Cross-nucleation between ROY polymorphs
Cross-nucleation between ROY polymorphs
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DOI：
10.1021/ja056072d
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发表时间：
2005-12-14
影响因子：
15
通讯作者：
Yu, L
中科院分区：
文献类型：
--
作者：
Chen, SA;Xi, HM;Yu, L
晶型间的交叉成核是一种新发现的现象，对于理解和控制晶体的多型性具有重要意义。它与奥斯特瓦尔德的阶段定律和其他多形体系中的结晶理论相矛盾。我们研究了5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile(ROY)自发熔融结晶和种子熔融结晶的现象，ROY是目前已知结构中最具多晶性的体系。我们观察到Roy多态之间广泛的，有时是选择性的交叉成核。某些多态在没有其他多态的帮助下是不能成核的。新的多晶型被发现比最初的多晶型在热力学上或多或少是稳定的，但总是比最初的多晶型生长得更快或一样快。晶种的温度和表面特性影响交叉形核的发生。我们的结果表明，晶型体系的结晶路径不仅取决于初始成核，还取决于晶型之间的交叉成核和不同的晶型生长速率。这项研究发现了该家族第10个成员Roy的一个新的亚稳态多态。
Cross-nucleation between polymorphs is a newly discovered phenomenon important for understanding and controlling crystal polymorphism. It contradicts Ostwald's law of stages and other theories of crystallization in polymorphic systems. We studied the phenomenon in the spontaneous and seeded melt crystallization of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (ROY), currently the most polymorphic system of known structures. We observed extensive and sometimes selective cross-nucleation between ROY polymorphs. Certain polymorphs could not nucleate without the aid of others. The new polymorph was found to be more or less thermodynamically stable than the initial one but to always grow faster than or as fast as the initial one. The temperature and surface characteristics of the seed crystals affected the occurrence of cross-nucleation. Our results show that the pathway of crystallization in polymorphic systems is not determined solely by the initial nucleation, but also by cross-nucleation between polymorphs and the different growth rates of polymorphs. This study identified a new metastable polymorph of ROY, the 10th of the family.