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Bis(2-methyl-8-quinolinolato)-(2,6-dimethylphenolate)aluminum is a newly synthesized material suitable for manufacturing organic light-emitting devices (OLED). NMR parameters such as chemical shift, dipolar and quadrupolar tensors are intimately related to the electronic and geometric structures which are important for understanding its physical and chemical properties. In this work, we report the solid state NMR studies of this material. By using two-field (corresponding to proton resonance frequencies of 200 MHz, 500 MHz , respectively) 1D 1H MAS, 27Al MAS, 1H/13C CP/MAS and 2D 13C nutation MAS techniques, the chemical shift tensors of 13C and quadrupolar coupling constant of 27Al have been obtained. The relationship between these values and the light-emitting properties of this material is discussed.

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The major directions of this thesis involve (1) the synthesis, immobilization, and characterization of tridentate phosphine linkers on silica, (2) the study of unprecedented Si2C bond cleavage in Rh and Ir phosphine complexes, and (3) the study of performance polymers with solid2state NMR techniques. First a brief overview of solid2state NMR and its relevance to the various areas of chemistry covered in this thesis is given. Following the synthesis, immobilization, and characterization of tridentate phosphine ligands, EtOSi[(CH2)nPPh2]3 (n = 4, 7, 11) and [MeP((CH2)nPPh2)3]+I? (n = 4, 7, 11) on silica is detailed. Both, immobilization by electrostatic interactions and by a covalent siloxane bond to the support, is studied and compared. Ligand exchange with Wilkinson?s catalyst affords immobilized Rh complexes. These materials are applied to catalytic olefin hydrogenation. In either case active hydrogenation catalysts are obtained that can easily and efficiently be recycled up to 30 times. Detailed investigations reveal that irrespective of the linkage to the support the catalysts consist initially of well2defined molecular species that form supported Rh nanoparticles with a narrow size distribution in the course of the catalytic reaction. The nanoparticles are active hydrogenation catalysts as well, and no metal leaching into solution is detected. The reaction of the tridentate phosphine ligands EtOSi[(CH2)2PPh2]3 and MeSi[(CH2)2PPh2]3 with Rh and Ir complexes is investigated. This reaction does not lead to the anticipated Wilkinson2type complexes with the metal in the +I oxidation state, but instead to oxidative addition of the C(sp3)2Si bond to Rh or Ir centers to yield octahedral complexes with the metal in the +III oxidation state. These complexes are fully characterized by multinuclear NMR in solution and in the solid state. Preliminary density functional theory (DFT) calculations corroborate the preference for oxidative addition. Subsequently the study of performance thermoplastics which are important materials for the oil and gas industry is presented. The polymer morphology is studied by solid2state NMR techniques. Special attention is devoted to potential decomposition pathways at elevated temperatures for polyetheretherketone (PEEK) and polyphenylene sulfide (PPS) polymers. 13C CP/MAS (cross polarization with magic angle spinning) NMR and IR spectroscopy reveal that PEEK polymers show no detectable chemical change on the molecular level, while PPS polymers display signs of oxidation of the thioether group and branching via formation of ether, thioether, and biphenyl linkages. Furthermore, the water absorption of polybenzimidazole (PBI), polyetherketoneketone (PEKK), and their blend PEKK2PBI is studied. It is demonstrated that steam2treatment even at high temperatures and pressures does not cause chemical decomposition and that the changes, which are morphological in nature, are fully reversible.

NMR crystallography is a new and developing area. Unlike solution state NMR, solid state NMR has the potential for structural studies of large, motionally restricted biological macromolecules, such as proteins in crystals which may, or may not, diffract. However, finding the best and the most useful sample form and geometry is still a major obstacle to rapid progress. Little has been reported about protein sample preparation for any class of protein for NMR crystallography, mainly since the availability of NMR labelled proteins is still not routine, especially for eukaryotic membrane proteins. The amino acid L-glutamate is the major excitatory neurotransmitter in the brain. Details of glutamate binding to any of its main brain or sensory receptors are not well resolved at the atomic level. In an effort to resolve the glutamate binding mechanism by solid state NMR methods, full-length taste and brain mGluR4 were expressed in E. coli, but proved to be toxic for the cells. The ligand-binding domains (LBD) of mGluR4, with various fusions for the periplasmic expression and with various fusions for expression in the cytoplasm therefore, were used. Solubilisation and then purification of the LBD from inclusion bodies is still under way, no crystals of mGluR4 for NMR were, therefore, grown. Initial NMR spectra of labelled 13C, 15N and 17O glutamate have been recorded to verify sensitivity requirements. Using homology modelling, a model for the truncated version of the ligand binding domain of mGluR4 has been constructed as a basis for designing solid state NMR experiments to probe the ligand binding site in the receptor. Bacteriorhodopsin is a large membrane protein and a model for G-protein coupled receptors (GPCRs). Spectra of bacteriorhodopsin produced in H. salinarium in purple membrane are reported here and compared to spectra of the protein crystallised from bicelles. Optimal conditions for producing spectra suitable for spectral assignment are reported as an initial step towards spectral resolution. Three differently labelled samples of bacteriorhodopsin were prepared to test the applicability of the various assignment strategies and the effects of deuteration on quality of solid state NMR spectra of a large, crystalline membrane protein.

Solid-state Nuclear Magnetic Resonance (NMR)is one of the premiere biophysical methods that can be applied for addressing the structure and dynamics of biomolecules, including proteins, lipids, and nucleic acids. It illustrates the general problem of determining the average biomolecular structure, including the motional mean-square amplitudes and rates of the fluctuations. Lineshape and relaxtion studies give us a view into the molecular properties under different environments. To help the understanding of NMR theory, both lineshape and relaxation experiments are conducted with hexamethylbezene (HMB). This chemical compound with a simple structure serves as a perfect test molecule. Because of its highly symmetric structure, its motions are not very difficult to understand. The results for HMB set benchmarks for other more complicated systems like membrane proteins. After accumulating a large data set on HMB, we also proceed to develop a completely new method of data analysis, which yields the spectral densities in a body-fixed frame revealing internal motions of the system. Among the possible applications of solid-state NMR spectroscopy, we study the light activation mechanism of visual rhodopsin in lipid membranes. As a prototype of G-protein-coupled receptors, which are a large class of membrane proteins, the cofactor isomerization is triggered by photon absorption, and the local structural change is then propagated to a large-scale conformational change of the protein. Facilitation of the binding of transducin then passes along the visual signal to downstream effector proteins like transducin. To study this process, we introduce 2H labels into the rhodopsin chromophore retinal and the C-terminal peptide of transducin to probe the local structure and dynamics of these two hotspots of the rhodopsin activation process. In addition to the examination of local sites with solid-state 2H NMR spectroscopy, wide angle X-ray scattering (WAXS) provides us the chance of looking at the overall conformational changes through difference scattering profiles. Although the resolution of this method is not as high as NMR spectroscopy, which gives information on atomic scale, the early activation probing is possible because of the short duration of the optical pump and X-ray probe lasers. We can thus visualize the energy dissipation process by observing and comparing the difference scattering profiles at different times after the light activation moments.

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