The self-assembly and structural regulation of a hydrogen-bonded dimeric building block formed by two NH···O hydrogen bonds on HOPG

The self-assembled behavior of an unsymmetric molecule (BCDTDA) with one imidazole group as center and benzoic acid group as functional group is studied, and the regulatory behaviors of coronene (COR) and three bipyridine derivatives (named BP, PEBP-C4 and PEBP-C8) on BCDTDA self-assembly structures are also investigated. Based on highly oriented pyrolytic graphite (HOPG) substrate, scanning tunneling microscopy (STM) is used to observe the variation of assembled behaviors at the solid-liquid interface. Because of the concentration effect, BCDTDA molecules can assemble into grids and Kagomés structures in the form of NH···O hydrogen bonded dimers. BCDTDA molecules still maintain dimeric structures in the regulation of COR and BP molecules to BCDTDA self-assembly. However, PEBP-C4 and PEBP-C8 destroy the structure of the dimers, and form a variety of co-assembled structures with BCDTDA. Different guest molecules coordinate the host molecules differently, which makes the experiment more meaningful. Combined with density functional theory (DFT) calculation, the discovery of molecular interactions provides a promising strategy for the construction of functional nanostructures and devices.