Understanding Enantioselective Interactions by Pulling Apart Molecular Rotor Complexes.
Understanding Enantioselective Interactions by Pulling Apart Molecular Rotor Complexes.
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通过拉开分子转子复合物来了解对映选择性相互作用。
DOI：
10.1021/acsnano.9b01781
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发表时间：
2019
期刊：
影响因子：
17.1
通讯作者：
E. Charles H. Sykes
中科院分区：
文献类型：
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作者：
Amanda M. Larson;Kyle Groden;Ryan T. Hannagan;Jean;E. Charles H. Sykes
对映选择性相互作用是从生物机制到化学催化的许多重要现象的基础。在这方面，人们对在分子水平上了解这些效应非常感兴趣。表面为这些研究提供了一个平台，并有助于实现设计异质对映特异性界面的长期目标。在此，我们报告了一种由分子转子组成的模型系统，一种是本质上手性的（环氧丙烷），另一种是当吸附在表面上时变成手性的（丙烯）。扫描隧道显微镜 (STM) 测量使每个分子的手性能够直接可视化，并进行基于密度泛函理论的计算，以合理化分子转子的手性时间平均外观。虽然分子种类本身之间不存在有吸引力的分子间相互作用，但当混合在一起时，强烈倾向于形成 1:1 的杂分子对。我们证明，STM 尖端诱导的分子操作可用于组装这些复合物，检查每个物种的手性，从而询问它们的相互作用是否具有对映选择性。对这些数据的统计分析表明，本质上手性的环氧丙烷优先以 3:2 的比例与丙烯的一种对映体结合，从而证明非手性小分子的表面手性可以通过手性改性剂来控制。因此，这项研究揭示了之前报道的整体研究，其中气相非手性分子的手性种子层可以导致对映选择性吸附的放大。
Enantioselective interactions underpin many important phenomena from biological mechanisms to chemical catalysis. In this regard, there is great interest in understanding these effects at the molecular level. Surfaces provide a platform for these studies and aid in the long-term goal of designing heterogeneous enantiospecific interfaces. Herein we report a model system consisting of molecular rotors, one intrinsically chiral (propylene oxide) and one that becomes chiral when adsorbed on a surface (propene). Scanning tunneling microscopy (STM) measurements enable the chirality of each individual molecule to be directly visualized, and density functional theory based calculations are performed to rationalize the chiral time-averaged appearance of the molecular rotors. While there are no attractive intermolecular interactions between the molecular species themselves, when mixed together there is a strong preference for the formation of 1:1 heteromolecular pairs. We demonstrate that STM tip-induced molecular manipulations can be used to assemble these complexes, examine the chirality of each species, and thereby interrogate if their interactions are enantioselective. A statistical analysis of this data reveals that intrinsically chiral propylene oxide preferentially binds one of the enantiomers of propene with a 3:2 ratio, thereby demonstrating that the surface chirality of small nonchiral molecules can be directed with a chiral modifier. As such, this investigation sheds light onto previously reported ensemble studies in which chirally seeded layers of molecules that are achiral in the gas phase can lead to an amplification of enantioselective adsorption.