Electron-transfer mediation on poly-aryl dendrimer-modified electrodes

Abstract

Electrochemical properties of a dendrimer-modified electrode that was prepared by immobilization of ferrocenyl-terminated dendrimers on a poly-phenyl acetate anchoring layer were investigated in CH 2Cl 2. The anchoring layer was made by electro-grafting of the corresponding diazonium salt on a glassy carbon surface. The method allows the fabrication of a robust interface where the properties of the dendrimers are well-preserved. Moreover, the control of the layer properties as the permeation of molecules from the solution to the surface could be tuned up from only limited to totally blocked through the electrochemical conditions used during the electro-grafting of the anchoring layer. Detailed investigations performed with cyclic voltammetry and on different types of layers show that the modified electrode catalyses the oxidation of redox substrates. The process depends on the standard potential of the redox couple compared to that of the adsorbed dendrimer molecules. Experiments indicate that the electron exchange with molecules in solution takes place mainly at the dendrimer film–solution interface as the dendrimers inside the film permit the charge-transfer through the modified film to the carbon substrate. The interest of using robust electrode dendrimer relies on the possibility of large structural variations allowing the careful introduction of specific properties in the layer.