Porphyrins bound to Ru(bpy)2 clusters: electrocatalysis of sulfite

Mono-, di-, tri- and tetra-ruthenated porphyrins derived from phenyl/4-pyridyl mesosubstituted porphyrin and a trans di-ruthenated dipyridyl octaethylporphyrin have been synthesised. Coated on carbon electrodes, they have been tested as a sensor for sulfite using the oxidation wave of the Ru(II)/Ru(III) couples in hydroalcoholic solutions. At least two peripheral Ru are necessary to trigger the catalysis off. No major influence of the central metallic ions has been detected, but the Co (II) is coordinated by the sulfite.