Temperature-Triggered Self-Assembled Structural Transformation: from Pure Hydrogen-Bonding Quad-rilateral Nano-Network to Trihexagonal Structures

The rational design and adequate control of structures of molecular building blocks plays an im-portant role in the fabrication of desired supramolecular nano-structures at interfaces. In this study, the formation of a pure hydrogen-bonding co-assembly supramolecular nano-network on a highly oriented pyrolytic graphite (HOPG) surface was demonstrated by means of scanning tunneling mi-croscope (STM). Thermal annealing process was conducted to monitor the temperature triggered structural transformation of the self-assembled nano-network. Based on careful measurements on the single molecule level STM images, as well as the density functional theory (DFT) calculations, the formation mechanism of the formed nano-arrays was proposed. The results have great signifi-cance in regard to controlled construction of complex nano-structures on surface.