Covalent modification of glassy carbon surfaces by using electrochemical and solid-phase synthetic methodologies: application to bi- and trifunctionalisation with different redox centres.

Glassy carbon electrodes functionalised with two redox centres have been prepared by using electrochemical and solid-phase synthetic methodologies. Initially the individual coupling of anthraquinone, nitrobenzene and dihydroxybenzene to a glassy carbon electrode bearing an ethylenediamine linker was optimised by using different coupling agents and conditions. Bifunctionalisation was then carried out, either simultaneously, with a mixture of nitrobenzene and dihydroxybenzene, or sequentially, with anthraquinone then nitrobenzene and with anthraquinone then dihydroxybenzene. Characterisation of these electrodes by cyclic voltammetry and differential pulse voltammetry clearly proved the attachment of the pairs of redox centres to the glassy carbon electrode. Their partial surface coverages can be controlled by varying the coupling agent or by controlling the substrate concentration during the solid-phase coupling process. Trifunctionalisation was also realised according to this methodology.