The Metal Complexes of Natural Compounds, Usnic Acid and Naringenin Immobilized on Mesoporous Silica: Solid Phase Extraction and Oxidative Catalytic Properties

Abstract

The novel semi-natural Schiff bases were synthesized with the reaction of the natural compounds usnic acid and naringenin extracted and purified in natural sources and chemically modified silica gel. Cu(II), Ni(II), Co(II) and Mn(II) complexes of the ligands were synthesized and the silica-supported ligands and their metal complexes were characterized by FT-IR, TG/DTA, SEM, EDX, ICP-OES and elemental analyses techniques. The solid-phase extraction behaviours of the novel silica-supported ligands were examined. It was found that the hybrid materials showed the very efficient adsorption properties to Cu(II), Cd(II), Pb(II) and Cr(III) metal ions maximum at pH=8-9. The metal ions could be recovered again nearly 100 % from the silica-supported ligands in the recycling experiments. The catalytic efficiencies of the metal complexes in the oxidation reactions of cyclohexane, cylohexene, cyclooctane and styrene subtrates were examined under microwave irradiation in the present of H2O2. The complexes showed very good catalytic activities in the oxidation reactions of the various tested substrates.