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在半金属bi(111)表面上四联苯分子的手性自组装
首发时间：2023-08-24
摘要：本文利用低温扫描隧道显微镜(stm)研究了四联苯分子在半金属bi(111)表面上的超分子手性和自组装结构。实验发现，在低覆盖度下形成的纳米团簇中，四联苯分子有平躺和侧躺两种不同的吸附取向。在亚单层的覆盖度下，四联苯分子形成多畴的自组装单层结构。自组装单层的基本单元是由两个平躺分子和一个侧躺分子构成的三聚体。高分辩的stm图表明，平躺的四联苯分子具有平面化的非手性结构，而侧躺的四联苯分子具有扭曲的非平面手性结构，从而导致三聚体团簇具有超分子手性。有趣的是，在畴区内部相邻三聚体的手性总是相反；而在畴界两侧三聚体的手性保持相同，表明同手性的三聚体之间存在空间位阻作用。当覆盖度增加到一个满层时畴界不复存在，整个分子单层形成长程有序的消旋结构。此外，由于四联苯分子与半金属bi(111)衬底之间较弱的相互作用，无论是侧躺的分子还是平躺的分子，都容易受到针尖电场的影响发生平移或转动。上述研究结果为理解四联苯分子和半金属之间的相互作用，超分子手性和分子自组装结构之间的关联，实现分子-衬底界面结构的长程有序提供了重要信息。
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chiral self-assembly of p-quaterphenyl on semimetallic bi(111) surface
abstract：the supramolecular chirality and self-assembly of p-quaterphneyl on the semimetallic bi(111) surface have been investgated with a low temperature scanning tunneling microscopy (stm). it is found that there are flat-lying and edge-on molecules in the nanoclusters of p-quaterphneyl. in the submonolayer regime,p-quaterphneyl molecules form the self-assembled structure with multiple domains. the building bolcks of self-assemblies are molecular trimer with two flat-lying and one edge-on molecules. high-resolution stm images demonstrate that the flat-lying molecules have a planar achiral structure, while the edge-on molecules have a twisted chiral structure, which result in the supramolecular chirality of p-quaterphneyl strimers. interestingly, theneighboring trimers inside the domains reveal opposite chirality, while the same chirality appears for the trimers at the domain boundaries, indicating the steric hindrance between the trimers with same handedness. when the voerage is increased to full monolayer, the domain boundaries disappear from the self-assembled structure, which have the long-range ordering with racemates. moreover, due to the weak molecule-substrate interaction, both the flat-lying and the edge-on molecules can be moved or rotated under the electrical filed of stm tip. these results provide important information for the understadning of interaction between p-quaterphneyl and bi(111) surface, the correlation between the supramolecular chirality and self-assembly, and realization of the organic-metal interface with long-range order.
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在半金属bi(111)表面上四联苯分子的手性自组装
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