Formation of Self-Assembled Monolayers by Adsorption of Alkylthioacetates on Au(111) in Catalytic Tetrabutylammonium Cyanide Solution

Abstract

Surface structures and binding conditions of octylthioacetate (OTA) self-assembled monolayers (SAMs) on Au(111) formed in catalytic tetrabutylammonium cyanide (TBACN) solution were examined by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Molecular-scale STM imaging revealed that OTA molecules on Au(111) can form well-ordered SAMs in TBACN catalytic medium compared to in pure solvent or NH4OH catalytic medium. We found that SAM formation by alkylthioacetates on Au(111) strongly depends on experimental conditions for the deprotection of acetyl group. In addition, XPS measurements showed a strong S 2p peak at 162 eV for OTA SAMs on Au(111), implying that the SAMs were formed via chemical reactions between the sulfur atoms and gold surfaces.