Synthesis, characterization and antimicrobial activity of homodinuclear complexes derived from 2,6-bis[3′-methyl- 2′-carboxamidyliminomethyl(6′,7′)benzindole]-4-methylphenol, an end-off compartmental ligand

Abstract

End-off compartmental pentadentate Schiff base, 2,6-bis[3′-methyl-2′-carboxamidyliminomethyl(6′,7′)benzindole]-4-methylphenol is synthesized and characterized by 2D NMR experiments and mass spectral techniques. The homodinuclear phenalato bridged end-off compartmental Schiff-base complexes Cu(II), Co(II), Ni(II), Mn(II), Fe(III), VO(IV), Zn(II), Cd(II) and Hg(II) have been prepared by the template method using the precursors 2,6-diformyl-4-methylphenol, 3-methyl(6′,7′)-2-benzindolehydrazide and metal chlorides in 1 : 2 : 2 ratio. The complexes are characterized by IR, NMR, UV-vis, FAB-mass, ESR and TGA techniques. Ni(II), Mn(II) and Fe(III) complexes have octahedral geometry, whereas the Cu(II), Co(II), VO(IV), Zn(II), Cd(II) and Hg(II) complexes have square pyramidal geometry. Low magnetic moment values for Cu(II), Co(II), Ni(II), Mn(II), Fe(III) and VO(IV) complexes indicate antiferromagnetic spin-exchange interaction between two metal centers. The metal complexes have been screened for their antibacterial activity against Escherichia coli and Staphyloccocus aureus and antifungal activity against Aspergillus niger and Fusarium oxysporum.

Keywords:

• End-off
• Benzindole
• Antiferromagnetic
• Phenalato bridged

Acknowledgments

We thank the Chairperson of the Department of Studies in Chemistry, Gulbarga University, Gulbarga, for providing research facilities. Authors are thankful to SIF, IISc Bangalore, CDRI, Lucknow, for providing ESR, Mass, and FAB mass spectral data. Authors are grateful to Prof. C.L. Khetrapal, Director, Center of Biomedical Magnetic Resonance, Lucknow, for providing NMR facility.