFs). Different properties are provided within the MOF by adding different photosensitive and catalytic units. The development of such materials is in its infancy and they have been mainly developed as crystalline powder. However the development of these MOFs onto a solid support is challenging but also essential toward obtaining a technologically advanced device.This project is focused on the growth controlled of MOFs crystals onto TCO support. From a Zirconium material, it was possible to obtain multifunctional systems by changing components directly during the synthesis or by post synthesis modifications. It has been possible to control the growth of materials on the support by direct in situ solvothermal synthesis and to obtain a monodisperse layer of crystals well anchored to the TCO supports. Photodegradation of methylene blue (organic pollutant) has been performed to validate their photoreactivity.The methodology developed with the Zirconium based MOF has been implemented successfully in a similar compound to include higher photosensitizer components and with titanium-based MOFs. It shows the portability of the strategy towards other types of MOFs. They were used in CO2 photo-reduction (in collaboration of the College de France) where selectively of formate production was observed.
88

Desenvolvimento de metodologias em síntese orgânica: uso do catalisador Eu-MOF na síntese de cianoidrinas e obtenção de anéis tetraidropirânicos utilizando [BIMIM][PF6]

Batista, Poliane Karenine 15 February 2017 (has links)
Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-01T12:29:24Z No. of bitstreams: 1 arquivototal.pdf: 4942842 bytes, checksum: f0ad011fa73c8b3eb2a49c98e8ca9de4 (MD5) / Made available in DSpace on 2017-08-01T12:29:24Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4942842 bytes, checksum: f0ad011fa73c8b3eb2a49c98e8ca9de4 (MD5) Previous issue date: 2017-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Currently several works have been developed in order to provide alternative routes for the synthesis of several organic compounds. These new protocols are generally aimed at obtaining softer and more eco-friendly reactive conditions, better yields and / or reactional times, and mechanistic studies, among others. This work consists of the study of synthesis routes of cyanohydrins and tetrahydropyrans, using lanthanide catalysts and ionic liquids, respectively. As cyanohydrins are products that can be transformed into important organic intermediates. They are obtained by the cyanosilylation of aldehydes reaction, which is synthetically viable only in the presence of a Lewis acid. In this work, the MOF [Eu2 (MELL)(H2O)6] was used as a heterogeneous catalyst in the cyanosilylation of aldehydes reaction. The catalytic assays were optimized using a thermally activated MOF in acetonitrile. Different aldehydes several structurally provided their respective cyanohydrins ranging from 1 to 6 hours and yields of 62 to 100%. The MOF was recycled in the addition reaction of TMSCN to 2-furfuraldehyde without loss of activity for five cycles. Tetrahydropyran rings (THP) are common in many natural products, so various strategies are being developed to synthesize them. In this work we also describe the study to obtain 2,4,6-trisubstituted tetrahydropyrans in a single step promoted by the ionic liquid (IL) BMIM][PF6] between the allyl bromide and aldehydes, through the Barbier-Prins reaction. The tests were performed under different conditions and optimized using 1: 4 benzaldehyde and allyl bromide. The use of IL [BMIM][PF6] provided THPs of various aldehydes in good yields ranging from 40% to 75% in 8 hours of reaction. In addition, IL [BMIM][PF6] was recovered and reused in the preparation of 4-bromo-2,6-diphenyl-tetrahydro-2H-pyran by up to 5 times without significant loss of yield of that product. The influence of the PF6- anion on the reaction between benzaldehyde and allyl bromide under the Barbier reaction conditions was investigated, as well as the influence of SnBr2 salt on the Prins cyclization reaction between homoallylic alcohol and benzaldehyde. The results show evidence that PF6- acts by accelerating the Barbier reaction and the excess of SnBr2 acts as Lewis acid in the Prins cyclization reaction. Subsequently, the use of KI in the reaction between benzaldehyde and allyl bromide was investigated, and it was found that depending on the ratio used between KI and SnBr2, the preferential formation of homoalyl alcohol or THP compound could occur. / Atualmente vários trabalhos têm sido desenvolvidos no intuito de possibilitar rotas alternativas para a síntese de diversos compostos orgânicos. Esses novos protocolos visam geralmente a obtenção de condições reacionais mais brandas e eco-amigáveis, melhores rendimentos e/ou tempos reacionais, estudos mecanísticos entre outros. Este trabalho consiste no estudo de rotas de síntese de cianoidrinas e tetraidropiranos, utilizando catalisadores de lantanídeos e líquidos iônicos, respectivamente. As cianoidrinas são substâncias que podem ser transformadas em intermediários orgânicos importantes. São geralmente obtidas através da reação de cianossililação de aldeídos, que é sinteticamente viável apenas na presença de um ácido de Lewis. Nesse trabalho, a MOF [Eu2(MELL)(H2O)6] foi utilizada como catalisador heterogêneo na reação de cianossililação de aldeídos. Os ensaios catalíticos foram otimizados utilizando a MOF ativada termicamente em acetonitrila. Diversos aldeídos estruturalmente diferentes forneceram suas respectivas cianoidrinas variando de 1 a 6 horas e com rendimentos de 62 a 100%. A MOF foi reciclada na reação de adição de TMSCN à 2-furfuraldeído sem perda de atividade durante cinco ciclos. Anéis tetraidropirânicos (THP) são comuns em vários produtos naturais, portanto várias estratégias estão sendo desenvolvidas para sintetizá-los. Nesse trabalho descrevemos também o estudo para a obtenção de tetraidropiranos 2,4,6-trissubstituídos meso em uma única etapa promovida pelo líquido iônico (LI) BMIM][PF6] entre o brometo de alila e aldeídos, através da reação Barbier-Prins. Os testes foram realizados sob diferentes condições e foi otimizado utilizando-se o benzaldeído e brometo de alila na proporção 1:4. A utilização LI [BMIM][PF6] forneceu produtos THPs de vários aldeídos com bons rendimentos variando-se de 40% a 75% em 8 horas de reação. Adicionalmente o LI [BMIM][PF6] foi recuperado e reutilizado na preparação do 4-bromo-2,6-difenil-tetraidro-2H-pirano em até 5 vezes sem perda significativa dos rendimentos desse produto. Foi investigado a influência isolada do ânion PF6- na reação entre o benzaldeído e o brometo de alila nas condições reacionais de Barbier, assim como a influência do sal SnBr2 na reação de ciclização de Prins entre o álcool homoalílico e o benzaldeído. Os resultados mostram evidências que o PF6- atua acelerando a reação de Barbier e o excesso de SnBr2 atua como ácido de Lewis na reação de ciclização de Prins. Posteriormente foi investigado a utilização do KI na reação entre o benzaldeído e o brometo de alila, e verificou-se que dependendo da proporção utilizada entre o KI e o SnBr2 pode ocorrer a formação preferencial do álcool homoalílico ou do composto THP.Atualmente vários trabalhos têm sido desenvolvidos no intuito de possibilitar rotas alternativas para a síntese de diversos compostos orgânicos. Esses novos protocolos visam geralmente a obtenção de condições reacionais mais brandas e eco-amigáveis, melhores rendimentos e/ou tempos reacionais, estudos mecanísticos entre outros. Este trabalho consiste no estudo de rotas de síntese de cianoidrinas e tetraidropiranos, utilizando catalisadores de lantanídeos e líquidos iônicos, respectivamente. As cianoidrinas são substâncias que podem ser transformadas em intermediários orgânicos importantes. São geralmente obtidas através da reação de cianossililação de aldeídos, que é sinteticamente viável apenas na presença de um ácido de Lewis. Nesse trabalho, a MOF [Eu2(MELL)(H2O)6] foi utilizada como catalisador heterogêneo na reação de cianossililação de aldeídos. Os ensaios catalíticos foram otimizados utilizando a MOF ativada termicamente em acetonitrila. Diversos aldeídos estruturalmente diferentes forneceram suas respectivas cianoidrinas variando de 1 a 6 horas e com rendimentos de 62 a 100%. A MOF foi reciclada na reação de adição de TMSCN à 2-furfuraldeído sem perda de atividade durante cinco ciclos. Anéis tetraidropirânicos (THP) são comuns em vários produtos naturais, portanto várias estratégias estão sendo desenvolvidas para sintetizá-los. Nesse trabalho descrevemos também o estudo para a obtenção de tetraidropiranos 2,4,6-trissubstituídos meso em uma única etapa promovida pelo líquido iônico (LI) BMIM][PF6] entre o brometo de alila e aldeídos, através da reação Barbier-Prins. Os testes foram realizados sob diferentes condições e foi otimizado utilizando-se o benzaldeído e brometo de alila na proporção 1:4. A utilização LI [BMIM][PF6] forneceu produtos THPs de vários aldeídos com bons rendimentos variando-se de 40% a 75% em 8 horas de reação. Adicionalmente o LI [BMIM][PF6] foi recuperado e reutilizado na preparação do 4-bromo-2,6-difenil-tetraidro-2H-pirano em até 5 vezes sem perda significativa dos rendimentos desse produto. Foi investigado a influência isolada do ânion PF6- na reação entre o benzaldeído e o brometo de alila nas condições reacionais de Barbier, assim como a influência do sal SnBr2 na reação de ciclização de Prins entre o álcool homoalílico e o benzaldeído. Os resultados mostram evidências que o PF6- atua acelerando a reação de Barbier e o excesso de SnBr2 atua como ácido de Lewis na reação de ciclização de Prins. Posteriormente foi investigado a utilização do KI na reação entre o benzaldeído e o brometo de alila, e verificou-se que dependendo da proporção utilizada entre o KI e o SnBr2 pode ocorrer a formação preferencial do álcool homoalílico ou do composto THP.
89

Conception de nouveaux matériaux hybrides types MOFs bio-inspirés à fonctionnalités avancées pour la catalyse / Design of new MOF-type bio-inspired hybrid materials with advanced functionalities for catalysis

Bonnefoy, Jonathan 27 October 2015 (has links)
Les MOFs sont des solides à la structure cristalline poreuse à base de clusters métalliques et de ligands organiques qui font l'objet de très nombreuses études, dans des champs d'applications très variés, qui vont de la catalyse au « drug delivery », en passant par le stockage de gaz et, plus récemment, en tant que senseurs biologiques. Les ligands organiques, qui les constituent, peuvent lorsqu'ils possèdent un point d'ancrage, comme des groupements amino, être fonctionnalisés grâce à des réactions chimiques. Les travaux présentés dans cette thèse reportent la fonctionnalisation de MOFs, via différentes stratégies, comme des greffages covalent et issues de la chimie de coordination, tel que le couplage peptidique ou encore la synthèse d'urée. Dans cette thèse, est notamment présentée une nouvelle méthode permettant de greffer très rapidement des peptides chiraux dans les nanopores des MOFs. Une large bibliothèque MOF-peptides a ainsi été obtenue et caractérisée. Ces nouveaux composés ont également été utilisés pour l'ancrage de complexes organométalliques dans les cavités des MOFs. Suivant un échange de ligands post-synthétique, il a aussi été possible d'intégrer un complexe organométallique photo-catalytique dans la structure d'un MOF, améliorant ainsi ses activités et sélectivités pour la photo-réduction de CO2. Enfin, les performances catalytiques de ces derniers matériaux MOFs se sont révélées supérieures aux versions homogènes des complexes, ce qui offre de nouvelles opportunités pour la catalyse fine / Metal Organic Frameworks, MOFs, are porous crystalline solid based on metal clusters and organic ligands, investigated for numerous applications such as catalysis, drug delivery, gas storage and, more recently, biosensors. The work presented in this thesis focuses on functionalizing MOFs through different strategies, such as covalent grafting or surface coordination chemistry, through chemical reactions, such as peptide coupling or synthesis of urea. In particular, a new method to very quickly graft chiral peptides into the nanopores of MOFs is reported. A large library of MOF-peptides has thus been obtained and characterized. These novel compounds have also been used for grafting organometallics in the cavities of MOFs. Following a post-synthetic ligand exchange, it was also possible to integrate a photocatalytic complex in the structure of a MOF, improving its activities and selectivities for the photocatalytic CO2 reduction. In general, the catalytic performances of these materials were superior to those of their homogeneous counterparts, thus further expanding the potential of MOFs as well-defined heterogeneous catalysts for fine chemistry
90

Pillared Paddle-Wheel Frameworks als stationäre Phasen für gaschromatographische Trennungen

Böhle, Tony 25 April 2013 (has links)
Metal-organic Frameworks (MOFs) sind eine neue Klasse poröser und kristalliner Feststoffe, die durch ihren modularen Aufbau aus organischen und anorganischen Einheiten einzigartige Eigenschaften unter den porösen Materialien besitzen. Im Mittelpunkt dieser Arbeit steht ihre Anwendung im Bereich der Gaschromatographie, die bislang nur wenig erforscht ist. Dazu werden drei verschiedene MOFs aus der Reihe der „Pillared Paddle-Wheel Frameworks“ (PPFs) in GC Kapillarsäulen abgeschieden und untersucht. Durch systematische Messungen kann gezeigt werden, dass PPFs nicht nur zur Analyse flüchtiger organischer Verbindungen, sondern auch für spezielle Anwendungen wie Größenausschlusschromatographie und Enantiomerentrennungen anwendbar sind. Weiterhin wurden Adsorptionsenthalpien und -entropien sowie Diffusionskonstanten und Massenübergangskoeffizienten für ein breites Analytenspektrum bestimmt.

Page generated in 0.0997 seconds