Solvent-dependent self-assembly of 4,7-dibromo-5,6-bis(octyloxy)benzo[c][1, 2,5] thiadiazole on graphite surface by scanning tunneling microscopy

Abstract

Solvent effect on self-assembly of 4,7-dibromo-5,6-bis(octyloxy)benzo[c][1, 2,5] thiadiazole (DBT) on a highly oriented graphite (HOPG) surface was investigated by scanning tunneling microscopy (STM) by using 1-phenyloctane, 1-octanoic acid, and 1-octanol as the solvents. Two different patterns were obtained in 1-phenyloctane and 1-octanoic acid, suggesting that the self-assembly of DBT was solvent dependent. At the 1-phenyloctane/HOPG interface, a linear structure was revealed due to the intermolecular halogen bonding. When 1-octanoic acid and 1-octanol are used as the solvents, the coadsorption of solvent molecules resulting from the hydrogen bonding between DBT and solvent made an important contribution to the formation of a lamellar structure. The results demonstrate that solvents could affect the molecular self-assembly according to the variational intermolecular interactions. © 2013 Bao Zha et al.