Is it usual to be unusual? An investigation into molecular conformations in organic crystals
Is it usual to be unusual? An investigation into molecular conformations in organic crystals
复制标题
平常就是不寻常吗？
DOI：
10.1039/c9ce02001b
复制
发表时间：
2020
期刊：
影响因子：
3.1
通讯作者：
Wright S
中科院分区：
文献类型：
--
作者：
Wright S
分子构象可以影响结晶固体的结构和性质。重要的固态现象，如构象多态性，来自于化合物以不同构象异构体结晶的能力。因此，非常需要一种容易地鉴定晶体构象是否被高度调节或可能对应于稀有构象异构体的方法。提出了一种从剑桥结构数据库（CSD）中的挠率分布识别分子晶体中异常构象的新方法。我们的方法允许识别扭转异常方面的构象调整和构象变化。作为该方法的一部分，计算来自CSD分布的两个新参数：Padjust和Pchange。根据DFT计算对这些参数进行了测试，以推导出有意义的CSD概率阈值，从而可以识别异常扭转。开发的方法，然后被用来调查不寻常的扭转分子晶体。我们发现CSD中10-13%的扭转是不寻常的，并且不寻常的构象调整比不寻常的构象变化更常见。
Molecular conformations can influence the structure and properties of crystalline solids. Important solid-state phenomena such as conformational polymorphism arise from the ability of compounds to crystallise in different conformers. A method to readily identify whether or not a crystal conformation is highly adjusted or may correspond to a rare conformer is, thus, very desirable. We present a new way of identifying unusual conformations in molecular crystals from distributions of torsions in the Cambridge Structural Database (CSD). Our method allows for identification of torsion unusualness with regards to conformational adjustment and conformational change. As part of this method, two new parameters derived from CSD distributions are calculated: Padjust and Pchange. These parameters were tested against DFT calculations for the derivation of meaningful CSD probability thresholds which allow for the identification of unusual torsions. The developed method was then used to investigate unusual torsions in molecular crystals. We found that between 10–13% of torsions in the CSD are unusual and that unusual conformational adjustment is significantly more common than unusual conformational change.