Cyclic voltammetry of benzo-15-crown-5 ether-vinyl-bipyridyl ligands, their ruthenium(II) complexes and bismethoxyphenyl-vinyl–bipyridyl ruthenium(II) complexes. Electrochemical polymerization studies and supporting electrolyte effects

Abstract

The cyclic voltammetry of benzo-15-crown-5 ether-vinyl-bipyridyl ligands, their ruthenium(II) complexes and the ‘model’ bismethoxyphenyl-vinyl-bipyridyl ligand ruthenium(II) complexes has been investigated in acetonitrile. The benzo-15-crown-5 ether units of the solution complexes are sensitive to supporting electrolyte, being more difficult to electro-oxidize on binding of sodium or magnesium cations. The tris(ligand) ruthenium(II) complexes can be reductively electropolymerized to form smooth, adherent electroactive orange films. For these electropolymerized films, the benzo-15-crown-5 ether irreversible electro-oxidation is electrocatalysed by Ru^III sites and is only observed on the first cyclic voltammogram. Ru^III/II redox potentials are insensitive to changes in the supporting electrolyte, apparent differences being due to variable liquid-junction potentials at the interface between the reference electrode and the supporting electrolyte solutions. Electropolymerized bismethoxyphenyl-vinyl-bipyridyl ligand ruthenium(II) complex films exhibit transparent/orange electrochromicity.