Host (nanocage of zeolite-Y)/guest (manganese(II), cobalt(II), nickel(II) and copper(II) complexes of 12-membered macrocyclic Schiff-base ligand derived from thiosemicarbazide and glyoxal) nanocomposite materials: Synthesis, characterization and catalytic oxidation of cyclohexene

A series of Mn(II), Co(H), Ni(II) and Cu(II) complexes with 12-membered macrocyclic tetradentate ligand; H6C6N6S2=1,2,5,6,8,11-hexaazacyclododeca-7,12-dithione-2,4,8,10-tetraene; have been synthesized and characterized as homogeneous and encapsulated into the nanopores of zeolite-Y. These catalytic systems show a good activity in the oxidation of cyclohexene to 2-cyclohexene-1-one, 2-cyclohexene-2-ol and 1-(tert-butylperoxy)-2-cyclohexene. The chelation of zeolite-exchanged metal(II) by N-containing ligand gives rise to a whole class of Host-Guest Nanocomposite Materials (HGNM) as heterogeneous liquid-phase oxidation, which exhibits similar catalytic performances than the homogeneous ones. The encapsulated complexes abbreviated here as [M(H4C6N6S2)]-NaY, catalyze the oxidation of cyclohexene using TBHP as oxidant in good yield. Cyclohexene catalyzed by [M(H4C6N6S2)]-NaY under optimized reaction conditions gave three reaction products namely, 2-cyclohexene-1-one, 2-cyclohexene-2-ol and 1-(tert-butylperoxy)-2-cyclohexene. In the presence of tert-butylhydroperoxide all catalysts gave 2-cyclohexene-1-one in major yield, though overall conversion has been found low (40-90%). (c) 2007 Elsevier B.V. All rights reserved.