Template synthesis, spectroscopic, antibacterial, and antifungal studies of trivalent transition metal ion macrocyclic complexes

Abstract

A novel series of complexes of the type [M(C₃₆H₂₂N₆)X]X₂, where M = Cr(III), Mn(III), Fe(III); X = Cl⁻, NO₃⁻, CH₃COO⁻; and (C₃₆H₂₂N₆) corresponds to the tetradentate macrocyclic ligand, have been synthesized by condensation of 1,8-diaminonaphthalene and isatin in the presence of trivalent metal salts in methanolic medium. The complexes have been characterized by elemental analysis, conductance and magnetic measurements, and UV/Vis, IR, and mass spectroscopy. On the basis of these studies, a five coordinate square pyramidal geometry for all of these complexes is proposed. All synthesized macrocyclic complexes have been tested for in vitro antimicrobial activities against some pathogenic bacterial strains, viz. Staphylococcus aureus, Bacillus subtilis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and two fungal strains, viz. Aspergillus niger, Aspergillus flavus. The MICs shown by the complexes against these microbial strains have been compared with MICs shown by standard antibiotic ciprofloxacin and the antifungal drug amphotericin-B.

Keywords::

• Antimicrobial activity
• isatin
• macrocyclic complexes
• mass spectra

Acknowledgments

The authors would like to thank the authorities of NIT, Kurukshetra, for providing necessary research facilities.

Declaration of interest

One of the authors (D.P.S.) thanks the University Grants Commission, New Delhi, for financial support in the form of a Major Research Project (MRP-F. No.32-196/2006 (SR)) and another of the authors (K.K.) for the award of Project Fellowship under the above project.