Polyzois Hector, Guo Rui, Srirambhatla Vijay K, Warzecha Monika, Prasad Elke, Turner Alice, Halbert Gavin W, Keating Patricia, Price Sarah L, Florence Alastair J
EPSRC Future CMAC Research Hub, University of Strathclyde, Glasgow G1 1RD, U.K.
Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K.
Cryst Growth Des. 2022 Jul 6;22(7):4146-4156. doi: 10.1021/acs.cgd.2c00152. Epub 2022 May 24.
Polymorphism and crystal habit play vital roles in dictating the properties of crystalline materials. Here, the structure and properties of oxcarbazepine (OXCBZ) form III are reported along with the occurrence of twisted crystalline aggregates of this metastable polymorph. OXCBZ III can be produced by crystallization from the vapor phase and by recrystallization from solution. The crystallization process used to obtain OXCBZ III is found to affect the pitch, with the most prominent effect observed from the sublimation-grown OXCBZ III material where the pitch increases as the length of aggregates increases. Sublimation-grown OXCBZ III follows an unconventional mechanism of formation with condensed droplet formation and coalescence preceding nucleation and growth of aggregates. A crystal structure determination of OXCBZ III from powder X-ray diffraction methods, assisted by crystal structure prediction (CSP), reveals that OXCBZ III, similar to carbamazepine form II, contains void channels in its structure with the channels, aligned along the crystallographic axis, oriented parallel to the twist axis of the aggregates. The likely role of structural misalignment at the lattice or nanoscale is explored by considering the role of molecular and closely related structural impurities informed by crystal structure prediction.
多晶型现象和晶体习性在决定晶体材料的性质方面起着至关重要的作用。在此，报告了奥卡西平（OXCBZ）III型的结构和性质，以及这种亚稳多晶型的扭曲晶体聚集体的出现情况。OXCBZ III型可以通过气相结晶和溶液重结晶来制备。发现用于获得OXCBZ III型的结晶过程会影响螺距，在升华生长的OXCBZ III型材料中观察到最显著的影响，随着聚集体长度的增加，螺距也增加。升华生长的OXCBZ III型遵循一种非常规的形成机制，在聚集体的成核和生长之前会形成凝聚液滴并合并。通过粉末X射线衍射方法并借助晶体结构预测（CSP）对OXCBZ III型进行晶体结构测定，结果表明，与卡马西平II型类似，OXCBZ III型在其结构中含有空穴通道，这些通道沿结晶轴排列，与聚集体的扭曲轴平行。通过考虑晶体结构预测所揭示的分子和密切相关的结构杂质的作用，探讨了晶格或纳米尺度上结构错位可能发挥的作用。
