Surface-Confined Monomers on Electrode Surfaces. 11. Electrochemical and Infrared Spectroscopic Characteristics of Aniline-Terminated Alkanethiol Monolayers on Au Electrochemically Treated in Nonaqueous Media

The stability and electrochemical properties in nonaqueous media of self-assembled alkanethiol monolayers containing an alkoxyaniline tail group tethered to a gold surface via a hexyl or heptyl chain were investigated. It was previously found that upon electrochemical oxidation in 1 M H2SO4, 2-(6-mercaptohexan-1-oxy)aniline (AnC6SH) and 2-(7-mercaptoheptan-1-oxy)aniline (AnC7SH) monolayers on Au give rise to surface-confined dimeric and oligomeric/polymeric anilines as well as surface-confined hydrolyzed aniline dimer. In the study at hand, AnC6SH/Au and AnC7SH/Au were electrochemically oxidized in 0.1 M LiClO4/CH3CN to discourage the formation of surface-confined hydrolyzed aniline dimer. The resulting voltammetry was compared to that observed for monolayers oxidized in 1 M H2SO4 and that of dimeric model compounds in 0.1 M LiClO4/CH3CN. Reflection−absorption infrared spectroscopy and electrochemical data reveal that upon oxidation in a nonaqueous electrolyte both AnC6SH/Au and AnC7SH/Au yield head-to-tail coupled, surface-confined oligomers and no detectable amounts of hydrolyzed products.