Synthesis, molecular geometry, spectroscopic studies and thermal properties of Co(II) complexes

Co(II) complexes (1-4) were prepared and characterized by elemental analyses, infrared spectra, spectral studies, magnetic susceptibility measurements, X-ray diffraction analysis and thermogravimetric analysis (TGA). The X-ray diffraction patterns of Co(II) complexes were observed many peaks which indicate the polycrystalline nature. The thermodynamic parameters were calculated by using Coats-Redfern and Horowitz-Metzger methods. The bond length, bond angle and quantum chemical parameters of the Co(II) complexes were studied and discussed. The Co(II) complexes were tested against various Gram-positive bacteria, Gram-negative bacteria and fungi. It was found that the Co(II) complex (1) has more antifungal activity than miconazole (antifungal standard drug) against P. italicum at all concentration. The Co(II) complex (2) has more antibacterial activity than the penicillin against K. pneumoniae at all concentration. The interaction between Co(II) complexes and calf thymus DNA show hypochromism effect. The relationship between the values of HOMO-LUMO energy gap (E) and the values of intrinsic binding constant (K-b) is revealed increasing of HOMO-LUMO energy gap accompanied by the decrease of K-b.