Ferrocene substituted N,N′-bis(3-aminopropyl)oxamide: A new electrochemical sensor for copper(II) and fluoride ions in the biological pH range

A new pH responsive ferrocene functionalized receptor N,N′-bis(3-ferrocenylmethyl aminopropyl)oxamide (R) was synthesized and characterized. The electrochemical responses of the receptor R as a function of pH have been determined using cyclic voltammetric technique. Increase in H+ ion concentration in the medium increases the redox potential of the Fc/Fc+ redox couple of the receptor. Addition of metal ions like Mn(II), Ni(II) and Zn(II) show anodic shift of the Fc/Fc+ redox couple. The presence of Cu(II) ion shows cathodic shift of the Fc/Fc+ redox couple at acidic pH values. The potential shifts between the free receptor and the receptor with anions (F−, Cl− and Br−) at different pH were determined. Among the halide anions, fluoride ion shows appreciable amount of cathodic potential shift.