Programmable binary crystallization behaviors assisted by hydrogen bond on HOPG surface

Crystallization behaviors of 1,3,5-tri(1H-benzo[d]imidazol-2-yl) benzene (BTIB), gallic acid derivative (A10), and their hydrogen-bonded complex BTIB/A10 on Highly Oriented Graphite(HOPG) surface were studied by scanning tunneling microscope (STM) in combination with density functional theory (DFT) calculations. Single component BTIB self-assembled into porous and linear nanostructures, and A10 aggregated into linear nanostructure. Induced by the intermolecular interactions, an ordered BTIB/A10 nanostructure with the molecular ratio of 1:3 was in situ obtained and identical to the bulk assembly structure. When 1,3,5-Tris(4-carboxyphenylethynyl) benzene (H₃BTE) or 1,3,5-tris(10-carboxydecyloxy)-benzene (TCDB) instead of A10 was adopted, porous nanostructure with the molar ratio of 1:1 was in situ prepared in BTIB/H₃BTE and BTIB/TCDB system respectively, which indicated the regulatory effect of the number of aromatic acids’ carboxyl groups on the co-assemblies of BTIB and aromatic acids. Simultaneously, the flexible connection groups between the three carboxyl groups and the central benzene ring in TCDB resulted in the formation of another co-assembly nanostructure in BTIB/TCDB system, which was different from the BTIB/H₃BTE system. These results would be contributed to deepening the understanding of the interfacial crystal behaviors and probably providing an efficient pathway of regulating the structures of binary hydrogen-bonded crystals.