[PDF] Solid State Nuclear Magnetic Resonance Of Exotic Quadrupolar Nuclei As A Direct Probe Of Molecular Structure In Organic Ionic Solids eBook

Author : Kevin Burgess
Publisher :
Page : pages
File Size : 15,52 MB
Release : 2015
Category : University of Ottawa theses
ISBN :

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In the past decade, the field of NMR spectroscopy has seen the emergence of ever more powerful superconducting magnets, which has opened the door for the observation of many traditionally challenging or non-receptive nuclei. In this dissertation, a variety of ionic solids with organic coordination environments are investigated using quadrupolar solid-state NMR experiments with an ultrahigh-field magnet (21.1 T). Two general research directions are presented including a 79/81Br solid-state NMR study of a series of 6 triphenylphosphonium bromides for which single-crystal X-ray structures are reported herein. A second research direction is also presented wherein alkaline-earth metal (25Mg, 43Ca, and 87Sr) solid-state NMR is used to characterize a systematic series of 16 aryl and alkyl carboxylates. In both studies, the quadrupolar nuclei studied are deemed zexoticy due to their unreceptive nature to NMR spectroscopic analysis including low natural abundances, large quadrupole moments, or low resonance frequencies. A variety of coordination modes to alkaline-earth metals, including N-atom coordination, are characterized herein for the first time using alkaline-earth metal solid-state NMR. In all cases, the electric field gradient (EFG) and chemical shift (CS) tensors are characterized and correlated to structural features such as interatomic distances measured from the crystal structure of the compound under study. In all of the projects undertaken herein, the gauge-including projector-augmented-wave density functional theory (GIPAW DFT) method is used, which allows for the prediction and rationalization of the experimental EFG and CS tensor parameters based on the input crystal structure. In the case of 43Ca solid-state NMR experiments reported in this dissertation, a linear correlation between the calculated and experimental 43Ca quadrupolar coupling constants, CQ, is used as a calibration curve for GIPAW DFT calculations performed on the 18 structural models currently available for the vaterite polymorph of CaCO3. Vaterite cannot be fully characterized by X-ray diffraction alone; therefore an NMR crystallography protocol is used in order to identify the model that best accounts for 43Ca solid-state NMR experiments performed on vaterite. It is expected that the conclusions from this dissertation can be used for future studies involving structural refinement and elucidation of solid materials containing challenging quadrupolar nuclei.

Author : Alexandra Faucher
Publisher :
Page : 234 pages
File Size : 20,89 MB
Release : 2016
Category : Exotic nuclei
ISBN :

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This thesis is concerned with NMR studies of solids containing NMR-active quadrupolar nuclei typically overlooked due to their unfavorable NMR properties, particularly moderate to large nuclear electric quadrupole moments. It is shown that 75As, 87Sr, and 121/123Sb NMR spectra of a wide range of solid materials can be obtained. Traditional 1D pulse sequences (e.g., Bloch pulse, spin echo, QCPMG) are used alongside new methods (e.g., WURST echo, WURST-QCPMG) to acquire the NMR spectra; the advantages of these new methods are illustrated. Most of these NMR spectra were acquired at an external magnetic field strength of B0 = 21.14 T. Central transition (mI = 1/2 to -1/2) linewidths of half-integer quadrupolar nuclei of up to a breadth of ca. 32 MHz are obtained at B0 = 21.14 T, demonstrating that nuclear sites with large nuclear quadrupolar coupling constants can be characterized. Many of the NMR spectra contained in this research depict situations in which the nuclear quadrupolar interaction is on the order of or exceeds the magnitude of the Zeeman interaction, thus rendering the high-field approximation invalid and requiring exact treatment in which the full Zeeman-quadrupolar Hamiltonian is diagonalized in order to properly simulate the NMR spectra and extract NMR parameters. It is also shown that both direct (Reff) and indirect (J) spin-spin coupling between quadrupolar nuclei can be quantified in some circumstances, and that the signs of the isotropic indirect spin-spin coupling and the nuclear quadrupolar coupling constants can be obtained experimentally in cases of high-field approximation breakdown. This research represents a relatively large and valuable contribution to the available 75As, 87Sr, and 121/123Sb NMR data in the literature. For example, experimentally determined chemical shift anisotropy is reported for the 87Sr nucleus in a powdered solid for the first time, and the NMR parameters for 11B-75As spin-spin coupling constants reported here add to a sparse collection of information on quadrupolar spin-pairs. Overall, this research is a step towards the goal of utilizing the entire NMR periodic table for the characterization of molecular and crystallographic structure as well as structural dynamics.

Author : Jerry C. C. Chan
Publisher : Springer
Page : 328 pages
File Size : 17,62 MB
Release : 2011-10-12
Category : Science
ISBN : 3642248039

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Dipolar Recoupling, by Niels Chr. Nielsen, Lasse A. Strassø and Anders B. Nielsen.- Solid-State NMR Techniques for the Structural Determination of Amyloid Fibrils, by Jerry C. C. Chan.- Solid-State 19F-NMR of Peptides in Native Membranes, by Katja Koch, Sergii Afonin, Marco Ieronimo, Marina Berditsch and Anne S. Ulrich.- Probing Quadrupolar Nuclei by Solid-State NMR Spectroscopy: Recent Advances, by Christian Fernandez and Marek Pruski.- Solid State NMR of Porous Materials Zeolites and Related Materials, by Hubert Koller and Mark Weiß.- Solid-State NMR of Inorganic Semiconductors, by James P. Yesinowski.-

Author : Andre Sutrisno
Publisher :
Page : pages
File Size : 44,68 MB
Release : 2012
Category :
ISBN :

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Preparation and characterization of inorganic materials is a crucial practice because understanding the relationship between structure and property is important for improving current performance and developing novel materials. Many metal centers in technologically and industrially important materials are unreceptive low- quadrupolar nuclei (i.e., possessing low natural abundance, low NMR frequencies and large quadrupole moments) and they usually give rise to very broad NMR resonances and low signal-to-noise ratios, making it difficult to acquire their solid-state NMR spectra. This thesis focuses on the characterization of inorganic materials using solid-state NMR (SSNMR) spectroscopy at very high magnetic field of 21.1 T in combination with quantum chemical calculations for computational modeling. In the first part of this thesis, 67Zn and 17O SSNMR studies of several microporous materials were reported. The results of 67Zn SSNMR studies from several important metal-organic frameworks (MOFs), in particular, zeolitic imidazolate frameworks (ZIFs) were presented. 67Zn SSNMR spectroscopy was used to gain structural information regarding the desolvation process in MOF-5. Furthermore, 67Zn SSNMR spectroscopy were utilized to study the host-guest interactions in ZIF-8 loaded with different guest molecules. Static 67Zn SSNMR spectra of microporous zinc phosphites (ZnP) and zinc phosphates (ZnPO) were also acquired at natural abundance. The Gaussian calculation results on a model cluster for ZnP indicate that Zn-O bond length is the most dominant factor to the observed quadrupolar coupling constant (CQ) among other geometric parameters around Zn centres. The local structures of the framework oxygen sites in molecular sieve SAPO-34 were directly probed by several 17O SSNMR techniques. The involvement of water vapor during the SAPO-34 formation in dry-gel conversion (DGC) synthesis was also investigated. In the second part, 91Zr and 33S SSNMR spectra of layered zirconium phosphates (ZrP) and transition metal disulfides (MS2) were obtained. The empirical correlations between NMR parameters and various structural parameters were used for obtaining partial structural information in Li+ and Co(NH3)63+ exchanged layered ZrP. For a series of closely related MS2 materials, the observed differences in the CQ(33S) values were rationalized by considering the difference in their geometrical arrangements. The final part of this thesis featured two examples of SSNMR spectroscopy of exotic nuclei in some interesting inorganic materials. (i) The experimental 135/137Ba SSNMR spectroscopy and theoretical studies of -BBO, an important non-linear optical (NLO) material, indicate that the true crystal structure of -BBO is R3c space group rather than R3. (ii) An ultrahigh field natural abundance 73Ge SSNMR study of two representative germanium containing materials [GeCl2-dioxane and GePh4] demonstrated that acquiring 73Ge wideline NMR spectra of germanium compounds where the Ge experiences an extremely large quadrupolar interaction is feasible and that the small 73Ge chemical shielding anisotropy (CSA) can be directly measured.

Author : Navnit Shah
Publisher : Springer
Page : 702 pages
File Size : 27,51 MB
Release : 2014-11-21
Category : Medical
ISBN : 1493915983

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This volume offers a comprehensive guide on the theory and practice of amorphous solid dispersions (ASD) for handling challenges associated with poorly soluble drugs. In twenty-three inclusive chapters, the book examines thermodynamics and kinetics of the amorphous state and amorphous solid dispersions, ASD technologies, excipients for stabilizing amorphous solid dispersions such as polymers, and ASD manufacturing technologies, including spray drying, hot melt extrusion, fluid bed layering and solvent-controlled micro-precipitation technology (MBP). Each technology is illustrated by specific case studies. In addition, dedicated sections cover analytical tools and technologies for characterization of amorphous solid dispersions, the prediction of long-term stability, and the development of suitable dissolution methods and regulatory aspects. The book also highlights future technologies on the horizon, such as supercritical fluid processing, mesoporous silica, KinetiSol®, and the use of non-salt-forming organic acids and amino acids for the stabilization of amorphous systems. Amorphous Solid Dispersions: Theory and Practice is a valuable reference to pharmaceutical scientists interested in developing bioavailable and therapeutically effective formulations of poorly soluble molecules in order to advance these technologies and develop better medicines for the future.

Author : Roshanak Teymoori
Publisher :
Page : 276 pages
File Size : 21,51 MB
Release : 2014
Category : Nuclear magnetic resonance
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This thesis is concerned with applications of modern solid-state NMR spectroscopy. Investigations of three quadrupolar nuclei (51V, 17O, and 23Na) are undertaken to demonstrate the practicality of solid-state nuclear magnetic resonance, SSNMR in studies of compounds containing these nuclei. The goal of each project is to gain insight into the effect of the local environment on the NMR observables. Vanadium-51 solid-state NMR has been used to study oxo- and peroxo-vanadium compounds. The 51V nucleus is examined to determine the vanadium magnetic shielding, MS and electric field gradient, EFG tensors. Density functional theory, DFT, has been utilized to calculate MS and EFG tensors to corroborate experimental data and to provide insight into the relationship between molecular and electronic structure. In addition the hyperbolic secant, HS pulse sequence has been used to provide spectra from which information about the shielding anisotropy of [V(O)(ONMe2)2]2O could be gained. An investigation of oxygen-17 solid-state NMR studies of ligand, 17OP(p-Anis)3 and complex of InI3[17OP(p-Anis)3]2 powder samples has also been carried out. Coordination of oxygen to indium causes a change in the 17O chemical shift tensor. DFT calculations are also utilized and the theoretical results are compared with the corresponding experimental values. Finally, solid-state sodium-23 NMR investigations of series of sodium salts, (sodium nitroprusside dihydrate, sodium bromate, sodium chlorate, sodium nitrate, sodium nitrite, sodium selenite and anhydrous disodium hydrogen phosphate) were carried out to determine 23Na MS and EFG tensor parameters. The CASTEP and BAND codes were employed to calculate the EFG and MS tensors. In addition, in the case of sodium nitroprusside solid-state 17O and 15N NMR studies, as well as computational investigations of the corresponding EFG and MS tensors, were undertaken. This Thesis reported the first experimental demonstration of sodium CS tensors determined from solid-state NMR spectroscopy of powder samples of these sodium salts. It also demonstrated the use of first-principles calculations, based on DFT theory in the CASTEP and BAND codes, to investigate the 23Na EFG and MS tensors for these sodium salts.