ELECTROCHEMICAL STUDIES OF THE TERMINALLY SUBSTITUTED ALKANETHIOL MONOLAYERS FORMED ON A GOLD ELECTRODE - EFFECTS OF THE TERMINAL GROUP ON THE REDOX RESPONSES OF FE(CN)6-N-3-, RU(NH3)H-6-3+ AND FERROCENEDIMETHANOL

Self-assembled monolayers of the alkanethiols having OH, COOH and NH2 terminal group were formed on a gold electrode via a sulfur attachment . The effects of their terminal groups on the redox responses of Fe(CN )63-, Ru(NH3)63+ and 1,1'-ferrocenedimethanol (FcDM0) aqueous solution s were investigated by cyclic voltammetry. The voltammetric response o f Fe(CN)63- was decreased in the order of NH2 much greater than OH > C OOH terminal group. In contrast, the response of Ru(NH3)63+ was increa sed in the order of NH2 < OH < COOH. In the case of FcDM0, the respons e was in the order of COOH > OH > NH2. These results were discussed in relations to the effect of charged terminal group on (a) the shift of the potential drop across the diffuse layer and (b) the change of the concentration of redox species at the electrode surface which is caus ed by the electrostatic interaction between the terminal group and ion ic redox species.