A new dioxomolybdenum (VI) complex with tridentate hydrazone Schiff base ligand (H2L) derived from 2‐hydroxy‐5‐nitrobenzaldehyde and benzhydrazide was synthesized and designated as [MoO2L (DMF)]·2H2O. The Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) nanocatalyst was successfully prepared by grafting H2L ligand on modified Fe3O4 nanoparticles followed by reacting with MoO2 (acac)2. The complex and nanocatalyst were characterized by various techniques such as elemental analysis, mass, FT‐IR, UV–Vis, 1H NMR, 13C{1H}‐NMR, TGA, XRD, XPS, TEM, SEM and VSM. The catalytic activity of [MoO2L (DMF)]2H2O and Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) were evaluated for the oxidation of various alkenes (cyclooctene, norbornene, cyclohexene, styrene and α‐methyl styrene) in the presence of tert‐butylhydroperoxide as oxidant. The results revealed that the catalysts were especially efficient for oxidation of cyclooctene and norbornene with 100% selectivity towards corresponding epoxide product. Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) showed higher catalytic activity, shorter reaction time and higher turnover number (TON) compared with homogeneous complex [MoO2L (DMF)]·2H2O. Moreover, simple magnetic recovery from the reaction mixture and reuse for several times with no significant loss in activity were other advantages of the nanocatalyst.

Please cite this article as: K. Nikoofar, M. Haghighi, M. Lashanizadegan, Z. Ahmadvand, ZnO nanorodes: efficient and reusable catalyst for the synthesis of substituted imidazoles in water media, Journal of Taibah University for Science (2015), http://dx. Abstract:A simple procedure has been represented for the synthesis of ZnO nanorodes (ZnO NRs). The characterization of newly synthesized crystals were studied by X-ray diffraction pattern (XRD), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) techniques. Moreover the catalytic activity has been examined in a one-pot, three component synthesis of 2,4,5-triaryl-1H-imidazoles in water under reflux conditions. The results confirmed ZnO NRs to be a mild, benign and effective catalyst for the trisubstituted imidazoles preparation in high yield via an operationally simple and environmentally-friendly procedure. Furthermore, the catalyst can be recovered conveniently and reused for at least three runs without any activity loss.

The Schiff base ligand trans-N,N′-bis[2-pyridinecarboxylidene] cyclohexane-1,2-diamine (L) was synthesized. This ligand when stirred with 1 equiv of MCl2.xH2O (M = Cu, Co, Zn) in ethanol, undergoes partial hydrolysis of the imino bond and the result tridentate ligand (L') and immediately forms the complexes with N3 coordination sphere. The reactions of L with MCl2.xH2O (M = Cu, Co, Zn) in THF give complexes [ML]Cl2. The ligand (L), complexes [M(L')Cl]Cl and [ML]Cl2 were characterized by elemental analysis, UV-Vis, FT-IR, 1H NMR, GC/MS and luminescence properties. The 1H NMR spectra of the ligand and its diamagnetic complexes were recorded in CDCl3 and DMSO solvents, respectively. Obtained data confirm that the donor atoms N in ligand coordinated to the metal ions. The luminescence studies show ligands and their complexes display intraligand (π-

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