Abstract

SYNTHESIS, SPECTROSCOPIC AND ANTIMICROBIAL STUDIES OF BINUCLEAR SCHIFF BASE COMPLEXES WITH N2O2 DONOR GROUPS

S.Vedanayaki*, P. Jayaseelan

ABSTRACT

A binuclear Schiff base, H2L, ligand synthesized by the reaction of 5-bromo-3-fluorosalicylaldehyde with 4, 4'– diaminodiphenylmethane in the molar ratio 2:1 forms complexes with transition metal ions such as Cu(II), Ni(II), V(IV) and Co(II). The elemental analysis, conductivity, IR, electronic, 1H NMR, LC-MS and magnetic susceptibility measurements were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with N2O2 tetradentate sites and two ligands coordinate with two metal ions to form binuclear complexes. The 1H - NMR data reveal that the Schiff base exists in enol – iminic form. The binding sites are the nitrogen atoms of azomethine groups and oxygen atoms of the phenolic groups. Substitution in phenyl ring of the complexes produces shift in the azomethine υ(C=N) stretching vibrational frequency. The non-electrolytic behavior of complexes indicates the absence of counter ions. EPR spectra provided further information to confirm the binuclear structure. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each complex. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria (S. aureus and B. subtilis) as Gram – positive bacteria (E. coli and K. pneumoniae) as Gram – negative bacteria and one pathogenic fungi (A. fumigatus) to assess their antimicrobial properties.

Keywords: Schiff base, binuclear, anti-microbial activity.