Synthesis, characterization and investigation of antioxidant activity of cobalt–quercetin complex

This article describes a novel synthesis of cobalt and quercetin·2H2O complex in methanol, characterized by using elemental analysis, UV–visible, 1H NMR, TGA, DSC and IR spectrometric techniques. The formation of complex is deduced from the UV–visible spectra which shows that the successive formation of cobalt–quercetin complex occurs in a ratio of 2:1 (metal/ligand) stoichiometrically. The antioxidant activity of the complex was evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. In this work, we have shown that the metal complexed flavonoids are much more effective free radical scavengers than the free flavonoids.