Self-assembly of binary molecular nanostructure arrays on graphite.

The controlled positioning and assembly of functional molecules into ordered nanostructures on surfaces depends on the interplay of multiple interactions on different strength and length scales. On metal surfaces, the relatively strong molecule-substrate interactions can constrain the molecules to adsorb in registry with the surface periodicity and lock them into specific adsorption sites. This can significantly reduce the structural tunability of the molecular nanostructure arrays formed. Inert graphite has a smooth potential-energy surface as well as relatively weak interfacial interactions with adsorbed molecules, and is therefore chosen as a supporting substrate for constructing molecular nanostructures with a high degree of controllability and tunability. The aim of this article is to highlight recent progress in the fabrication of self-assembled molecular nanostructures on inert graphite surfaces in ultra-high vacuum, with particular emphasis on the role of intermolecular interactions in the self-assembly process. We describe the formation of tunable two-dimensional (2D) binary molecular networks by directional and selective hydrogen bonding, as well as the templating effect of these 2D molecular networks, demonstrating the rational design and construction of long-range ordered 2D molecular nanostructures with desired functionality.