Synthesis, characterization, fluorescence and biological studies of Mn(II), Fe(III) and Zn(II) complexes of Schiff bases derived from Isatin and 3-substituted-4-amino-5-mercapto-1,2,4-triazoles

A series of Mn(II), Fe(III) and Zn(II) complexes have been synthesized with Schiff bases derived from isatin and 3-substituted-4-amino-5-mercapto-1,2,4-triazole. The elemental, spectroscopic (Infrared, nuclear magnetic resonance, ultraviolet-visible, fast atom bombardment-mass, fluorescence and electrochemistry) and magnetic studies suggested that the metal complexes possess octahedral geometry. The Schiff bases and their metal complexes exhibit fluorescent properties. The antimicrobial studies of Schiff bases and their metal complexes against various bacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis) and fungal (Aspergillus niger, and Penicillium chrysogenum) species by the minimum inhibitory concentration method revealed that the metal complexes possess more healing antibacterial activities than the Schiff bases. DNA cleavage property of Mn(II), Fe(III) and Zn(II) complexes revealed the important role of metal ion in the biological system.