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copper catalyst

Edurne S Larrea, Roberto Fernández de Luis, María I Arriortua
The {Cu(NO₃)(H₂O)}(HTae)(4,4'-Bpy) (H₂Tae = 1,1,2,2-tetraacetylethane, 4,4'-Bpy = 4,4'-Dipyridyl) 1D coordination polymer has been obtained by slow evaporation. The crystal structure consists of parallel and oblique {Cu(HTae)(4,4'-Bpy)} zig-zag metal-organic chains stacked along the [100] crystallographic direction. Copper(II) ions are in octahedral coordination environment linked to two nitrogen atoms of two bridging 4,4'-Bpy and to two oxygen atoms of one HTae molecule in the equatorial plane. The occupation of the axial positions varies from one copper atom to another, with different combinations of water molecules and nitrate anions, giving rise to a commensurate super-structure...
December 1, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Nagaraj Anbu, Amarajothi Dhakshinamoorthy
Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylic acid) showed to be an efficient and reusable heterogeneous solid catalyst for the formation of SiO bond through dehydrogenative coupling of dimethylphenylsilane (1) with phenol under mild reaction conditions. It is observed that Fe(BTC), MIL-101(Cr) and UiO-66(Zr) are not able to promote this cross coupling between 1 and phenol. Cu3(BTC)2 exhibits higher stability and activity compared to other MOFs studied here. Furthermore, Cu3(BTC)2 is reused for three consecutive cycles with a slight decay in its activity...
November 24, 2016: Journal of Colloid and Interface Science
Chun-Chao Hou, Chuan-Jun Wang, Qian-Qian Chen, Xiao-Jun Lv, Wen-Fu Fu, Yong Chen
One-dimensional core-shell nanowire materials have recently received great attention as durable catalysts for water splitting. Herein we report the facile and rapid synthesis of ultralong Fe(OH)3:Cu(OH)2 core-shell nanowires grown in situ on an open 3D electrode to function as a highly efficient electrocatalyst for water oxidation. It only requires an overpotential of ∼365 mV to reach a 10 mA cm(-2) current density in 1.0 M KOH. As far as we know, this shows the best result amongst Cu-based heterogeneous OER systems reported to date...
December 1, 2016: Chemical Communications: Chem Comm
Kenichi Koizumi, Katsuyuki Nobusada, Mauro Boero
The reaction mechanisms of CO molecules interacting with a Cu/CeO2 surface and related morphological modifications occurring upon removal of O atoms to generate CO2 are investigated by first-principles dynamical simulations complemented by a free-energy sampling technique. We show that the reactivity of oxygen atoms located in the first layer in the vicinity of the Cu site is remarkably high because of a reduction of the O coordination number. Moreover, we evidence that the doped Cu atoms are responsible for an enhancement of the exposure of other surrounding O atoms, even below the first surface layer, which can then easily react with CO and are gradually removed from the system in the oxidation process...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
Tao Liu, Michael C Myers, Jin-Quan Yu
Selective bromination of γ-methylene C(sp(3) )-H bonds of aliphatic amides and δ-methylene C(sp(3) )-H bonds of nosyl-protected alkyl amines are developed using NBS as the brominating reagent and catalytic amount of Cu(II) /phenanthroline complexes as the catalyst. Aryl and benzylic C-H bonds at other locations remain intact during this directed radical abstraction reaction.
November 29, 2016: Angewandte Chemie
Yuxia Liu, Chao Wang, Dong Xue, Miao Xiao, Chaoqun Li, Jianliang Xiao
A binuclear copper-salicylate complex, [Cu(Sal)2(NCMe)]2 (Sal = salicylate), was found to be an active catalyst for the aerobic oxidation of N-aryltetrahydroisoquinolines to the corresponding iminium ions, which could be trapped by a wide range of nucleophiles to form coupled products. The reactions took place under 1 bar of O2 at room temperature with 1 mol% of the copper catalyst being sufficient in most cases, and are considerably accelerated by catalytic chloride anions. Mechanistic studies show that the Cu(II) dimer oxidizes the amine into the iminium and this two-electron process necessitates O2, with the resulting Cu(I) being concomitantly reoxidized back to Cu(II)...
November 23, 2016: Chemistry: a European Journal
Yuxia Liu, Chao Wang, Dong Xue, Miao Xiao, Jiao Liu, Chaoqun Li, Jianliang Xiao
N-aryltetrahydroisoquinolines were oxidised to dihydroisoquinolones through the relay catalysis of a binuclear paddle-wheel copper complex and a vitamin B1 analogue with oxygen as oxidant. Mechanistic studies revealed that the copper catalyst oxidises amines to the corresponding iminium salts, which were then oxygenated to lactam products by the catalysis of the vitamin B1 analogue.
November 23, 2016: Chemistry: a European Journal
Boran Xu, Elizabeth M Hartigan, Giancarlo Feula, Zheng Huang, Jean-Philip Lumb, Bruce A Arndtsen
We describe the use of simple copper-salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure, and allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations.
November 22, 2016: Angewandte Chemie
Austin Baranek, Han Byul Song, Mathew McBride, Patricia Finnegan, Christopher N Bowman
Bulk photopolymerization of a library of synthesized multifunctional azides and alkynes was carried out toward developing structure-property relationships for CuAAC-based polymer networks. Multifunctional azides and alkynes were formulated with a copper catalyst and a photoinitiator, cured, and analyzed for their mechanical properties. Material properties such as the glass transition temperatures (Tg) show a strong dependence on monomer structure with Tg values ranging from 41 to 90 °C for the series of CuAAC monomers synthesized in this study...
February 23, 2016: Macromolecules
Xin Chang, An-Feng Liu, Bo Cai, Jin-Yue Luo, Hui Pan, Yao-Bing Huang
The catalytic transfer hydrogenation of furfural to the fuel additives 2-methylfuran (2-MF) and 2-methyltetrahydrofuran (2-MTHF) was investigated over various bimetallic catalysts in the presence of the hydrogen donor 2-propanol. Of all the as-prepared catalysts, bimetallic Cu-Pd catalysts showed the highest catalytic activities towards the formation of 2-MF and 2-MTHF with a total yield of up to 83.9 % yield at 220 °C in 4 h. By modifying the Pd ratios in the Cu-Pd catalyst, 2-MF or 2-MTHF could be obtained selectively as the prevailing product...
November 9, 2016: ChemSusChem
Mark A Iron, Alex Martin Szpilman
Identifying the mechanism of a catalytic reaction is paramount for designing new and improved catalysts. Several alternative catalytic cycles for the copper-TEMPO catalyzed aerobic oxidation of alcohols to the corresponding aldehydes or ketones were examined in their entirety using density functional theory at the SMD(CH3CN)-RIJCOSX-DSD-PBEB95/def2-TZVP//DF-PBED3BJ/def2-SVP level of theory. A novel catalytic cycle in which TEMPO remains complexed to copper throughout, was identified as the most likely mechanism...
November 9, 2016: Chemistry: a European Journal
Jessica Clavadetscher, Scott Hoffmann, Annamaria Lilienkampf, Logan Mackay, Rahimi M Yusop, Sebastien A Rider, John J Mullins, Mark Bradley
The copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has proven to be a pivotal advance in chemical ligation strategies with applications ranging from polymer fabrication to bioconjugation. However, application in vivo has been limited by the inherent toxicity of the copper catalyst. Herein, we report the application of heterogeneous copper catalysts in azide-alkyne cycloaddition processes in biological systems ranging from cells to zebrafish, with reactions spanning from fluorophore activation to the first reported in situ generation of a triazole-containing anticancer agent from two benign components, opening up many new avenues of exploration for CuAAC chemistry...
November 15, 2016: Angewandte Chemie
Bablu Hira Mandal, Md Lutfor Rahman, Mashitah Mohd Yusoff, Kwok Feng Chong, Shaheen M Sarkar
Corn-cob cellulose supported poly(hydroxamic acid) Cu(II) complex was prepared by the surface modification of waste corn-cob cellulose through graft copolymerization and subsequent hydroximation. The complex was characterized by IR, UV, FESEM, TEM, XPS, EDX and ICP-AES analyses. The complex has been found to be an efficient catalyst for 1,3-dipolar Huisgen cycloaddition (CuAAC) of aryl/alkyl azides with a variety of alkynes as well as one-pot three-components reaction in the presence of sodium ascorbate to give the corresponding cycloaddition products in up to 96% yield and high turn over number (TON 18,600) and turn over frequency (TOF 930h(-1)) were achieved...
January 20, 2017: Carbohydrate Polymers
Maria Vittoria Spanedda, Marcella De Giorgi, Fatouma Saïd Hassane, Francis Schuber, Line Bourel-Bonnet, Benoît Frisch
Click chemistry represents a new bioconjugation strategy that can be used to conveniently attach various ligands to the surface of preformed liposomes. This efficient and chemoselective reaction involves a Cu(I)-catalyzed azide-alkyne cycloaddition which can be performed under mild experimental conditions in aqueous media. Here we describe the application of a model click reaction to the conjugation, in a single step, of unprotected α-1-thiomannosyl ligands, functionalized with an azide group, to liposomes containing a terminal alkyne-functionalized lipid anchor...
2017: Methods in Molecular Biology
Seongwan Jang, Chohye Yoon, Jae Myung Lee, Sungkyun Park, Kang Hyun Park
HKUST-1, a copper-based metal organic framework (MOF), has been investigated as a catalyst in various reactions. However, the HKUST-1 shows low catalytic activity in the oxidation of catechol. Therefore, we synthesized Fe₃O₄@HKUST-1 by layer-by layer assembly strategy and Cu@Cu₂O by reduction of HKUST-1 for enhancement of catalytic activity. Cu@Cu₂O nanoparticles exhibited highly effective catalytic activity in oxidation of 3,5-di-tert-butylcatechol. Through this method, MOF can maintain the original core-shell structure and be used in various other reactions with enhanced catalytic activity...
November 2, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Dengfeng Wu, Haoxiang Xu, Dapeng Cao, Adrian Fisher, Yi Gao, Daojian Cheng
In order to combine the advantages of both 0D and 1D nanostructured materials into a single catalyst, density functional theory (DFT) calculations have been used to study the PdCu alloy NP-decorated Cu nanotubes (PdCu@CuNTs). These present a significant improvement of the electrocatalytic activity of formic acid oxidation (FAO). Motivated by our theoretical work, we adopted the seed-mediated growth method to successfully synthesize the nanostructured PdCu@CuNTs. The new catalysts triple the catalytic activity for FAO, compared with commercial Pd/C...
November 9, 2016: Nanotechnology
Jung Tae Han, Won Jun Jang, Namhyeon Kim, Jaesook Yun
An efficient synthetic method for preparing enantioenriched secondary borylalkanes has been achieved through a copper-catalyzed regio- and enantioselective hydroallylation of alkenyl boronates and boramides employing hydrosilanes and allylic phosphates. In the presence of a copper catalyst with chiral Walphos ligand, a range of alkenylboron compounds with an aryl, heteroaryl, or alkyl substituent produced secondary homoallylic alkylboron compounds in good yields and with high enantioselectivities up to 99% ee...
November 3, 2016: Journal of the American Chemical Society
Zihao Li, Fei Meng, Jie Zhang, Jianwei Xie, Bin Dai
Copper-based MOF-199 was used as an efficient heterogeneous catalyst to catalyze cross-coupling reactions between N-containing heterocycles and aryliodides with high yields. The catalyst can be easily separated from the reaction mixture, and can be reused at least 5 times without significantly decreasing the activity. The XRD results showed that the crystallinity and structure of MOF-199 can be maintained well during the coupling reaction.
November 3, 2016: Organic & Biomolecular Chemistry
Rahul Jain, Tony J Gibson, Mark S Mashuta, Robert M Buchanan, Craig A Grapperhaus
The catalytic aerobic oxidation of benzylic alcohols to corresponding aldehydes has been investigated employing a tetradentate copper(ii) complex that incorporates N-methyl imidazole (NMI) as an integral part of an N4-ligand framework. The complex [L3-Cu](2+) [(L3 = 1-methyl-4,5-dihydro-1H-imidazol-2-yl)methyl(2-ethyl)amine] has been synthesized, characterized by spectroscopic and structural techniques, and its catalytic activity towards the aerobic oxidation of benzylic alcohols studied under ambient conditions...
November 3, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Seohyun Shin, Jeong-Yu Son, Changwook Choi, Sanghyuck Kim, Phil Ho Lee
Rhodium-catalyzed denitrogenative cyclization of (E)-ethyl 2-(1-alkyl and arylsulfonyl-1H-1,2,3-triazol-4-yl)-3-arylacrylate generated from (E)-ethyl 2-benzylidenebut-3-ynoates and N-sulfonyl azides in the presence of a copper catalyst was developed for the synthesis of a large number of functionalized benzofulvenes. Moreover, the synthesis of benzofulvenes was demonstrated as a one-pot method through tandem copper-catalyzed [3 + 2] cycloaddition and rhodium-catalyzed denitrogenative cyclization from (E)-ethyl 2-benzylidenebut-3-ynoates and N-sulfonyl azides...
November 1, 2016: Journal of Organic Chemistry
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