Synthesis, characterization, DNA cleavage, and in-vitro antimicrobial studies of Co(II), Ni(II), and Cu(II) complexes with Schiff bases of coumarin derivatives

A series of Co(II), Ni(II), and Cu(II) complexes ML center dot 3H(2)O have been synthesized with Schiff bases derived from 3-substituted-4-amino-5-mercapto-1,2,4-triazole and 5-formyl-6-hydroxy coumarin. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that the complexes are non-electrolytes. In view of analytical, spectral (infrared, UV-Vis, ESR, TG, and FAB-mass), and magnetic studies, it has been concluded that all the metal complexes possess octahedral geometry in which ligand is coordinated to metal through azomethine nitrogen, phenolic oxygen, and sulfur via deprotonation. The Schiff bases and their complexes have been screened for antibacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhi) and antifungal activities (Aspergillus niger, Aspergillus flavus, and Cladosporium) by the minimum inhibitory concentration method. DNA cleavage is studied by agarose gel electrophoresis.