Ship-in-a-bottle synthesis, characterization and catalytic oxidation of cyclohexane by Host (nanopores of zeolite-Y)/guest (Mn(II), Co(II), Ni(II) and Cu(II) complexes of bis(salicyaldehyde)oxaloyldihydrazone) nanocomposite materials

The monomer transition metal complexes; [ML] (M = Mn(II), Co(II), Ni(II) and Cu(II)) have been synthesized from the reaction of metal acetate with bis(salicyaldehyde)oxaloyldihydrazone, H2L; in 1: 1 molar ratio in ethanol under reflux. In all of the complexes, the principal dihydrazone ligand has been suggested to coordinate to the metal centres in the anti-cis-configuration. The complexes (Co(II), Ni(II) and Cu(II)) are suggested to have four-coordinate square-planar stereochemistry while the Mn(H) complex is suggested to have tetrahedral stereochemistry. These metal complexes with tetradendate Schiff-base ligand was entrapped in the nanocavity of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(salicylaldiniinato)metal(II)]; [M(sal)(2)]-NaY; in the supercages of the zeolite, and (ii) in situ Schiff condensation of the metal(H) precursor complex with oxaloyldihydrazone; [ML]-NaY. The new Host-Guest Nanocomposite Materials (HGNM) was characterized by several techniques: chemical analysis, spectroscopic methods (DRS, NMR, BET, FTIR and UV/vis), conductometric and magnetic measurements. The catalytic activities for oxidation of cyclohexane with HGNM and neat were reported. (c) 2008 Elsevier B.V. All rights reserved.