Formation of Tolane Self-Assembled Monolayers on Au(111): Effects of Chemical Structure and Solution Temperature

Abstract

Self-assembled monolayers (SAMs) formed by conjugated aromatic molecules on gold have drawn much attention as a result of their potential applications in molecular electronics. In this study, the surface structures and adsorption conditions of self-assembled monolayers (SAMs) formed by tolane compounds were examined by scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy (XPS). We found that tolane thioacetate (TTA) and tolane methylthioacetate (TMTA) on Au(111) can form two-dimensional ordered SAMs in a NH4OH basic solution. However, a small difference in chemical structure between TTA and TMTA shows large structural variations such as the formation of domains and vacancy islands as well as the adsorption condition of sulfur atoms. In addition, it is also revealed that the solution temperature plays a very important role in determining the surface structures of TTA and TMTA SAMs on Au(111) surface.