Iron (III) and zinc (II) monodentate Schiff base metal complexes: Synthesis, characterisation and biological activities

Abstract Schiff bases being active biological moieties, possess diverse pharmacological activities. Metal ions play a vital role in various functions of the human body. The importance of metal ion complexes of Schiff bases has been acknowledged in the field of biomedical sciences. Herein, two Schiff base ligands (L1, L2) underwent metal complex formation, to get their iron and zinc metal complexes, respectively. Later, these Schiff base ligands and their iron and zinc metal complexes were compared for various biological activities. Ligands and their metal complexes were characterised physically as well as by using spectral characterisation techniques including Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (NMR) and Mass spectrometry (MS). Pharmacological activities including antibacterial, antifungal, antioxidant and antitumor assays were performed. All compounds have shown antibacterial and antifungal activities, but the metal complexes showed better activities as compared to the original ligands, especially all zinc complexes. All compounds showed better antifungal activity against Candida albican as compared to Candida glabrata. Free ligands illustrated better antioxidant behaviour and anti-tumour activity as compared to the metal complexes. The above results suggest that both ligands and their metal complexes have the potential to be explored as active pharmaceutical agents.