Synthesis, Structural Characterization and DPPH Radical Scavenging Activity of Cu(II), Ni(II), Zn(II) and Cd(II) Complexes of 2,6-diacetylpyridine bis(benzenesulfonohydrazide)
Cu(II), Ni(II), Zn(II) and Cd(II) complexes were synthesized from 2,6-Diacetylpyridine bis(benzenesulfonohydrazide) ligands; DAP(BSH)2, DAP(CH3BSH)2 and DAP(OCH3BSH)2. All complexes were characterized using IR and UV-Vis spectroscopic techniques. The IR spectra revealed the disappearance of ν(N-H) absorption band, which suggests that the proton on the imine nitrogen atom of the ligand was deprotonated upon complexation. The involvement of sulfonyl oxygen atoms in the coordination was evident by the absence of νas(SO2) absorption bands. This was further confirmed by the appearance of SO2 bending vibration band, which suggests the distortion of SO2 from its structure. The antioxidant activity of the complexes was determined by their DPPH radical scavenging activity. The result showed that the DPPH radical scavenging activity of the parent ligands was reduced when they were chelated with Cu(II), Ni(II), Zn(II) and Cd(II) ions. Of the complexes studied, Zn(II) complexes of DAP(BSH)2 and DAP(OCH3BSH)2 exhibited better antioxidant activity.