Symmetry Breaking in Molecular Crystal Structures

分子晶体结构的对称性破缺

• 批准号: EP/E031153/1
• 负责人: Jonathan Steed
• 金额: $ 39.3万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE031153%2F1
• 关键词: Symmetry; Breaking; Molecular; Crystal; Structures

This project aims to understand and manipulate crystal packing effects and crystal structure based on a parameter termed Z'. Broadly, Z' represents the number of molecules it takes to produce a building block that will tesselate in space to produce a crystal structure. For most molecular compounds Z' = 1 and hence the few that have Z' > 1 (8.8% of known structures of small organic molecules) are exceptions in some way. We believe that the exceptions prove the rule. Why is it that this subset of compounds do not pack in a normal way? What is special about them? It is the primary focus of this proposal that in order to understand crystal packing it is not merely instructive, but vital to go beyond space group prediction and surveys, and to examine on a chemical basis, cases in which more than one molecule occupies the crystallographic asymmetric unit (Z' > 1). By definition, interactions between such molecules are not of the usual crystallographic symmetry and thus indicate cases in which a supramolecular synthon (a crystal packing interaction of predictive utility) is sufficiently robust to buck the trend. Moreover, these structures can sometimes be interpreted as 'fossil relics of the fastest growing crystal nucleus' and hence can also provide fundamental insight into crystal nucleation and growth processes.

这个项目的目的是理解和操纵基于参数Z'的晶体堆积效应和晶体结构。广义地说，Z'代表了产生一个在空间中镶嵌形成晶体结构的构件所需的分子数量。对于大多数分子化合物来说，Z' = 1和少数具有Z' > 1的分子（占已知小有机分子结构的8.8%）在某种程度上是例外。我们相信例外证明规则。为什么这类化合物不以正常方式堆积？它们有什么特别之处？本提案的主要焦点是，为了理解晶体堆积，它不仅具有指导意义，而且至关重要的是超越空间群预测和调查，并在化学基础上检查多个分子占据晶体不对称单元（Z' > 1）的情况。根据定义，这类分子之间的相互作用不具有通常的晶体对称，因此表明在这种情况下，超分子合成（具有预测效用的晶体堆积相互作用）足以抵御这种趋势。此外，这些结构有时可以被解释为“生长最快的晶核的化石遗迹”，因此也可以为晶体成核和生长过程提供基本的见解。

项目成果

Designing Co-Crystals of Pharmaceutically Relevant Compounds That Crystallize with Z ' > 1

设计 Z > 1 结晶的药物相关化合物的共晶

• DOI: 10.1021/cg8009089
• 发表时间: 2008
• 期刊: Crystal Growth & Design
• 影响因子: 3.8
• 作者: Anderson K