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pb(111)表面上五螺烯单层中同手性到异手性的结构相变
首发时间：2025-02-28
摘要：手性分离作为外消旋体系结晶过程中的核心科学问题，其本质在于揭示结晶成核阶段分子手性识别的动态机制。本研究基于亚分子分辨率扫描隧道显微镜（stm），系统研究了五螺烯分子在pb(111)表面手性分离的动态演变过程。研究发现，在低覆盖度下（低于0.3 ml），分子与衬底之间的吸附构型不稳定，导致二维无序气态相的形成。随着分子覆盖度的不断增加，分子通过自发手性分离，先后形成了以范德华同手性二聚体为基本单元的同手性蜂窝状网格结构和同手性对映体交替排列的外消旋棋盘结构。当覆盖度超过1 ml时，增强的分子间π-π堆积作用驱动体系重构，最终形成由直立异手性二聚体组成的外消旋相。该工作在分子尺度揭示了外消旋体系结晶过程中手性分离的动态演变路径，为手性晶体工程和分子自组装调控提供了重要的理论和实验依据。
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homochirality to heterochirality transition in pentahelicene monolayers on pb(111) surface
abstract：chiral resolution, as a fundamental scientific issue in the crystallization of racemic systems, fundamentally lies in elucidating the dynamic mechanisms of molecular chiral recognition during the nucleation stage. in this study, we systematically investigated the dynamic evolution of chiral separation in pentahelicene molecules on a pb(111) surface using submolecular-resolution scanning tunneling microscopy (stm). our findings reveal that at low coverage (<0.3 ml), unstable molecular-substrate adsorption configurations lead to the formation of a two-dimensional disordered gaseous phase. as molecular coverage increases, spontaneous chiral resolution drives sequential structural transitions: first into a homochiral honeycomb lattice stabilized by van der waals homochiral dimers, followed by a racemic checkerboard architecture with alternating homochiral enantiomers. upon exceeding 1 ml coverage, enhanced intermolecular π-π stacking triggers system reconfiguration, ultimately yielding a racemic phase composed of upright heterochiral dimers. this work elucidates, at the molecular scale, the dynamic pathway of chiral resolution during racemic crystallization, providing fundamental insights into chiral crystal engineering and the precise regulation of molecular self-assembly processes.
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pb(111)表面上五螺烯单层中同手性到异手性的结构相变
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