固体酪氨酸^1^3C核磁屏蔽张量的实验与理论研究

应用最近发展的三回波二维慢速魔角旋转(Triple-Echo 2D MAT)实验方法测得了酪氨酸中各不等价碳的化学位移各向异性(CSA)张量主值。由从头计算获得的结果与实验值符合较好, 说明对于具有复杂结构的多原子体系, 对杂原子使用较小的基函数, 而对所关心的碳原子使用较大的基函数以提高计算精度, 这样可以达到既节省计算机空间与计算时间而不影响计算精度的目的。

Experimental and theoretical studies of the ^1^3C chemical shift tensors of solid-state L-tyrosine

The principal values of ^1^3C chemical shift tensors in powdered L-tyrosine were measured by a newly developed Triple-echo two-dimensional magic angle turning (MAT) experiment. Theoretical results obtained by using the gauge invariant atomic orbitals (GIAO) ab initio method are basically in agreement with the observed values. It is shown that in complex system like L-tyrosine, using a locally dense basis set with a large number of atomic basis functions for the carbon atom of interest and smaller sets of atomic functions for the other atoms can not only save the disk capacity and computing time but also produce satisfactory results.