Solvent effect on the electrochemical behavior of self-assembled monolayers

The electrodes modified with 4-hydroxy-2-mercapto-6-methylpyrimidine(HMMP) monolayers were prepared in solvents acetone, dimethyl sulfoxide(DMSO), eth anol, dimethyl formamide(DMF) and water respectively, and their electrochem ical behavior for ascordic acid and dopamine were studied by cyclic voltamm etry, impedance spectroscopy and STM. The results confirmed that the solven t molecules could be trapped in the monolayers during the process of self-a ssembly, and the monolayers prepared with different solvents showed a diffe rent electrochemical behavior in electrocatalytic oxidation to ascordic aci d and dopamine. By the impedance analysis, exchange current density and cov erage of HMMP (Acetone)/Au electrode and HMMP(DMSO)/Au electrode were 1.14, 2.04 muA/cm(2) and 96.2%, 93.2%, respectively. STM images showed that the monolayers prepared with acetone and DMSO as solvent possessed different de grees of order and compactness.