Two-dimensional Structural Changes and Displacement of Cyclohexanethiol Self-Assembled Monolayers on Au(111)

Abstract

The spontaneous adsorption of cyclohexanethiol (CHT) containing a flexible cyclic ring CHT on Au(111) in a 1 mM ethanol solution at room temperature leads to long-range two-dimensional ordered SAMs, which can be a (5 2 10)R48 superstructure with a low density surface compared to alkanethiol SAMs with a ( 3 3)R30 . Recently, we found that the molecular packing structures and adsorption conditions of CHT SAMs on Au(111) are influenced by solution concentration, unlike the case of alkanethiol. These results may be due to a conformation change of CHT molecules in CHT SAMs having two energetically stable conformers, i.e., the equatorial and axial chair conformers. In addition, due to a low-packing density of CHT SAMs on Au(111), we expect that CHT molecules in SAMs can be easily exchanged by other incoming molecules. Although single-component benzenethiol (BT) or alkanedithiols (ADT) can not form ordered SAMs, we obtain two-dimensional (2D) ordered structures of BT and ADT SAMs using displacement and CHT SAM-based molecular template.