Investigation of the structure of self-assembled monolayers of asymmetrical disulfides on Au(111) electrodes by electrochemical desorption

In this paper the reductive desorption for homogeneously mixed self-assembled monolayers (SAMs) on Au(lll) electrodes formed from an asymmetrical disulfide, i.e. butyl hexadecyl disulfide [C4H9-S-S-C16H33; H4H16] or decyl 2-(perifluorohexyl)ethyl disulfide [C10H21-S-S-(CH2)(2)(CF)(5)CF3; H10F8] was studied by cyclic voltammetry. Peak potentials of electrochemical desorption waves for the SAMs of these asymmetrical disulfides were different from those of SAMs containing only one of the constituent chains. The peak potential deviation from those of the single component SAMs suggests mixing of the two constituent chains in molecular dimensions. The ratio of the two constituent chains of the asymmetrical disulfide in each of the SAMs was considered to be exactly 1:1 when the homogeneously mixed SAMs were prepared under favorable conditions with respect to reaction concentration and temperature. We will discuss features of cyclic voltammograms in terms of the structure of the SAMs. (C) 1999 Elsevier Science S.A. All rights reserved.