Design, synthesis, spectral, antibacterial activities and quantum chemical calculations of new Cu (II) complexes of heterocyclic ligands

Abstract

New Cu (II) complexes were obtained by reaction of Cu (II) cation with new heterocyclic Schiff base ligands derived from benzo[1,2-c]isoxazoles. The ligands and their Cu (II) complexes were characterized by elemental analyses, IR, mass, and NMR spectra. The optical properties of the compounds were also investigated by UV–Vis and fluorescence spectroscopy. The DFT methods were employed to achieve deeper insight into geometry, spectral properties and energy difference between the frontier orbitals of the ligands and their Cu (II) complexes. The DFT-calculated spectral properties are in good agreement with the experimental values, confirming suitability of the optimized geometries for Cu (II) complexes. In addition, the new ligands and their Cu (II) complexes demonstrated potent antibacterial activity against a panel of strains of Gram negative bacterial and Gram positive species and their MIC was also determined. The results revealed that Cu (II) complexes, displayed greater antibacterial activity against Gram-negative and Gram positive bacteria than did the well known antibacterial agent Sulfamethoxazole.