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···F hydrogen bonding between the ortho carbon of the phenyl ring and the fluorine of the BF₂ group 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. © 2007 American Chemical Society