Cyclic voltammograms for A and B in ACN were recorded against ferrocene using NBu 4 PF 6 (0.1 M) as supporting electrolyte, glassy carbon anode, Pt cathode and Ag reference electrode. The corresponding redox potentials were calculated as follows: potential of sample against Ag electrode minus potential of ferrocene reference system against Ag electrode plus correction of +0.38 V for conversion to the potential against saturated calomel electrode (SCE).