Electrochemical properties of Doyle catalyst immobilized on carbon paste in the presence of DNA

The electrochemical behaviour of Doyle catalyst, dirhodium(II) tetrakis [methyl-2-oxopyrrolidine-5(S)-carboxylate] (Rh2(5S-MEPY)4), immobilised in graphite powder was evaluated preparing the carbon paste electrode, as well as its electrochemical properties in the presence (DCDE) and absence (DCE) of DNA. In both cases, one redox couple at 0.35 V vs. SCE in 0.5 mol l−1 KCl solution at pH 7 and 10 mV s−1 was observed. The resolution of the peak current in the voltammetric studies and other electrochemical properties were improved when the Doyle catalyst was immobilised in the presence of DNA. The estimated rate constants were of 17 and 26 s−1 for a scan rate of 1 V s−1 for DCE and DCDE, respectively. Furthermore, the interaction between rhodium carboxylates and electrolytes become more evident, suggesting a good hydrophilic and conductor character of this biopolymer.