Transition metal cation and phosphate anion electrochemical recognition in water by new polyaza ferrocene macrocyclic ligands

Abstract

New polyaza ferrocene macrocyclic ligands 4–7 have been synthesised and with 4, copper(II) and nickel(II) transition metal complexes isolated. Electrochemical investigations reveal these redox-active ligands can electrochemically sense various transition metal cations in polar organic solvents and in water at high pH values with ligands 4 and 5. Aqueous electrochemical competition experiments with Ni 2+, Cu 2+ and Zn 2+ suggest 4 and 5 exhibit a selectivity preference for the copper(II) cation. At lower pH values (6–8) the respective protonated polyammonium forms of 4, 5 and 7 complex and electrochemically detect the biologically important phosphate anions, ATP and hydrogen phosphate in the aqueous environment.