Preparation and characterization of biomimetic heterogeneous catalysts with Cu(II) and Mn(III) complexes

Abstract

New catalysts were synthesized by immobilization of Cu(II) and Mn(III) biomimetic complexes onto mesoporous SBA-15 silica, amino-functionalized SBA-15, montmorillonite and Al-pillared montmorillonite supports. [Cu(acac)(phen)(OH2)](ClO4) and [Cu(acac)(Me2bipy)](ClO4) copper complexes and [Mn(III)(valen)(H2O)(CH3CN)](ClO4)∙CH3CN manganese complex supported on silica pore surface or intercalated into the interlayer spaces of clays, were characterized by X-ray diffraction, N2 adsorption-desorption, TGA-DTA analysis, IR and UV-Vis spectroscopy. These results have confirmed the structural stability of the mesoporous hosts and successful anchoring of the metal complexes over the supports. In order to verify the biomimetic comportment, catalytic activities of the free and immobilized complexes and that of Trametes versicolor laccase, immobilized on the same supports, were tested by oxidation with air of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), the most used substrate for estimation of specific activity of laccases. The supported complexes were more active than the free ones. Furthermore, the stability tests for the most active heterogeneous catalyst confirmed that the best support was NH2-SBA-15.