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Grey, Clare P. "A '1'1'9Sn an '8'9Y MAS NMR or rare-earth pyrochlores." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276535.
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Christopher, Elizabeth Anne. "Solid-state NMR study of polymorphism in pharmaceuticals." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5752/.
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This thesis is concerned with attempts to establish solid-state NMR as a complementary technique to X-ray crystallography for providing information on crystal structure, i.e. information regarding conformation, packing and inter- or intra-molecular interactions. Methods of assigning the solid-state NMR spectrum have been used which rely upon (^1)H-(^13)C dipolar interactions and upon the shielding anisotropy experienced by the nuclei. Single pulse experiments have also been used to identify solvate molecules. Of particular importance, the anisotropy and asymmetry have been found for a number of steroids, and the values used to assign the high frequency region of the spectrum. This has enabled chemical shifts to be linked to the hydrogen bonds that are present. Thus, the mode of hydrogen bonding can be predicted in forms of cortisone acetate for which the crystal structure is not available. Chemical shifts have also been linked with the conformation of the D ring. In this way, important crystallographic information has been gleaned from the solid-state NMR spectrum. The effect of the formation of hydrogen bonds upon the shielding tensor components of carbonyl and ester carbons has been studied, and found to cause a high frequency shift in δ22, which is probably oriented along the C=0 bonds. This leads to a high frequency shift in the isotropic chemical shift. The effect of the spinning speed upon the centreband intensity of a peak as the anisotropy and asymmetry are varied has been investigated. It has been found that at low spiiming speeds, the centreband intensity does not vary in a simple fashion. Thus it is recommended that full shielding tensor analysis is performed. The effect of the spinning speed on the sample temperature has also been studied. Results show that at low spinning speeds (up to 2 kHz) there is sample cooling as the spinning speed increases (attributed to the Joule -Thompson effect). But at higher spinning speeds (above 2 kHz) then there is sample heating as the spinning speed increases. The importance of this result is discussed. The effect of quadrupolar nuclei (35C1 and (^14)N) upon the spectrum of a spin-(^1)(_2) nucleus ((^13)C) has been studied. In favourable cases, the anisotropy in the spin-spin coupling constant has been found, whilst in other cases, the sign and magnitude of the quadrupolar coupling constant have been obtained. The broadening of resonances of carbon atoms adjacent to quadrupolar nuclei has been valuable in assigning the solid-state NMR spectra. The broadening effect has also been observed at more distant sites. It has not been possible to distinguish the effects of (^37)C1 and (^35)C1 on the carbon spectra of chlorine containing steroids.
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Vlachou, Maria C. "17O solid state NMR study of ceria systems." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/108288/.
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Ceria is a highly commercial, valuable material. Its diverse set of real-world applications demonstrates its far-reaching influence on modern society. Indeed, one only has to consider its extensive employment as an essential component of automotive, three-way catalysis (TWC) for reducing pollutants in vehicular exhaust gases; a technology that is used on a daily basis by millions of people, to appreciate its importance. Its popularity is partially due to its extraordinary oxygen storage capacity, i.e. its ability to release and store oxygen through redox reactions mediated by the two oxidation states of cerium (Ce3+/Ce4+). This unique ability can be heavily influenced by ceria’s particle size and shape, dopant concentration and surface chemistry, and is still a very active area of research today. Whilst there have been over 26,000 scientific publications on ceria since the 1950s, and although the bulk-ceria oxygen chemical shift (877 ppm) was first observed with 17O solid-state NMR in 1989, it is only within the past decade that solid-state NMR has been employed as a probe for ceria’s structure-function relationships. This study presents an extensive 17O solid-state NMR investigation into various ceria systems, in conjunction with complementary Raman spectroscopy (for which the literature is abundant). An alternative spectral assignment for the 17O NMR spectrum of nanoceria based on experimental deductions and DFT quantum mechanical calculations is proposed. The current working assignment for nanoceria is based on the work of Wang et al., where DFT calculations of a core-shell model are used to deconvolute the NMR data. In contrast to this model, it is suggested that the most upfield peak at δCG = 822 ppm (that is actually part of a multicomponent region centred at ~830 ppm), corresponds to oxygen species displaced from their standard sublattice positions, to occupy a Frenkel type defect site. The resonance regions observed at ~830 and 920 ppm are proposed to be bulk oxygen environments feeling the effects of the Frenkel defect and concomitant oxygen vacancy. For reduced ceria systems, a broad component is detected that spans > 1000 ppm, and is assigned to oxygen directly bonded to Ce3+, in agreement with the current working model. Finally, it is observed that the most deshielded peak at ~1030 ppm is multi-component and (one of these components) possesses an extensive spinning sideband manifold in comparison to the other 17O resonances. Variable temperature investigations show a small inverse temperature dependence of the peak positions, suggesting weak pseudocontact paramagnetic shifts are influencing the spectrum. In light of this, the peak at ~1030 ppm is assigned to oxygen in closer proximity to (but not directly bonded) to Ce3+, as is reported by current 27Al solid-state NMR studies of Ce3+ doped systems and as is reflected by the extensive sideband manifold. The novel 17O preparation treatments implemented in this work were engineered to probe oxygen environments near defects. Ceria’s defects are manipulated by exposure to certain temperature/atmospheric conditions, and when these replicate those of possible catalyst operating temperatures with 17O enriched gas, 17O is able to probe the distribution of oxygen in distinct sites that are important to the OSC process. A prereduction of ceria was therefore implemented, following 17O2 reoxidation to target these sites. This process was also able to identify a surface reorganization mechanism in which a low reoxidation temperature/ pressure of 17O2 is insufficient to reverse the onset of bulk oxygen diffusion induced by the reduction, an effect which is seen to be enhanced with the loading of Pd. Furthermore, the storage of these treated systems dictates the evolution of the 17O species, with an almost closed-system (to air) detecting the pathway of reoxidised oxygen species to more stable sites over time. Ceria zirconia systems are also investigated in this work. The 17O solid-state NMR spectra show an even greater sensitivity to the 17O2 enrichment conditions. The pre-reduction of the systems induces a greater oxygen removal compared to pure ceria, and thus an increase in Ce3+ paramagnetic centres, i.e. the broad component (> 1000 ppm) characterising the oxygen-Ce3+ bond reveals a greater relative intensity. The complication of increasing Ce3+ paramagnetic centres near the 17O adsorption sites is evidenced by the significant loss in 17O spectral resolution. These effects are exacerbated when ceria zirconia is supported with Pd, known to (stably) reduce the state of the system even further. A straight exchange of the 17O isotope in ceria zirconia helps to inhibit these effects, allowing observation of (1) the chemical shift of the bulk-ceria oxygen move to a more shielded position compared to the pure ceria material at 877 ppm (caused by the inherent contraction of the ceria zirconia lattice), and (2) a broad resonance at ~730 ppm, attributed to oxygen species bridging cerium and zirconium.
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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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Huster, Daniel. "Solid-state NMR spectroscopy to study protein-lipid interactions." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-190961.
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The appropriate lipid environment is crucial for the proper function of membrane proteins. There is a tremendous variety of lipid molecules in the membrane and so far it is often unclear which component of the lipid matrix is essential for the function of a respective protein. Lipid molecules and proteins mutually influence each other; parameters such as acyl chain order, membrane thickness, membrane elasticity, permeability, lipid-domain and annulus formation are strongly modulated by proteins. More recent data also indicates that the influence of proteins goes beyond a single annulus of next-neighbor boundary lipids. Therefore, a mesoscopic approach to membrane lipid-protein interactions in terms of elastic membrane deformations has been developed. Solid-state NMR has greatly
contributed to the understanding of lipid-protein interactions and the modern view of biological membranes. Methods that detect the influence of proteins on the membrane as well as direct lipid-protein interactions have been developed and are reviewed here. Examples for solid-state NMR studies on the interaction of Ras proteins, the antimicrobial peptide protegrin-1, the G protein-coupled receptor rhodopsin, and the K+ channel KcsA are discussed.
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Huster, Daniel. "Solid-state NMR spectroscopy to study protein-lipid interactions." Universität Leipzig, 2014. https://ul.qucosa.de/id/qucosa%3A14047.
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The appropriate lipid environment is crucial for the proper function of membrane proteins. There is a tremendous variety of lipid molecules in the membrane and so far it is often unclear which component of the lipid matrix is essential for the function of a respective protein. Lipid molecules and proteins mutually influence each other; parameters such as acyl chain order, membrane thickness, membrane elasticity, permeability, lipid-domain and annulus formation are strongly modulated by proteins. More recent data also indicates that the influence of proteins goes beyond a single annulus of next-neighbor boundary lipids. Therefore, a mesoscopic approach to membrane lipid-protein interactions in terms of elastic membrane deformations has been developed. Solid-state NMR has greatly
contributed to the understanding of lipid-protein interactions and the modern view of biological membranes. Methods that detect the influence of proteins on the membrane as well as direct lipid-protein interactions have been developed and are reviewed here. Examples for solid-state NMR studies on the interaction of Ras proteins, the antimicrobial peptide protegrin-1, the G protein-coupled receptor rhodopsin, and the K+ channel KcsA are discussed.
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Bornes, Carlos Manuel Pereira. "Study of zeolites acidic properties using solid-state NMR." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22764.
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Mestrado em QuímicaOs zeólitos têm propriedades únicas, como a porosidade, acidez e estabilidade térmica, desejadas quer na investigação académica, quer nas aplicações industriais. Neste trabalho foram preparadas amostras do zeólito ZSM-5 (Zeolite Socony Mobil–5) com propriedades de acidez distintas, nomeadamente o tipo e a força dos centros ácidos, investigadas recorrendo a experiências multinucleares 1D e 2D de RMN do estado sólido. As moléculas sonda de fósforo apresentam um grande potencial para caracterizar detalhadamente as propriedades de acidez destes materiais, por RMN do estado sólido. Esta tese apresenta novos resultados, mostrando que a interação entre a molécula sonda (TMPO) e os centros ácidos de Brønsted e Lewis não resulta em duas regiões distintas do espectro de RMN de 31P, contrariamente ao que está descrito na literatura. Experiências 2D 1H-31P CP-HETCOR foram utilizadas pela primeira vez em zeólitos com TMPO adsorvida para obter mais informação acerca da interação desta molécula sonda com os centros ácidos. Combinando as experiências 1D e 2D de um conjunto de zeólitos com propriedades distintas, foi possível obter resultados e refutar ou resolver atribuições controversas encontradas na literatura. Neste trabalho foram também utilizados cálculos computacionais DFT, usando o método de cluster, para investigar a interação entre a molécula sonda e os centros ácidos de Brønsted.
Zeolites have unique properties, such as porosity, acidity and thermal stability, desired for a wide range of both academic research and industrial applications. In this work, several ZSM-5 zeolite samples (Zeolite Socony Mobil–5) with distinct acidic properties, namely acid type and strength, were prepared and investigated through multinuclear 1D and 2D NMR experiments. Phosphorous containing probes show great potential to achieve a comprehensive characterization of zeolite’s acidic features, via solid-state NMR. New results presented in this thesis reveal that the interaction of TMPO with Brønsted and Lewis acid sites, does not result in two distinct regions in the 31P NMR spectra, in contrast with literature reports. 2D 1H-31P CP-HETCOR experiments were used for the first time in TMPO-loaded zeolites to gain more information on the interaction of TMPO molecules with the zeolite centers. Combining 1D and 2D experiments obtained for a group of ZSM-5 zeolites with tuned acidic properties, provided results that refute or solve certain controversial literature assignments. Cluster-based DFT computational methods were also used to investigate the interaction between TMPO and Brønsted acid sites.
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Dyball, Helen Catherine Jane. "A study of 3He films using SQUID NMR." Thesis, Royal Holloway, University of London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252057.
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Lewis, Wendy Lee. "Study of the Chain Dynamics of Polyaniline by Solid-State." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1227535369.
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Lu, Kwong M. "A study of winding interactions in the NMR imagers." Thesis, University of Aberdeen, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303405.
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In an NMR imaging system, there are five principal sets of windings, namely the main magnet, the radio frequency coil and three sets of field gradient windings. In principle, these windings should all be mutually orthogonal, that is, their mutual inductance should be zero. However, when these windings are assembled together in a limited space inside an NMR imager, they are found to be interacting with each other, which can significantly degrade the imager performance. The experimental investigations on the existing winding sets indicate that there are significant interactions between the rf receiver coil and three distributed gradient windings. In particular, the longitudinal gradient winding, acting along the rf field direction, can interact more severely with the rf coil than the other two gradient windings. Such interactions can seriously damp the desired resonance of the rf receiver coil, and displace its desired resonant frequency, leading to a lower signal-to-noise ratio in the image. To understand the interactions between the rf coil and this particular gradient winding, theoretical models have been developed and experimentally verified. The analysis based on these model calculations shows that there is a mutual coupling between the rf coil and the individual parts of the gradient winding. This can introduce a significant loss into the rf coil and change its resonant frequency. The model study has also been extended to the analysis of the multiple resonance properties of distributed gradient windings. The effects of these resonances on the rf coil are also discussed. The possibility of isolating the rf coil from the gradient windings by means of an rf shield has been considered. The experimental results indicate that, for a 3:2 shield radius to coil radius ratio, the losses of the rf coil due to such a shield are much smaller than those due to the winding interactions. The investigations also indicate a noticeable improvement of the rf field homogeneity when using such a shield.
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Padro, Daniel. "Solid state NMR study of quadrupolar nuclei at high magnetic fields." Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248866.
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Chung, Chun-Wa. "NMR techniques for the study of quadrupolar relaxation and spin topology." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281928.
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Fortier-McGill, Blythe. "A solid state NMR study of polymer complexes, multilayer films and capsules." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110461.
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The dynamics of polymeric capsules and multilayer films supported by colloidal silica in addition to their bulk complex analogues were quantified using solid state NMR. Aqueous suspensions of polyelectrolyte complexes, supported multilayers deposited on silica colloids, and capsules were characterized by 2H NMR spectroscopy as a function of layer number, temperature, and ionic strength. It was demonstrated that the chain mobility is faster in systems containing excess positive charge, including multilayers and capsules terminated with poly(diallyldimethyl ammonium chloride) (PDADMAC). Selective deuteration of different layers confirms that the alternation in chain mobility with the terminating layer is a through-film effect. Differential scanning calorimetry (DSC)-detected phase transitions were found to occur between 32 and 45 °C for the poly(styrene sulfonate) (PSS)/PDADMAC complexes, supported multilayers, and capsules that is attributed to the breaking of ionic linkages and a solvation process.The chain mobility of a series of hydrogen-bonded polymer complexes and multilayers were compared by variable temperature 2H NMR spectroscopy. Poly-(methacrylic acid), deuterated at the methyl group, PMAA-d3, was complexed with five different hydrogen bond acceptor polymers—poly(ethylene oxide) (PEO), poly(acrylamide) (PAAM), poly(vinyl methyl ether) (PVME), poly(vinylpyrrolidone) (PVPon), and poly(vinylcaprolactam) (PVCL)—as well as with chitosan, which also includes ion pairing. The overall chain mobility of PMAA in its water-saturated complexes was observed to increase in the following order: PVCL < PVPon < chitosan < PVME < PAAM < PEO. For these polymer pairs, the same trend in chain mobility was also confirmed for the first few layers deposited on colloidal silica. The observed chain dynamics correlate well with the reported variation of the critical pH, bilayer thickness, and the permeability for multilayer films of the same polymers. The contribution of different types of hydrogen bonded structures to the relative stabilities and dynamic properties of the same series of PMAA complexes was assessed by combining 13C CP-MAS NMR, 1H-13C HETCOR, 1D and 2D DQ 1H MAS NMR experiments. It was demonstrated that there is a selective disruption of the weaker open intra-PMAA dimers in the presence of PEO and PVME. This effect was correlated with the fact that these materials form the thickest bilayers and have the highest permeability as compared to the other systems studied. The effect of temperature and water on the populations and dynamics of the different types H-bonds within PMAA-polyether complexes and multilayers was characterized by 13C solid-state NMR. As the complexes are heated, the population of the non-complexed carbonyls with weaker disordered hydrogen bonds, diminishes relative to the carbonyls participating in the stronger intra-PMAA cyclic dimers. The 2D 13C exchange (EXSY) spectroscopy experiments showed that ultra-slow exchange, at a rate less than 0.5 s-1, occurs between the intra-PMAA cyclic dimers and either a labile open type dimer associated with water or an inter-polymer H-bond through a short lived free state. The addition of water increases the population of disordered hydrogen bonded carbonyls as well as the exchange rate. In general the NMR studies presented in this thesis demonstrate that the structural and dynamic properties of the hydrated polymer complexes can form the basis for designing multilayer films with the desired responses to external stimuli.Les dynamiques des capsules, des particules colloïdales de silice enrobées de films de multicouches de polymères et de leurs complexes analogues ont été quantifiées par résonance magnétique nucléaire (RMN) solide. Les suspensions aqueuses de complexes, les multicouches déposées sur les colloïdes de silice, et les capsules de polyélectrolytes ont été analysées par RMN 2H en fonction du nombre de couches, de la température et de la force ionique. Il a été démontré que le mouvement du squelette des polyélectrolytes est plus rapide lorsque les systèmes ont un excès de charge positive, ce qui survient lorsque le poly (chlorure de diallyldiméthylammonium) (PDADMAC) forme la couche terminale des multicouches et capsules. La deutération sélective des différentes couches confirme la dépendance du mouvement du squelette sur la couche terminale, qui influence l'ensemble du film. Des transitions de phases entre 32 et 45°C ont été détectées par calorimétrie (DSC) pour les complexes multicouches, et les capsules formées de la bi-couche poly (styrène sulfonate) (PSS)/PDADMAC, et sont liées au bris des liaisons ioniques de même qu'au processus de solvatation.Les mobilités des chaînes d'une série de complexes et de multicouches de polymères liés par des ponts hydrogènes ont été comparées par spectroscopie 2H RMN à température variable. Le poly-(acide méthacrylique), possédant un groupe méthyle deutéré (PMAA-d3), a été complexé avec cinq polymères différents : le poly (oxyde d'éthylène) (PEO), le poly (acrylamide) (PAAM), le poly (vinyl méthyl éther) (PVME), le poly (vinylpyrrolidone) (PVPon), le poly (vinylcaprolactam) (PVCL), ainsi qu'avec le chitosane, où il y a aussi les interactions ionique. La mobilité de la chaîne de PMAA dans les complexes saturés avec de l'eau a augmenté dans l'ordre suivant PVCL < PVPon < chitosan < PVME < PAAM < PEO. Pour ces paires de polymères, la même tendance dans la mobilité de la chaîne a également été confirmée pour les premières couches déposées sur la silice colloïdale. Les résultats des dynamiques des chaînes corrèlent bien avec les variations de pH critique, l'épaisseur de la bi-couche et la perméabilité, rapportées pour les films de multicouches composés des mêmes polymères. Le rôle des différentes structures de liaisons hydrogène dans les stabilités et les propriétés dynamiques de la même série de complexes PMAA a été évalué en combinant les expériences 13C CP-MAS RMN, 1H-13C HETCOR, 1D et 2D DQ 1H MAS RMN. Il a été démontré qu'il y a la perturbation sélective des dimères intra-PMAA ouverts en présence de PEO et PVME. Cet effet a été corrélé avec le fait que ces matériaux ont la plus haute perméabilité et les bicouches les plus épaisses, en comparaison avec les autres systèmes étudiés. L'effet de la température et de l'eau sur les populations et la dynamique des liaisons hydrogène des complexes et multicouches de PMAA-polyéther, a été caractérisé par 13C RMN. Lorsque les complexes sont chauffés, la population des carbonyles non complexés, avec les liaisons hydrogène désordonnées les plus faibles, diminue par rapport à celle des carbonyles participant à la formation de dimères cycliques intra-PMAA forts. Les expériences de spectroscopie EXSY 2D 13C ont démontré un échange ultra lent, en deçà de 0.5s-1, entre les dimères cycliques intra-PMAA associés avec, soit un dimère instable de type ouvert associé avec de l'eau, soit un inter-polymère lié par des ponts hydrogènes ayant des états libres de courtes durées. L'addition d'eau augmente la population de carbonyles ayant des liaisons hydrogène désordonnées, ainsi que la vitesse d'échange. En général, les études RMN présentées dans cette thèse démontrent que les propriétés structurales et dynamiques des complexes de polymères hydratés sont à la base de la conception de films de multicouches générant les réponses souhaitées face à des stimuli externes.
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Volgmann, K., V. Epp, P. Bottke, C. V. Chandran, S. Nakhal, M. Lerch, M. Wilkening, and P. Heitjans. "Multinuclear Solid-State NMR Study of Local Structure and Dynamics in Li0.7Nb3S4." Diffusion fundamentals 21 (2014) 24, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32434.
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Milette, Jonathan. "Study of nanoparticle - liquid crystal dispersions using optical microscopy and solid-state NMR." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106294.
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This Thesis presents the synthesis of a new family of liquid crystal (LC)-capped gold nanoparticles (AuNPs) for a rationalized miscibility and assembly in liquid crystal matrices.A new protocol based on the thiol-for-dimethylaminopyridine (DMAP) ligand exchange reaction was developed to prepare 4-5 nm AuNPs with mono and binary capping layers made of alkanethiol (CH3(CH2)mSH; m = 5, 11) and liquid crystal ligand 4'-(n-mercaptoalkoxy)biphenyl-4-carbonitriles (CBO(CH2)nSH; n = 8, 12, 16). AuNPs with a 1 : 1 CH3(CH2)5SH/CBO(CH2)12SH ratio were found to have an unprecedented miscibility in isotropic 4-n-pentyl-4'-cyanobiphenyl (5CB) and 4-n-octyl-4'-cyanobiphenyl (8CB) liquid crystals exceeding 25 wt% Au. While low NP concentrations are normally used to avoid aggregation, concentrated dispersions of these AuNPs form new structures at the LC phase transitions through coupling of the interparticle attractive forces with the LC elastic interactions. Upon cooling to TN-I, the AuNPs form a reversible, micron-scale network by concentrating at the nematic-isotropic liquid interfaces. The network topology and LC director field orientation are controlled by the cooling rate, surface alignment, film thickness, AuNP concentration and ligand shell composition. Completely different structures are formed at the nematic to smectic phase transition. AuNPs dispersed in homotropically aligned LC films reversibly form macroscopic domains of curved or linear arrays with micron scale periodicities. Based on the variation of the arrays with boundary conditions, AuNPs are proposed to concentrate at the edge dislocation defects in the smectic phase. The molecular interactions that determine the miscibility and assembly of the AuNPs in LCs were studied using multinuclear solid-state NMR and isotopically labeled AuNPs and LCs. The interaction of the host LC with the AuNP surfaces is striking manifested by partial alignment of the ligands. The detection of an isotropic-nematic biphasic region of the host LC matrix below TN-I is an important finding that will be used to refine theoretical models of the network formation. Finally another type of nanoparticle network, formed by aerosil in a Schiff-base-type of LC with a small dipole moment was studied by wideline 2H NMR to investigate the effect of different surface anchoring strengths on the memory effects displayed by these dispersions.Cette Thèse présente la synthèse d'une nouvelle famille de nanoparticules (NPs) d'or enrobées de cristaux liquides (CLs) afin de rationaliser leur miscibilité et assemblage dans des matrices faites de cristaux liquides. Un nouveau protocole basé sur la réaction d'échange de ligand thiol-pour-diméthylaminopyridine (DMAP) a été développé afin de préparer des NPs d'or de 4 à 5 nm de diamètre avec une monocouche simple et binaire faite d'alcanethiol (CH3(CH2)mSH; m = 5, 11) et du ligand CL 4'-(n-mercaptoalkoxy)biphényle-4-carbonitriles (CBO(CH2)nSH; n = 8, 12, 16). Nous avons découvert que les NPs d'or avec un ratio de 1:1 des ligands CH3(CH2)5SH/CBO(CH2)12SH possèdent une miscibilité sans précédent jusqu'à 25% en poids d'or dans la phase isotrope des CLs 4-n-pentyl-4'-cyanobiphényle (5CB) and 4-n-octyl-4'-cyanobiphényle (8CB). Bien qu'une faible concentration en NPs soit normallement utilisée afin d'éviter la formation d'agrégats, les dispersions concentrées de ces NPs d'or forment de nouvelles structures à la tansition de phase du CL par l'entremise du couplage des forces d'attraction interparticulaires avec les intéractions élastiques du CL. En refroidissant à TN-I, les NPs d'or forment de manière réversible un réseau à l'échelle microscopique en se concentrant à l'interphase nématique-isotrope. La topologie et l'orientation du domaine des directeurs CL sont controllées par la vitesse de refroidissement, l'alignement de surface, l'épaisseur du film, et la concentration et composition de la monocouche des NPs d'or. Des structures tout à fait différentes sont formées à la transition de phase nématique à smectique. Les NPs d'or dispersées dans des films de CLs alignés homotropiquement forment de manière réversible des domaines macroscopique de rayures parallèles courbées ou droites ayant une périodicité microscopique. Selon la variation des rayures en function des limites de surface, nous proposons que les NPs d'or se concentrent aux défauts des dislocations coin dans la phase smectique.Les intéractions moléculaires qui déterminent la miscibilité et l'assemblage des NPs d'or dans des CLs ont été étudiées avec l'aide la RMN multinucléaire à l'état solide, et de NPs d'or et CLs marqués isotopiquement. L'intéraction de la matrice CL avec la surface des NPs d'or se manisfeste de manière surprenante par l'alignement partielle des ligands. La détection d'une région biphasique isotrope-nématique de la matrice CL en-dessous de TN-I est une découverte importante qui va être utilisée afin de perfectionner les modèles thèoriques de la formation de réseaux. Finallement, un autre modèle de réseau fait de NPs, formé à partir de la dispersion d'aérosil dans un CL base de Shiff et ayant un moment dipolaire faible, a été étudié par la RMN du 2H. Nous avons examiné l'impact qu'a différentes forces d'ancrage de surface sur l'effet mémoire qu'affiche ces dispersions.
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Fonseca, Isa Alexandra Queiroz da. "On the way to molecular optical switches a solid-state NMR study of trans-cinnamic acids." Aachen Shaker, 2008. http://d-nb.info/991163389/04.
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Lo, Karen. "A solid state deuterium NMR study of local dynamics of DNA with TpA junctions /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/8521.
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Lewis, Wendy. "Study of the chain dynamics of polyaniline by solid-state nuclear magnetic resonance (NMR)." Akron, OH : University of Akron, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1227535369.
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Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2008."December, 2008." Title from electronic dissertation title page (viewed 12/30/2008). Advisor, Matthew Espe; Committee members, Peter Rinaldi, James Hardy, Claire Tessier, Jutta Luettmer-Strathmann; Department Chair, Kim Calvo; Dean of the College, Ronald F. Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Johnston, Karen Elizabeth. "A complementary study of perovskites : combining diffraction, solid-state NMR and first principles DFT calculations." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1837.
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Perovskites, ABX₃, and their associated solid-solutions are a particularly important and attractive area of research within materials chemistry. Owing to their structural and compositional flexibility and potential physical properties they are one of the largest classes of materials currently under investigation. This thesis is concerned with the synthesis and structural characterisation of several perovskite-based materials using a combined approach of high-resolution synchrotron X-ray and neutron powder diffraction (NPD), solid-state Nuclear Magnetic Resonance (NMR) and first-principles Density Functional Theory (DFT) calculations. Initial investigations concentrated on room temperature NaNbO₃, a perovskite widely debated in the literatue. Published crystallographic data indicate NaNbO₃ possesses two crystallographically distinct Na sites in space group Pbcm. Whilst some of our materials appear in agreement with this (notably a commercially purchased sample) many of our laboratory-synthesised samples of NaNbO₃ routinely comprise of two phases, which we show to be the antiferroelectric Pbcm and polar P2₁ma polymorphs. Several different synthetic methods were utilised during this investigation and the quantity of each phase present was found to vary as a function of preparative method. ²³Na, ⁹³Nb and ¹⁷O DFT calculations were used in conjunction with experiment to aid in spectral analysis, assignment and interpretation. In addition, ab initio random structure searching (AIRSS) was utilised in an attempt to predict the most stable phases of NaNbO₃. This proved to be both successful and highly informative. A series of NaNbO₃-related solid-solutions, namely K[subscript(x)]Na[subscript(1-x)]NbO₃ (KNN), Li[subscript(x)]Na[subscript(1-x)]NbO₃ (LNN) and Na[subscript(1-x)]Sr[subscript(x/2)]□[subscript(x/2)]NbO₃ (SNN) have also been synthesised and characterised. The substitution of K⁺ , Li⁺ and Sr²⁺ cations onto the A site appears to produce the same polar P2₁ma phase initially identified in the room temperature NaNbO₃ investigation. The abrupt change in cation size in the KNN and LNN series, and the introduction of vacancies in the SNN series, is thought to result in a structural distortion which, in turn, causes the formation of the P2₁ma phase. A low temperature synchrotron X-ray powder diffraction study (12 < T < 295 K) was completed for a sample of NaNbO₁ composed of the P2₁ma polymorph (~90%) and a small quantity of the Pbcm phase (~10%). A region of phase coexistence was identified between the P2₁ma, R3c and Pbcm phases over a relatively large temperature range. Full conversion of the P2₁ma phase to the low temperature R3c phase was not possible and, consistently, the P2₁ma phase was the most abundant phase present. Factors such as structural, strain, crystallite size and morphology are thought to be crucial in determining the exact phases of NaNbO₃ produced, both at low and room temperature. The solid-solution La[subscript(1-x)]Y[subscript(x)]ScO₃ was also investigated. Compositions x = 0, 0.2, 0.4, 0.6, 0.8 and 1 were successfully synthesised and characterised. Refined high-resolution NPD data indicates that an orthorhombic structure, in space group Pbnm, was retained throughout the solid-solution. Using ⁴⁵Sc and ⁸⁹Y MAS NMR each sample was found to exhibit disorder, believed to result from both a distribution of quadrupole and chemical shifts. NMR parameters were calculated for several model Sc and Y compounds using DFT methods to determine the feasibility and accuracy of ⁴⁵Sc and ⁸⁹Y DFT calculations. These proved successful and subsequent calculations were completed for the end members LaScO₃ and YScO₃. DFT calculations were also utilised to gain insight into the disorder exhibited in the La[subscript(1-x)]Y[subscript(x)]ScO₃ solid-solution.
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Ramanathan, Chandrasekhar. "Biomedical solid state NMR : an ADRF cross polarization study of calcium phosphates and bone mineral." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38389.
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Pace, Nicola. "Exploring solid state NMR spectroscopy as a tool to study F-actin and its complexes." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/exploring-solid-state-nmr-spectroscopy-as-a-tool-to-study-factin-and-its-complexes(8da09ed8-d827-454e-87f9-2fd23d1b1d2d).html.
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Actin plays a central role in eukaryotic cells in various physiological processes, such as cell motility, cell division and DNA transcription. In addition, actin is the key protein in cardiac muscles, forming filaments that are crucial to its function. The possibility to have the structure of these actin filaments at atomic resolutions is fundamental to understand the molecular mechanism of these events. Although the atomic structure of the monomer of actin has been already characterized, only models based on data at low resolution are available for the structure of actin filaments. This is mainly due to the impossibility of exploiting the full potential of the two most common techniques used in structural biology: NMR in solution and x-ray crystallography. The former cannot be used because the size of actin exceeds the limit of detection, the latter because of the intrinsically disorder contained in a sample of actin filaments which does not allow the growing of a useful crystal. This work aims to investigate the possible application of solid state NMR spectroscopy to the study of actin filament and its complexes, as this technique is not affected by the above mentioned limitations. In order to simplify the approach to this technique we decided to start with the study of a small actin binding domain, the Villin Head Domain (VHD), complexed with F-actin. Despite the limited number of VHD residues (67), its assignment in the bound state is not still complete, meaning that the structure of the complex is not available yet. Nevertheless, thanks to the implementation of phosphorous and Double-Quantum ssNMR spectroscopy, alongside the possibility to acquire proton spectra at high resolution, it has been possible to create a platform of experiments that can be used to approach the study of thin filament complexes in order to solve their structure. The availability of the structure of F-actin and its complexes at atomic resolution will be the starting point for further investigations to understand how actin is implicated in health and disease.
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Haaks, Michael Verfasser], Michael [Akademischer Betreuer] [Vogel, and Roland [Akademischer Betreuer] Böhmer. "Ion dynamics in solid-state batteries - A 7Li NMR study / Michael Haaks ; Michael Vogel, Roland Böhmer." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/115970404X/34.
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Shahid, Shakeel Ahmad [Verfasser]. "Structure and function of the autotransporter protein YadA : a solid-state MAS NMR study / Shakeel Ahmad Shahid." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1030383162/34.
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George, Laurel. "Applications of solid-state 15N NMR spectroscopy to the study of nitrogen cycling in sub-tropical forest plantations." View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/39262.
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Thesis (Ph.D.) -- University of Western Sydney, 2008.A thesis submitted to the University of Western Sydney, College of Health and Science, School of Natural Sciences, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographical references.
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Kalfarisi, Rony Gustam. "Investigation of Local Structures in Cation-Ordered Microwave Dielectric a Solid-State Nmr and First Principle Calculation Study." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639864.
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Solid-state Nuclear Magnetic Resonance (ssNMR) spectroscopy has proven to be a powerful method to probe the local structure and dynamics of a system. In powdered solids, the nuclear spins experience various anisotropic interactions which depend on the molecular orientation. These anisotropic interactions make ssNMR very useful as they give a specific appearance to the resonance lines of the spectra. The position and shape of these resonance lines can be related to local structure and dynamics of the system under study. My research interest has focused around studying local structures and dynamics of quadrupolar nuclei in materials using ssNMR spectroscopy. $^7$Li and $^{93}$Nb ssNMR magic angle spinning (MAS) spectra, acquired at 17.6 and 7.06 T, have been used to evaluate the structural and dynamical properties of cation-ordered microwave dielectric materials. Microwave dielectric materials are essential in the application of wireless telecommunication, biomedical engineering, and other scientific and industrial implementations that use radio and microwave signals. The study of the local environment with respect to average structure, such as X-ray diffraction study, is essential for the better understanding of the correlations between structures and properties of these materials. The investigation for short and medium range can be performed with the use of ssNMR techniques. Even though XRD results show cationic ordering at the B-site (third coordination spehere), NMR spectra show a presence of disorder materials. This was indicated by the observation of a distribution in NMR parameters derived from experimental $^{93}$Nb NMR spectra and supported by theoretical calculations.
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Weiss, Joseph. "A Solid-State 11B NMR and Computational Study of Boron Electric Field Gradient and Chemical Shift Tensors in Boronic Acids and Boronic Esters." Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19737.
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The results of a solid-state 11B NMR study of a series of boronic acids, boronic esters, and boronic acid catechol cyclic esters with aromatic substituents are reported in this thesis. Boron-11 electric field gradient (EFG) and chemical shift (CS) tensors obtained from analyses of spectra acquired in magnetic fields of 9.4 T and 21.1 T are demonstrated to be useful for gaining insight into the molecular and electronic structure about the boron nucleus. It can be concluded that when adequate electronic variation is present in the compounds being studied, Ω is generally the most characteristic boron NMR parameter of the molecular and electronic environment for boronic acids and esters. Importantly, these data are only reliably accessible in ultrahigh magnetic fields. The experimental span values result from a delicate interplay of several competing factors, including hydrogen bonding, the value of the dihedral angle, and the type of aromatic ring system present.
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Popham, Jennifer Mei-An. "A solid state NMR dipolar recoupling study of surface interactions of a N-terminal statherin fragment bound to hydroxyapatite /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/8517.
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Kunjir, Shrikant. "Study of new porous materials by NMR." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC211/document.
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Les zéolites sont des «tamis moléculaires» connus pour leurs nombreuses applications en adsorption, échange d'ions et catalyse. Dans cette thèse, nous nous sommes concentrés sur l'étude de quelques questions liées à la synthèse et à la post-synthèse de la zéolithe, qui ne sont pas encore résolues par d'autres techniques.La RMN a été l'outil principal dans ce travail, donnant accès à des informations structurales locales sur les nanocristaux même lorsque les techniques de diffraction trouvent leurs limites. Elle peut également être utilisée pour étudier la porosité en utilisant l'adsorption de molécules sondes, et en particulier, le xénon est connu comme une bonne molécule pour cet objectif. En effet, l'isotope 129Xe peut être hyperpolarisé pour augmenter la sensibilité de détection, et il présente une large plage de déplacement chimique en fonction du confinement et donc de la porosité du matériau étudié.(I) Dans la première étude, les étapes initiales de la cristallisation de nano-faujasite (FAU) ont été étudiées en utilisant la RMN classique (principalement par 29Si et 23Na MAS RMN) et la RMN avancée (129Xe). RMN HP). Il a été montré que la cristallisation commence à des stades de synthèse bien antérieurs à ceux observés par d'autres techniques classiques (XRD, SEM, adsorption de N2 ...). La première SBU semble être les prismes hexagonaux, avant les cages sodalite, qui forment rapidement un environnement confiné puis des supercages. De plus, il a été démontré par RMN 129Xe HP et 2D EXSY que la zéolithe nano-faujasite présente des cages sodalite ouvertes et une structure plus souple que dans la zéolite de type micro-faujasite.(ii) La seconde étude est une recherche sur les phénomènes de recristallisation survenant au cours du processus de hiérarchisation de la zéolithe et qui pourrait expliquer la distribution homogène des tailles de mésopores. Comme résultat remarquable, il a été montré dans ce travail que lors de la hiérarchisation de la zéolithe bêta avec le TPAOH, la recristallisation conduisait à la formation de minuscules particules de MFI, formées à la surface des mésopores (RMN 1H MAS, RMN 129Xe HP et 2D EXSY)The zeolites are ‘molecular sieves’ known for their numerous applications in adsorption, ion exchange, and catalysis. In this thesis, we focused on the study of some questions related to zeolite synthesis and post-synthesis, which are not yet resolved by other techniques. NMR was the primary tool in this work, as it gives access to local structural information on nanocrystals even when diffraction techniques found their limits. NMR can also be used to study porosity using probe molecules adsorption, and in particular, xenon is known as a good molecule for this purpose. Indeed, the isotope 129Xe can be hyperpolarized to increase the detection sensitivity, and interestingly it presents a wide chemical shift range depending on its confinement and thus the porosity of studied material. Two studies are reported in this manuscript: (i) In the first study, the initial steps during the crystallization of nano-faujasite (FAU) type materials were investigated using classical NMR (mainly by 29Si and 23Na MAS NMR) and advanced NMR (129Xe HP NMR). It was shown that crystallization starts at much earlier synthesis stages than those observed by other classical techniques (XRD, SEM, N2 adsorption…). The first SBU seems to be the hexagonal prisms, prior to the sodalite cages, which rapidly form confined environment and then supercages. Moreover, it has been proved by 129Xe HP NMR and 2D EXSY that nano-faujasite zeolite presents opened sodalite cages and a more flexible structure than in micro-faujasite zeolite. (ii) The second study is an investigation on the recrystallization phenomena occurring during hierarchization process of zeolite and which could explain the homogenous distribution of the mesopore sizes. As a remarkable result, it has been shown in this work that during the hierarchization of beta zeolite with TPAOH, the recrystallization lead to the formation of tiny MFI particles, formed at the surface of the mesopores (1H MAS NMR, 129Xe HP NMR and 2D EXSY)
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Speight, Richard James. "A study of industrial Fischer-Tropsch catalysts, primarily by means of zero-applied field cobalt-59 solid-state NMR spectroscopy." Thesis, University of Warwick, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495012.
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The primary concem in this thesis is quantitative characterisation of metallic Co sites in industrial Cobalt(Co)-based catalysts used in the Fischer-Tropsch (FT) reaction, which is part of the Gas to Liquid process, which converts synthesis gas (a mixture of H2 and CO) to diesel via long-chain hydrocarbons. This characterisation was mainly done by means of zero-applied field Co nuclear magnetic resonance (NMR) spectroscopy that takes advantage of the fact Co is ferromagnetic and hence has a strong intemal magnetic field.
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Peel, Martin D. "A crystallographic study of group I niobate perovskites." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6530.
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In this work, X-ray and neutron powder diffraction experiments and complementary solid-state NMR spectroscopy are used to characterise NaNbO₃-based perovskite phases. Samples of NaNbO₃, KₓNa₁₋ₓNbO₃ and LiₓNa₁₋ₓNbO₃ are synthesised using a variety of techniques and subsequently characterised. For NaNbO₃, it is observed that at least two room temperature perovskite phases can co-exist, P and Q, and that each phase can be formed exclusively by manipulating the synthetic approach utilised. Phase Q can also be formed by the substitution of a small amount of K⁺ or Li⁺ for Na⁺. The room temperature phases of these materials are also analysed using NMR spectroscopy and X-ray diffraction. It is found that, for KₓNa₁₋ₓNbO₃, preferential A-site substitution of K⁺ for Na⁺ may occur, and this observation is supported using a range of NMR techniques and density functional theory calculations. The high-temperature phase behaviour of NaNbO₃ and KₓNa₁₋ₓNbO₃ (x = 0.03 to 0.08) is analysed using high-resolution neutron and X-ray powder diffraction to determine when phase changes occur and to characterise each phase. Characterisation of these materials is supported used complementary symmetry mode analysis. For the LiₓNa₁₋ₓNbO₃ perovskite system, complex phase behaviour is observed at room temperature. High-resolution neutron powder diffraction data shows that, over the range 0.08 < x < 0.20, phase Q may co-exist with a rhombohedral phase, with the proportions of the two highly dependent upon the synthetic conditions used. Furthermore, using X-ray diffraction and NMR spectroscopy, phase Q is shown to undergo a crystal-to-crystal transition to the rhombohedral phase. For higher values of x, two compositionally-distinct rhombohedral phases are formed, termed Na-R3c and Li-R3c, as determined from neutron powder diffraction data.
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Dria, Karl Jay. "Carbon and nitrogen distribution and processes in forest and agricultural ecosystems a study involving solid- and liquid-state NMR and pyrolysis GC/MS /." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1085700625.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xv, 214 p.; also includes graphics (some col.). Includes bibliographical references (p. 194-206). Available online via OhioLINK's ETD Center
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Fonseca, Isa Alexandra Queiroz da [Verfasser]. "On the way to molecular optical switches : a solid-state NMR study of trans-cinnamic acids / Isa Alexandra Queiroz da Fonseca." Aachen : Shaker, 2008. http://d-nb.info/992711045/34.
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Borysenko, Artem, Ben Clennell, Iko Burgar, David Dewhurst, Rossen Sedev, and John Ralston. "Application of low field and solid-state NMR spectroscopy to study the liquid/liquid interface in porous space of clay minerals and shales." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191838.
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In petroleum research understanding displacement, redistribution, and adsorption of oil and water plays an important role. To study complex multi-component systems such as liquid/liquid/mineral interactions in the porous space of clays and shales we applied low
field (2 – 15 MHz) and high resolution (300 MHz) NMR spectroscopy. The detailed NMR analysis shows that the results from low field NMR measurements are in good correlation with the solid-state data. Consequently the process of liquid/liquid displacement can be characterised by considering the relaxation times, signal amplitudes and chemical shifts together.
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Borysenko, Artem, Ben Clennell, Iko Burgar, David Dewhurst, Rossen Sedev, and John Ralston. "Application of low field and solid-state NMR spectroscopy to study the liquid/liquid interface in porous space of clay minerals and shales." Diffusion fundamentals 11 (2009) 2, S. 1-4, 2009. https://ul.qucosa.de/id/qucosa%3A14091.
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In petroleum research understanding displacement, redistribution, and adsorption of oil and water plays an important role. To study complex multi-component systems such as liquid/liquid/mineral interactions in the porous space of clays and shales we applied low
field (2 – 15 MHz) and high resolution (300 MHz) NMR spectroscopy. The detailed NMR analysis shows that the results from low field NMR measurements are in good correlation with the solid-state data. Consequently the process of liquid/liquid displacement can be characterised by considering the relaxation times, signal amplitudes and chemical shifts together.
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Voreck, Anja Marion [Verfasser]. "Structural Characterization of a Transmembrane Protein by Solid-state NMR : A Biophysical and Functional Study of the ABC Transporter ArtMP-J / Anja Marion Voreck." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1065670214/34.
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Attrell, Robert J. "A Solid-State 35Cl and 81Br NMR and Computational Study of Chlorine and Bromine Electric Field Gradient and Chemical Shift Tensors in Haloanilinium Halides." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20546.
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The results of a systematic 35Cl, 81Br, and 127I SSNMR spectroscopic study of a series of halogen-substituted anilinium halide salts are presented. Solid-state NMR of these nuclides, bromine-/81 and iodine-127 in particular, is not well established. Twenty-one compounds thought to exhibit halogen bonding were prepared based on modified literature procedures, and two crystal structures were solved. Experiments show that collection of SSNMR spectra of the anions is feasible, though ultrahigh magnetic fields (21.1 T) and variable offset data acquisition were found to be essential. Electric field gradient and chemical shift tensors are measured experimentally for all 21 compounds, significantly expanding the body of data for the quadrupolar halogen nuclei. Quadrupolar coupling constants for chlorine-35 ranged from 2.12 to 6.04 MHz, for bromine-81 from 12.3 to 45.3 MHz, and for iodine-127 from 57.50 to 152.50 MHz. Gauge-including projector-augmented wave density functional theory (GIPAW-DFT) calculations were used to provide insight as to how the NMR parameters vary with local environment and long-range crystal packing. Overall, calculations reproduced the experimental trends in quadrupolar coupling constants and chemical shift tensor span (Ω) but failed to provide quantitative agreement within experimental error. Experimental and computational data were analyzed in order to provide insight into how halogen bonding influences NMR parameters. Several trends were elucidated from this study, including an inverse correlation between Ω and the length of the shortest halogen-halide contact (d). In selected bromine compounds, for example, Ω (81Br) was measured to increase from 120 to 240 ppm as d decreased from 3.838 to 3.443 Å. In summary, this study has demonstrated the feasibility and utility of quadrupolar halogen SSNMR, and that these techniques may prove useful in characterizing halogen bonding interactions in solids.
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Gee, Myrlene. "Phosphorus chemical shift and indirect ³¹P-³¹P spin-spin coupling tensors in compounds containing P-P bonds, a solid-state ³¹ NMR and theoretical study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ66648.pdf.
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Wilkening, Martin, and Paul Heitjans. "Comparison of 3D and 2D Li diffusion in cubic and hexagonal Li x TiS 2: a study by solid state 7 Li NMR methods." Diffusion fundamentals 6 (2007) 40, S. 1-13, 2007. https://ul.qucosa.de/id/qucosa%3A14217.
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Li diffusion in spinel-type structured cubic and hexagonal LixTiS2 with x = 0.6 and 0.7, respectively, was investigated by solid state NMR spectroscopy. In layered hexagonal LixTiS2, Li diffusion is known to be confined to the van-der-Waals gap between the TiS2 planes, i. e., it is two-dimensional (2D). In cubic LixTiS2, however, Li diffusion takes place in the three-dimensional (3D) interstitial space formed by the TiS6-polyhedra. Both polymorphs form a unique pair for studying the effects of dimensionality on Li diffusion within a host structure of the same chemical composition. 7Li spin-alignment echo and spin-lattice relaxation NMR methods were
applied to measure Li jump rates. Additionally, solid echo NMR spectroscopy was used to estimate the Li diffusivity in cubic Li0.6TiS2. The activation energies for Li jumps in the two materials are very similar. Nevertheless, Li diffusion in the 3D host is slower than in the layered modification by a factor of about ten.
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Chapman, Rebecca. "Development and Application of Chlorine Solid-State Nuclear Magnetic Resonance and Quantum Chemical Calculations to the Study of Organic and Inorganic Systems." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20555.
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Chlorine solid-state nuclear magnetic resonance (SSNMR) is an ideal site specific probe of chloride-containing solids as SSNMR tensor properties are sensitive to the local chlorine environment. In this thesis, the development and use of chlorine SSNMR as a method to characterize a wide variety of chemical environments was explored. Ultrahigh field, and multi-field studies were essential to overcome the difficulties associated with the collection of chlorine SSNMR spectra.
Benchmark chemical shift (CS) and electric field gradient (EFG) tensor data were collected for organic chloride systems, including several amino acid hydrochlorides. These experiments demonstrated the sensitivity of chlorine SSNMR to slight changes in chemical environment. Quantum chemical calculations were used to complement experimental data, with the gauge-including projector augmented wave DFT (GIPAW-DFT) method shown to yield better agreement than B3LYP or RHF methods. The GIPAW-DFT method was found to slightly, but systematically, overestimate the chlorine quadrupolar coupling constant and the CS tensor span. Other organic chlorides examined by chlorine SSMR included a known ion receptor, meso-octamethylcalix[4]pyrrole. This compound was found to have a very small quadrupole interaction (QI), but significant chemical shift anisotropy (CSA). GIPAW-DFT calculations were also utilized and, in combination with the experimental results, used to identify the solvate structure of the material analyzed by NMR.
Chlorine SSNMR was further used to study different solvate structures and polymorphism. The technique was an effective means to distinguish different room temperature polymorphs of benzidine hydrochloride, despite the similarities of the chloride environments. In the case of magnesium chloride, chlorine SSNMR was sensitive to the level of hydration and through the use of GIPAW-DFT calculations, the identity of an unknown hydrate was determined.
An analysis of several group thirteen chlorides demonstrated that chlorine SSNMR was also capable of characterizing the chlorine environment in cases where the QI is large, despite the resulting broad line widths. In these systems GIPAW-DFT calculations also yielded excellent agreement with experimental values.
Throughout this research, chlorine SSNMR has been shown to be a useful and effective means to study both organic and inorganic chlorides, with computational methods proving to be an important complement to experimental data.
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Denike, John Kane Carleton University Dissertation Chemistry. "The synthesis and complexation of bis-crown ethers and polymers bearing pendant crown ethers and the study of molecular motion of crown ethers in solids using solid state 2H NMR." Ottawa, 1992.
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Lindström, Fredrick. "Biological membrane interfaces involved in diseases : a biophysical study." Doctoral thesis, Umeå universitet, Kemi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-806.
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Interactions between peptides and biological lipid membranes play a crucial role in many cellular processes such as in the mechanism behind Alzheimer’s disease where amyloid-beta peptide (Abeta)is thought to be a key component. The initial step of binding between a surface active peptide and its target membrane or membrane receptor can involve a non specific electrostatic association where positively charged amino acid residues and a negatively charged membrane surface interact. Here, the use of high resolution MAS NMR provides a highly sensitive and non perturbing way of studying the electrostatic potential present at lipid membrane surfaces and the changes resulting from the association of peptides. The interaction between pharmacologically relevant peptides and lipid membranes can also involve incorporation of the peptide into the membrane core and by complementing the NMR approach with differential scanning calorimetry (DSC) the hydrophobic incorporation can be studied in a non invasive way. By using 14N MAS NMR on biological lipid systems for the first time, in addition to 31P, 2H NMR and differential scanning calorimetry (DSC), gives a full picture of the changes all along the phospholipid following interactions at the membrane interface region. Being able to monitor the full length of the phospholipid enables us to differentiate between interactions related to either membrane surface association or hydrophobic core incorporation. This approach was used to establish that the interaction between nociceptin and negatively charged lipid membranes is electrostatic and hence that nociceptin can initially associate with a membrane surface before binding to its receptor. Also, it was found that Abeta can interact with phospholipid membranes via two types of interactions with fundamentally adverse effects. The results reveal that Abeta can associate with the surface of a neuronal membrane promoting accelerated aggregation of the peptide leading to neuronal apoptotic cell death. Furthermore it is also shown that Abeta can anchor itself into the membrane and suppress the neurotoxic aggregation of Abeta.
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Ocampo, Juan. "Etude des phénomènes d'interface dans la glace : adsorption, croissance des clathrates et désordre protonique : [thèse en partie soutenue sur un ensemble de travaux]." Grenoble 1, 1988. http://www.theses.fr/1988GRE10087.
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Etude depuis l'etat amorphe a 77 k jusqu'a l'etat hexagonal pres du point de fusion de l'evolution structurale et dynamique de la surface de la glace en contact ou non avec des gaz (he, kr, ar, n::(2), co::(2), nc::(4)h::(10)) ou des solides (sio::(2), pvc, h::(2)so::(4)). Approche thermodynamique (adsorption de gaz), cinetique (frittage et croissance de clathrates) et spectroscopique (rmn des protons). Mecanisme de reconstruction de la surface depuis l'adsorption jusqu'a la clathration, en tenant compte des coefficients de diffusion et des energies d'activation mesurees. Existence d'une couche quasi-liquide sur la surface de la glace pour des temperatures superieures a 238 k, et dans le cas des interfaces avec d'autres corps solides
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Zahidi, Assou. "Etudes structurales et dynamiques de complexes macrocycliques par rmn heteronucleaire." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13171.
Full textAbstract:
Etude de la complexation de cations et d'anions par des ligands synthetiques a l'aide de la rmn heteronucleaire (**(6)li, **(7)li, **(13)c, **(14)n, **(15)n, **(19)f, **(31)p, **(35)cl et **(109)ag) et de mesures d'effet overhauser homo- et heteronuclaires
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SUNG, WANG CHOU, and 宋旺洲. "Study of Motion of Liquid Crystal by Solid State NMR." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/56532940904725630737.
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碩士國立成功大學
化學系
87
Three series of liquid crystalline（LC）monomers have been successfully prepared and characterized. These materials contain oligo（oxyethylene）spacers with different length and phenyl biphenyl carboxylate as mesogen. There are two compounds in each series differing only in deutration of phenyl groups or not. The temperature ranges of LC phase were identified by differential scanning calorimetry (DSC) and optical polarizing microscopy（OPM）.The influences of spacer length on the formation of mesophases were investigated. The deutration at phenyl group exhibited little influence in their LC property. In order to evaluate the orientation order parameter, solid state NMR spectra were measured at various temperature. The change of order parameter in different liquid crystal phases was discussed in detail. The results show that all the monomers have two apparent liquid crystalline textures. The textures have been characterized as nematic and smectic A phase by OPM. The increase of the spacer length resulted in a gradual decrease of the phase transition temperature in each compound. The orientation order parameter show abrupt change during transition from smectic A phase to nematic phase. However spacer length exhibited little influence on the order parameter.
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Liu, Hann-Wen, and 劉漢文. "High Resolution Solid State NMR Study in Electro-optic Materials." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/49314748082623448493.
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碩士國立中央大學
化學系
84
There are three topics in this research. First, we use single crystal NMR to study BaTiO3(BT) and KTiOPO4(KTP). The second order quadrupolar shiftsof Ba(137) can be a powerful tool to distinguish differences of the fine stru-cture and crystal orientation. The special magneto-acoustic ringing-down fea-ture, the interaction between the high power ratio frequency and single cry-stal of BT, would be discussed. From the single crystal and MAS NMR studies ofP(31) in KTP, the structural information can be obtained. Then, compared borontetrafluoride dopant and methyl substituent in polythiophene by NMR, we can study the relationships of chain structures, mobility, and electron transfer by characteristic chemical shifts at different temperatures. The RF dopingbrings about new perspectives in studying interaction between electro-magneticwave and electronic structure in conjugated polymers. ESR studies yield comple- mentary molecular dynamic information with that obtained by NMR. At last, va-riable temperature NMR studies of intercalated C60 reveal the connection of ground state with the exited state of spin-rotation coupling interaction be-tween nuclear spin with C60 reorientation by the intercalated water molecules.A superb resolution of 0.03 ppm of C(13) solid state NMR of C60 crystals isachieved by delay-acquisition. This results is helpful to observe the feature of fien structures.
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Haaks, Michael. "Ion dynamics in solid-state batteries - A 7Li NMR study." Phd thesis, 2018. https://tuprints.ulb.tu-darmstadt.de/7363/7/Dissertation_Haaks_Version_19.04.2018.pdf.
Full textAbstract:
Rising energy demand, in combination with a mobile society, makes it more and more important to store energy when available and release it upon demand. Rechargeable lithium ion batteries are widely used today for powering small devices, e.g., smartphones and cameras. However, further improvements are required, if lithium ion batteries are supposed to power electric vehicles. One requirement to achieve this task is the development of an all-solid state battery. Here, the flammable liquid electrolyte is replaced by a solid material. A few years ago, the main drawback of solid materials was the relatively low conductivity in comparison to that of their liquid counterparts. While the conductivity of solid electrolytes could be enhanced to the level of liquid electrolytes used in modern lithium ion batteries, the mechanism of lithium ion dynamics in those amorphous solids is still not understood.
The aim of this work is to analyse the dynamics of lithium ions in highly conducting solid materials on broad time and length scales. For this purpose, a combination of well established and newly developed 7Li NMR methods are used.
The new conjunction of 7Li diffusion measurements and 7Li field cycling relaxometry achieved in this work turns out to be an ideal combination. While the former probes the long-range transport on a mesoscopic length scale, the latter gives insight into local lithium ion jump dynamics on a microscopic length scale in the same temperature range. Additionally, field-cycling experiments allow the determination of the true activation energy by measuring temperature dependent susceptibility or relaxation-rate maxima.
The present research study reveals heat induced changes of the investigated samples when approaching their glass-transition temperatures Tg with partly opposite effects. While the 0.7Li2S–0.3P2S5 system is known for an enhanced dynamics due to this kind of ceramization, the heat treatment of the 0.7Li2S–0.3B2S3 samples leads to an occurance of a second lithium species with reduced dynamics. Additionally, comparison with literature reveals that the results strongly depend on details of the methods used to prepare the samples. Furthermore, it is shown in this work that a broad Gaussian distribution of activation energies exists in all studied solid lithium ion conductors, which is responsible not only for the local lithium ion jump dynamics, but also for the long-range diffusion. This indicates that the difference of activation energies usually obtained from distinct methods is a mere consequence of probing various averages of the resulting logarithmic distribution of correlation times. Hence, no specific model is necessary to describe the activation energy discrepancy often observed when comparing results of DC conductivity and NMR experiments. These findings are comfirmed by re-analyzing data given in the literature.
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Jamieson, Rebecca. "A Solid-state NMR Study of Tin and Phosphorus Containing Compounds." Thesis, 2013. http://hdl.handle.net/10214/7407.
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Various compounds were studied with solid-state 119Sn and 31P NMR spectroscopy and quantum chemical calculations. Connections were made between the shielding tensors and the geometric and electronic structures of the molecules. First, the 119Sn chemical shielding anisotropy of various para substituted tetraaryl tin compounds was shown to be dependent on the tilt angle of the phenyl rings. Tetrakis(o-tolyl) tin did not have the shielding anisotropy predicted by the tilt angle of the rings. It was suggested that ortho substitution distorts the structures of the phenyl rings causing the discrepancy. Analysis of the solid-state 31P NMR spectra of triphenylphosphorane ylides, Ph3P=CHC(O)R, determined that increasing the electron-donating effects of the R group decreased the δ33 component. Theoretical calculations showed that the component lay along the ylidic bond and was dependent on the difference in phosphorus-carbon bond lengths between the phenyl and ylidic bonds. Another study concerned the solid-state 31P NMR of the series of triphenylphosphine derivatives, PPh3-x(o-tolyl)x where x = 0 to 3. The addition of ortho methyl groups changed the position of the δ11 component which could be the result of the change in energy gap between the lone pair (HOMO) and σ* anti-bonding (LUMO).
The solid-state 31P NMR spectra of deuterated piperazinium phosphonate and phosphonic acid were influenced by the shielding, dipolar and spin-spin interactions, as well as, second order quadrupolar effects. The spectrum of deuterated piperazinium phosphonate had a chemical shielding anisotropy of 130 ppm, an effective dipolar coupling of 2500 kHz and a one-bond phosphorus-deuterium J coupling of 90 Hz. The phosphorus-deuterium bond length was predicted to be 1.44(2) Å. A deuterium quadrupolar coupling constant of 104 kHz was obtained from the CP/MAS 2H spectrum. The non-axial symmetry of phosphonic acid complicated the analysis of the 31P spectrum. Phosphorus-deuterium bond lengths of 1.44(5) Å and 1.40(4) Å were obtained for the two inequivalent sites in the unit cell.
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Tsai, Yi-Ling, and 蔡易玲. "Solid state nmr study of dentin structure and dental filling materials." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33943288804008148887.
Full textAbstract:
博士國立臺灣大學
化學研究所
99
The main subject of this thesis is focused on the study of calcium phosphate biominerals using novel solid-state NRM techniques and the synthesis of the related materials. Geopolymer is a material based on aluminosilicates. In chapter 3, the sol-gel method is used to synthesize precursor materials for the preparation of geopolymers. The results are very similar to those obtained for the geopolymers prepared from natural kaolinite. The well-defined chemical composition in this synthetic approach offers a good opportunity for the mechanistic studies and medical applications in the future. In chapter 4, magnesium-substituted hydroxyapatite of high crystallinity is prepared as a model compound for the 25Mg high-field solid state NMR study. The study of this model compound will help us to solve the problem of the location of magnesium. In chapter 5 and 6, the structure of Wistar rat dentin and human dentin were studied by varieties of spectroscopic techniques, especially emphasize on the solid-state NMR method. The phosphorus structures of rat dentin, base on the solid-state NMR data, could be distinct into three species, viz. hydroxyapatite (HAp), hydroxyl-deficient apatite (HDAp) and amorphous calcium phosphates. We find that the amount of amorphous matrix (ACP) decreased upon the rat age. Because the growing rate of rat incisor decreased with age as well as the amorphous matrix content, it is reasonable to deduce that the amorphous matrix of dentin plays an important role for the teeth growth. Moreover, we find that the apatite crystal is a core-shell structure, with HAp surround by HDAp, embedded in the amorphous matrix. Finally, the human dentin with different ages is studied by the strategies which have been applied on Wistar rat dentin. However, no significant changes on the phosphorus units are observed. This result is consistent with the clinical observation because the growth of human teeth nearly stops after the tooth mature. Besides, the ACP content of human dentin is only half the amounts of that in rat dentin. This is also an evidence showing that the different growing rate of the rat dentin and the human dentin.
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Chandran, C. Vinod, Kai Volgmann, Suliman Nakhal, Reinhard Uecker, Elena Witt, Martin Lerch, and Paul Heitjans. "Local Ion Dynamics in ß-LiGaO2: A Solid-State NMR Study." 2017. https://ul.qucosa.de/id/qucosa%3A31626.
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Mo, Yiming Cross Timothy A. "Study of structure-function correlations in ion channels by solid state NMR." Diss., 2006. http://etd.lib.fsu.edu/theses/available/etd-12212005-141748.
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Thesis (Ph. D.)--Florida State University, 2006.Advisor: Timothy A. Cross, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed June 9, 2006). Document formatted into pages; contains xv, 98 pages. Includes bibliographical references.