Cyclic voltammetric studies of some bis(phenanthrolines)copper(II) complexes

Abstract

The electrochemical properties of some bis(phenanthrolines)copper(II) complexes, [Cu(NN) 2 ](ClO 4 ) 2 (NN denotes 1,10-phenanthroline (phen); 4,7-diphenyl-1,10-phenanthroline (bathophen); 2,9-dimethyl-1,10-phenanthroline (dmp) and 2,9-diphenyl-1,10-phenanthroline (dpp) have been studied by cyclic voltammetry at a platinum working electrode in dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) containing 0.1 M tetrabutyl ammonium perchlorate (TBAP) as the supporting electrolyte. All these complexes display a quasireversible Cu 2+/+ redox couple. Both the electron-donating methyl groups and electron-withdrawing phenyl groups at the 2,9-positions of the phen ligand elevate the Cu 2+/+ redox potentials of the [Cu(dmp) 2 ](ClO 4 ) 2 and [Cu(dpp) 2 ](ClO 4 ) 2 complexes. The redox potentials of [Cu(dmp) 2 ] 2+ are nearly 50 mV more positive than that of [Cu(dpp) 2 )] 2+ in a given solvent. It is found that the Cu 2+/+ reduction potential (E pc ) as well as formal potential (E 0' ) for a given complex all shifted to more positive values in DMF as compared to that in DMSO.