A Precursor for Chiral Separation during Crystallization

为了了解NaClO_3在结晶过程中的手性对称性破缺，我们用偏光显微镜直接观察了水溶液中结晶的初始阶段。首次在原位观察到了非手性亚稳相的结晶及其向手性立方相的转变。通过低温单晶X射线结构分析，分析了非手性亚稳相的晶体结构。非手性亚稳相为单斜晶系，a=8.42，b=5.26，c=6.70A，109.71O，空间群为P21/a，随着空间群的增大，非手性单斜晶转变为手性立方晶体，表明非手性相是手性相的先驱体。

To understand the chiral symmetry breaking during crystallization of NaClO3, we directly observed the initial stage of crystallization from an aqueous solution by usingpolarized-light microscopy. Crystallization of an achiral metastable phase and its transformation into a chiral cubic phase were observed in situ for the first time. The crystal structure of the achiral metastable phase was analyzed by cryogenic single-crystal X-ray structural analysis. The achiral metastable phase was monoclinic with a = 8.42, b = 5.26, c = 6.70 A, and = 109.71o, space group P21/a. As they grew larger, the achiral monoclinic crystals transformed into chiral cubic crystals, showing that the achiral phase acts as aprecursor of the chiral phase.