Utilization of immobilized biomimetic iron complexes within nanoreactors of Al-MCM-41 as cyclohexane oxidation catalyst

Abstract

Biomimetic iron(III) complexes such as [Fe(en) 2Cl 2]Cl, [Fe(bpy) 2Cl 2]Cl, [Fe(salen)Cl], [Fe(TPP)Cl] and [Fe(TMC)Cl] in which en, bpy, salen, TMC, and TPP refer to ethylenediamine, 2,2′-bipyridine, N,N′-bis(salicylidene)ethylenediamine), 5,7,12,14-tetramethyl-1,4,8,11 tetraazacyclotetradeca 4,6,11,13-tetraene and meso-tetraphenylporphyrin were immobilized within nanoreactors of Al-MCM-41. The structures of immobilized complexes were characterized by powder X-ray diffraction (XRD), nitrogen adsorption–desorption, FTIR and UV–vis spectroscopy. The pore volume, surface area and pore diameter of Al-MCM-41 were found to decrease after immobilization of iron complexes. It was found that immobilized iron complexes within Al-MCM-41 with the order of [Fe(bpy) 2Cl 2] > [Fe(TPP)Cl] > [Fe(TMC)Cl] ∼ [Fe(salen)Cl] > [Fe(en) 2Cl 2]Cl catalyze the oxidation of cyclohexane to cyclohexanol and cyclohexanone with hydrogen peroxide in refluxing acetonitrile.