Steric Effects on the Formation of Self‐Assembled Monolayers of Alicyclic Thiol Derivatives on Au(111)

Abstract

To understand the steric effects on the formation of alicyclic thiolate self‐assembled monolayers on Au(111), the surface structures and reductive desorption behaviors of self‐assembled monolayers on Au(111) derived from cyclohexanethiol (CHT) and 1‐methylcyclohexanethiols (MCHT) were characterized using scanning tunneling microscopy (STM) and cyclic voltammetry. STM observations showed that the adsorption of CHT on Au(111) resulted in the formation of well‐organized monolayers with an unit cell of a = 14.5 ± 0.3 Å and b = 10.2 ± 0.3 Å, while the adsorption of MCHT with a methyl substituent bonded to the 1‐position of the cyclohexyl ring resulted in the formation of a disordered phase. The reductive desorption potentials for CHT and MCHT monolayers on Au electrodes were observed at −0.984 and −0.974 V, respectively. This difference in potentials can be attributed to the difference in lateral interactions, which depend on the structural order of monolayers.