Electrochemistry of the inclusion complexes of metallocene derivatives with cucurbit[7]uril on glassy carbon and mercury electrodes

Abstract

• The electrochemical behavior of ferricenium and cobalticenium cations and supramolecular complexes formed by such cations and ferrocene with a cucurbit[7]uril was studied on GC and Hg electrodes. • Revealed significant differences in the kinetics of heterogeneous electron transfer for these systems due to the principally different adsorption behavior of supramolecular complexes of these metallocenes on GC and Hg. The aim of this work is to compare the electrochemical behavior of ferricenium and cobalticenium cations and supramolecular complexes formed by these cations and ferrocene with a cavitand – cucurbit[7]uril on glassy carbon and mercury electrodes. On the Hg electrode the adsorption properties of these supramolecular complexes were also studied. The substantial differences in the processes of heterogeneous electron transfer for these systems are explained by the principally different adsorption behavior of supramolecular complexes of these metallocene derivatives on GC and Hg. It was found that the mechanism of reactions of these supramolecular complexes on the Hg electrode is determined by the conditions of formation of their adlayers in the potential region preceding the beginning of electrochemical processes. For complexes formed by ferricenium cation and cobaltocene with cucurbit[7]uril we have determined the more precise values for the constants of complex formation as compared to the literature data (7 × 10 9 M −1 and 1 × 10 8 M −1 , respectively).