ELECTROCHEMICALLY ASSISTED SOL-GEL PROCESS FOR THE SYNTHESIS OF POLYSILOXANE FILMS INCORPORATING PHENOTHIAZINE DYES ANALOGOUS TO METHYLENE-BLUE - STRUCTURE AND ION-TRANSPORT PROPERTIES OF THE FILMS VIA SPECTROSCOPIC AND ELECTROCHEMICAL CHARACTERIZATION

A sol-gel process is directed toward an electrode surface via electroc hemical manipulation of the solubility of trimethoxysilyl group-modifi ed methylene blue in an aqueous environment. The process lasts for 2-3 h and results in electrode derivatization with a polysiloxane network incorporating methylene blue. Cross-linking (curing) is completed by drying the films at room temperature for 2 days. The concentration of the phenothiazine moieties in the resulting xero films was calculated at similar to 3.9 M, and the film density at similar to 2.6 g/cm(3). T he average distance between phenothiazine moieties is <5 Angstrom allo wing interactions between their pi-systems. The narrow pores between m onomer units restrict movement of hydrated charge-compensating ions, s o that the redox switching of the films depends upon the chemical iden tity of both the cation and anion of the supporting electrolyte. The f ilms retain the electrochromic and electrocatalytic properties of the parent dye; for example, gold electrodes derivatized with the film med iate reduction of cytochrome c at potentials close to its standard ele ctrochemical potential.