Solid-state nuclear magnetic resonance of paramagnetic systems, graphite materials and amyloid peptide

Solid-State NMR (SSNMR) has been widely used as an important tool to characterize and identify organic compounds and biological systems. However, applications of high-resolution SSNMR to paramagnetic systems have been very limited because paramagnetic compounds often exhibit severe line broadening and large paramagnetic shifts. Recently, our group developed a new approach using very fast magic angle spinning (VFMAS) to study and characterize different paramagnetic compounds and other materials. This has opened an avenue to obtain structural information for different paramagnetic systems by 1H and 13C SSNMR. The work in this thesis demonstrates the applications of VFMAS to three classes of systems.;First, we applied the VFMAS techniques to paramagnetic polymorphs of Cu(II)(quinolinole)2, Cu(II) (Imidazole)2 and Cu(II) phthalocyanine. We were able to distinguish between these polymorphs both qualitatively and quantitatively. Assignments of these polymorphs were obtained experimentally and confirmed by ab-initio calculations.;Secondly, we utilized the properties of paramagnetic molecules, which often have short 1H T1 relaxation time, in order to increase the sensitivity of 13C SSNMR for non paramagnetic biomolecules using VFMAS methods. We specifically examined the application of doping paramagnetic CuEDTA molecules to the amyloid intermediate species found in misfolding of Abeta(1-40) peptide into amyloid fibrils. A 7 fold reduction of an experimental time was obtained with the use of small amounts of CuEDTA in 1D and 2D 13C SSNMR for the Abeta intermediate. Simple measurements of paramagnetic 13C T 1 relaxation rate enhancement to obtain supermolecular information for the Abeta(1-40) intermediates were also performed.;Third, we examined the possibility of obtaining structural information for amorphous graphene- and graphite-based materials using SSNMR methods. 13C labeled graphite oxide (GO) was used as a model system of these chemically modified graphenes. The detailed chemical structure of GO was revealed by our VFMAS methods. Qualitative and quantitative analysis for 13 C naturally abundant graphite nano-fibers by 13 C high resolution VFMAS SSNMR was also demonstrated. As a result of these studies, we believe that our VFMAS SSNMR methods can be widely used to study various systems ranging from polymorphs of large paramagnetic systems to non-paramagnetic biological macromolecules and nano-materials.