Effect of C−H···F and O−H···O Hydrogen Bonding in Forming Self-Assembled Monolayers of BF2-Substituted -Dicarbonyl Derivatives on HOPG:  STM Investigation

The role of hydrogen bonding in forming self-assembled monolayers of two BF2-substituted -dicarbonyl derivatives has been studied by scanning tunneling microscopy (STM). Both molecules spontaneously adsorb on HOPG surface and self-organize into well-ordered two-dimensional (2D) lamellae. The hydrogen bonding at different positions is found to have a significant impact on the self-assembled structures. On one hand, the C−H···F hydrogen bonding between the ortho carbon of the phenyl ring and the fluorine of the BF2group dominates the formation of the lamellae. On the other hand, the O−H···O hydrogen bonding between the neighboring carboxyl groups doubles the width of the lamellae. The present results provide significant information in understanding the noncovalent effect on molecular self-organization.