Synthesis, characterization and antimicrobial studies of transition metal complexes of Schiff base derived from salicylaldehyde and L-tyrosine amino acid

Abstract

Biologically active tridentate Schiff base Salicylidene-tyrosine (H₂L) derived from salicyaldehyde and L-tyrosine and their Mn(II), Fe(II), Co.(II), Cu(II) and Ni(II) complexes have been prepared in 1:1 stochiometric ratio and characterised on the basis of their solubility , metal analysis, infrared, UV-Visible and magnetic measurements. The synthesised complexes have varying shades of colour and decomposed at a temperature above 360oC. Salicylidenetyrosine acts a tridentate ligand coordinating to the metals through the azomethine nitrogen atom, the oxygen atom of hydroxyl group of COOH and the phenolic oxygen to give an octahedral geometry. The electronic spectra are in consistent with the proposed octahedral geometry around the metal ions. The metal complexes were screened for their antimicrobial activities against Staphylococcus aureus (ATCC 12600), Escherichia.coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 10145), Bacillus subtilis (ATCC 39090), Salmonella typhi(ATCC 6539), Klebsiella pneumonia (ATCC 35657), Candida albicans (ATCC 10231), Penicillium notatum (ATCC 20269), Rhizopus stolonifer (ATCC 14037) and Aspergillus niger (ATCC 16888). The copper complex [Cu(L)(H₂O)₃].H₂O exhibited the greatest activity in all the organisms tested It is active against all microorganisms tested at virtually all concentrations.

Keywords: Antimicrobial, Salicyladehyde, L-tyrosine, Schiff base,