Developments and Applications of Two-Dimensional Correlation Solid-State NMR Techniques

点击翻译按钮获取中文摘要

1. The NMR spectrometer was improved for measurements of two-dimensional wideline spectra. Asimulation program was developed for analyzing two-dimensional wideline spectra.2. Amethod for measurements of two-dimensional wideline spectra due to the chemical shift tensors of two C^<13>N nuclei and their dipolar interactions was developed. It was applied to DL-mandelic acid with 10%-doubly-enriched methin and carboxyl carbons ; the principal values and principal axis directions of the two chemical shift tensors and the bond length between the two carbons were obtained from the experiment and the spectral simulation.3. A general simulation program was developed by which spectra or magnetization behavior of a homonuclear or heteronuclear system in a static (powder or single crystal) or rotating sample for various pulse sequences (involving finite pulse width effects) of 1D or 2D NMR can be calculated without approximation theories.4. In the cholic acid inclusion compound enclathrating gamma-valerolactone with C^<13>N-enriched methyl, two-dimensional exchange NMR was done ; cross peaks between the C^<13>NH_3 signals of the S and R enantiomers of gamma-valerolactone were observed. This origin was concluded to be spin diffusion between the two enantiomers. This fact indicates that the S and R enantiomers are microscopically mixed in the cholic acid channels, denying the reported result of X-ray diffraction that only the S enantiomer is enclathrated.5. The two-dimensional C^<13>N chemical shift/C-H dipolar powder pattern of enriched indole-4 carbon in L-tryptophan was measured under off-magic angle spinning. From the results, the principal values and principal axis directions of the C^<13>N chemical shift tensor and the C-H bond distances were determined.