Diquinoline molecules have been shown previously to have interesting inclusion properties. Of the nine new, targeted molecules produced for this work, seven formed inclusion compounds, and their solid-state structures are discussed herein. Chapter 2 shows the effect that substituting a hydrogen atom with a chlorine atom has on the inclusion properties. This comes about because of the additional intermolecular attractions that are now possible, and a wider range of guest molecules is included as a result. A new homochiral aromatic 'swivel offset face-face (OFF)' interaction is observed. Chapters 3 and 4 deal with the effect of adding extra aromatic planes to the target molecules, two or four planes, respectively. Each of these host molecules formed dimeric host-host units that are extremely similar across all crystal structures. These dimers mainly employed aromatic edgeface (EF) interactions. Chapter 5 looks at the effect of combining the modifications described in Chapters 2-4, namely additional aromatic surfaces and atom substitution. The resulting host molecule specifically includes polyhalomethane guests. In addition, this host molecule formed two concomitant pseudo-dimorph compounds with chloroform-d. The diquinoline host molecule presented in Chapter 6 incorporated an isomeric central linker ring to the other compounds. Although only a single crystal structure could be obtained, 1H NMR spectroscopy experiments show other small aromatics may be included. The effect of electron donating chemical substituents was examined in Chapter 7. These compounds were found to be quite insoluble, and did not produce crystals suitable for X-ray analysis. The host molecules in Chapter 8 contain electron withdrawing nitro groups. The two isomeric compounds that act as inclusion hosts show quite different properties. One of these hosts forms a series of inclusion compounds with water, in which the site occupancy of the guest can range from 0-100% without change to the overall structure. All the X-ray structures described have been analysed in crystal engineering terms, and their supramolecular interactions described in detail.

abstract: This work describes the investigation of novel cathode and anode materials. Specifically, several mixed polyanion compounds were evaluated as cathodes for Li and Na-ion batteries. Clathrate compounds composed of silicon or germanium arranged in cage-like structures were studied as anodes for Li-ion batteries. Nanostructured Cu4(OH)6SO4 (brochantite) platelets were synthesized using polymer-assisted titration and microwave-assisted hydrothermal methods. These nanostructures exhibited a capacity of 474 mAh/g corresponding to the full utilization of the copper redox in an conversion reaction. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies were preformed to understand the mechanism and structural changes. A microwave hydrothermal synthesis was developed to prepare a series compounds based on jarosite, AM3(SO4)2(OH)6 (A = K, Na; M = Fe, V). Both the morphology and electrochemical properties showed a compositional dependence. At potentials >1.5 V vs. Li/Li+, an insertion-type reaction was observed in Na,Fe-jarosite but not in K,Fe-jarosite. Reversible insertion-type reactions were observed in both vanadium jarosites between 1 – 4 V with capacities around 40 - 60 mAh/g. Below 1 V vs. Li/Li+, all four jarosite compounds underwent conversion reactions with capacities ~500 mAh/g for the Fe-jarosites. The electrochemical properties of hydrogen titanium phosphate sulfate, H0.4Ti2(PO4)2.4(SO4)0.6 (HTPS), a new mixed polyanion material with NASICON structure was reported. A capacity of 148 mAh/g corresponding to2 Li+ insertion per formula unit was observed. XRD and XPS were used to characterize the HTPS before and after cycling and to identify the lithium sites. Evaluation of the HTPS in Na-ion cell was also performed, and a discharge capacity of 93 mAh/g was observed. A systematic investigation of the role of the processing steps, such as ball-milling and acid/base etching, on the electrochemical properties of a silicon clathrate compound with nominal composition of Ba8Al16Si30 was performed. According to the transmission electron microscope (TEM), XPS, and electrochemical analysis, very few Li atoms can be electrochemically inserted, but the introduction of disorder through ball-milling resulted in higher capacity, while the oxidation layer made by the acid/base treatment prevented the reation. The electrochemical property of germanium clathrate was also investigated, unlike the silicon clathrate, the germanium one underwent a conversion reaction. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2017

The first project in this work used classical molecular dynamics to study the ice recrystallization inhibition potential of a series of carbohydrates and alcochols, using the hydration index, partial molar volumes and isothermal compressibilities as parameters for measuring their cryogenic efficacy. Unfortunately, after 8 months of testing, this work demonstrates that the accuracy and precision of the density extracted from simulations is not sufficient in providing accurate partial molar volumes. As a result, this work clearly demonstrates that current classical molecular dynamics technology cannot probe the volumetric properties of interest with sufficient accuracy to aid in the research and development of novel cryoprotectants.The second project in this work used molecular dynamics simulations to evaluate the Gibbs free energy change of substituting CO2 in sI clathrate hydrates by N2,CH4, SO2 and H2S flue gas impurities under conditions proposed for CO2 capture (273 K, 10 bar). Our results demonstrate that CO2 substitutions by N2 in the small sI cages were thermodynamically favored. This substitution is problematic in terms of efficient CO2 capture, since the small cages make up 25% of the sI clathrate cages, therefore a significant amount of energy could be spent on removing N2 from the flue gas rather than CO2. The thermodynamics of CO2 substitution by CH4, SO2 and H2S in sI clathrate hydrates was also examined. The substitution of CO2 by these gases in both the small and large cages were determined to be favorable. This suggests that these gases may also disrupt the CO2 capture by sI clathrate hydrates if they are present in large concentrations in the combustion flue stream. Similar substitution thermodynamics at 200 K and 10 bar were also studied. With one exception, we found that the substitution free energies do not significantly change and do not alter the sign of thermodynamics. Thus, using a lower capture temperature does not significantly change the substitution free energies and their implications for CO2 capture by sI clathrate hydrates.

La disparition attendue des combustibles fossiles dans un avenir proche est l'un des grands défis de ce siècle auquel nous devons faire face. Pour cela, il serait judicieux de transférer l’énergie primaire utilisée aujourd'hui en énergies renouvelables. Le secteur des transports est l'un des plus concernés par cette problématique. Une application dans ce secteur nécessite de nombreux travaux de recherche et c'est dans ce contexte que le stockage de l'hydrogène à l'intérieur des clathrate hydrates a été entrepris au cours de mon programme de recherche doctoral. Cette étude avait pour objectif d’étudier les interactions hôte-invité (dynamique) dans les clathrates hydrates et s’est étendue de la synthèse de clathrates hydrates jusque l’insertion de l'hydrogène en leur sein. Cette étude a été faite à la fois d’un point de vue expérimental et théorique : des simulations de Dynamique Moléculaire (MD) ont été utilisées afin de guider l’interprétation d’expériences de Diffusion incohérente Quasi Elastique des Neutrons (QENS). Dans un premier temps, nous avons développé cette approche méthodologique en étudiant la dynamique du clathrate hydrate de bromométhane, système prototype. Dans un deuxième temps, nous avons appliqué cette approche multi-technique à l'étude de clathrate hydrates impliqués dans la problématique du stockage d'hydrogène. Pour cela, nous avons étudié le clathrate hydrate de tétrahydrofurane (THF), utilisé comme sous-structure hôte au stockage d'hydrogène. Un dispositif expérimental original a été développé pour la préparation d'un hydrate clathrate binaires H2-THF. L’analyse des expériences de diffusion neutronique effectuée sur ce clathrate binaire a révélé l’existence de mouvements diffusifs localisés des molécules d’hydrogène à l’intérieur des cages. / The expected disappearance of fossil fuels in the near future is one of the major challenges of this century which we need to face up and it is necessary to anticipate it. For that, it will be convenient that we have begun the primary energy transfer used today to renewable energy. The sector of transport is one of the most concerned by these renewable energies. An application in this sector would require numerous research works and it is in this context that the hydrogen storage inside the clathrate hydrates has been undertaken during my PhD. This work aimed at investigating the host-guest interactions (dynamics) of clathrate hydrates and ranged from the synthesis of clathrate hydrates to the insertion of hydrogen within them. This study has been done both from experimental and theoretical point of view. Molecular Dynamics (MD) simulations were used to guide the interpretation of incoherent Quasi-Elastic Neutron Scattering (QENS) experiments. At first, we developed a methodology combining MD and QENS to investigate the dynamics of bromomethane clathrate hydrate, a prototypical system. Having validated the multi-technique approach, the methodology has been applied to investigate clathrate hydrates involved in the hydrogen storage problematic. In this issue, the tetrahydrofuran (THF) clathrate hydrate, used as host sub-structure for storing hydrogen, has been studied. An original experimental set-up has been developed for the preparation of a binary H2-THF clathrate hydrate. The analysis of QENS experiments performed on this binary clathrate hydrate revealed the existence of localized translational motion of hydrogen molecules within the clathrate cages.

Thesis: M.S., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 1980 / Includes bibliographcial references. / by Farhad Hakimi. / M.S. / M.S. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Yes / Gas hydrates, or clathrate hydrates, are solid crystalline compounds, which are formed by combination of water and gas and/or some volatile liquid molecules. Prediction of hydrate stability/dissociation/equilibrium conditions of natural gases is important in separation processes, gas storage, and in preventing blockage of gas transmission pipelines. In this study, initially, the different sets of the Kihara Potential Function Parameters, KPFP, reported in the literature were used to predict the experimental hydrate dissociation conditions of methane, ethane, propane and i-butane and mixtures of these four compounds. In most cases, however, based on these sets of KPFP, the hydrate structure cannot be predicted correctly. Consequently due to incorrect estimation of the hydrate structure, especially for natural gas mixture, the predicted hydrate dissociation conditions are found inaccurate. For overcoming this fault and by using a genetic algorithm, a new set of KPFP were optimized based on the new definition of the objective function considering hydrate structure. The results show good agreement with experimental data, both in the prediction of hydrate dissociation conditions and hydrate structure.

No description available.

Die vorliegende Untersuchung behandelt den Homogenitätsbereich, sowie die strukturellen und physikalischen Eigenschaften der Clathrat-I-Phasen im System Ba-Au-Ge. Im Zustandsdiagramm existieren zwei separate Phasenbereiche mit Clathrat-I-Phasen unterschiedlicher Symmetrie, welche durch Au-Gehalt und Leerstellenkonzentration bestimmt wird. Bei niederem Goldgehalt existiert die Clathrat-I-Phase mit einer 2 × 2 × 2 Überstruktur des Basistyps in der Raumgruppe Ia-3d. Der Existenzbereich dieser Phase reicht bei 800 °C bis zur Zusammensetzung Ba8Aux•3–0.563xGe43–0.437x mit x = 1.1. Nach einem schmalen Zweiphasenbereich im Bereich 1.1 < x < 1.6 folgt für höhere Au-Konzentrationen eine neue, tetragonale Clathrat-I-Variante mit Raumgruppe P42/mmc. Diese umfasst den gesamten Homogenitätsbereich von x = 1.6 - 5.4. Für höherer Au-Konzentrationen nähert sich die Symmetrie dem Pm-3n-Basistyp an. Der thermoelektrische ZT-Wert steigt jeweils mit der Temperatur und erreicht für die Proben im Bereich x ≈ 5.4 bei 670 K ein Maximum von ≈ 0.9. Die Aufskalierung der Präparation und Voraussetzungen für den Generatorbau werden untersucht. / The present study deals with the homogeneity range as well as the structural and physical properties of clathrate I phases in the Ba-Au-Ge system. The phase diagram comprises phases with the clathrate I type of structure in two separate regions. The symmetry of the respective crystal structures is governed by both, Au content and vacancy concentration. At low gold content, the clathrate I phase forms a 2 × 2 × 2 superstructure of the base type with space group Ia-3d. At 800 °C this phase exists for the general composition formula Ba8Aux•3–0.563xGe43–0.437x till x = 1.1. After a narrow two-phase range in the region 1.1 < x < 1.6, a new, tetragonal clathrate I variant with space group P42/mmc follows for higher Au concentrations x = 1.6 - 5.4. For higher Au concentrations the crystal symmetry gradually approximates the common Pm-3n type of structure. The thermoelectric ZT value increases with temperature reaching a maximum of ≈ 0.9 for the samples in the range x ≈ 5.4 at 670 K. The upscaling of the preparation and other requirements for generator construction are examined.

Cette thèse présente les mesures et l'analyse thermodynamique d'équilibres de phases de systèmes d'hydrates contenant du dioxyde de carbone (CO2), dans le contexte de procédés alternatifs de captage du CO2. Le développement de nouveaux procédés de séparation par voie de cristallisation par hydrates est un point crucial de cette thématique. Les conditions de température et de pression requises et l'utilisation de promoteurs thermodynamiques sont au-delà des opérations habituelles et des bases de données existantes. La connaissance précise des conditions de formation et dissociation d'hydrates de gaz en présence d'additifs chimiques constitue une contrainte importante d'un point de vue thermodynamique et est nécessaire pour la modélisation et l'établissement de la faisabilité de nouveaux procédés industriels impliquant des hydrates de gaz. Dans cette thèse, nous présentons un nouveau dispositif expérimental qui combine techniques statiques et techniques analytiques, ce dernier a été spécialement développé pour mesurer des données d'équilibres des phases hydrate-liquide-gaz à des températures variant entre 233 et 373 K et à des pressions jusqu' à 60 MPa. De nouvelles données d'équilibre de phases des systèmes (CO2 + méthane), (CO2 + azote) et (CO2 + hydrogène) ont été mesurées dans des conditions de formation d'hydrates en suivant la méthode isochorique avec variation de la pression en fonction de la température, et en analysant la composition en phase gazeuse. Les données d'équilibre et les conditions de dissociation d'hydrates générées dans ce travail sont comparées avec les données de la littérature. La fiabilité des modèles thermodynamiques les plus couramment utilisés est aussi étudiée. Les comparaisons entre les données expérimentales et prédites de dissociation d'hydrates suggèrent la nécessité de réajuster les paramètres des modèles thermodynamiques pour les systèmes contenant des hydrates de CO2. En outre, l'effet promoteur du bromure de tetrabutylammonium (TBAB) sur les équilibres des phases des gaz purs et de mélanges contenant du CO2 a été étudié. L'effet le plus important de promotion (réduction de la pression de formation des hydrates > 90%) est observé pour le système (TBAB + azote). Les résultats expérimentaux suggèrent que le CO2 peut être séparé de mélanges de gaz industriels ou de combustion à des températures douces et à de basses pressions à l'aide de TBAB en tant que promoteur thermodynamique. La pression requise pour la formation d'hydrates à partir de mélanges de (CO2 + azote) est réduite de 60 % en présence de TBAB. / This thesis addresses the measurement and thermodynamic analysis of the phase equilibrium behavior of carbon dioxide (CO2) hydrate-forming systems in the context of alternative capture engineering approaches. The development of new technologies based on gas hydrates requires specific temperature and pressure conditions and the utilization of thermodynamic promoters that are beyond usual operations and existing databases. Accurate knowledge of gas hydrates formation and dissociation from thermodynamics point of view in the presence of chemical additives is necessary for modeling purposes and to establish the feasibility of emerging industrial processes involving gas hydrates. In this thesis, a new experimental set-up and method for measuring pressure, temperature and compositional phase equilibrium data of high accuracy are presented. The equipment is based on the ‘static-analytic' technique with gas phase capillary sampling and it is suitable for measurements in a wide temperature range (i.e. 233 to 373 K) and pressures up to 60 MPa. New phase equilibrium data in the (CO2 + methane), (CO2 + nitrogen) and (CO2 + hydrogen) systems under hydrate formation conditions were measured following an isochoric pressure-search method in combination with gas phase compositional analysis. The equilibrium data generated in this work are compared with literature data and also with the predictions of two thermodynamic literature models. Comparisons between experimental and predicted hydrate dissociation data suggest a need of readjusting model parameters for CO2 hydrate-forming systems. In addition, the thermodynamic stability of Tetra-n-Butyl Ammonium Bromide (TBAB) semi-clathrates (sc) with pure and mixed gases was investigated. The largest promotion effect (> 90% reduction in hydrate formation pressure) is observed for (TBAB + nitrogen) sc. The experimental results suggest that CO2 can be separated from highly to low concentrated industrial/flue gas mixtures at mild temperatures and low pressures by using TBAB as thermodynamic promoter. The pressure required for hydrate formation from (CO2 + nitrogen) gas mixtures is reduced by 60% in the presence of TBAB.

Capturer le CO2 est devenu un domaine de recherche important en raison principalement des forts effets de serre dont il est jugé responsable. La formation d'hydrate de gaz comme technique de séparation montre un potentiel considérable, d'une part pour sa faisabilité physique et d'autre part pour une consommation énergétique réduite. En bref, les hydrates de gaz (clathrates) sont des composés ″cages″ non-stoechiométriques, cristallins comme la glace et formés par une combinaison de molécules d'eau et de molécules hôtes convenables, à basses températures et pressions élevées. Puisque la pression exigée pour la formation d'hydrate de gaz est généralement forte, il est judicieux d'ajouter du bromure tétra-n-butylique d'ammonium (TBAB) comme promoteur de formation d'hydrate de gaz. En effet, le TBAB permet généralement de réduire la pression exigée et/ou d'augmenter la température de formation aussi que de modifier la sélectivité des cages d'hydrates au profit des molécules de CO2. TBAB participe à la formation des cages par liaisons ″hydrogène″. De tels hydrates sont nommés "semi-clathrate hydrates". Évidemment, des données d'équilibres de phase fiables et précises, des modèles thermodynamiques acceptables, et d'autres études thermodynamiques sont requises pour concevoir des procédés de séparation efficaces utilisant la technologie mentionnée ci-dessus. Dans ce but, des équilibres de phase de clathrate/semi-clathrate hydrates de de divers mélanges avec des gaz contenant CO2 (CO2 + CH4/N2/H2) ont été mesurés, ici, en présence d'eau pure et de solutions aqueuses de TBAB. La partie théorique de la thèse présente un modèle thermodynamique développé avec succès sur la base de la théorie des solutions solides de van der Waals et Platteeuw (vdW-P) associée aux équations modifiées de la détermination des constantes de Langmuir des promoteurs d'hydrates pour la représentation/prédiction des équilibres en présence de ″semi-clathrate hydrates″ de CO2, CH4, et N2. Plusieurs tests de cohérence thermodynamique basés soit sur l'équation de Gibbs-Duhem, soit sur une approche statistique ont été appliqués aux données d'équilibre de phase des systèmes de ″clathrate hydrates″ simples/mélanges afin de statuer sur leur qualité.