Electron transfer properties of 2-acetylferrocenyl2-thiophenecarboxylsemicarbazone and its copper (ii) complex

Abstract

This work is aimed at obtaining the electrochemical properties of 2-acetylferrocenyl-2thiophenecarboxylsemicarbazone (LH) and Copper (II) complex of 2-acetylferrocenyl-2thiophenecarboxylsemicarbazone (CuL2), which were there earlier found to have different biological activities against malaria parasites. Cyclic voltammetric studies on these compounds (LH and CuL2) mainly gave one peak for each of the cathodic and anodic scans. These reduction/oxidation responses were attributed to FeIII/FeII for LH and CuII/Cu1 for CuL2 redox couples. The mid-point potentials were found to be +0.536 V for LH and -0.350 V for CuL2 versus Ag/AgCl. Literature shows that more positive redox potentials than negative potentials are associated with higher biological activities. The average peak separations for LH and CuL2 were found to be ~48 mV and ~363 mV between the scan rates of 0.01 V/s and 0.1 V/s while their diffusion coefficients were 5.21 x 10-7 cm2/s and 2.67 x 10-7 cm2/s, respectively. This difference in diffusion coefficients was attributed partially to the differences in their molecular weights and the overall geometry, whereby CuL2 was almost double that of LH. The rates of electron transfer constants were also found to be 12.3 cm/s for LH and 1.0 cm/s for CuL2.