Oxovanadium(IV) Complexes with Cephradine: Synthesis, Semi-Empirical Study,Spectroscopy, Potentiometric Study and Antimicrobial Activity

The reactions between cephradine and VOSO4.3H2O in 1:1, 1:2 and 1:3 molar ratios in methanol were investigated at room temperature, 0 °C and -10 °C. In various pH conditions, the different complexes formulated as VO(H2O)3L2-, VO(H2O)L2 2- and VL3 - were formed by titration of VOSO4.3H2O and cephradine with NaOH. These complexes were characterized by elemental analysis and IR spectroscopy. IR spectra of all the complexes show the disappearance of ν(O-H) band of cephradine, which confirms complexation. Estimation of vanadium in the complexes was carried out by ICP-AES. The stability constants of each complex were calculated on the basis of which a general mechanism is hereby proposed with regard to the formation of these complexes. In complex (1) the cephradine ligand bind in bidentate [O,O] fashion together with a terminal oxo ligand and water molecules complete the metal coordination sphere. In complex (2) the cephradine ligands bind in bis-bidentate [O,O] fashion and the axial positions are occupied by the oxo ligand and a trans-water molecule. Biological screening tests show significant antibacterial and anti-fungal activities against various bacterial and fungal strains