Synthesis, characterization, structural description, TGA, micellization behavior, DNA-binding and antioxidant activity of mono-, di- and tri-nuclear Cu(II) and Zn(II) carboxylate complexes

Mono-, di- and tri-nuclear Cu(II) and Zn(II) carboxylate complexes were synthesized and structurally characterized having general formulas [Cu-2(biphenylacetate)(4)(DMSO)(2)] (1), [Zn(3,4-dichlororophenylacetate)(2)(1,10-phenanthroline)(H2O)] (2) and [Zn-3(3,4-dichlororophenylacetate)(6)(2,2-bipyridine)(2)] (3). Complex 1 is a dinuclear Cu(II) complex with distorted square pyramidal geometry. Complex 2 is a mononuclear Zn(II) complex with distorted octahedral geometry while 3 is a tri-nuclear Zn(II) complex with octahedral (central Zn) as well as square pyramidal (terminal Zn) geometries. The stability of all complexes was checked by TGA and were found thermally stable. The solubility of the complexes was enhanced by using cationic (CTAB) and anionic (SDS) surfactants. Lower CMC values for SDS revealed good interaction as compared to CTAB. DNA-binding ability of the complexes was determined by UV-vis spectrophotometry and viscometry. All complexes bind with DNA effectively. The binding constant values from spectral analysis are 1.00(+/- 0.02) x 10(4), 1.34(+/- 0.01) x 10(5) M-1 and 1.11(+/- 0.01) x 10(4) M-1 for 1-3, respectively. The DPPH-scavenging assay was performed by UV-vis spectrophotometry. All complexes showed good inhibition against the free radical. IC50 values for 1-3 are 109.98, 167.31 and 153.12 mu M, respectively. The complexes were found to possess nice biological relevance.