Polymorph evolution during crystal growth studied by 3D electron diffraction
Polymorph evolution during crystal growth studied by 3D electron diffraction
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DOI：
10.1107/s2052252519016105
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发表时间：
2020-01-01
期刊：
影响因子：
3.9
通讯作者：
Parsons, Simon
中科院分区：
文献类型：
--
作者：
Broadhurst, Edward T.;Xu, Hongyi;Parsons, Simon
三维电子衍射（3DED）已被用来跟踪多晶型的演变，从水溶液中结晶甘氨酸。在环境条件下存在的甘氨酸的三种多晶型物遵循稳定性顺序β <α <γ。最不稳定的β多晶型物在前3分钟内形成，但仅在1分钟后就开始产生α形式。这两种结构可以确定从连续旋转电子衍射数据收集在小于20秒的晶体厚度类似于100 nm。尽管γ-型在化学上是最稳定的多晶型，但动力学有利于α-型，其在长时间静置后占主导地位。在同一样品中，还观察到一些β和一个γ多晶型物的微晶。
3D electron diffraction (3DED) has been used to follow polymorph evolution in the crystallization of glycine from aqueous solution. The three polymorphs of glycine which exist under ambient conditions follow the stability order beta < alpha < gamma. The least stable beta polymorph forms within the first 3 min, but this begins to yield the alpha-form after only 1 min more. Both structures could be determined from continuous rotation electron diffraction data collected in less than 20 s on crystals of thickness similar to 100 nm. Even though the gamma-form is thermodynamically the most stable polymorph, kinetics favour the alpha-form, which dominates after prolonged standing. In the same sample, some beta and one crystallite of the gamma polymorph were also observed.