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Situ Reduction (situ + reduction)
Selected AbstractsPalladium Nanowire from Precursor Nanowire: Crystal-to-Crystal Transformation via In,Situ Reduction by Polymer Matrix,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2007S. Porel Abstract Precursor nanowires of potassium palladium(II) chloride crystallized inside a poly(vinyl alcohol) film are reduced to palladium nanowires by the polymer itself under mild thermal annealing. The chemical reaction occurring in situ inside the polymer film, including byproduct formation, is investigated through electronic absorption and X-ray photoelectron spectroscopy together with atomic force and electron microscopy. The overall process can be described as a novel case of crystal-to-crystal transformation at the nanoscopic level. Optical limiting characteristics of the nanowire-embedded polymer film are explored. The fabrication procedure developed, involving chemistry inside a polymer matrix mediated by the polymer, opens up a convenient route to the fabrication of free-standing metal nanowire-embedded thin films. [source] Cobalt Nanoskeletons: One-Pot Solution Synthesis of Cubic Cobalt Nanoskeletons (Adv. Mater.ADVANCED MATERIALS, Issue 16 200916/2009) Cubic Co nanoskeletons with an edge length of 100 nm can be prepared by a facile one-step solution method. In work reported on p. 1636 by Ying Ma, Fangli Yuan, Jiannian Yao, and co-workers, CoO nanoparticles of ,10 nm are subjected to self-aggregating, in situ reduction, Ostwald ripening, and facet-selective coordination-assisted etching to form these novel structures, which exhibit excellent magnetic properties. Simple control of the shape can be achieved by altering the reaction time. [source] Organocatalysis in Natural Product Synthesis: A Simple One-Pot Approach to Optically Active ,-DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Nikolaj Røjkjær Andersen Abstract Optically active ,-diols have been prepared using an organocatalytic one-pot approach from ,,,-unsaturated aldehydes using (E) -benzaldehyde oxime as nucleophile in an oxa-Michael reaction with subsequent in situ reduction or Grignard addition. With this protocol at hand, two biologically active compounds, an insect sex pheromone and a glycerol kinase substrate have been synthesized. [source] Gold nanoparticle-incorporated core and shell crosslinked micelles fabricated from thermoresponsive block copolymer of N -isopropylacrylamide and a novel primary-amine containing monomerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2008Yueming Zhou Abstract A novel primary amine-containing monomer, 1-(3,-aminopropyl)-4-acrylamido-1,2,3-triazole hydrochloride (APAT), was prepared from N -propargylacrylamide and 3-azidopropylamine hydrochloride via copper-catalyzed Huisgen 1,3-dipolar cycloaddition (click reaction). Poly(N -isopropylacrylamide)- b -poly(1-(3,-aminopropyl)-4-acrylamido-1,2,3-triazole hydrochloride), PNIPAM- b- PAPAT, was then synthesized via consecutive reversible addition-fragmentation chain transfer polymerizations of N -isopropylacrylamide and APAT. In aqueous solution, the obtained thermoresponsive double hydrophilic block copolymer dissolves molecularly at room temperature and self-assembles into micelles with PNIPAM cores and PAPAT shells at elevated temperature. Because of the presence of highly reactive primary amine moieties in PAPAT block, two types of covalently stabilized nanoparticles namely core crosslinked and shell crosslinked micelles with ,inverted' core-shell nanostructures were facilely prepared upon the addition of glutaric dialdehyde at 25 and 50 °C, respectively. In addition, the obtained structure-fixed micelles were incorporated with gold nanoparticles via in situ reduction of preferentially loaded HAuCl4. High resolution transmission electron microscopy revealed that gold nanoparticles can be selectively loaded into the crosslinked cores or shells, depending on the micelle templates employed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6518,6531, 2008 [source] Bimetallic Au,Ni Nanoparticles Embedded in SiO2 Nanospheres: Synergetic Catalysis in Hydrolytic Dehydrogenation of Ammonia BoraneCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2010Hai-Long Jiang Dr. Abstract Gold,nickel nanoparticles (NPs) of 3,4,nm diameter embedded in silica nanospheres of around 15,nm have been prepared by using [Au(en)2Cl3] and [Ni(NH3)6Cl2] as precursors in a NP-5/cyclohexane reversed-micelle system, and by in situ reduction in an aqueous solution of NaBH4/NH3BH3. Compared with monometallic Au@SiO2 and Ni@SiO2, the as-synthesized Au,Ni@SiO2 catalyst shows higher catalytic activity and better durability in the hydrolysis of ammonia borane, generating a nearly stoichiometric amount of hydrogen. During the generation of H2, the synergy effect between gold and nickel is apparent: The nickel species stabilizes the gold NPs and the existence of gold helps to improve the catalytic activity and durability of the nickel NPs. [source] | |||||||||||||