非手性的棒状分子在非手性表面形成的风车团簇

Pinwheel clusters of achiral rod-like molecules formed on achiral surface

利用低温STM研究了非手性的棒状并五苯分子在Bi(111)表面形成的手性风车团簇.在团簇内部,并五苯分子分别沿Bi(111)的3个对称轴方向平行排列,形成6个不同的分子带.在每个分子带中,相邻分子之间有一个滑移错位.当平行排列的分子数多于4时,滑移错位发生反向,形成弯曲的风车扇叶.我们认为,分子的滑移错位来自于分子之间的π-π相互作用;而滑移错位的反向是团簇内部的吸引力导致的密堆积的结果.这两种作用的竞争是形成手性风车团簇的微观机制.

The molecular arrangement and chirality of the self-assembly of pentacene on Bi（111） were investigated using scanning tunneling microscopy（STM）.Upon adsorption on Bi（111）,this achiral molecule spontaneously forms two types of chiral pinwheel clusters with opposite chirality.Within the clusters,each pentacene molecule is aligned in the symmetric axis of Bi（111）,resulting the formation of six molecular rows.In each row,the adjacent pentacene molecule is shifted along the long molecular axis.When the molecule number exceeding four,the shifting directions is reversed,lead to the formation of bent flabellum.The formation mechanism is attributed to the competition between ？Э？Рinteraction and the net attractive interaction among the pentacene molecules.