Dissertations / Theses on the topic 'Solid state chemistry'
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Qin, J. "Studies in organometallic solid state chemistry." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379942.
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Brown, Craig. "Solid state chemistry of selected fullerenes." Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264552.
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Peacock, Heather Margaret. "Solid state oxide chemistry of ruthenium." Thesis, University of Aberdeen, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257552.
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The oxygen stoichiometry of RuO2+atop -x was investigated by thermogravimetric and isopiestic techniques, in the temperature range 200-800oC. RuO2+atop -x could be made hyperstoichiometric to a maximum of RuO2.014 at 500oC and hypostoichiometric to a maximum of RuO1.9808 at 600oC. Above 800oC loss of ruthenium as the volatile species RuO3(g) and RuO4(g) prevented any reasonable determination of oxygen stoichiometry. Solid solutions were prepared in the Ru-V-O, Ru-Nb-O, Ru-W-O and Ru-Mo-O systems by solid state reaction. Complete solid solution was observed in the Ru-V-O system. Unit cell parameters were determined by X-ray powder diffraction for a range of compositions in the Ru-V-O system. Large deviations from the linearity predicted by Vegard's law were found for both a and c, e.g. at 5 wt.% vanadium a = 4.489, c = 3.089 and at 75 wt.% vanadium a = 4.592, c = 2.873. Conductivity of polycrystalline pressed pellets of RuO2:VO2 solid solutions was measured using a four point probe technique. All small vanadium concentrations conductivity increased with percent dopant i.e. resistivity decreased from 8.5 k Ω cm at 2 wt.% vanadium to 4.5 k Ω cm at 5 wt.% vanadium. Solid solutions containing 25-85 wt.% vanadium were found to be semiconducting and increasing amounts of vanadium in this range produced no significant change in resistivity. Solid solutions containing 95 wt.% vanadium showed a transition, at -13oC, from metallic to semiconducting behaviour as the temperature was lowered. In the Ru-Nb-O, Ru-W-O and Ru-Mo-O systems only 5 wt.% dopant could be successfully incorporated into the RuO2 lattice. On the basis of the Ru-V-O system however these materials are considered to be potentially good conductors. Resistor inks dilute in ruthenium could prove economically viable. The high vanadium containing materials may have potential as temperature sensitive electronic switching devices. The temperature programmed reduction of an RuO2:VO2 solid solution containing 25 wt.% vanadium showed that the onset of reduction occurred at a much higher temperature (234oC) than for RuO2 itself (63oC). This suggests that vanadium containing solid solutions of RuO2 are more resistant to reduction than RuO2 itself, a much sought after property in the production of thick film resistors.
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Wilson, Graeme. "Solid-state chemistry of zirconium dioxide." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU009973.
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A systematic literature search on the system Na2O-ZrO2-SiO2 is presented which reveals inconsistencies on the number and identity of the ternary phases. New X-ray diffraction data are presented for Na2ZrSiO5, Na2ZrSi2O7 and Na2ZrSi4O11; these data are substantiated by good agreement with data calculated from single-crystal work. The unit-cell parameters were redetermined. The compounds Na2ZrSi4O11 and Na4Zr2Si10O31 have now been successfully synthesised by solid state reaction, although the latter could not be prepared phase-pure; these phases had previously only been synthesised hydrothermally. The subsolidus compatibility relations at 1000oC have been reassessed, taking into account the two phases mentioned above, which have not featured in any previously published phase diagram. The addition of dopants, such as calcia, magnesia or yttria, as the oxide, carbonate etc., into solid solution with zirconia are known to stabilise the cubic phase to room temperature. A comparative trial is reported of the physical properties of these powders produced using either organic or inorganic gel-processing routes; the organic route consistently provided powders with greater thermal stability and surface area, which should lead to a more sinterable product, therefore this method was extended to include lanthanide oxide dopants. The incorporation of these dopants has been previously reported, but long sintering times at elevated temperatures were necessary; the organic precursor route described above successfully produced cubic zirconia more rapidly and at much reduced temperatures. The gelation tendencies of the lanthanide dopants are discussed. The binary system ZrO2-SnO2 was investigated at various temperatures; at 1000oC one metastable phase, zirconium stannate, which was observed previously but was poorly characterised, has been studied by X-ray diffraction techniques; new unit-cell parameters and X-ray diffraction data are presented; these data have been substantiated by agreement with calculated data. This phase has now been shown, by various techniques, to exsolve to two distinct phases with average compositions 90ZrO210SnO2 and 82SnO218ZrO2. The monoclinic zirconia solid-solution has been proven by the influence of this inclusion of tin oxide on the physical properties of pure monoclinic zirconia. A discussion of the crystallography of zirconium titanate, which is isostructural with zirconium stannate, is also reported. The extent of solid solubility of tin oxide in zirconium titanate has been determined at 1000, 1350, 1500 and 1550oC; the compositions in this single-phase region are known as zirconium tin titanates and are used as microwave dielectric resonators. A large metastable region of ZrO2-TiO2 solid solution was noted at 1000oC which is similar to data previously published. At 1350oC, the extent of solid solution in the ternary region was also as previously published, but a vast increase in solid-solubility was noted at higher temperatures. A comparison of the dielectric properties of pellets produced by mixed oxide sintering and gel-processing is reported.
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Vitorica, Inigo. "Solid state supramolecular chemistry : gas-solid reactions and intermolecular interactions." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/3926/.
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Gallon, Daniel. "Structure-property relationships in solid state chemistry." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270616.
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Khamar, Dikshitkumar. "Solid state chemistry of hydrate forming compounds." Thesis, Liverpool John Moores University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555688.
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Polymorphism presents complex issues for the pharmaceutical industry from processing, regulatory, patenting and stability perspectives. It can be further challenging to control the same form throughout processing and development when it has the capacity to form a hydrate. Incorporation of water into the crystal lattice contributes to significant differences in solubility, stability and bioavailability of the active pharmaceutical ingredient (API). During processing and formulating steps, water is used in many procedures such as, recrystallisation, wet granulation, aqueous coating lyophilisation etc. This can trigger anhydrous to hydrate conversion and could be detrimental for bioavailability and stability of the product. The factors responsible for this type of transition such as, role of solvent, activity of solvent, thermodynamic stability of different forms, equilibrium conditions, processing induced transformations are investigated. Theophylline, a channel hydrate, is chosen as a model compound which exhibits both polymorphs and solvates. The value of water activity at which the theophylline monohydrate is thermodynamically stable form was investigated using solubility, cooling crystallisation and slurry experiments and found to be aw 2: 0.70 at 25 QC. Full characterisation of the solid state chemistry of theophylline has resulted in the discovery of a new, previously unreported, anhydrous form of theophylline, called Form IV. Using solubility, crystallisation, slurrying and thermal experiments, Form IV was found to be thermodynamically more stable than the currently known stable form, Form H. The crystal structure of Form IV and Form I was determined by single crystal :X-Ray diffraction technique. The crystal structures for Form IV and Form I are deposited in Cambridge Structural Database (CSD) with reference code BAPLOT03 and BAPLOT04 respectively. The experimentally observed stability behaviour was correlated with the structural features of solid forms and also with the energy calculations. The kinetic ally stable Form H serves as the intermediate for polymorphic and hydrate-anhydrate transformations as the catemer motif observed in Form II can easily propagate by forming a strong and directional hydrogen bonds. In contrast, the dimer of theophylline molecules as observed in Form IV needs the presence of solvent to link through other dimers only by weak interactions. This results in the generation of Form IV only via solvent mediated transformations. Solid state chemistry of hydrate forming compounds Theophylline has also been used here as a model compound to study eo crystallisation with various saturated, dicarboxylic acids. A new, eo crystal of theophylline with adipic acid was generated and using thermal methods and PXRD, the stoichiometry (1 :2, adipic acid: theophylline) is confirmed. The complex hydration-dehydration behaviour of theophylline was investigated. The samples subjected to different pharmaceutical processing conditions for hydration-dehydration, generated various .intermediate phases suggesting multiple dehydration mechanisms and the potential of phase transformations during processing of such kind of hydrate forming compounds. The sensitivity of thermal methods over other bulk methods such as PXRD, in detecting a small amount of phase impurity, has been highlighted.
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Brown, Michael Ewart. "Reactions in the solid state." Link to this resource, 2005. http://eprints.ru.ac.za/252/.
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Thesis (D.Sc. (Chemistry)) - Rhodes University, 2006.[Appendix]. Dedication - Acknowledgements - Curriculum vitae - Biographical notes - Publication list - Introduction to my research - Commentary-books - Commentary-research papers - Conclusions.
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Brown, Michael Ewart. "Reactions in the solid state." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1015762.
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I have chosen the title for this thesis, "Reactions in the Solid State", for two reasons: Firstly, it is broad enough to cover all of my areas of research, which have been: • Effects of irradiation on solids (PhD topic) • Silver refining (while at the Chamber of Mines) • Kinetics of decomposition of solids (with Dr A.K. Galwey and various others) • Techniques of thermal analysis • Pyrotechnic delay systems (with support from AECI Explosives) • Thermal and photostability of drugs (with Prof B.D. Glass) and, secondly, it was the title of the very successful book co-authored by Drs Andrew Galwey, David Dollimore and me. A large part of my research has been involved in the writing and editing of books, so these are covered in a separate commentary, while commentary on the more than 100 papers to which I have contributed forms the main part of this compilation. It is hoped that the electronic format will enable ready access of to all aspects of my research, including electronic versions of the original papers. The reader will need a copy of Adobe Acrobat Reader to access these.
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Drummond-Brydson, Richard. "Electron energy loss spectroscopy in solid-state chemistry." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237906.
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Wang, Wang-Nang. "Solid-state chemistry of acridizinium and pyridinium salts." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236088.
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The work described in this thesis is concerned with the study of extending known crystal engineering principles to the influence of anions on crystal packing and reactivity. Some features arising from this study include: single-crystal to single-crystal reactivity; an important role of water in modifying the course of the reaction; the movement of water associated with the reacting pair of acridizinium cations during the photodimerization process; possible martensitic phase transition from the acridizinium bromide monohydrate P21/a isomer to P1 isomer; phase transformations accompanying dimerization; the generation of crystalline solutions incorporating two or more anions and the modification of structure as a function of anion with consequential differences in reactivity. Results from both theoretical approach and experimental studies on acridizinium and 9-methylacridizinium salts suggest that ionic molecules pack preferrentially in a centrosymmetric manner favoured by both the geometrical close-packing model and Coulombic energy. Crystal morphologies are modified by varying anions. The morphological changes can be correlated consistently with the size and shape of the anion, and the electronic property of the anion also contributes to this change (e.g. the formation of hydrogen bond). Molecular packing arrangements (structural relationship) of these compounds can also be correlated consistently with the size, shape and the electronic properties of the anions. There is a good correlation between the photoreactivity and the crystal structure. The relative conversion rate, assuming that the excimer formation is the rate determining step, can be predicted reasonably well from the ground state structure of the monomer pair. A possible mechanism for the photodimerization of acridizinium and 9-methylacridizinium salts was proposed based on the results from the electrochemical, spectroscopic and electron resonance studies.
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Barbero, Mauro. "Chemistry of APIs: Synthesis and Solid-State Properties." Doctoral thesis, Università del Piemonte Orientale, 2020. http://hdl.handle.net/11579/114868.
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Questo programma di dottorato si è focalizzato sia sulla chimica degli APIs, ovvero sui principi attivi farmaceutici, sia su altre importanti molecole utilizzate in ambito farmaceutico. In particolare, sono state analizzate diverse strategie sintetiche, con lo scopo di evidenziare possibili processi sintetici alternativi degli APIs, sono state studiate le trasformazioni chimiche, così come le reazioni di derivatizzazione, di importanti molecole largamente utilizzate campo chimico e chimico farmaceutico. In aggiunta, sono state studiate le proprietà fisico-chimiche di APIs focalizzate a valutare la presenza di eventuali polimorfi attraverso diverse tecniche analitiche quali diffrattometria a raggi-X (cristallo singolo o polveri), DSC e TGA. In conclusione, questo programma di dottorato, ha permesso di identificare diverse strategie sintetiche per la sintesi del principio attivo Maropitant, ha evidenziato reazioni inattese della vanillina, così come la derivatizzazione chimica della DMAP ai fini della sua eterogeneizzazione. Infine, sono state valutate ed analizzate le proprietà allo stato solido di tre importanti principi attivi quali Pirfenidone, Gepirone e Moxidectina.
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Oburn, Shalisa M. "Applications in supramolecular chemistry and solid-state reactivity: template-mediated solid-state reactions, dynamic covalent chemistry, mechanochemistry, and pharmaceutical co-crystals." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/7004.
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Supramolecular chemistry and crystal engineering seek to control molecular packing in the solid state to influence the physical and chemical properties of crystalline solid materials. A goal of supramolecular chemistry that seeks to control molecular packing in the solid state focuses on exploiting non-covalent interactions to assemble molecules into desirable arrangements. Strategies implemented to control molecular packing rely on strong, directional interactions such as hydrogen bonding, halogen bonding, and metal coordination to direct localized arrangement of molecules in solids. In this context, small molecules can be used as linear templates in co-crystals to assemble reactive alkenes into specific geometries allowing reactivity in the solid state. A linear template method has been used to achieve [2+2] photocycloadditions of discrete assemblies containing alkenes to afford cyclobutanes in high stereospecificity and in quantitative yield.
Herein, we describe the use of a nonlinear template, in the form of 1,4-butynediol (1,4-bd), to pre-organize alkenes in the solid state. The nonlinear template of 1,4-bd hydrogen-bonds to the alkene 1,2-bis(N-pyridyl)ethene (where N = 3 or 4) to form 1D hydrogen-bonded polymers. The hydrogen-bonded polymer chains form infinite stacks which are sustained by C-H···O interactions occurring between polymer chains. The stacked alkenes undergo a UV-induced [2+2] photocycloaddition to produce rctt-tetrakis(N-pyridyl)cyclobutane photoproducts (where N = 3 and 4) in non-quantitative yields. The yield of the photoreaction is increased to nearly quantitative by applying a supramolecular catalysis approach with the 1,4-bd template.
Functional groups on reactant molecules can compete via non-covalent interactions with templates employed for the self-assembly process. One method to inhibit competition between functional groups involves chemically modifying a functional group employing a supramolecular protecting group. Here, we describe an acetyl supramolecular protecting group approach employed to mask alkenes containing phenolic and pyridyl functional groups. The acetyl protecting group prevents the phenolic substituents of the targeted alkene from participating in non-covalent interactions employed for the template-mediated self-assembly process. Thus, a cyclobutane molecule was obtained using the novel acetyl supramolecular protecting group strategy applied to a solid-state [2+2] photodimerization that affords a head-to-head cyclobutane. After deprotection, the resulting cyclobutane possessed tetrahedrally-disposed cis-hydrogen-bond-donor and cis-hydrogen-bond-acceptor groups. Thus, a purely organic three-dimensional hydrogen-bonded network based on a rare Michael O'Keeffe (mok) topology was constructed using an organic molecule synthesized in the organic solid state. The phenolic substituents of the cyclobutane adopt different orientations (syn-, anti-, and gauche-) to conform to the structural requirements of the mok net.
A challenge surrounding template-directed solid-state reactivity requires alkenes to be lined with functional groups that coordinate (or bind through other non-covalent interactions) to the template. Herein, we describe a dual approach of supramolecular assistance to covalent bond formation that utilizes a combination of imine and metal-organic chemistry to generate cyclobutanes lined with aldehyde groups. Specifically, dynamic imine chemistry was implemented to install a temporary recognition site on an aldehyde-containing alkene of cinnamaldehyde for a template-directed [2+2] photocycloaddition in the solid state. The resulting modified alkene aligns using Ag(I) ions into desirable arrangements for the covalent-bond-forming [2+2] photocycloaddition. The result is a 1D coordination polymer undergoes a UV-induced, regio-controlled [2+2] photocycloaddition in the solid state. The photoreaction proceeds stereospecifically with quantitative yield of the corresponding aldehyde-functionalized photodimer, α-truxilaldehyde. Additionally, we investigate the influence of the Ag(I) counterions on the assembly of imine containing alkenes to generate reactive assemblies for the purpose of producing aldehyde-containing cyclobutanes.
This dissertation also encompasses research pertaining to pharmaceutical solids and mechanical properties of organic molecular crystals. Specifically, we describe the discovery of two polymorphic co-crystals containing acetylsalicylic acid (aspirin) combined with 4,4’-bipyridine. The initial discovery of the form I polymorph was aided by mechanical dry-grinding, while an additional form II polymorph was revealed by rapid cooling in ethanol. The polymorphs differ by relative twists of carboxylic acid groups of the aspirin molecules and of the pyridyl rings of 4,4’-bipyridine. Additionally, the form I polymorph contains aspirin molecules that are linked via discrete catemeric methyl C-H···O interactions, while the form II polymorph is linked via both infinite methyl C-H···O catemers and centrosymmetric dimers. These results demonstrate the importance of dry mechanical grinding for the discovery of pharmaceutical co-crystals and polymorphs.
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Sinnwell, Michael Alan. "Organic fluorine in solid-state [2+2] photocycloadditions." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5853.
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The use of principles of supramolecular chemistry to direct reactions in the crystalline state has emerged as a reliable means to facilitate highly selective reactions in a solvent-free environment. In this context, we have utilized the fixed spatial arrangements of molecules in a crystal lattice to promote intermolecular [2+2] photodimerizations. We have shown how principles of supramolecular chemistry can be used to preorganize olefins to undergo intermolecular [2+2] photodimerizations in the solid state. Explorations into fluorinated and partially fluorinated olefinic substrates has allowed for development of underutilized supramolecular interactions to direct such chemical reactions. We reported interactions between fluorinated molecules in inorganic complexes and organic solids that supported intermolecular [2+2] photodimerizations as well as cross-reactions between olefinic species.
Analogous to the hydrogen bond templates commonly utilized by our group to engineer reactive solids, we expanded the methodology by developing templates that direct reactions via halogen bonding. We report on the use of a halogen-bond-acceptor template to direct the formation of a small molecule lined with I- and F-atoms. We demonstrate the olefins in the solid undergo a [2+2] photodimerization with UV radiation in a stereoselective and quantitative manner. Our work provides the first use of halogen bonds to direct the formation of a small-molecule lined with halogen atoms in a solid. We reveal the halogenated product provides access to a unique family of host-guest materials that exhibit an extremely rare form of self-inclusion.
We describe the ability of halogen bonds to undergo bending deformations. There are currently great interests in halogen bonds as related to applications to organic synthesis, supramolecular chemistry, and materials science. While halogen bonds are often compared to hydrogen bonds, the wealth of knowledge concerning the fundamentals and behavior of halogen bonds has admittedly experienced less time to develop. In our work on single-crystal reactions and transformations, we have discovered the ability of halogen bonds based on rigid interacting partners to bend and deform. We provide a quantitative comparison of the bending to the literature to demonstrate how the geometric landscape of the bending compares to known data. We report a single-crystal-to-single-crystal transformation of a cocrystalline material involving a fluorinated, olefinic compound. The olefins adopt a well-defined, reactive geometry mediated by halogen-bonding templates.
We exploit metal-organic complexes to fix spatial arrangements of molecules in crystal lattices to promote intermolecular [2+2] photodimerizations. Perfluorophenyl-perfluorophenyl (C6F5···C6F5) interactions have recently emerged as a means to control supramolecular architectures and frameworks. However, it was not clear whether perfluorophenyl-perfluorophenyl interactions can be integrated in [2+2] photodimerizations in solids.
We describe the significant effect fluorine exercised on the structure and photoreactivity of an octafluoro stilbene derivative in the solid state. Specifically, we report the olefin, trans-1,2-bis(2,3,5,6-tetrafluorophenyl)ethylene, self-assembles via C-H···F and perfluorophenyl-perfluorophenyl interactions for a stereoselective and quantitative topochemical photodimerization.
Lastly, principles of crystal engineering and supramolecular chemistry are exploited to design and achieve a supramolecular protecting group strategy for the solid-state synthesis of a cyclobutane—a cyclobutane that supports a rare hydrogen-bonded self-catenating framework. The application of a hydrogen bonding coformer to separate a trans-isomer of a pyrimidyl olefin directly from a Wittig reaction is demonstrated. The coformer supports a head-to-head [2+2] photodimerization in the solid state.
The work demonstrated here describes our explorations into the supramolecular interactions of organic fluorine, and how such interactions can be used to facilitate the synthesis of small molecules via [2+2] photodimerizations in solids—alone and in accompaniment of other crystal engineering strategies.
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Rovnyak, David S. (Davis Sherman) 1971. "Solid-state nuclear magnetic resonance of quadrupolar nuclei with applications to biological solids." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85294.
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Elliott-Martin, Richard J. "Solid state studies of phthalocyanines." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385246.
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Schneider, Sebastian. "Novel contributions to the solid-state chemistry of diazenides." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-164379.
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In solid-state chemistry, the existence of homonuclear diatomic nitrogen anions has proven existence only very recently, although the latter represent a common and well-characterized structural motif in biological and synthetic chemistry. Thereby, high-pressure/high-temperature (HP/HT) syntheses starting from the elements and using specialized equipments have introduced binary diazenides (M = Sr, Ba, La) and pernitrides (M = Os, Ir, Pd, Pt) with MN2 stoichiometry consisting of [N2]2– and [N2]4– ions, respectively. Nevertheless, synthesis and characterization of only a handful of examples of both materials classes since their identification in 2001 is quite surprising. Within this context, it is likewise remarkable that solids with isoelectronic, homonuclear diatomic ions consisting of elements to the left (carbon) and to the right (oxygen) of nitrogen in the periodic table have already been synthesized and characterized decades ago.
Introducing the approach of controlled thermal decomposition of ionic azides of Group I and II metals in a multianvil device at extreme conditions resulted in a renaissance of homonuclear diatomic nitrogen chemistry. This high-pressure route proved as excellent tool for the synthesis of hitherto unknown binary and even ternary materials with homonuclear diatomic nitrogen anions. However, compared to the classification of valencies in bound N2 entities observed in bioinorganic or metal-organic chemistry, their adequate description in solid-state chemistry is hindered due to, for example potential metallicity in such compounds. Nevertheless, by the use of a variety of complementary experimental and theoretical methods, such as powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), density functional theory (DFT), infrared spectroscopy (FTIR), nuclear magnetic and electron spin resonance spectroscopy (NMR, ESR), the identification of [N2]2- anions in solid-state compounds was possible.
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Hazael, R. T. "High pressure studies in solid state chemistry and biology." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1346454/.
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The new family of multiferroic perovskites SeMO3 (M= Ni, Mn, Cu) are obtained under high-P,T synthesis conditions from mixtures of the oxides (NiO, MnO, SeO2 etc.) or the corresponding metal hydroxides at pressures between 2-7 GPa and at temperatures up to 1000°C. However, those syntheses can result in retention of the starting oxides in the reaction products, leading to difficulties in analysis of the magnetic properties. We have developed a precursor route based on the reaction of Na2SeO3 with anhydrous MCl2 compounds, leading to the formation of the crystalline perovskite material with formation of only diamagnetic NaCl as a reaction product. This reaction procedure also allows us to lower the reaction temperature. We studied the synthesis both in the laboratory using multi-anvil and piston cylinder techniques, and also using in situ synchrotron X-ray diffraction using the Paris-Edinburgh press at ESRF ID27, to follow the synthesis reactions and optimise the reaction conditions. Our results indicate initial formation of Se-bearing perovskites such as SeCuO3, in a low-P, T range kinetically stabilised during the early stages of the reaction, followed by further reactions to yield well-crystallised materials at higher-P, T conditions. We also used similar techniques to study possible formation of SeMS3 perovskites indicated to be stable from DFT calculations. Here we could not find any evidence for formation of the perovskite structures, but instead we observed synthesis of pyrite-type materials Bacteria show the greatest adaptability, which enables them to occupy extreme habitats on the planet. It is important to complete a proper evaluation of the biosphere of our planet and to achieve this we must understand the mechanisms and limits for bacterial survival. This work will help us constrain models for the origin of life and is readily transferable to many astrobiological studies. It is now extremely relevant to study the effect of high P on the development and evolution of organisms to understand their survivability mechanisms. We are experimenting with the adaptability of E.coli to pressures greater than 1 GPa. Until recently it was thought that no organisms could survive at P> 120 MPa (Zeng et al 2009). However, a recent study indicated that E.coli and S. onodeinsis remained viable to 1.4-1.7 GPa (Sharma et al 2002), but the results have been questioned (Yayanos 2002). However, our collaborative directed evolution study of E. coli has now confirmed that microbes can adapt and survive at least up to 2 GPa (Vanlint et al 2011).
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Jones, Barry Richard. "Tunability and reactivity of selected solid state materials." Diss., Online access via UMI:, 2006.
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Bennett, David Alexander. "Structural methods in solid-state NMR." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13242/.
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New solid-state NMR experiments for measuring internuclear distances are designed using symmetry principles. The “recoupling” sequences described here are intended to reintroduce the MAS-averaged heteronuclear dipole-dipole coupling between a spin-1/2 nucleus (e.g. 1H) and a half-integer quadrupolar nucleus (e.g. 17O, I = 5/2). The magnitude of the dipolar interaction depends on the separation between the coupled nuclei, so the evolution of the spin system under the recoupled Hamiltonian can be used to measure the internuclear distance. Simulations of the spin dynamics are used initially to select candidate sequences and these are subsequently employed to measure both long-range and direct O–H distances in powdered L-Tyrosine.HCl (isotopically enriched with 17O at 20%to 30% at the O$^\eta$ site). Improvements to existing methods for the data analysis for this type of NMR experiment are also discussed, including the restriction and/or removal of certain fit parameters and the explicit inclusion of inhomogeneous radio-frequency fields as part of the fitting procedure. The effects of processing on the uncertainty of experimentally determined distances are considered, and a new analysis method which circumvents several of these effects is presented. Similar recoupling sequences can be used to measure the anisotropy of proton chemical shifts, and some preliminary results are also presented for this application. A systematic method for the assignment of congested spin-1/2 spectra resulting from molecules with large numbers of chemically similar sites is also described. This makes use of a comparison between the chemical shift tensor measured as usual by the 2D-PASS experiment and its principal components calculated from first principles using the density functional theory package CASTEP. The initial peak assignment is generated randomly and then varied using a steepest-ascent hill climbing algorithm with the square sum of the difference between the experimental and calculated principal values of the chemical shift tensor as the target function. The new method is tested on the 13C spectrum of the anti-inflammatory drug flufenamic acid and found to be superior to simple assignments using only the isotropic chemical shift.
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Lansing, Jonathan C. (Jonathan Clifford) 1974. "Solid-state NMR investigations of the bacteriorhodopsin photocycle." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8050.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2002.Vita.
Includes bibliographical references.
Bacteriorhodopsin (bR) is a heptahelical integral membrane protein with a retinylidene prosthetic group from H. salinarum. The protein creates a proton gradient across the cell membrane by harvesting light energy. Proton transfer events can be segregated into transfers between the Schiff base of the chromophore and the cytoplasmic and extracellular half-channels. Critical to pump function is the switch in accessibility between the two half-channels. Models of the accessibility switch invoke protein or chromophore structural changes. This thesis describes the application of solid-state Nuclear Magnetic Resonance (NMR) to investigate each of the competing models in the native purple membrane environment. Conformational changes of the chromophore have been characterized by correlation of 13C-1H and 5N-1H dipolar interactions to determine chromophore dihedral angles in multiple photocycle intermediates. The resting state of the protein is found to contain a pre-loaded chromophore, with distortion about the Schiff base linkage and the neighboring C15-C14 bond. Changes of the dihedral about the C15-C14 were characterized during the photocycle, although the timing of the changes precludes their direct involvement in the accessibility switch. Putative protein conformation changes at the X-Pro peptide bonds were probed via the peptide 1 N and 13C chemical shifts. Proposed roles of the X-Pro bonds discriminate between structural and dynamic roles during the photocycle.
(cont.) Analysis of the three membrane-embedded X-Pro bonds indicates only slight differences between the resting state of the protein and the two species with a deprotonated chromophore, indicating that the buried prolines serve a principally structural role. General application of the proton-dependent dihedral angle measurement techniques to protein structure determination is hampered at sites with methylene carbons due to the pair of directly bonded protons. A general method is described for the preparation of stereoselectively deuterated glycine, which can be subsequently incorporated into peptides and proteins. This stereoselectively labeled glycine is expected to enable more precise determination of protein secondary structure.
by Jonathan C. Lansing.
Ph.D.
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Chen, Songela Wenqian. "Modeling ion mobility in solid-state polymer electrolytes." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122534.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 31-32).
We introduce a course-grained model of ion diffusion in a solid-state polymer electrolyte. Among many tunable parameters, we investigate the effect of ion concentration, ion-polymer attraction, and polymer disorder on cation diffusion. For the conditions tested, we find that ion concentration has little effect on diffusion. Polymer disorder creates local variation in behavior, which we call "trapping" (low diffusion) and "free diffusing" (high diffusion) regions. Changing ion-polymer attraction modulates the relative importance of trapping and free diffusing behavior. Using this model, we can continue to investigate how a number of factors affect cation diffusion both mechanistically and numerically, with the end goal of enabling rapid computational material design.
by Songela Wenqian Chen.
S.B.
S.B. Massachusetts Institute of Technology, Department of Chemistry
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Nordon, Alison. "Solid-state NMR studies of inclusion compounds." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4758/.
Full textAbstract:
The work contained within this thesis is a study of inclusion compounds using solid-state NMR. Such compounds typically exhibit static and/or dynamic disorder, which precludes the use of diffraction-based techniques to obtain detailed structural information. Hence, due to its ability to probe local environments, solid- state NMR can be used to provide information which would otherwise be inaccessible. However, the dynamic nature of the guest molecules within inclusion compounds can yield unusual results for routinely applied experiments, such as cross polarisation, heteronuclear dipolar decoupling and dipolar dephasing. Therefore, some of the more fundamental aspects of solid-state NMR have first been explored. The inclusion compounds of particular interest are those which contain urea or thiourea as the host species. The ordering of guest molecules and host dynamics have been investigated via both one- and two-dimensional (^13)C and (^1)H NMR experiments for the 2-hydroxyalkane/urea inclusion compounds. For the 1-fluorotetradecane/urea inclusion compound, an approach involving a combination of (^1)H→(^13)C and (^19)F→(^13)C cross-polarisation experiments, with both single-channel (^H) and double-channel decoupling ((^1)H,(^19)F) has been devised to assign (^13)C resonances and hence deduce guest ordering. Steady-state and transient (^19)F MAS NOE experiments have been used to probe the dynamics of the 1-fluorotetradecane/urea inclusion compound. Using the considerable sensitivity advantage of (^19)F NMR, over that of (^13)C, a detailed study of the conformational dynamics exhibited by fluorocyclohexane molecules included within thiourea has been performed via bandshape analysis, selective polarisation inversion and 2D exchange experiments. Intermolecular distance measurements have been determined for adjacent fluoroalkane molecules within urea tunnels using a series of static (^19)F NMR experiments. From the results obtained, conclusions regarding the mutual orientations of adjacent end-groups in such compounds have been made.
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Laird, Rebecca Christine. "Functional diversity in templated solid state reactions." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1347.
Full textAbstract:
Solid-state chemistry presents itself as a rapidly growing field of materials chemistry. When compared to solution phase chemistry, solid-state chemistry offers the potential for significant benefits to the researcher including better stereoselectivity and product selectivity as well as the ability to synthesize products that may be difficult to obtain in the solution phase. The solid-state [2+2] photocycloaddition reaction, as first demonstrated by Schmidt, exemplifies these benefits through the selective photoreaction of olefins. Within these benefits however, certain limitations such as unpredictable crystal packing and limited functional group diversity remain, limiting the applications and expansion of solid-state chemistry.
It has been our goal to overcome these limitations through the use of the template method, crystal engineering, and post-synthetic modification (PSM) techniques. As first developed by MacGillivray, the template method relies on supramolecular interactions within cocrystals to guide photostable olefins into photoacitve assemblies. While it does not provide overall control of crystal packing, it guides local packing within the crystal. Our work has focused on utilizing both the template method, as well as PSM techniques to develop a library of analogous, yet functionally diverse molecules to undergo the [2+2] photocycloaddition reaction in the solid state. To this end, we have performed the click reaction to generate a library of molecules and incorporate the 1,4 disubstituted 1,2,3 triazole ring within our olefinic systems. Our efforts to study the triazole ring as a functional group in the solid state and also to perform the [2+2] photocycloaddition on a click-derived molecule will be described within this thesis.
Additionally, we have sought to expand the template method through the development of the first non-covalently templated intramolecular [2+2] photocycloaddition reaction in the solid state. Our work towards understanding the effects on crystal packing due to functional group diversity on a template, as well as the design of a novel molecule able to undergo an intramolecular [2+2] photocycloaddition reaction will be presented in this thesis.
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Likovec, Wayne Robert. "Solid state NMR studies of elastomers." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058875640.
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Khawam, Ammar. "Application of solid-state kinetics to desolvation reactions." Diss., University of Iowa, 2007. http://ir.uiowa.edu/etd/170.
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Kay, C. W. M. "Magnetic field effects in chemistry and biology." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334813.
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Fowkes, Amelia Jane. "High resolution powder neutron diffraction in solid state inorganic chemistry." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299525.
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Bond, A. D. "Solid-state chemistry of cyclic thiohydroxamic acids : prediction and measurement." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596761.
Full textAbstract:
In this thesis, the solid-state chemistry of a variety of closely-related cyclic thiohydroxamic acids is examined. Primarily, derivatives of two molecules are considered: 1-hydroxy-2(1H)-pyridinethione (PT) and 3-hydroxy-4-methyl-2(3H)-thiazolethione (MTT). Although less extensively studied to date, MTT is likely to exhibit antimicrobial activity similar to that of PT. The database of crystallographic information for organic PT and MTT derivatives, and their divalent complexes with zinc, copper, nickel and cobalt is expanded significantly. In addition to single-crystal X-ray diffraction using laboratory sources, several other techniques are employed for elucidation of the crystal structures. These include diffraction utilising synchrotron sources, and Rietveld refinement using laboratory powder X-ray diffraction data. Molecular-modelling procedures, including lattice-energy calculation and minimisation, are also employed extensively. Prediction of crystal structure on the basis of molecular information only is a particularly attractive prospect. It is shown in this thesis that existing methodology is adequate for prediction of the crystal structures of PT, MTT and their divalent complexes with zinc, copper and nickel. An extension to existing methodology for the treatment of general divalent complexes is proposed. Prediction in conjunction with Rietveld refinement is shown to be a viable strategy for determination of the crystal structures of divalent complexes. This may be of particular value where single crystals suitable for X-ray analysis cannot be obtained. The physicochemical properties of a molecular material are known to depend on both molecular and crystal structure. Modification of solid-state structure in a controlled manner may, therefore, provide materials with enhanced physicochemical properties. Strategies employed for structure modification in this thesis include the formation of hydrates and mixed crystals. A novel hydrate of zinc pyrithione with enhanced aqueous solubility is reported, and a mixed crystal incorporating zinc complexes of PT and MTT is also described.
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Yoshizawa, Kazunari. "STUDIES ON ELECTRONIC AND MAGNETIC PROPERTIES IN SOLID STATE CHEMISTRY." Kyoto University, 1992. http://hdl.handle.net/2433/168752.
Full textAbstract:
本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第5090号
工博第1211号
新制||工||864(附属図書館)
UT51-92-J137
京都大学大学院工学研究科分子工学専攻
(主査)教授 山邊 時雄, 教授 清水 剛夫, 教授 藤本 博
学位規則第4条第1項該当
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Ortega, San Martín Luis. "“Solid state chemistry and its applications” by Anthony R. West." Revista de Química, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/101028.
Full textAbstract:
Repaso de algunos de los aspectos más destacados e interesantes de la segunda edición del libro de texto de química del estado sólido escrito por el conocido químico Anthony R. West titulado “Solid state chemistry and its applications”. John Wiley and Sons, Ltd., Chichester, 2014. 556 páginas. ISBN: 978-1-119-94294-8Short review of the most important and interesting sections of the textbook in solid state chemistry “Solid state chemistry and its applications” written by the well-known chemist Anthony R. West. John Wiley and Sons, Ltd., Chichester, 2014. 556 pages. ISBN: 978-1-119-94294-8
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Caporini, Marc Anthony. "Structural studies of amyloid fibrils using solid-state NMR." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46038.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.Vita.
Includes bibliographical references.
he development of solid-state NMR techniques and application to amyloid fibrils are presented. In addition, a new method of selective inversion based on chemical shift anisotropy is presented. An improved method for highly accurate distance measurement across parallel [beta]-sheets in amyloid fibrils has been developed. This method combines the a double quantum filtered version of the dipolar recoupling sequence DRAWS with the simulation and data fitting program SPINEVOLUTION to provide a simple and effective way to measure interstrand distances. This method was applied to TTR105.115 fibrils. Several other methods were applied to the TTR fibrils to measure interstrand and intersheet distances including REDOR, TEDOR, R2TRW, and DARR. The intermolecular distances were combined with the previously solved monomer structure to generate a high resolution (RMSD of 1.0 Å) of the TTR protofiliment. A disease associated mutant (L 11 M) of these fibrils was also studied by solid-state NMR to determine the monomer structure. Distance measurements on this system were done via 3D TEDOR and R2W, and torsion angle were also measured. A high resolution structure of the monomer is presented. Some non-fibril related research concerning the exploration of chemical shift anisotropy and cross polarization is presented in the later chapters. Both experimental evidence and a theoretical framework are presented to demonstrate the phenomenon of selective inversion based on the size of the chemical shift anisotropy. Further work concerning the use of cross polarization selectively was developed and is presented.
by Marc Anthony Caporini.
Ph.D.
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Haghighat, Siavash. "Melt and solid state behaviour of polyolefin blends." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/28165.
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Polymer–polymer blends are rapidly growing as an important resource for obtaining new and improved polymeric materials; and polyolefins are among the most widely used thermoplastics in the polymer industries due to their low cost, desirable physical properties and wide range of applications. For this reason several polyolefin polymers were melt blended and different experimental techniques were used to investigate their characteristics and their properties. The blends under investigation are reported in four chapters, following a literature survey and a description of experimental techniques.
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Ruff, Philip William. "Structural aspects of certain inorganic solid-state materials." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/33879.
Full textAbstract:
An introduction to the theory of phase transitions is presented which includes both thermodynamic and structural treatments of phase transitions. A literature review of the role of vibrational spectroscopy in the investigation of phase transitions is given for the period covering 1978 to 1987. Full experimental procedures are outlined covering the design and use of the diamond anvil cell (d.a.c.) utilised in the experimental investigations undertaken in this work. The single crystal structure of Re(C0)5I has been determined by x-ray diffraction techniques, together with a structural comparison with the other members of the Re(C0)5X series (where X = Cl, Br). Following on from the above, a vibrational investigation of the M(C0)5X series (where M = Mn, Re; X = Cl, Br, I) is presented. An accompanying high-pressure Raman investigation of Re(CO)5I is also shown. The group I metal halate series MXO3 (where M = K, Na; X = Cl, Br) have been investigated by infrared and Raman spectroscopy. High-pressure data are available for some of the series. In continuation of earlier work a phase structural investigation, at high-pressure, of KCIO3 was performed using synchrotron radiation at the SRS, Daresbury.
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Simpson, W. Mark. "Solid state NMR studies of molecular crystalline materials." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362006.
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Ball, Thomas James. "Development of new methods in solid-state NMR." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/385/.
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Many chemically important nuclei are quadrupolar with half-integer spin (i.e., spin I = 1.5, 2.5, etc.) The presence of quadrupolar broadening for such nuclei can limit the information that may be extracted using NMR. MAS is able to remove first-order quadrupolar broadening but can only reduce the second-order contribution to the linewidth. The MQMAS and STMAS techniques have enabled high-resolution NMR spectra of half-integer quadrupolar nuclei in the solid state to be obtained by two-dimensional correlation under MAS conditions. Both of these experiments have several well-known limitations. One is that the conversion pulses in particular are very inefficient and the other is that the longer acquisition times required for two-dimensional experiments can be a limiting factor. Both of these disadvantages are addressed in this thesis. For the former case, existing composite pulse schemes designed to improve the efficiency of the conversion of multiple-quantum coherences are compared using 27Al and 87Rb MQMAS NMR of a series of crystalline and amorphous materials. In the latter case, a new experiment, named STARTMAS, is introduced that enables isotropic spectra of spin I = 1.5 spectra to be acquired in real time. The theoretical basis of the technique is explained and its applicability demonstrated using 23Na and 87Rb NMR of a wide range of solids. The nuclear Overhauser effect (NOE) is one of the most widely exploited phenomena in NMR and is now widely used for molecular structure determination in solution. NOEs in the solid state are rare and those to quadrupolar nuclei rarer still, this being due to the general absence of motion on the correct timescale and the usual efficiency of quadrupolar T1 relaxation, respectively. In this thesis, 11B{1H} transient NOE results are presented for a range of solid borane adducts. A comparison is made of the 11B NMR enhancements observed under MAS and static conditions and a rationale is proposed for the behaviour in the latter case.
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Maydwell, Alan P. "The solid state properties of metal cluster compounds." Thesis, University of Kent, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357094.
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Samaniego, Reyna Jose Cuauhtemoc. "Ab initio quantum mechanical approaches in solid state." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289791.
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Martin, David Richard. "Solid state deuterium NMR studies of some disaccharides." Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282274.
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Liu, Zhe. "Novel solid state materials for chemical hydrogen storage." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8324/.
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This work investigates the hydrogen storage potential of a variety of solid state materials. The work has showed their synthesis, structure, morphology and hydrogen storage properties comprehensively. An MgH2 nanocomposite composed of 80% tetragonal α-MgH2 and 18% orthorhombic γ-MgH2 has been prepared for the first time without recourse to high pressure or temperature. By optimizing the ball milling conditions, addition of LiCl and use of THF solvent, the α-/γ-MgH2 nanocomposite so-produced is capable of releasing 6.6 wt% H2 with rapid kinetics, from ca. 260 °C without the use of a catalyst. Moreover, Ti-catalyzed MgH2 offering a capacity of 5.5 wt. % of H2 and superior hydrogen desorption kinetics has been successfully prepared by a novel wet chemical route. The MgH2 material, containing approximately 2~3 wt. % of Ti-additive exhibits hydrogen desorption at a temperature approximately 220 °C lower than pristine MgH2 where pure hydrogen evolution starts at ca. 420 °C via a synergetic effect of mechanochemical treatment and additives. Neutron scattering was employed to study the structure of activated MgD2 and for the first time local disorder in activated MgD2 has been verified using total neutron scattering (PDF fitting). Small angle neutron scattering (SANS) analysis indicates a surface fractal geometry, i.e high degree of surface roughness for activated MgD2 particles, in accordance with SEM analysis suggesting the morphological alteration introduced by mechanochemical treatment. A novel PANI-LiBH4 composite has been successfully fabricated through simple mixing. It is found that PANI-LiBH4 composites dehydrogenates from ca. 200 °C with over 10 wt.% H2 released by 400 °C, significantly outperforming pristine LiBH4. Importantly, rehydrogenation can be achieved under conditions unprecedented for LiBH4 in isolation (200 °C; 100 bar H2 or 330 °C, 20 bar H2 vs. 600 °C, 350 bar H2). Moreover, the PANI-LiBH4 composite can be readily cycled and a new endothermic uptake event at 140 °C, a remarkably low temperature for LiBH4-based systems, suggests that the polymer thermodynamically alters the hydrogenation mechanism. PANI-NaBH4 and PANI-LiH also exhibit vastly improved dehydrogenation properties compared with the respective hydride materials alone. The structures of some first row transition metal halide hydrazinates, TMX2·2N2H4 (TM= Mn, Fe, Co, Ni, Cu and Zn; X= Cl and Br), have been revisited and detailed structural information of three typical complexes, MnCl2·2N2H4, ZnCl2·2N2H4 and MnBr2·2N2H4 have been accurately determined by using a combination techniques of PXD, FTIR and PND. It is also found that TMX2·2N2H4 decomposes at relatively high temperature ( > 250 °C) with massive weight loss due to the dissociation and decomposition of the N2H4 ligand. However the major gas evolution has been determined to be N2 and NH3 with only a minor amount of H2 (and undesired impurity N2H2) released, which makes TMX2·2N2H4 unsuitable for hydrogen storage. Our strategy to combine TMCl2·2N2H4 with LiBH4 to fabricate novel transition metal borohydride hydrazinates has been proven to be successful. Two novel complexes, Mn(BH4)2·2N2H4 and Zn(BH4)2·2N2H4 have been successfully prepared via a facile mechanochemical route with careful manipulation over the milling parameters. The crystal structure of Mn(BH4)2·2N2H4 has been determined using SR-PXD to be isostructural with its parent material MnCl2·2N2H4. The phase evolution behaviour of Zn(BH4)2·2N2H4 has been probed with evidence of various intermediate phases during preparation when various milling conditions were employed. The dehydrogenation properties of both complexes have been studied using DTA-TGA coupled with MS. Mn(BH4)2·2N2H4 and Zn(BH4)2·2N2H4 are very promising materials for off-board hydrogen storage due to their high hydrogen content and useful dehydrogenation properties.
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Haies, Ibraheem. "New methods for nitrogen-14 solid state NMR." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/382902/.
Full textAbstract:
Nitrogen is one of the most abundant elements. It plays a significant role in different scientific disciplines, like materials science, chemistry, biochemistry and pharmaceutical chemistry. Most NMR studies of nitrogen have been performed on samples enriched with 15N. To avoid enrichment and overcome the problem of using NMR where isotopic enrichment is not feasible, NMR of 14N that has 99.6% natural abundance is a viable alternative. However, the 14N spin quantum number 1 and high quadrupolar interactions lead to a few challenges for NMR investigation. Recently, two approaches appeared which overcome the complications associated to the first order quadrupolar line broadening, namely indirect detection using vicinal nuclei and overtone transition. Paper 1 describes a novel version of HMQC experiments, which requires the application of a moderate RF field to the 14N nucleus to correlate the 14N with a 13C ‘spy’ nucleus, which provides good sensitivity on natural abundance and labelled materials. In addition, overtone 14N NMR spectroscopy is a promising route for the direct detection of 14N signals with good spectral resolution. Overtone NMR is the main topic of my research. To overcome the poor efficiency of the overtone transition, polarization transfer techniques have been implemented. Papers 2 and 4 present respectively polarization transfer methods from 1H to the 14N overtone using symmetry-based R-sequences and cross polarization methods. Signal enhancements of 6.7 and 2 have been obtained when cross polarization methods and symmetry-based R-sequences are used respectively. Paper 3 shows results obtained with the DOR (double rotation) technique to reduce 14N overtone linewidth, with 14N overtone spectra with linewidth reduced by nearly one order of magnitude. Analysis of the results has been facilitated through the use of a new simulation strategy for 14N overtone NMR spectroscopy of spinning samples, using Spinach library.
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Furman, Joshua D. "Novel phosphors for solid state lighting." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/228686.
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Solid state white light emitting diode lighting devices outperform conventional light sources in terms of lifetime, durability, and lumens per watt. However, the capital contribution is still to high to encourage widespread adoption. Furthermore, the colour from today's devices is unsuitable for general room illumination and thus new phosphor materials are needed. This dissertation will examine the synthesis of inorganic nanoparticles and the possibility of using hybrid inorganic-organic frameworks in the search for new lighting phosphors. Nanoparticles of the oxide compound yttrium aluminium garnet were synthesized using an emulsion technique, though it was found that the high temperature processing needed for good optical properties was not compatible with maintaining nanosized particles. In terms of hybrid framework phosphors, several aspects of this new area have been explored. The mechanical and optical properties of a dense cerium oxalate formate hybrid framework compound have been investigated. Its strength was found to be nearly as great as some classical ceramic compounds, and clearly robust enough for device applications. While the photoluminescence of the cerium oxalate formate was not suitable for solid state lighting, the impressive mechanical properties evaluated are expected to be valid for a wide range of dense inorganic-organic frameworks. A novel approach to solid state lighting phosphors was introduced by using ligand-based photoluminescence in hybrid frameworks. Novel frameworks were prepared using 9,10-anthraquinone-2,3-dicarboxylic acid in combination with calcium, manganese, nickel, and zinc. These compounds show excellent photoluminescent emission for use in solid state lighting applications, although the luminescence is quenched at room temperature due to dynamic effects. The excitation, while reaching the blue part of the spectrum, falls just short of what is needed for use today's devices. To address these issues, a second class of novel framework compounds was prepared using 9-fluorenone-2,7-dicarboxylic acid in combination with calcium, strontium, barium, cadmium, and manganese. They are more rigid structures and show good luminescence at room temperature with a photoluminescent excitation spectrum extending further into the blue than the anthraquinones. Additionally, quantum yield in the calcium fluorenone is nearly double that of its parent ligand, suggesting that there is an enhancement in luminescent properties as a result its inclusion in a framework structure. An explanation for the differences in efficiency between seemingly similar compounds are drawn from their compositions, crystal structures, photoluminescence, and specific heat properties. Finally, some structural and chemical targets for future hybrid phosphor development are identified based on the relationships identified in this work.
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Alasaad, Khatoon Hamza. "Kanamycin: Solid-State Characterization and Hydrate Formation." University of Toledo Health Science Campus / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=mco1576193333612323.
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Xing, Dongxia. "Stereoselective Solid-State NaBH₄ Reduction of 1-Methylpentacyclo[5.4.0.0²,⁶.0³,¹⁰,0⁵,⁹]undecane-8, 11-Dione, Synthesis and Chemistry of Strained Alkenes, and Chemical and Microbial Synthesis of Racemic and Optically Active (S)-4-Hydroxy-2-Cyclohexenone." Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc278368/.
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Part I. Reduction of the 1-methylpentacyclo [5.4.0.0²,⁶.0³,¹⁰,0⁵,⁹]undecane-8, 11-dione (9) with solid NaBH₄ resulted in highly stereoselective reduction of both C=O groups in the substrate, thereby affording the corresponding endo-8, endo-11-diol (11a). The configuration of 11a was established unequivocally by converting 11a into the corresponding cyclic thiocarbonate ester, 12. Part II. Z-1,2-Di(1'-adamantyl)ethene (14) was synthesized with a high degree of stereoselectively in four steps (Scheme 9 in Chapter 2). E-1,2-di(1'-adamantyl)ethene (15) was synthesized by iodine promoted isomerization of 14. Both structures were established unequivocally via single-crystal X-ray structural analysis. E-1-(exo-8'-Pentacyclo[5.4.0.0²,⁶.0³,¹⁰,0⁵,⁹]undecyl)-2-phenylethylene (16a) was synthesized, and its structure was established via analysis of its 1H, 13C, and 2D COSY NMR spectra. Part III. Reactions of electrophiles, i.e.,:CCl_2, PhSCl, and Br_2, to Z- and E-1,2-di(1'-adamantyl)ethenes (14 and 15, respectively) are described (Scheme 5, 8, 10, and 13 in Chapter 3). Structures of the corresponding products were established unequivocally via analysis of their respective one- and two-dimensional NMR spectra and/or single-crystal X-ray structural analysis. Part IV. An improved asymmetric synthesis of optically active (S)-4-hydroxy-2-cyclohexenone 1 (64%ee, determined via Mosher's method) has been developed (Scheme 5 in Chapter 4). The key step in this synthesis involves the baker's yeast reduction of 13. The absolute configuration of the major product, (S)-1, was established unequivocally via single-crystal X-ray structural analysis of a precursor. The optical purity of the major product 14a (80%de, 67%ee) was established via careful integration of relevant gated-decoupled 13C NMR spectra.
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Pawsey, Shane. "A solid-state NMR study of self-assembled monolayers /." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83090.
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Hydrocarbon and perfluorinated fatty acids deposited on high surface area ZrO2 and TiO2 substrates have been studied by solid-state nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy for characterization as potential surface modification agents and for fundamental studies of monolayer conformation and dynamics. Alkanoic acids of sufficient chain length (CH3(CH3)nCO2H, n > 15) were found to form conformationally ordered monolayers on ZrO2 powder via a chelating bidentate zirconium carboxylate surface bond. Variable temperature and 2D solid-state NMR experiments demonstrate that alkanoate monolayers display chain dynamics similar to other self-assembled monolayers (SAMs). o-Hydroxy-alkanoic acids (HO(CH3)15CO 2H) produce hydrophilic monolayers, with no evidence of the hydroxyl group looping to the metal oxide substrate.Unlike the hydrocarbon analogues, perfluoroalkanoic acids chemisorbed on both ZrO2 and TiO2 powders via a carboxylate bond forming stable and thermally robust SAMs. Spin-lattice relaxation measurements showed that the adsorbed SAMs are more mobile than in the bulk state. The motions associated with this enhanced mobility are proposed to involve reorientations about the chain axis. No evidence was found for chain melting in the fluorocarbon SAMs at temperatures well above the melting point of the bulk acids.
Since both long chain carboxylic and phosphonic acids form SAMs, a series of diacids, (HO2C(CH2)nPO3H 2, n = 2, 3, 11, and 15), were deposited on TiO2 and ZrO 2 powders and ZrO2 nanopowder to examine the structures formed by bifunctional surfactants where both groups strongly interact with the substrate. Solid-state 31P NMR data in combination with IR showed that the phosphonic acid group binds selectively to the surface, producing a monolayer of carboxylic acid terminated chains. The average chain conformation depends on the substrate and chain length. Ordered samples display thermal order/disorder transitions similar to other hydrocarbon SAM systems demonstrating that phosphonic acids are useful for selectively introducing pendant polar functional groups on metal oxide surfaces. The chain mobility relative to analogous methyl terminated chains is more restricted and is attributed to hydrogen bonding among the pendant carboxylic acid groups. 1H fast MAS NMR experiments revealed the nature of the surface hydrogen bonding in these systems. Whereas dipolar coupled P-OH protons were observed on TiO2, only isolated residual P-OH groups were detected on ZrO2, reflective of the stronger interaction of phosphonic acids with the latter substrate. Two dimensional 1H double-quantum fast MAS experiments revealed that only hydrogen bonded homodimers occur in the bulk diacids while hydrogen bonding between the carboxylic and phosphonic acid groups exists in multilayers of the diacids on the ZrO2 nanopowder.
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Wright, Elaine Ann. "Solid state crystallisation of oligosaccharide ester derivatives." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249016.
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Lee, Myungwoon. "Structure and dynamics of membrane proteins from solid-state NMR." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120908.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references.
Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is an essential tool to elucidate the structure, dynamics, and function of biomolecules. This thesis mainly focuses on the structure determination of the hydrophobic domains for fusion proteins which are involved in membrane fusion between the cell membrane and viral envelope. Although extensive structural studies have been conducted on the soluble ectodomain by crystallography, the structural topologies of the hydrophobic TMD of the fusion proteins have been poorly understood. Here, we introduced SSNMR to investigate the secondary structure and oligomeric states of the TMD of two fusion proteins, PIV5 F and HIV gp41. For the PIV5 TMD, the membrane dependent secondary structure was determined by measuring the chemical shifts: predominant a-helical conformation in the POPC/cholesterol membrane shifts to the [Beta]-strand in the POPE membrane. Using 19F spin diffusion experiments on the fluorinated TMD, we have determined that the TMD forms a trimeric helical bundle. For the HIV gp4l MPER-TMD, we found the presence of a turn between the MPER helix and the TMD helix by measuring intramolecular distances and probing the lipid-peptide and water-peptide interactions. Intermolecular 19F- 19F distances of the fluorinated peptides indicate that the MPER-TMD is a trimeric. In addition to membrane fusion proteins, we have studied the oligomeric structure and the zinc-bound coordination geometry of a de novo designed amyloid fibril that catalyzes ester hydrolysis. By measuring the intermolecular contacts, we determined that peptides form parallel-in- register P-sheets and further assemble into stacked bilayers in an antiparallel orientation. The zinc binding sites were confirmed by the chemical shifts perturbation of histidines with zinc and the specific zinc-bound geometry was identified by measuring intra-residue distances of histidines. We also investigated the effects of cryoprotectants on the spectral resolution of lipid membranes and membrane peptides at low temperature. 13C and 1H MAS spectra of various cryoprotected membranes showed that DMSO provides the best resolution enhancement with the best ice formation retardation at low temperature and DLPE lipid exhibits the excellent resolution.
by Myungwoon Lee.
Ph. D.
48
Rienstra, Chad M. "Solid state nuclear magnetic resonance methodology for biomolecular structure determination." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9524.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999.Includes bibliographical references.
Several developments in solid state nuclear magnetic resonance (SSNMR) spectroscopy methods are presented. All studies are performed with magic angle spinning (MAS) and high-power proton decoupling, for optimal sensitivity and resolution. Chemical shift are assigned by multi-dimensional correlation spectroscopy in isotopically enriched molecules ...
by Chad Michael Rienstra.
Ph.D.
49
Landman, Andreas Adriaan. "Aspects of solid-state chemistry of fly ash and ultramarine pigments." Thesis, Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-06042004-062900.
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Mollison, Neil Bruce. "Structural characterisation of amorphous materials by solid state NMR." Thesis, University of Kent, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269106.
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