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

1.对核磁共振谱仪进行了改进，使之能测量二维宽谱。编制了二维宽谱分析的模拟程序.发展了一种测量两个C^ N核及其偶极相互作用的化学位移张量的二维宽谱的方法<13>。将其应用于甲次甲基和羧基双富集度为10%的DL-扁桃酸，通过实验和光谱模拟得到了两个化学位移张量的主值和主轴方向以及两个碳原子之间的键长.开发了一个通用的模拟程序，该程序可以在没有近似理论的情况下，计算一维或二维核磁共振不同脉冲序列（包括有限脉宽效应）下，在静态（粉末或单晶）或旋转样品中的同质或异质体系的光谱或磁化行为.在γ-戊内酯与富C^N甲基包合的胆酸包合物中<13>，进行了二维交换NMR，观察到<13>γ-戊内酯S和R对映体的C^ NH_3信号交叉峰。这一起源被认为是两种对映体之间的自旋扩散。这一事实表明S和R对映体在胆酸通道中微观上混合，否定了X射线衍射报道的仅S对映体被包合的结果。在<13>离魔角旋转条件下，测量了L-色氨酸中吲哚-4碳富集的二维C^ N化学位移/C-H偶极粉末谱。根据计算结果，确定了C^<13>N化学位移张量和C-H键长的主值和主轴方向。

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.