Microwave-assisted synthesis of Schiff base metal complexes: Biological, photocatalytic activity and fabrication of their metal oxide nanoparticles

Abstract

Three transition metal complexes of the type [M(ABzC)(H2O)(CH3COO)] denoted as M-ABzC where M = Cu(II), Ni(II) & Zn(II), and ABzC = 3-((5‑chloro-2-hydroxybenzylidene)amino)benzoic acid; were synthesized under microwave irradiation and characterized by using spectroscopic methods, including 1H & 13CNMR, UV–vis, FTIR, and EI-MS. All the synthesized compounds were optimized using the DFT approach. The ligand-to-metal coordination was established by spectroscopic and DFT analyses, which suggest that ligand coordinated through O, N donor atoms. According to the electronic and DFT optimized data, Zn(II) complex showed distorted tetrahedral geometry, whereas geometry of Ni(II) and Cu(II) complexes is square planar. The complexes were calcined at 560 °C to obtain the metal oxide nanoparticles (CuO, NiO, and ZnO). XRD, HR-TEM, SEM, EDX, and UV–vis spectrophotometer were used to characterize the nanoparticles. The DNA interaction activity of the synthesized complexes were performed using electronic absorption and fluorescence spectroscopy. The complexes displayed effective intercalative binding mode with CT-DNA having a binding constant in the range 105 M−1. Based on the antioxidant activity data, it can be inferred that Ni(II) and Cu(II) complexes have better activity than Zn(II) complex. Photodegradation experiment of metal complexes and oxide nanoparticles were performed without hydrogen peroxide using crystal violet dye as model pollutant in aqueous solution under sun light. The results established that the highest degradation was achieved with ZnO, which is 95.5 %. Further, the enzyme structures of B-DNA and 1HD2 have been used in molecular docking simulations to determine the potential binding energies of inhibitors.