Synergetic Radical-Scavenging effect in the complex of copper(II) with the thiosemicarbazone of Salicylaldehyde

The radical scavenging activities of salicylaldehyde thiosemicarbazone and its copper(II) and cadmium(II) complexes were evaluated by in vitro experiments in the reaction with 2,2'-diphenyl-1-picrylhydrazyl. Salicylic aldehyde thiosemicarbazone complex with Cu(II) shows significantly higher radical-scavenging activity than Cu2+ ions, salicylaldehyde thiosemicarbazone, and Cd(II) complex. Electrochemical, EPR and kinetic studies revealed that the high rate of reaction and efficiency is due to the mechanism of electron transfer, which is enhanced by the synergetic effect of the ligand structure and the ability of the copper ion to exhibit variable valencies.