Effect of C-H•••F and O-H•••O hydrogen bonding in forming self-assembled monolayers of BF2-substituted β-dicarbonyl derivatives on HOPG:: STM investigation

The role of hydrogen bonding in forming self-assembled monolayers of two BF2-substituted beta-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 (21)) 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 center dot center dot center dot F hydrogen bonding between the ortho carbon of the phenyl ring and the fluorine of the BF, group dominates the formation of the lamellae. On the other hand, the O-H center dot center dot center dot 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.