Environmental Effects on Redox Potentials of Viologen Groups Embedded inElectroactive Self-Assembled Monolayers

摘要

The electrochemical behavior of a new class of redox surfactant capable offorming electroactive, self-assembled monolayers was described. These compounds have redox moieties derived from the well known viologens, which display two distinct, reversible, one-electron couples. Their well behaved electrochemistry has lead to their use in a variety of studies ranging from electron transfer mediation to redox proteins to surface enhanced Raman studies of adsorption at electrode surfaces to the behavior of supermolecular assemblies at electrode surfaces. Our interest in understanding the influence of ionic interactions and solvation processes on redox behavior in such supermolecular assemblies lead us to synthesize several of these compounds and study their redox behavior in such assemblies using both electrochemical (cyclic voltametric, CV) and quartz crystal microbalance (EQCM) techniques. In this report we describe the strong dependence of the redox potential of the viologen moiety on its exact position within the assembly (i.e. with respect to the monolayer/electrode and monolayer/solution interfaces) and expand on our previous report of the dependence of electrochemical behavior on the type of anion present within the monolayer assembly.