Synthesis, spectral and biological studies on some mixed ligand Ni(II) complexes

Mixed ligand Ni(II) complexes of the type [M(Q)(L) x 2H2O] have been synthesized by using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-serine, L-isoleucine, L-proline, 4-hydroxy-L-proline and L-threonine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes in methanol at 10(-3) M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed paramagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand, charge transfer and d-d transitions, respectively. The thermal analysis data of the complexes indicate the presence of coordinated water molecules. Tube dilution method has been used to study the antibacterial activity of the complexes against the pathogenic bacteria C. diphtheriae, S. aureus and C. albicans. The results have been compared with those of control tetracycline, which was screened simultaneously and indicated mild antibacterial activity of the complexes.