ELECTROCHEMICAL-BEHAVIOR OF AZOBENZENE SELF-ASSEMBLED MONOLAYERS ON GOLD

The self-assembly and electrochemical properties of a novel thiol-func tionalized azobenzene derivative were studied on gold electrodes by cy clic voltammetry. The compound was 4-ethoxy-4'-((N-(2 ''-mercaptoethyl )amino)carbonyl)azobenzene (C2AzoC2SH), which was synthesized using a simple and general technique by our laboratory. The C2AzoC2SH formed u niform and reproducible self-assembled monolayers (SAMs) on gold with a surface coverage of 4.21 x 10(-10) mol/cm(2). The SAMs showed voltam metric responses in a B-R buffer at a pH range of 3.2-8.6 that corresp onded to the two-electron, two-proton reduction-oxidation of azobenzen e. The voltammetric behavior was totally irreversible, exhibiting very large peak-to-peak splitting and other distortions. The dependence of apparent surface electrochemical rate constant on pH value has a V-sh ape, owing to the influence of protonation reactions on the multistepp ed reduction-oxidation of azobenzene functionality.