Electrochemical recognition of alkali metal cations by electrodes modified withpoly[tris-(2,2′-bipyridine) ruthenium(II)] films

Abstract

The electrochemical behavior of tris-substituted bipyridine ruthenium (II) complexes containing the aza-crown-substituted 2,2′-bipyridine ligands L 2 and L 3 (L 2 is 4,4′-disubstituted by 1-aza-18-crown-6 moieties; L 3 is bridged at its 4,4′-positions by a 4,13-diaza-18-crown-6 group), has been studied by cyclic voltammetry in acetonitrile electrolyte, and in the presence of alkali metal cations (Li +, Na +, K +). Cyclic voltammetry curves show that these complexes are able to recognize potentiometrically a metal cation. The L 2-based complex is sensitive to Li + and Na + cations, while the L 3-based complex is only sensitive to the presence of potassium ions. Glassy carbon electrodes have been modified by electropolymerization ofthe related complexes containing pyrrole-substituted bipyridine ligands. The electrochemical behavior of the resulting redox-active films in the presence of the surveyed alkali metal cations shows that the electrochemical recognition properties of these complexes are mainly retained after their immobilization onto an electrode surface, which is a prerequisite to the construction of new prototypes of electrochemical sensor.