Synthesis, structural studies and catalytic activity of dioxidomolybdenum(VI) complexes with aroylhydrazones of naphthol-derivative

Reaction of the salicylhydrazone of 2-hydroxy-1-naphthaldehyde (H2L1), anthranylhydrazone of 2hydroxy-l-naphthaldehyde (H2L2), benzoylhydrazone of 2-hydroxy-1-acetonaphthone (H2L3) and anthranylhydrazone of 2-hydroxy-1-acetonaphthone (H2L4; general abbreviation H2L) with MoO2(acac)21 afforded a series of 5- and 6- coordinate Mo(VI) complexes of the type MoO2L1-2(ROH)] where R = C2H5 (1) and CH3 (2)], and MoO2L3-4] (3 and 4). The substrate binding capacity of 1 has been demonstrated by the formation of one mononuclear mixed-ligand dioxidomolybdenum complex MoO2L1(Q)] (where Q= gamma-picoline (la)). Molecular structure of all the complexes (I, la, 2,3 and 4) is determined by X-ray crystallography, demonstrating the dibasic tridentate behavior of ligands. All the complexes show two irreversible reductive responses within the potential window -0.73 to -1.08 V, due to Movl/Mov and Mov/Mow processes. Catalytic potential of these complexes was tested for the oxidation of benzoin using 30% aqueous H2O2 as an oxidant in methanol. At least four reaction products, benzoic acid, benzaldehydedimethylacetal, methyl benzoate and benzil were obtained with the 95-99% conversion under optimized reaction conditions. Oxidative bromination of salicylaldehyde, a functional mimic of haloperoxidases, in aqueous 1-1202/KEr in the presence of HC1O4 at room temperature has also been carried out successfully. (C) 2013 Elsevier Ltd. All rights reserved.

Tuning the metal-insulator transition in NdNiO3 heterostructures via Fermi surface instability and spin fluctuations

We employed in situ pulsed laser deposition (PLD) and angle-resolved photoemission spectroscopy (ARPES) to investigate the mechanism of the metal-insulator transition (MIT) in NdNiO3 (NNO) thin films, grown on NdGaO3(110) and LaAlO3(100) substrates. In the metallic phase, we observe three-dimensional hole and electron Fermi surface (FS) pockets formed from strongly renormalized bands with well-defined quasiparticles. Upon cooling across the MIT in NNO/NGO sample, the quasiparticles lose coherence via a spectral weight transfer from near the Fermi level to localized states forming at higher binding energies. In the case of NNO/LAO, the bands are apparently shifted upward with an additional holelike pocket forming at the corner of the Brillouin zone. We find that the renormalization effects are strongly anisotropic and are stronger in NNO/NGO than NNO/LAO. Our study reveals that substrate-induced strain tunes the crystal field splitting, which changes the FS properties, nesting conditions, and spin-fluctuation strength, and thereby controls the MIT via the formation of an electronic order parameter with QAF similar to (1/4,1/4,1/4 +/- delta).