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Reaction Route (reaction + route)
Selected AbstractsNanoparticle-Structured Ligand Framework as Electrode InterfacesELECTROANALYSIS, Issue 1-2 2004Nancy Abstract Nanostructured thin film assemblies derived from metal or oxide nanocrystal cores and functionalized molecular shells provide large surface-to-volume ratio and three-dimensional ligand frameworks. In this article, we report results of an investigation of the nanostructured materials for electroanalysis. Monolayer-capped gold nanoparticles of 2-nm core diameter and carboxylic acid-functionalized alkyl thiols were assembled on electrode surfaces via an exchange-crosslinking-precipitation reaction route, and were studied as a model system. The network assemblies exhibit open frameworks in which the void space forms channels with the nanometer sized cores defining its size and the shell structures defining its chemical specificity. Such nanostructures were exploited to demonstrate the viability of responsive materials for interfacial incorporation and fluxes of ionic species. The nanomaterials were characterized by an array of techniques, including cyclic voltammetry, electrochemical quartz-crystal nanobalance, flow injection analysis, and surface infrared reflection spectroscopy. The current responses and mass loading as a result of the incorporation of ionic species into the nanostructure have been analyzed. The potential application of the nanostructured thin films for electrochemical detection in microfluidic systems is also discussed. [source] Stereoselective Synthesis of the First Chatt-Type Bis(dinitrogen)-Molybdenum(0) Complex with a Tetraphosphane LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2008René Römer Abstract The first Chatt-type Mo0 dinitrogen complex with a tetraphosphane ligand has been prepared and characterized by NMR as well as infrared and Raman spectroscopy. Importantly, the employed reaction route allows the stereospecific synthesis of this complex as trans -[Mo(N2)2(meso -prP4)] (prP4 = a tetraphos ligand with a central propylene bridge). The stereoselectivity in the reaction course is induced by the oxido-iodido-molybdenum(IV) precursor [Mo(O)I(prP4)]+ which directs both phenyl groups of the bridging P atoms of prP4 into a meso configuration. The paper establishes a general strategy to synthesize mononuclear Mo0 dinitrogen and related molybdenum complexes with multidentate phosphane ligands which has not been possible to date. Moreover, the obtained molybdenum tetraphos N2 complex should exhibit a higher thermodynamic stability in the reactions of the Chatt cycle of synthetic nitrogen fixation than the conventional bis(diphos) complexes, due to the linkage of the two diphosphane units by an alkyl bridge. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis and Lasing Properties of Highly Ordered CdS Nanowire Arrays,ADVANCED FUNCTIONAL MATERIALS, Issue 9 2007L. Cao Abstract Highly ordered large-area arrays of wurtzite CdS nanowires are synthesized on Cd-foil substrates via a simple liquid reaction route using thiosemicarbazide and Cd foil as the starting materials. The CdS nanowires are single crystals growing along the [001],direction and are perpendicular to the surface of the substrate. The characteristic Raman peaks of CdS are red-shifted and show asymmetric broadening, which is ascribed to phonon confinement effects arising from the nanoscale dimensions of the nanowires. Significantly, the uniform CdS nanowire arrays can act as laser cavities in the visible-light range, leading to bandgap lasing at ca.,515,nm with obvious modes. The high density of nuclei and the preferential growth direction induce the formation of aligned CdS nanowires on the metal substrate. [source] Low-Temperature Synthesis of Bismuth Titanate Niobate (Bi7Ti4NbO21) Nanoparticles from a Metal-organic Polymeric PrecursorJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2000Pedro Durán This paper describes the preparation of homogeneous Bi7Ti4NbO21 single-phase ceramic powders of ,55 nm crystallite size, at temperatures as low as 400°,500°C using a metal citrate complex method based on the Pechini-type reaction route. The thermal decomposition/oxidation of the polymerized resin, as investigated by TG/DTA, XRD, and SEM, led to the formation of a well-defined orthorhombic Bi7Ti4NbO21 compound with lattice parameters a= 0.544, b= 0.540, and c= 2.905 ± 0.0005 nm. Reaction takes place through an intermediate binary phase with a stoichiometry close to Bi20TiO32 which forms between 300° and 375°C. The metal-organic precursor synthesis method, where Bi, Ti, and Nb ions are first chelated to form metal complexes and then polymerized to give a gel, allows control of the Bi/Ti/Nb stoichiometric ratio leading to the rapid formation of nanosized bismuth titanate niobate (Bi7Ti4NbO21) ceramic powders, at temperatures much lower than usually needed by conventional processing of mixed-oxide powders. [source] A Novel Tripodal Ligand Containing Three Different N -Heterocyclic Donor Functions and Its Application in Catechol Dioxygenase MimickingCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2009Marit Wagner Dipl.-Chem. Abstract Prominent donors: A pyridyl, an imidazolyl, and a pyrazolyl donor function are part of the novel tripodal ligand depicted, which thus combines three of the most prominent donors applied in ligands for bioinorganic chemistry within one coordination unit. To exploit its behaviour and potential, first investigations have been carried out in relation to catechol dioxygenase mimicry. We describe a novel chiral ligand, L, in which three different N -donor functions are linked to a methoxymethine unit: a methylpyrazole derivative, a methylimidazole unit, and a pyridyl residue. Complexes with FeCl2, FeBr2, and FeCl3 have been synthesized and fully characterized, including with respect to their molecular structures. While in combination with FeCl3L coordinates in a tripodal fashion, with FeX2 (X=Cl, Br) it binds only through two functions and the pyridyl unit remains dangling. For potential modelling of intradiol and extradiol catechol dioxygenase reactivity, the complexes [LFeCl2], 1, and [LFeCl3], 3, have been treated with 3,5-di- tert -butylcatechol, triethylamine, and O2. Both complexes yielded similar results in such investigations, since the LFeII,catecholate complex reacts with O2 through one-electron oxidation in the first step. Employing 3 in acetonitrile solution, intradiol cleavage occurred, although the undesired quinone was formed as the main product. If reagents were added (NaBPh4, H+) or reaction conditions were chosen (CH2Cl2 instead of CH3CN as the solvent) that made the coordination sphere at the iron centre more accessible for a third substrate donor function, an alternative reaction route, presumably involving O2 binding at the metal, became more important, which led to extradiol cleavage. In the extreme case (CH2Cl2 as the solvent and with the addition of NaBPh4), mainly the extradiol cleavage products were formed; the intradiol products were only observed as side products then and quinone formation became negligible. Protonated base functions in the second coordination sphere increased the efficiency of extradiol cleavage only slightly. The obtained results are in line with current understanding of the function of intradiol/extradiol dioxygenases. [source] Shape and Magnetic Properties of Single-Crystalline Hematite (,-Fe2O3) NanocrystalsCHEMPHYSCHEM, Issue 9 2006Huaqiang Cao Prof. Unusual magnetic behavior of ,-Fe2O3: Rice- (a) and cube-shaped (b) single-crystalline ,-Fe2O3 nanostructures (see microstructure images) are obtained by a new hydrothermal reaction route. Different magnetic anisotropies are observed for the rice- and cube-shaped ,-Fe2O3 nanocrystals. This behavior offers possibilities for technological applications of ,-Fe2O3 with magnetic properties tailored by shape-controlled synthesis. [source] Identification of flurbiprofen and its photoproducts in methanol by gas chromatography,mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 5 2007Su-Hui Chao Abstract A sample of 10 mm flurbiprofen in methanol (or ethanol) was photoirradiated with sixteen 8 W low-pressure quartz mercury lamps irradiated at 306 nm in a Panchum PR-2000 photochemical reactor. In total, four major photoproducts derived from each sample were observed from the HPLC chromatogram. The photoproducts were separated and their structures elucidated by various spectroscopic methods. Alternatively, using GC-MS, 11 major photoproducts were observed. A reaction scheme of flurbiprofen in methanol is proposed: the photochemical reaction routes occur mainly via esterification and decarboxylation, followed by oxidation with singlet oxygen to produce a ketone, alcohols and other derivatives. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||