Synthesis, characterization and antimicrobial activity of some mixed ligand Co(II) and Ni(II) complexes

Mixed ligand Co(II) and Ni(II) complexes have been synthesized by using 8-hydroxyquinoline as primary ligand and N- and/or O- donor ligands such as tartaric acid/phenylalanine 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 solution at 10(-3) M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements are indicative of an octahedral geometry for Co(II) and Ni(II) complexes. Electronic spectra of the complexes show intra-ligand, charge transfer and the crystal field transitions, which are supportive of the proposed octahedral geometries of the complexes. The thermal analysis data of the complexes indicate the presence of crystallization water. The antibacterial and antifungal activities of the complexes have been studied again some of the pathogenic bacteria and fungi. The cup-plate method has been used to study the antibacterial activity of the compounds against C. diphtheriae, E. coli, S. typhi, S. dysentariae, S. aureus and V. cholerae. The results have been compared against those of controls, which were screened simultaneously. The activity is measured by measuring the diameter of the inhibited zone in millimeters (mm). The antifungal activity of the complexes against Candida albicans and Aspergillus niger has been studied by the tube dilution method. The complexes have been screened for acute oral toxicity in rats. The LD50 values have been determined by the method of Litchfield and Wilcoxon.