Formation of 2D Halogen Bond-Based Supramolecular Assemblies by 1,3,5-Trifluoro-2,4,6-triiodobenzene and 4,4'-Bipyridine N,N'-Dioxide on HOPG Surface.

Halogen bonding interactions are crucial in the design of 2D supramolecular assemblies. In this study, we introduce the N-oxide moiety as a halogen-bonding acceptor for the formation of 2D coassemblies. The monomers 4,4'-bipyridine N,N'-dioxide (BPYD) and 1,3,5-trifluoro-2,4,6-triiodobenzene (1,3,5-TFTIB) coassemble into well-ordered, close-packed nanoarchitectures on HOPG surfaces. BPYD forms both halogen and hydrogen bonds with 1,3,5-TFTIB, resulting in pentameric structural units. At high concentrations, these units pack into dense ordered structures. When octanoic or nonanoic acid is used as a solvent, the formation of a 3-component linear structure with the interdigitated solvent molecules between the linear-arranged pentameric units is observed at low concentrations of reactants.