Drastic symmetry breaking in supramolecular organization of enantiomerically unbalanced monolayers at surfaces
Drastic symmetry breaking in supramolecular organization of enantiomerically unbalanced monolayers at surfaces
复制标题
DOI：
10.1038/nchem.295
复制
发表时间：
2009-08-01
期刊：
影响因子：
21.8
通讯作者：
Raval, Rasmita
中科院分区：
文献类型：
--
作者：
Haq, Sam;Liu, Ning;Raval, Rasmita
有相当大的兴趣在倾斜的手性传输，或'handedness'，从分子到超分子水平，使单手的超结构是从混合对映异构体系统创建。一种方法是将所有分子构建块的手性翻转为相同的手性。然而，操纵分子手性是不可能的非互变对映异构体，和机制，歪斜这样的系统是不清楚的。在这里，我们跟踪分子到超分子的手性转移在这样的系统在纳米尺度上探测分子单层表面。扫描隧道显微镜和理论模型表明，对映体的不平衡导致非线性对称性破缺的组织，驱动的构型熵效应。因此，多数对映体很容易组织成其上层结构，而少数则支离破碎，杂乱无章，从而阻碍了其上层结构的实现。这种效应为手性分离和对映选择性过程提供了新的策略，并可能有助于复杂物质从生物环境中的纯手性进化。
There is considerable interest in skewing the transmission of chirality, or 'handedness', from the molecular to the supramolecular level so that single-handed superstructures are created from mixed enantiomer systems. One approach is to flip the chirality of all the molecular building blocks to the same handedness. However, manipulation of molecular chirality is not possible for non-interconvertible enantiomers, and mechanisms that skew such systems are unclear. Here, we track the molecule-to-supramolecular chiral transfer in such systems at the nanoscale by probing molecular monolayers at surfaces. Scanning tunnelling microscopy and theoretical modelling show that enantiomeric imbalances lead to nonlinear symmetry breaking in organization, driven by configurational entropy effects. Thus, the majority enantiomer readily organizes into its superstructure with the minority left fragmented and disorganized, and thus impeded from realizing its superstructure. Such effects promise new strategies in chiral separations and enantioselective processes, and may have contributed to the homochiral evolution of complex matter from prebiotic environments.