Cheung Eugene Y, Harris Kenneth D M, Kang Ting, Scheffer John R, Trotter James
School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales.
J Am Chem Soc. 2006 Dec 13;128(49):15554-5. doi: 10.1021/ja063706n.
A prerequisite for the development of structure-reactivity correlations for photoreactive crystalline materials is to have detailed knowledge of the structural properties of the reactant crystalline phase. In some cases, however, the materials of interest can be prepared only as microcrystalline powders and are not amenable to structural characterization by single-crystal X-ray diffraction. This paper demonstrates the utility of modern powder X-ray diffraction techniques for obtaining structural understanding in such cases, leading to the development of structure-reactivity correlations. In particular, a series of three photoreactive organic salts are considered, which undergo the same photochemical asymmetric reaction but with high enantiomeric excess in two cases and low enantiomeric excess in the other case. The structural properties of the three salts determined from powder X-ray diffraction data are shown to provide a direct rationalization of these observations.
建立光反应性晶体材料的结构-反应性关联的一个先决条件是详细了解反应物晶相的结构性质。然而，在某些情况下，感兴趣的材料只能制备成微晶粉末，无法通过单晶X射线衍射进行结构表征。本文展示了现代粉末X射线衍射技术在这种情况下获得结构理解的实用性，从而建立结构-反应性关联。特别地，考虑了一系列三种光反应性有机盐，它们都经历相同的光化学不对称反应，但在两种情况下对映体过量率高，在另一种情况下对映体过量率低。从粉末X射线衍射数据确定的这三种盐的结构性质被证明可以直接解释这些观察结果。
