Hughes Colan E, Hamad Said, Harris Kenneth D M, Catlow C Richard A, Griffiths Peter C
School of Chemistry, Cardiff University, Park Place, Cardiff, Wales, UK CF10 3AT.
Faraday Discuss. 2007;136:71-89; discussion 107-23. doi: 10.1039/b616611c.
We are engaged in a multidisciplinary study of fundamental aspects of the crystallization of organic molecular materials from solution, focusing on polymorphic systems under the recognition that such systems represent an ideal opportunity for obtaining a systematic understanding of competing pathways in crystallization processes. The range of techniques employed in this work are sensitive to structural properties on different length scales and are thus appropriate for mapping the changes that occur at different stages of the crystallization process, starting from the early aggregation events in solution (probed by solution-state NMR and molecular dynamics simulations, including studies of diffusion properties), leading to the growth of molecular aggregates (probed by small-angle neutron scattering), then the emergence of solid microcrystals dispersed in the crystallization solution (probed by small-angle neutron scattering and solid-state NMR) and finally the formation of the bulk solid crystalline phase (probed by powder X-ray diffraction). This paper reports preliminary results on the application of this multi-technique approach to study the crystallization of glycine (which has three known polymorphic forms under ambient conditions) from aqueous solution.
我们正在开展一项关于从溶液中结晶有机分子材料基本方面的多学科研究，重点关注多晶型体系，因为我们认识到此类体系是系统理解结晶过程中竞争途径的理想契机。本研究中使用的一系列技术对不同长度尺度的结构性质敏感，因此适用于描绘结晶过程不同阶段发生的变化，这些变化始于溶液中的早期聚集事件（通过溶液态核磁共振和分子动力学模拟探测，包括扩散性质研究），进而发展为分子聚集体的生长（通过小角中子散射探测），然后是分散在结晶溶液中的固体微晶的出现（通过小角中子散射和固态核磁共振探测），最后是块状固体结晶相的形成（通过粉末X射线衍射探测）。本文报道了将这种多技术方法应用于研究甘氨酸（在环境条件下有三种已知多晶型形式）从水溶液中结晶的初步结果。
