New mono- and polynuclear copper(II) complexes: Structural characterization, quantum chemical calculations and antioxidant superoxide dismutase studies

Abstract

Two copper(II) complexes have been synthesized and characterized using elemental and spectral analysis. The molecular structures of both complexes have been confirmed by single crystal X-ray analysis. The stability of the metal centre was examined using cyclic and differential pulse voltammetry in DMSO solution. X-band electron paramagnetic spectra were recorded both in solid and frozen solution to confirm the <em>d⁹</em> configuration. Frozen solution spectra of complexes have the trend in the spin Hamiltonian parameters g_ǁ > g<img src='http://nopr.niscair.res.in/jinfo/ijcanew.gif' border=0> > 2.0023 and A_ǁ <img src='http://nopr.niscair.res.in/jinfo/tiled1.gif' border=0> 156 x 10^-4 cm^-1 revealing a d_x²-_y² ground state with tetragonal symmetry for copper(II) ion. Density functional calculations have been performed and results are found to agree with the experimental results. Antibacterial activities of complexes were screened by taking gram-positive and gram-negative bacteria. Further, <em>in vitro</em> antioxidant (superoxide dismutase) properties of <strong>1 </strong>and <strong>2</strong> showed considerable activity compared to other SOD mimics.