Molecular-Scale STM Observation for Self-Assembled Monolayers of Organic Thiols Containing Aromatic Ring as an End Group on Au(111)

Abstract

The discovery of molecular assemblies by the spontaneous adsorption of organic thiols on gold surfaces has proven to be a major advance for chemists and surface scientists in the research fields ranging from biomedicine, wetting, corrosion inhibition, molecular sensors, and nanopatterning. SAMs prepared from n-alkanethiols and -functionalized alkanethiols have been extensively studied to date. SAMs generated from aromatic thiols have attracted significant attention because of their properties compared to alkanethiol SAMs.1,2 The benzenethiol (BT) and benzeneethanethiol (BET) with an even unit have ordered SAMs show the lower density and line structures, whereas the benzenemethanethiol (BMT) and benzenepropanethiol (BPT) with an odd unit have ordered SAMs with the higher packing density domains and hexagonal structure. Although BT on gold generally does not form ordered SAMs, the well ordered BT SAMs were formed by increasing the solution temperature. In addition, BT and BET with an even unit SAMs show high quality of surface structure when both SAMs were formed at high solution temperature. And we can obtained 2-D ordered structures of BT SAMs using displacement and CHT SAM-based molecular template.