Derollez Patrick, Dudognon Emeline, Affouard Frédéric, Danède Florence, Correia Natália T, Descamps Marc
Unité Matériaux et Transformations (UMR CNRS 8207), Université Lille 1, Sciences et Technologies, 59655 Villeneuve d'Ascq CEDEX, France.
Acta Crystallogr B. 2010 Feb;66(Pt 1):76-80. doi: 10.1107/S0108768109047363. Epub 2010 Jan 22.
Annealing of the quenched ibuprofen at 258 K yielded a new crystalline form, called phase II. Powder X-ray diffraction patterns of this phase II were recorded with a laboratory diffractometer equipped with an INEL G3000 goniometer and a curved position-sensitive detector CPS120. The starting structural model was found by a Monte-Carlo simulated annealing method. The final structure was obtained through Rietveld refinements with rigid-body constraints for the phenyl group and soft restraints on the other interatomic bond lengths and bond angles. The cell volume is 5% larger than that of the conventional phase I at 258 K. It is also shown that the orientation of the propanoic acid group is drastically changed with respect to phase I, leading to strong modifications of the orientation of the O-H...O hydrogen bonds with respect to the chains of dimers. These structural considerations could explain the metastable character of this phase II.
将淬灭的布洛芬在258 K下进行退火处理，得到了一种新的晶型，称为II相。使用配备INEL G3000测角仪和弯曲位置敏感探测器CPS120的实验室衍射仪记录了该II相的粉末X射线衍射图谱。通过蒙特卡罗模拟退火方法找到了初始结构模型。最终结构是通过Rietveld精修得到的，对苯基采用刚体约束，对其他原子间键长和键角采用软约束。在258 K时，晶胞体积比传统的I相大5%。还表明，丙酸基团的取向相对于I相发生了剧烈变化，导致O-H...O氢键相对于二聚体链的取向发生了强烈改变。这些结构上的考虑可以解释该II相的亚稳特性。
