Antimicrobial and corrosion inhibition studies of homoleptic metal (II) complexes of fluoroaniline schiff base: Synthesis, and characterization

Abstract

A Schiff base ligand, HL derived from 4-fluoroaniline and 2-hydroxy-1-nalphaldehyde was reacted with acetate salts of Cu(II), Zn(II), Co(II), Mn(II), Ni(II) and Fe(II) sulfate to give their corresponding metal(II) complexes. The synthesized compounds were characterized via analytical methods, spectral assessments; and were applied as corrosion inhibitors. The Fourier Transformation Infrared (FTIR) spectrum of HL presented a band at 1632cm^-1 which were observed within 1623-1630 cm^-1 in the spectra of the complexes; and was apportioned to an azomethine moiety. The electronic (UV-vis) studies showed that complexes displayed octahedral geometries with various transitions within the synthesized compounds. The ligand and its metal complexes were completely soluble in C₂H₆OS, and C₃H₇NO but was sparingly soluble in CH₃Cl except for Fe(II) and Co(II) which were insoluble and completely soluble respectively. Divalent iron, nickel, copper and zinc complexes exhibited high melting points (240-285^oC) and different shades of brown, except for nickel which was olive green. The ligand melted at 160^oC. The Cu(II) complex show high activity against Bicilus cerus (11.0 ± 1.41) and mild activity against S. aueus, P. aeruginosa, K. pneumonia  (6.5 ± 0.71, 4.0 ± 0.0, 2.0 ± 2.82) respectively and no activity against proteus mirabilis. The compounds were found to be inactive against K. Pneumonia  except for  iron(II) and copper(II) complexes. However, outstanding antifungal actions were acquired for the compounds against Aspergillus flavus, fuserium sp. and Aspergillus Niger. The ligand with its bivalent complexes also presented substantial corrosion inhibition behaviour in opposition to corrosion of mild steel in aggressive HCl solution with values ranging from 68% to 91% at different hours.