表面主客体复合自组装纳米结构的STM研究

Host-guest co-assembly on solid surfaces investigated by scanning tunneling microscopy

基于自组装的基本原理,以"自下而上"的方式在表面构筑主客体复合纳米结构是纳米科学与技术研究的重要内容之一,并在单分子科学和纳米电子学等领域具有重要意义.扫描隧道显微镜(STM)以其原位、实时、实空间和原子级分辨的优点,在主客体复合体系表面自组装的研究中发挥了不可替代的作用.在表面组装中,主客体分子之间有多种不同的复合模式,最常见的是客体分子填充于由主体分子构成的含有空腔的二维骨架结构,空腔的大小和对称性由主体分子的结构调节,客体分子通过尺寸匹配等效应填充;客体分子能够沿着主体分子形成的单层结构外延生长,在主体分子层上面形成第二层客体结构;此外,主体分子形成的组装结构能够根据客体分子的尺寸和形状做出相应的改变来适应不同的客体分子,进一步丰富了主客体复合结构的内涵.本文以主客体分子之间的复合方式为主线介绍固体表面构筑主客体复合纳米结构的最新进展.

The host-guest assembly on solid surface is a representative bottom-up approach to build up functional molecular nanostructures, and has attracted great attention in nanoscience and nanotechnology. With the great feature to get in-situ, real-time and real-space surface and interface structure information with sub-molecular resolution, scanning tunneling microscopy （STM） has been widely used to explore the host-guest co-assemblies on solid surfaces and reveal the underlying mechanism of the host-guest assembly process. Host and guest molecules can interact in different modes to form the host-guest assemblies. A common mode is that the host molecules self-assemble into two-dimensional nanoporous networks with well-ordered voids which can be filled with suitable guest molecules. Secondly, guest molecules can epitaxially assemble on the monolayer of host molecules to form a second layer with the structure mirroring that of host molecule adlayer. In some special cases, the nanostructures formed by host molecules can coordinately adjust themselves to accommodate guest molecules with different size and shape. Herein, we review the recent progress of the construction of host-guest co-assemblies on solid surfaces.