Disappearing and reappearing polymorphism in p-methylchalcone
Disappearing and reappearing polymorphism in p-methylchalcone
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DOI：
10.1021/cg7007733
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发表时间：
2008-01-01
影响因子：
3.8
通讯作者：
Henck, Jan-Olav
中科院分区：
文献类型：
--
作者：
Barsky, Inna;Bernstein, Joel;Henck, Jan-Olav
已经获得了对甲基查耳酮的一种稳定形式（形式I）和两种亚稳定形式（形式II和IV），其中形式II先前已被报道为消失的多晶型物。为了防止熔点为89-91 ℃的II型转化为稳定型，在不含稳定型晶种的条件下制备。偶然发现IV型为在II型粉末的制备中出现的单晶。还通过光学显微镜、差示扫描量热法（DSC）、变温粉末X射线衍射和光谱分析表征了形式I和II。这三种形式的晶体结构已经解析，形式I和IV通过单晶方法，形式II通过同步加速器粉末衍射。这项调查强调了这样一个事实，即再现实验结果的挑战（即，特定晶形的产生）可以通过系统地寻找新的条件来克服，在所述新的条件下可以重新获得先前获得的结果。
One stable form (Form I) and two metastable forms (Forms II and IV) of p-methylchalcone have been obtained, with Form II having previously been reported to be a disappearing polymorph. To prevent the conversion of Form II, which has a melting point of 89-91 degrees C, into the stable form it was produced in conditions free from seeds of the stable form. Form IV was discovered serendipitously as a single crystal that appeared in the preparation of a powder of Form II. Forms I and II have also been characterized by optical microscopy, differential scanning calorimetry (DSC), variable temperature powder X-ray diffraction, and spectroscopic analysis. The crystal structures of these three forms have been solved, Forms I and IV by single-crystal methods and Form II from synchrotron powder diffraction. This investigation highlights the fact that the challenges of reproducing experimental results (i.e., the production of a particular crystal form) may be overcome by a systematic search for new conditions under which previously obtained results can be regained.