Synthesis, characterization and catalytic oxidation of cyclohexane using a novel host (zeolite-Y)/guest (binuclear transition metal complexes) nanocomposite materials

Transition metal (M = Mn(II), Co(II), Ni(II) and Cu(II)) complexes with octahydro-Schiff base (H-4-N4O4) = 2,7,13,18-tetramethyl-3,6,14,17-tetraazatricyclo-[17.3.1.1]-tetracosa-1(23), 2,6,8(24), 9,11,13,17,19,21-decaene-9,11,20,22-tetraol; H-4([H](8)-N4O4) = 2,7,13,, 18-tetramethyl-3,6,14,17-tetraazatricyclo-[17.13.1. 1.]-tetracosa-1(23), 8(24), 9,11,19,21-hexane-9,11,20,22-tetraol) have been encapsulated in nanopores of zeolite-Y; [M([H](8)-N4O4)]@NaY; with Flexible Ligand Method (FLM) for the first time. The new Host-Guest Nanocomposite Materials (HGNM) was characterized by several techniques: chemical analysis, spectroscopic methods (DRS, FT-IR and UV/Vis), BET technique, conductometric and magnetic measurements. The catalytic activities for oxidation of cyclohexane with HGNM complexes are reported. Zeolite encapsulated octahydro-Schiff base copper(II) complex; [Cu([H](8)-N4O4)]@NaY; was found to be more active than the corresponding cobalt(II), manganese(II) and nickel(II) complexes for cyclohexane oxidation. The catalytic properties of the complexes are influenced by their geometry and by the steric environment of the active sites. HGNM are stable enough to be reused and are suitable to be utilized as partial oxidation catalysts. The encapsulated catalysts systems; [M([H](8)-N4O4)]@NaY; were more active than the corresponding neat complexes; [M([H](8)-N4O4)))]. (C) 2009 Elsevier B. V. All rights reserved.