Co(II) and Fe(II) Mixed Ligand Complexes of Pefloxacin and Ascorbic Acid:Synthesis, Characterization and Antibacterial Studies

Mixed ligand metal complexes of 1-ethyl-6-fluoro-7-(4-methylpiperazin-1-yl)-4-oxo-quinoline-3-carboxylic acid (pefloxacin) and ascorbic acid were synthesized using Fe(II) and Co(II). The mixed ligand complexes were characterized by IR, UV-Vis., ¹H and ¹³C NMR spectroscopy to determine the complexation behaviour of the metal ions towards the mixed ligand. The yield, melting point, colour and solubility were determined. Electronic spectra of the mixed ligand complexes show intra ligand charge transfer, ligand to metal charge transfer and d-d transition. Based on the spectroscopic data obtained, the mixed complexes were proposed to have the formulae: [Fe(PfAs)]_x and [Co(PfAs)]; Pf = pefloxacin and As = Ascorbic acid. The spectral studies of the mixed ligand complexes suggest that in the complexes, pefloxacin and ascorbic acid behaved as tridentate ligands coordinating through the two carbonyl oxygen atom and oxygen atom of the hydroxyl group in pefloxacin, while ascorbic acid coordinated through the oxygen of the carbonyl and enolic C-2 and C-3 hydroxyl groups. Octahedral structure was proposed for [Fe(PfAs)]_x and [Co(PfAs)]_x. The antibacterial activity of the ligand and the mixed ligand complexes was carried out against both gram positive and gram negative bacterial species which include; Staphylococcus aureus, E. coli., Bacillus subtilis, Pseudominas Spp. and Candida Spp. at 0.1g. The zone of inhibition of the pefloxacin-ascorbic acid mixed ligand complexes were significantly higher (P < 0.05) than the free ligands.