Thesis (Ph. D.)--University of California, Riverside, 2008. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 10, 2010). Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 171-177).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 141-161).

Thesis (Ph. D.)--University of Oregon, 2002. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 159-167). Also available for download via the World Wide Web; free to University of Oregon users.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

This dissertation presents solid-state NMR studies that probe the dynamic and conformational properties of polymers adsorbed on solid surfaces in the dry state. The systems studied include a series of ethylene based random copolymers where the binding group is modified, and two diblock copolymer systems where the blocks have different intrinsic mobilities and surface interactions. The thesis begins by looking at the structures formed by the adsorption of poly (ethylene-co-acrylic acid) (PEA), poly (ethylene- co-vinyl alcohol) (EVOH), poly (ethylene-co-vinyl acetate) (EVA), and polyethylene (PE) on metal oxide powders (zirconia and alumina). NMR spectroscopy, FTIR-PAS, and TGA were used to characterize the surface behaviour of the systems with comparisons made between the bulk and adsorbed copolymers. 13C CPMAS, 1H and T 1 relaxation measurements were all recorded with the aim of correlating the microscopic structure of the surface with changes in NMR data. The chain conformation of adsorbed ethylene copolymers was found to strongly depend on the binding strength of the polar sticker groups with the substrates. / The chain dynamics of adsorbed diblock copolymers in the dry state are reported for the first time. Poly (styrene)-b-poly ( t-butyl acrylate) (PS-PtButA) and poly (styrene)-b-poly (acrylic acid) (PS-PAA) were selected to vary both the block size and the binding strength. Once again the primary surface characterization methods are NMR spectroscopy, FTIR-PAS, and TGA. 13C CPMAS, 1H, T1, and T1rho relaxation measurements were all recorded with the aim of correlating the surface structures with changes in NMR data. For the most part, the observed trends in the chain mobilities of the anchor (PAA) and buoy (PS) blocks with block size can be correlated with the predicted mushroom, intermediate and extended brush structures which collapse upon removal of the solvent. However, the chain mobility of the PS buoys decreases with increasing anchor block size. Although the chain mobility of the PS buoys are moderately enhanced relative to the bulk state, the mobility is sufficiently restricted to comfirm the picture of a thin glassy layer with adhesive properties similar to the surface of bulk polystyrene. / The diblock copolymers poly (2-vinylpyridine), poly (isoprene)- b-poly (2--vinylpyridine), (PI-P2VP) and poly (isoprene)- b-poly (4-vinylpyridine) (PI-P4VP) were selected to complement the PS-PAA system as both systems have been studied by surface force microscopy. The large contrast in chain mobilities of the PI and PVP blocks allowed spectral editing through variation of the 13C cross polarization parameters. The trends in mobility with block size differ from that of PS-PAA in that the segmental mobility of the buoys increases with anchor block size as expected. The chain mobility of the collapsed PI brushes is significantly enhanced as compared to the bulk state, again supporting the interpretation of surface microscopy studies which require an entropically unfavorable flattened, yet rubbery, surface structure.

The topology and dynamics of biomolecules are intricately linked with their biological function. The focus of this thesis is the NMR-based measurement of topology and dynamics in biomolecular systems, and methods of measuring immersion depth and orientation of membrane-associated molecules. In detergent micelles and lipid bilayers, the local concentrations of hydrophobic and hydrophilic molecules are a function of their bilayer immersion depth. For paramagnetic molecular oxygen or metal cations, the magnitudes of the associated paramagnetic isotropic contact shifts and relaxation rate enhancements (PREs) are therefore depth-dependent. NMR measurements of these effects reveal the immersion depth of bilayer- or detergent-associated molecules. This work first explores transbilayer oxygen solubility and thermodynamics, as measured from contact shifts and PREs of the constituent lipid molecules in the presence of 30 bar oxygen. Contact shifts revealed the transmembrane O2 solubility profile spans a factor of seven across the bilayer, while PREs indicated that oxygen partitioning into bilayers and dodecylphosphocholine (DPC) micelles is entropically driven. Next, this work describes how paramagnetic effects from molecular oxygen and Ni(II) cations may be employed to study the immersion depth and topology of drug and protein molecules in DPC micelles. In one study, the positioning of the amphipathic drug imipramine in micelles was determined from O2- and Ni(II)-induced contact shifts. A second study, relying solely on O2-induced PREs, determined the tilt angles and micelle immersion depths of the two alpha helices in a monomeric mutant of the membrane protein phospholamban. A third study utilized 19F NMR to explore the importance of juxtamembraneous tryptophans on the topology of the membrane protein synaptobrevin, via O2-induced contact shifts and solvent-induced isotope shifts of a juxtamembraneous 19F-phenylalanine. Comparison of synaptobrevin constructs with zero, one, and two juxtamembraneous tryptophans revealed that while one tryptophan is sufficient to ‘anchor’ the protein in micelle, the addition of a second tryptophan dampens local dynamics. These solution state NMR studies demonstrate how paramagnetic effects from dissolved oxygen, complemented with measurements of local water exposure, provide detailed, accurate descriptions of membrane immersion depth and topology. These techniques are readily extended to the study of a wide range of biomolecules.

Shaped pulses can be used for uniform spin-1 excitation. The effects of the pulses on spin-1 excitation is seen as distortion of two types: phase distortions and amplitude distortions. By reducing the distortions a spin-1 excitation becomes more uniform. In the case of time-symmetric shaped pulses, spin-1 excitation is free of phase distortions. The spin-1 excitation in that case can be made uniform over a larger frequency bandwidth. The number of possible shaped pulses is so large that a computer-aided search is needed to find the desirable shaped pulses. A theoretical analysis is used to find the connection between a shaped pulse and the corresponding spin-1 excitation. The theoretical analysis in density matrix formalism gives the spin-1 excitation in closed-form expressions that are too complicated. In such a case the connection between a shpaed pulse and spin-1 excitation is not straightforward. A brute-force search for a desirable shaped pulse can consume too much computer time and thus time the scope of the search. By using the formalism of quaternions in the theoretical analysis, spin-1 excitation is presented in simple closed form expressions. It is then shown tht if the choice is limited to time-symmetric shaped pulses then these closed form expressions become much simpler. It is also shown that a spin-1 excitation is free of phase distortions in that case. These simple closed form expressions can be used as the building blocks of a much more concise program code for the computer aided search. As a result a computer aided search for a desirable shaped pulse becomes much faster in speed and larger in scope. More shaped pulses for improved spin-1 can be found. / xiii, 99 leaves : ill. ; 28 cm.

High-resolution one-dimensional 1H, 19F, 31P and 13C MAS NMR experiments were used in a morphological study of solvent-cast and heat-treated poly[bis(trifluoroethoxy)phosphazene] (PBFP). Deconvolution analyses performed on all Nuclear Magnetic Resonance (NMR) spectra are presented. These results suggest the presence of broad and narrow overlapping components at ambient temperature, which were assigned to the crystalline, amorphous and the mesophase regions within the polymer, respectively. The number of signals in the spectra was independently verified using 1H, 19F and 13C Discrimination Induced by Variable Amplitude Minipulses (DIVAM) nutation experiments. Deconvolution analyses showed that heat-treatment increases the overall crystallinity of the solvent-cast PBFP. Further studies conducted on two preparations of the polymer showed significant differences in crystallinity due to variations in the reaction conditions. Magic-Angle Spinning (MAS) NMR spectra of PBFP obtained via living cationic polymerization at ambient temperature indicated that the polymer contains mostly amorphous and mesophase regions with only a small contribution from the crystalline domain. Variable-temperature 31P NMR experiments suggested that the thermotropic transition occurs in a temperature range of 80ºC to 90ºC, where the crystalline signal disappears and a new signal due to a liquid crystalline phase emerges. Spin-lock 31P experiments provided rates of the transverse relaxation in the rotating frame for each signal, showing that the crystalline and the amorphous regions within the polymer are characterized by significantly different mobilities at ambient temperatures, while the v comparable degree of motion occurs between the amorphous and mesophase environments at temperatures above 90ºC. The process of thermal ring-opening polymerization of hexachlorocyclotriphosphazene was monitored using one-dimensional 31P MAS NMR at different stages of the reaction. The ratio between cyclic species and the high molecular weight poly(dichlorophosphazene) was seen to change over time. 31P NMR was seen to be a potentially valuable tool in monitoring rates of chain propagation, branching and cross-linking. Two-dimensional 31P homonuclear Radio-Frequency Driven Recoupling (RFDR) and Incredible Natural Abundance Double Quantum Transfer (INADEQUATE) MAS NMR experiments were first tested on the partially phenoxy-substituted hexachlorocyclotriphosphazene, and subsequently applied in the study of a preparation of the partially trifluoroethoxy-substituted poly(dichlorophosphazene). Very high resolution was obtained in the direct dimension due to the presence of low molecular weight species. Preliminary spectral assignments of all of the observed signals were made on the basis of both known chemical shifts of the related species, and the through-space and through-bond phosphorous-phosphorous connectivities. / xiii, 188 leaves : ill. ; 29 cm

Trimethyltin fluoride (Me3SnF) is a useful fluorinating agent in organometallic chemistry. Its solid-state structure has been investigated by X-ray crystallography showing a polymeric fluorine-bridged structure. Disorder, however, has precluded the accurate refinement of all structural parameters. In order to obtain accurate structural information, trimethyltin fluoride was investigated using high-resolution 13C, 19F, and 119Sn solid-state NMR spectroscopy using a four-channel HFXY capability. The 119Sn{1H} solid-state NMR spectrum agrees with pentacoordination about Sn in this compound. The high-resolution 119Sn{19F, 1H}, 13C{1H,19F} and 19F{1H} NMR spectra offer unambiguous determination of 1J(119Sn-19F) and 1J(119Sn-13C) coupling constants. Furthermore, the analysis of the 119Sn{19F, 1H}, 119Sn{1H}, and 19F{1H} MAS spectra as a function of spinning speed allowed for the determination of the 119Sn CSA and J anisotropy, as well as the 119Sn-19F dipolar couplings. These were determined via SIMPSON simulations of the 13C, 19F, and 119Sn NMR spectra. Finally the 119Sn{19F, 1H} revealed fine structure as the result of 119Sn-117Sn two bond J-coupling, seen here for the first time. Sulfur tetrafluoride can act as a Lewis acid. Claims had been presented for the formation of an adduct between SF4 and pyridine, but no conclusive characterization had been performed. In the present study, adducts of SF4 with pyridine, lutidine, 4-picoline and triethylamine were prepared and characterized by low-temperature Raman spectroscopy. Sulfur tetrafluoride also acts as a fluoride-ion donor towards strong Lewis acids, such as AsF5 and SbF5, forming SF3 + salts. Variable-temperature (VT) solid-state 19F NMR spectroscopy showed that SF3 +SbF6 – exists in three phases with phase transitions at ca. –45 and –85°C, while SF3 +AsF6 – exists only as one phase between +20 and –150 °C. The phases of SF3 +AsF6 – were also characterized by VT Raman spectroscopy. / xvi, 170 leaves : ill. (some col.) ; 29 cm