Immobilisation of Alkylamine-Functionalised Osmium Redox Complex on Glassy Carbon using Electrochemical Oxidation

The electrochemical oxidation of alkylamines provides a method for modification of carbon, and other surfaces via formation of a radical amine that reacts with the surface. Direct electrochemical oxidation of an alkylamine functional group of a redox complex provides a simple route to preparation of a redox active layer on carbon surfaces. Here we report on oxidation of an osmium redox complex, containing an alkylamine ligand distal to the metal co-ordination site, on carbon electrodes to directly produce a redox active film on the surface. The presence of the redox-active layer of osmium complexes is confirmed by cyclic voltammetry and X-Ray photoelectron spectroscopy. The average surface coverage of the attached film upon electrolysis of an [Os(2,2′-bipyridine)2(4-aminomethylpyridine)Cl].PF6 complex is 0.84 (± 0.3) × 10−10 moles cm−2, demonstrating that coverages close to that predicted for a close-packed monolayer of complex is attained. The bioelectrocatalytic activity of the modified electrode was evaluated for oxidation of glucose in presence of glucose oxidase in solution. Hence, electrochemical coupling of alkylamine functionalised osmium redox complexes provides a simple and efficient methodology for obtaining redox active monolayers on carbon surfaces with potential applications to biosensor and biofuel cell device development.