Supramolecular Assemblies of 1,4-Benzene Diboronic Acid on KCl(001)

The self-assembly of benzene diboronic acid molecules on KCl(001) is investigated at room temperature by means of noncontact atomic force microscopy. When depositing the molecules on the freshly cleaved surface, the molecules self-assemble into an extended two-dimensional supramolecular phase driven by H-bonds. Theoretical calculations based on density functional theory show that the cohesion energy of the structure yields almost 1 eV per molecule. In combination with high-resolution structural analysis of the molecular layer and theoretical calculations, it is inferred that the growth of the supramolecular phase is made possible owing to the conformational adaptation of the molecule at the surface, which strengthens the intermolecular H-bonds, while avoiding the intermolecular steric hindrance. This work is the first experimental evidence of an extended H-bonded supramolecular network grown on a bulk insulator at room temperature.