- Hierarchical Copper with Inherent Hydrophobicity Mitigates Electrode Flooding for High-Rate CO2 Electroreduction to Multicarbon Products
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Copper is currently the material with the most promise as catalyst to drive carbon dioxide (CO2) electroreduction to produce value-added multicarbon (C2+) compounds. However, a copper catalyst on a carbon-based gas diffusion layer electrode often has poor stability - especially when performing at high current densities - owing to electrolyte flooding caused by the hydrophobicity decrease of the gas diffusion layer during operation. Here, we report a bioinspired copper catalyst on a gas diffusion layer that mimics the unique hierarchical structuring of Setaria's hydrophobic leaves. This hierarchical copper structure endows the CO2 reduction electrode with sufficient hydrophobicity to build a robust gas-liquid-solid triple-phase boundary, which can not only trap more CO2 close to the active copper surface but also effectively resist electrolyte flooding even under high-rate operation. We consequently achieved a high C2+ production rate of 255 ± 5.7 mA cm-2 with a 64 ± 1.4% faradaic efficiency, as well as outstanding operational stability at 300 mA cm-2 over 45 h in a flow reactor, largely outperforming its wettable copper counterparts.
- Niu, Zhuang-Zhuang,Gao, Fei-Yue,Zhang, Xiao-Long,Yang, Peng-Peng,Liu, Ren,Chi, Li-Ping,Wu, Zhi-Zheng,Qin, Shuai,Yu, Xingxing,Gao, Min-Rui
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p. 8011 - 8021
(2021/05/29)
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- Theoretical and Experimental Evaluation of the Reduction Potential of Straight-Chain Alcohols for the Designed Synthesis of Bimetallic Nanostructures
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Recently, the development of bimetallic nanoparticles with functional properties has been attempted extensively but with limited control over their morphological and structural properties. The reason was the inability to control the kinetics of the reduction reaction in most liquid-phase syntheses. However, the alcohol reduction technique has demonstrated the possibility of controlling the reduction reaction and facilitating the incorporation of other phenomena such as diffusion, etching, and galvanic replacement during nanostructure synthesis. In this study, the reduction potential of straight-chain alcohols has been investigated using molecular orbital calculations and experimentally verified by reducing transition metals. The alcohols with a longer chain exhibited higher reduction potential, and 1-octanol was found to be the strongest among alcohols considered. Furthermore, the experimental evaluation carried out via the synthesis of metallic Cu, Ni, and Co particles was consistent with the theoretical predictions. The reaction mechanism of metallic particle formation was also studied in detail in the Ni-1-octanol system, and the metal ions were confirmed to be reduced via the formation of nickel alkoxide. The results of this investigation were successfully implemented to synthesize Cu-Ni bimetallic nanostructures (core-shell, wire, and tube) via the incorporation of diffusion and etching besides the reduction reaction. These results suggest that the designed synthesis of a wide range of bimetallic nanostructures with more refined control has become possible.
- Ishijima, Masanao,Matsumoto, Takatoshi,Cuya Huaman, Jhon L.,Shinoda, Kozo,Uchikoshi, Masahito,Matsuo, Kohei,Suzuki, Kazumasa,Miyamura, Hiroshi,Balachandran, Jeyadevan
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p. 9432 - 9441
(2021/05/06)
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- Synthesis of an Ag@AgCl catalyst with amorphous copper as the support and its catalytic performance in the reduction of 4-nitrophenol
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The support used in a composite catalyst has an important influence on the catalytic performance of the catalyst. Amorphous metals have good electron-transfer properties and the presence of defect structures on the surface will introduce additional active sites and should be excellent catalyst supports. In this study, an Ag@AgCl composite catalyst with amorphous Cu (a-Cu) as the support is prepared by a two-step precipitation method at room temperature and a light irradiation reduction method. Compared to the Ag@AgCl and a-Cu, the catalytic rate of the Ag@AgCl/a-Cu composite catalytic rate was 2.04 times and 6.69 times faster during the reduction of 4-NP in NaBH4 aqueous solution. The high-performance catalytic efficiency and reusability of Ag@AgCl/a-Cu may be attributed to the synergistic effect between Ag@AgC and amorphous metal elements. This work may provide an effective reference for the synthesis of high activity catalysts using amorphous metals as supports.
- Bao, Lei,Dong, Hanfeng,Fu, Xucheng,Gan, Wei,Hao, Hequn,Liu, Luying,Qin, Chenchen,Wang, Yujuan,Zhang, Jian
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p. 551 - 557
(2020/07/24)
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- Synthesis, Structure, DFT, and Biological Activity of Metal Complexes of Norfloxacin and Metformin Mixed Ligand
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Abstract: A new series of mixed ligand metal complexes has been synthesized by the reaction of Co(II), Ni(II), Cu(II), Zr(IV), Pd(II), and Cd(II) with norfloxacin (NOR) and metformin hydrochloride (MF) in 1 : 1 : 1 molar ratio. The complexes have been characterized by FT-IR, UV-Vis, and 1H NMR spectra, TG/DTG and elemental analysis, molar conductance, and magnetic susceptibility data. According to FT-IR, NOR chelates with metal ions as a bidentate ligand via one oxygen of the carboxylate group and pyridone oxygen, and MF chelates with metal ions via two imine groups. Complexes have been identified as electrolytes. Electronic and magnetic data have indicated the octahedral structure for all complexes except square planar Pd(II) complex. Antibacterial and antifungal activities of the compounds have been tested against several species, and have indicated higher inhibition against micro-organisms for the metal complexes than the mixed ligands.
- Abbass, L. M.,El-Shwiniy, W. H.,El-Telbany, M.,Sadeek, S. A.,Zordok, W. A.
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p. 1774 - 1782
(2021/11/01)
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- The composition dependent structure and catalytic activity of nanostructured Cu-Ni bimetallic oxides
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Nanostructured bimetallic oxides have received a great amount of attention in the field of catalysis. Here, the influence of composition on the structure and catalytic activity of CuO/NiO bimetal oxides is reported. Oxides with different ratios of Cu : Ni (0 : 100, 25 : 75, 50 : 50, 75 : 25 and 100 : 0) were prepared via a hydrothermal process and subsequently heat-treated at 600 °C for 4 h. XRD and Raman spectroscopic analysis clearly indicated the co-existence of NiO and CuO phases in the bimetallic oxides. Electron microscopy studies revealed a reduction in particle size for the bimetallic oxide compared to the monometallic oxide. The highest catalytic activity with good recyclability for the reduction of 4-nitrophenol was observed with Cu50Ni50-600, having a rate constant of 5.08 × 10-3 s-1. Cyclic voltammetry investigations confirmed the high reactivity of Cu50Ni50-600 for 4-nitrophenol, showing a high oxidation current peak compared to that of other samples. The results show that the presence of CuO and NiO enhances the catalytic activity by their synergetic effect, unlike the monometal oxides. This journal is
- Preethi, S.,Sundramoorthy, Ashok K.,Suresh Babu, K.,Vivek, S.
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p. 9691 - 9698
(2020/07/03)
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- A Low-Temperature Molecular Precursor Approach to Copper-Based Nano-Sized Digenite Mineral for Efficient Electrocatalytic Oxygen Evolution Reaction
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In the urge of designing noble metal-free and sustainable electrocatalysts for oxygen evolution reaction (OER), herein, a mineral Digenite Cu9S5 has been prepared from a molecular copper(I) precursor, [{(PyHS)2CuI(PyHS)}2](OTf)2 (1), and utilized as an anode material in electrocatalytic OER for the first time. A hot injection of 1 yielded a pure phase and highly crystalline Cu9S5, which was then electrophoretically deposited (EPD) on a highly conducting nickel foam (NF) substrate. When assessed as an electrode for OER, the Cu9S5/NF displayed an overpotential of merely 298±3 mV at a current density of 10 mA cm?2 in alkaline media. The overpotential recorded here supersedes the value obtained for the best reported Cu-based as well as the benchmark precious-metal-based RuO2 and IrO2 electrocatalysts. In addition, the choronoamperometric OER indicated the superior stability of Cu9S5/NF, rendering its suitability as the sustainable anode material for practical feasibility. The excellent catalytic activity of Cu9S5 can be attributed to the formation of a crystalline CuO overlayer on the conductive Cu9S5 that behaves as active species to facilitate OER. This study delivers a distinct molecular precursor approach to produce highly active copper-based catalysts that could be used as an efficient and durable OER electro(pre)catalysts relying on non-precious metals.
- Chakraborty, Biswarup,Kalra, Shweta,Beltrán-Suito, Rodrigo,Das, Chittaranjan,Hellmann, Tim,Menezes, Prashanth W.,Driess, Matthias
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p. 852 - 859
(2020/02/28)
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- Synthesis, Crystal Structures, and Thermolysis Studies of Heteronuclear Transition Metal Aluminum Alcoholates
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Heteronuclear alcoholate complexes [M{Al(OiPr)4}2(bipy)] (2-M, M = Fe, Co, Ni, Cu, Zn) and [M{Al(OcHex)4}2(bipy)] (3-M, M = Fe, Co, Ni, Zn) are formed by adduct formation of [M{Al(OiPr)4}2] (1-M, M = Fe, Co, Ni, Cu, Zn) with 2,2'-bipyridine and transesterification reaction with cHexOAc. According to crystal structure analyses, in 2-M and 3-M the central transition metal ion M2+ is coordinated by two chelating Al(OR)4– moieties and one bipyridine ligand in an octahedral arrangement. Treating 1-Cu with 2,2'-bipyridine leads to a reduction process, whereat the intermediate [Cu{Al(OiPr)4}(bipy)2][Al(OiPr)4] (4) could be structurally characterized. During conversion of the iso-propanolate ligands in 1-Cu to cyclohexanolate ligands, Cu2+ is reduced to Cu+ forming [Cu{Al(OcHex)4}(py)2] (5). UV/Vis-spectra and results of thermolysis studies by TG/DTA-MS are reported.
- Küsel, Sebastian,Krautscheid, Harald
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- Selective hydrogenation of quinolines over a CoCu bimetallic catalyst at low temperature
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Quinoline derivatives are widely exist in the environment, and mainly separated from the coal tar pitch fraction. Hydrogenation of these compounds to 1,2,3,4-tetrahydroquinolines, an important class of natural products and medicinal agents, is a significant transformation of waste to valuable chemicals. In the present work, we developed a cheap and highly efficient Co3Cu1Ox bimetallic catalyst and used it for the hydrogenation of quinolines at a temperature down to 60 °C. The introduction of Cu into Co catalyst changed the physical and chemical features of Co catalyst, which was characterized by Raman spectra, N2-adsorption/desorption isotherms, H2-TPR and H2-TPD tests. The recycling experiments indicated the catalyst was stable and possessed good reusability. Importantly, the gram-scale experiment provided a high yield (92%) to the target product, demonstrating that the catalytic system has a potential practical application.
- He, Zhen-Hong,Li, Na,Wang, Kuan,Wang, Wei-Tao,Liu, Zhao-Tie
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p. 120 - 126
(2019/04/10)
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- Sustainable fixation of CO2 into epoxides to form cyclic carbonates using hollow marigold CuCo2O4 spinel microspheres as a robust catalyst
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The present work demonstrates the chemical fixation of CO2 for the synthesis of organic carbonates using mesoporous hollow marigold CuCo2O4 spinel microspheres as a catalyst prepared using the solvothermal method. The synthesized microspheres were characterized using contemporary analytical and spectroscopic tools. The CuCo2O4 spinel microspheres with the best morphological behaviour obtained after solvothermal treatment for 3 h were employed as a heterogeneous catalyst for the solvent-free conversion of epoxides and CO2 to generate cyclic carbonates. As a result, the model reaction of styrene oxide and CO2 revealed 94% conversion, 88% yield and 94% selectivity towards styrene carbonate in the presence of TBAI as a base under mild reaction conditions (80 °C, 20 bar, 3 h). Notably, the enhanced catalytic activity was attributed to the cooperative effect of the exposed Lewis acidic sites of CuCo2O4 and the efficient basic nature of TBAI. The effects of different reaction variables such as catalyst loading, temperature, pressure and time were investigated and discussed. Additionally, the effect of different bases was also experimentally determined. Further, the substrate scope using the CuCo2O4 and TBAI catalytic system revealed good performance towards CO2 fixation with a variety of terminal and internal epoxides. The catalyst was easily separated out after the reaction and tested for its recyclability. Results showed good recyclability up to five cycles without a substantial loss of catalytic activity. Based on the results obtained from XPS, XRD, and TPD and the available literature, an effort to predict a plausible mechanism was made in order to support the cycloaddition reaction. The present protocol is the first report of hollow marigold CuCo2O4 spinel microspheres as an outstanding and efficient catalyst with high selectivity towards fixation of CO2 into epoxides for cyclic carbonate formation.
- Prasad, Divya,Patil, Komal N.,Bhanushali, Jayesh T.,Nagaraja, Bhari Mallana,Jadhav, Arvind H.
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p. 4393 - 4412
(2019/08/22)
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- Cylindrical shaped ZnO combined Cu catalysts for the hydrogenation of CO2 to methanol
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Hydrogenation of CO2 to chemicals is of great importance in the reduction of greenhouse gas emission. And the interaction and/or the boundary between Cu and ZnO played a crucial role in the performance of the Cu-ZnO catalyst for CO2 hydrogenation to methanol. In this work, cylindrical shaped ZnO was first synthesized via controlled hydrothermal precipitation of Zn(CO2CH3)2·2H2O, and Cu was further deposited on ZnO via in situ reduction in aqueous solution. Characterizations indicated that the crystallization degree of ZnO decreased with the increasing content of Cu, while the exposed surface area of Cu exhibited a volcano shaped curve. It was found that the cylindrical shaped ZnO combined Cu catalysts were active for the hydrogenation of CO2, and the space time yield of methanol reached 0.50 g-MeOH (g-cat h)-1 at H2/CO2 = 3, 240 °C, 3.0 MPa, and 0.54 mol (g-cat h)-1, but the methanol selectivity decreases with the reduction of the (002) polar plane of ZnO. The conversion of CO2 and methanol selectivity were discussed with the detected exposed Cu surface area and the number of oxygen vacancies.
- Lei, Hong,Zheng, Ruheng,Liu, Yeping,Gao, Jiacheng,Chen, Xiang,Feng, Xiaoliang
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p. 13696 - 13704
(2019/05/17)
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- Pharmacological properties of dicyanidoaurate(I)-based complexes: characterization and single crystal X-ray analysis
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Absract: The synthesis of three bimetallic cyanido complexes with edbea [2,2′-(ethylenedioxy)bis(ethylamine)] ligand is reported. [NiII(μ-edbea)2{Au(μ-CN)2}2]n (1), [{CuII(edbea)}2{Au(μ-CN)2}4]n (2) and [CdII(edbea)2][Au(CN)2]2·H2O (3) were fully characterized by elemental, infrared, XRD (3), ESI-MS and thermal analysis. The DNA/BSA binding properties of these complexes were evaluated by spectrophotometric titration, fluorometric ethidium bromide kinetics, and DNA electrophoresis studies and their partially minor groove binding mode between the base pairs of DNA and electrostatic interaction between the amino acid residues of BSA were explained. The complexes were tested for their pharmacological properties. These molecules had excellent in vitro antiproliferative activity and also exhibited a strong tumor inhibiting effect against HT29, HeLa, C6 and Vero cell lines. These complexes had metastatic features as they are able to reduce cell migration activity and suppress tumor growth in vitro. Analysis of the DNA topoisomerase I relaxing activity indicates that the complexes do not inhibit topoisomerase I which regulates the topological states of the DNA double helix during DNA processing reactions. The TUNEL and DNA laddering assay results indicated that these compounds may destroy cell maintenance by triggering apoptosis. Immunohistochemistry staining analysis demonstrated that these complexes significantly decreased the expression of Bcl-2 in HeLa and HT29 cells while increasing the expression of P53 levels. Overall, the potent antiproliferative activity, low cytotoxic effect, good solubility, and micro molar range dosage observed for these complexes emphasizes their potential as anticancer drug candidates.
- Karada?, Ahmet,Aydin, Ali,Tekin, ?aban,Akba?, Hüseyin,Dede, Süreyya
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p. 860 - 878
(2019/03/11)
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- Directing Boron-Phosphorus Bonds in Crystalline Solid: Oxidative Polymerization of P═B═P Monomers into 1D Chains
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Over 20 years after the last inorganic ternary B-P compound was reported, Na2BP2, a new compound containing one-dimensional B-P polyanionic chains has been synthesized. Common high-temperature synthetic methods required for the direct reaction of boron and phosphorus negate the possible formation of metastable or low temperature phases. In this study, oxidative elimination was used to successfully condense 0D BP23- anionic monomers found in a Na3BP2 precursor into unique 1D BP22- chains consisting of five-member B2P3 rings connected by bridging P atoms in the crystal structure of Na2BP2. The synthesis was guided by in situ X-ray powder diffraction studies, which revealed the metastable nature of the products of oxidative elimination reactions. Na2BP2 is predicted to be an electron balanced semiconductor which was confirmed by UV-vis spectroscopy with the experimentally determined band gap of 1.1 eV.
- Woo, Katherine E.,Wang, Jian,Mark, Justin,Kovnir, Kirill
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supporting information
p. 13017 - 13021
(2019/09/03)
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- Structural Transformations of [CuEn 3]WO4 Complex Salt in the Range 100–390 K and Its Degradation to [CuEn 2](WO4)·2H2O
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The crystal structure of [CuEn3]WO4 (En is ethylenediamine) is studied in the temperature range 100–390 K. Crystallographic data at 100 K are: a = 27.6903(8) ?, c = 9.9405(3) ?, space group P3?, V = 6600.8(4) ?3, Z = 18. Copper atomic coordination is a distorted square bipyramid. Four short Cu–N distances are within 2.038(5)–2.110(6) ?; two long distances are within 2.374(8)–2.514(7) ?. The lengths of N–H…O interionic contacts lie within 1.96–2.17 ?. A temperature elevation makes the Cu–N distances equal: at 298 K they are within 2.066(2)–2.256(3) ?(a = 16.0391(8) ?, c = 9.9608(6) ?, space group P3?c1, V = 2219.1(3) ?3, Z = 6), and at 390 K they are 2.151(6) ?(a = 9.2986(10) ?, c = 10.0520(14) ?, P3?1c, V = 752.7(2) ?3, Z = 2). In the range from 100 K to 390 K the average W–O distances decrease from 1.776 ? to 1.734 ?. Hirshfeld surfaces of complex cations are analyzed. It is shown that with increasing temperature the number of interionic N–H…O contacts decreases. The [CuEn3]WO4 phase is found to be unstable and on storing in air it transforms into [CuEn2](WO4)·2H2O.
- Khranenko,Sukhikh,Komarov, V. Yu.,Gromilov
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p. 1790 - 1798
(2019/12/24)
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- Controlling Fast Nucleation and Crystallization of Two New Polyoxoniobates
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Applying identical amounts of starting materials allowed the solvothermal preparation of two new polyoxoniobates by controlling the pH value of the reaction mixture. Stirring the slurries afforded crystallization of K5[Cu(H2O)2(cyclam)]1.5{[Cu(cyclam)][Cu(H2O)(cyclam)]2HSiNb18O54}(NO3)·30H2O (I) and {[Cu(cyclam)(H2O)]2[Cu(cyclam)][Nb10O28]}n·9nH2O (II) within short reaction times and in high yields. While compound I crystallizes from the mother liquor at room temperature after hydrothermal treatment at pH values >10.3, compound II is isolated at pH 18O54]14- anion is found, which is surrounded by [Cu(cyclam)]2+ complexes and K+ cations. The water molecules form a very unusual hydrogen bonding pattern which may be classified as a L4(2)4(4)5(4)10(4)16(6)42(14) water cluster. Compound II features the decaniobate anion [Nb10O28]6-, is obtained after short reaction time in high yields and exhibits a reversible release/uptake of crystal water molecules.
- Dopta, Joanna,Krause, Dana-Céline,N?ther, Christian,Bensch, Wolfgang
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p. 4130 - 4139
(2018/06/25)
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- Syntheses, Structures, and Reactivity of NHC Copper(I) Boryl Complexes: A Systematic Study
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Five novel NHC copper(I) boryl complexes were synthesized by B-B activation via σ-bond metathesis of symmetrical tetraalkoxy and unsymmetrical dialkoxy diamino diborane(4) derivatives. Despite their low stability, the NHC copper boryl complexes were thoroughly characterized spectroscopically and structurally. Variation of the NHC ligand (ItBu or Me2IiPr) as well as of the boryl ligand (Bpin, Bdmab, or BiPrEn) allowed, for the first time systematically, a study in such complexes of the dependence on steric encumbrance. For sterically more demanding ligand combinations, mononuclear linear complexes were obtained, while with less demanding ligand combinations, dimeric dinuclear complexes with two bridging μ-boryl ligands were obtained, exhibiting extremely short Cu···Cu distances (?). The decomposition of all these complexes was found to proceed via a common pathway, leading ultimately to elemental copper, the free NHC ligand, and the respective symmetrical diborane(4) derivative. The rate of decomposition depended strongly on the steric encumbrance of the individual complex. Two apparently low-valent copper clusters were observed and suggested to be relevant species with respect to the reductive decomposition of the copper(I) boryl complexes.
- Kleeberg, Christian,Borner, Corinna
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p. 4136 - 4146
(2018/11/23)
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- New bimetallic dicyanidoargentate(I)-based coordination compounds: Synthesis, characterization, biological activities and DNA-BSA binding affinities
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Four compounds -two (2 and 3) completely new- of composition [Ni(edbea)Ag3(CN)5] (1), [Cu(edbea)Ag2(CN)4]·H2O (2), [Cd(edbea)Ag3(CN)5]·H2O (3) and [Cd(edbea)2] [Ag(CN)2]2·H2O (4) {edbea; 2,2′-(ethylenedioxy)bis (ethylamine)}, were synthesized and characterized using elemental, FT-IR, X-Ray (4), thermal, variable temperature magnetic measurement (1 and 2) and biological techniques. The DNA/BSA binding affinities of 2 and 3 were evaluated by UV–Vis spectrophotometric titrations, ethidium bromide exchange experiments and electrophoretic mobility measurements. Compounds 1 and 4 have previously been characterized and shown to reduce the proliferation and migration of tumor cells. For the sake of clarity, 1 precise mechanism of action on microbial organisms and temperature magnetic measurement were determined. The crystallographic analyses showed that 4 was built up of [Cd(edbea)2]II cations and [Ag2(CN)4]II anions. Complexes demonstrated a remarkable antibacterial (1–4), antifungal (1–4) and antiproliferative activities (2 and 3) to ten human bacterial pathogens, four plant pathogenic fungi or three tumor cells (HeLa, HT29, and C6), respectively. Therefore, our results strongly confirm that cell proliferation, cell morphology, Bcl-2, P53 changes and apoptosis can be related to the pharmacological effects of the complexes as suitable candidate for clinical trials.
- Korkmaz, Nesrin,Ayd?n, Ali,Karada?, Ahmet,Yanar, Yusuf,Maa?o?lu, Yelis,?ahin, Ertan,Tekin, ?aban
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supporting information
p. 1007 - 1022
(2016/12/16)
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- Composition and particle size of electrolytic copper powders prepared in water-containing dimethyl sulfoxide electrolytes
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The possibility of the electroprecipitation of copper powder via the cathodic reduction of an electrolyte solution containing copper(II) nitrate trihydrate and dimethyl sulfoxide (DMSO) is shown. The effect electrolysis conditions (current density, concen
- Mamyrbekova, Aigul,Abzhalov,Mamyrbekova, Aizhan
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p. 1332 - 1336
(2017/06/19)
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- Structural Changes of Binary/Ternary Spinel Oxides During Ethanol Anaerobic Decomposition
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Several M-modified iron oxides of the spinel family have proven to be effective electron and O2? vectors for the production of hydrogen in the chemical-loop reforming of bio-alcohols. The present work is specifically focused on investigation of ethanol anaerobic decomposition over spinel oxides, which results in significant structural changes of the oxygen carrier material itself and corresponds to a first step of the chemical-loop reforming process. In particular, a series of binary/ternary M-modified ferrospinels were prepared by a co-precipitation method and tested in terms of both redox properties and intrinsic catalytic activity in addition to a complex ex situ study that encompasses the solid-state chemistry investigations of the fresh and reduced oxygen carrier materials. It was found that Co/Cu incorporation facilitates total/partial oxidation of ethanol, giving rise to high yields of H2, COx, and H2O; whereas Mn incorporation predominantly favored dehydrogenation and condensation reactions, leading to the formation of acetaldehyde and acetone. In addition, the incorporation of Mn contributed to significantly reduce the amount of coke formed; however, it caused a lower intrinsic reducibility, which was explained by the formation of a thermodynamically stable and hardly reducible layer of MnxFeyO solid solution.
- Vozniuk, Olena,Bazzo, Cristian,Albonetti, Stefania,Tanchoux, Nathalie,Bosselet, Fran?oise,Millet, Jean-Marc M.,Di Renzo, Francesco,Cavani, Fabrizio
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p. 2219 - 2230
(2017/06/27)
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- Elusive Phosphine Copper(I) Boryl Complexes: Synthesis, Structures, and Reactivity
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We report the first isolation of phosphine copper boryl complexes - species pivotal to numerous copper-catalyzed borylation reactions. The reaction of diboron(4) derivatives with copper tert-butoxide complexes of phosphine ligands allows the isolation of the dimeric μ-boryl-bridged Cu(I) complexes [(iPr3P)Cu-Bdmab]2 (4) and [(C6H4(Ph2P)2)Cu-Bpin]2 (6) with Cu···Cu distances of 2.24-2.27 ? (dmab = (NMe)2C6H4, pin = (OCMe2)2)). A slightly more sterically demanding boryl ligand furnishes the unprecedented multinuclear copper boryl complex [(iPr3P)2Cu8(B(iPrEn))3(OtBu)3] (5), a potential intermediate of the decomposition of an initial Cu(I) boryl complex (iPrEn = (NiPr)2C2H4). All complexes were characterized by single-crystal X-ray diffraction, NMR spectroscopy, and elemental analysis. DFT computations support the nature of these unique complexes and give insight into their electronic structures.
- Borner, Corinna,Anders, Lisa,Brandhorst, Kai,Kleeberg, Christian
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supporting information
p. 4687 - 4690
(2018/02/07)
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- Reaction intermediate/product-induced segregation in cobalt-copper as the catalyst for hydrogen generation from the hydrolysis of sodium borohydride
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Cobalt is the most attractive catalyst for hydrogen generation from the hydrolysis of sodium borohydride, NaBH4, but its potential is further improved when it is combined with an inactive element like copper. Accordingly, several cobalt-copper catalysts (CoxCu1-x, with x as a mole ratio equal to 0, 0.1, 0.25, 0.5, 0.75, 0.9 or 1) were prepared. Under our conditions, Co0.9Cu0.1 shows the best performance, being able to complete H2 evolution in 0.9Cu0.1 is not as stable as expected; after the first cycle, the catalytic activity in terms of the H2 generation rate halves, and then remains quite constant for additional cycles (up to five under our conditions). XPS measurements show that the surface composition of Co0.9Cu0.1 is subject to changes during hydrolysis; the anti-segregation of copper concomitantly takes place with the segregation of cobalt. This is explained through the occurrence of borate-induced segregation, favored due to the well-known strong affinity of cobalt for borate species. In other words, the catalytic activity of cobalt can be improved through combination with copper but, under our conditions, it cannot be stabilized. This is evidenced and discussed in detail herein.
- Kahri,Flaud,Touati,Miele,Demirci
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p. 102498 - 102503
(2016/11/11)
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- Experimental and Computational Studies of the Copper Borate Complexes [(NHC)Cu(HBEt3)] and [(NHC)Cu(HB(C6F5)3)]
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The synthesis of the Cu-borate complexes [(6Mes)Cu(HBR3)] featuring the unusual [HBEt3]?(5) and [HB(C6F5)3]?(6) ligands is described. Experimental and computational studies show both compounds feature a direct Cu–H interaction, but that while 5 is two-coordinate, 6 displays an additional, stabilizing Cu–Cipso(C6F5) interaction.
- Collins, Lee R.,Rajabi, Nasir A.,Macgregor, Stuart A.,Mahon, Mary F.,Whittlesey, Michael K.
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supporting information
p. 15539 - 15543
(2016/12/09)
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- REDUCTANT AND METHOD FOR PRODUCING METAL USING THE SAME
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PROBLEM TO BE SOLVED: To provide a novel reductant that can reduce metal ions by a reduction reaction in solvent, and a method for producing metal using the reductant. SOLUTION: A reductant comprises a compound represented by the general formula (where X1 and X2 are the same or different to represent a nitrogen atom or a methine group, R1, R2, R3, R4, R5 and R6 are the same or different to represent a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group or a tert-butyl group). There is also provided a method for producing metal by bringing the reductant into contact with a metal ion source in solvent. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0031
(2017/03/25)
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- TG–MS study on the kinetics and mechanism of thermal decomposition of copper ethylamine chromate, a new precursor for copper chromite catalyst
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Copper chromite is a well-known burn rate modifier for the combustion of composite solid propellants. In this study, basic copper ethylamine chromate (CEC), a new precursor for copper chromite catalyst, was synthesized by precipitation method. The thermal decomposition of the precursor was followed by thermogravimetry–mass spectroscopy (TG–MS) and X-ray diffraction techniques and compared with that of copper ammonium chromate, a conventional precursor for copper chromite catalyst. TG–MS analysis for the decomposition of CEC revealed that the decomposition starts with the liberation of ethylamine. The change in enthalpy for the decomposition reaction of copper ethylamine chromate was higher than that of copper ammonium chromate due to the oxidation of ethyl group. The reducing atmosphere created by the presence of carbon during the decomposition of CEC produced a mixture of Cu, CuCr2O4, CuCrO2 and CuO, while the oxidizing atmosphere of copper ammonium chromate produced a mixture of CuCr2O4 and CuO. Mechanistic study based on Criado and Coats–Redfern methods showed that CEC follows random nucleation (F1) mechanism as the rate-determining step for the thermal decomposition process.
- Paulose, Sanoop,Thomas, Deepthi,Jayalatha,Rajeev,George, Benny K.
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p. 1099 - 1108
(2016/07/06)
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- Electrochemical sulfur removal from chalcopyrite in molten NaCl-KCl
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Electrolysis of solid chalcopyrite (CuFeS2) against a graphite inert anode has been studied in equimolar NaCl-KCl melt at 700?°C. During electrolysis, S2? ions are released from the solid CuFeS2 cathode, transfer to the graphite anode and discharge to S2 gas. The reduction mechanism of CuFeS2 was investigated by cyclic voltammetry, potentiostatic and constant voltage electrolysis together with spectroscopic and scanning electron microscopic analyses. The reduction contains mainly three stages: the insertion of Na+ or K+ into CuFeS2, forming LxCuFeS2 (L?=?Na or K, x?≤?1); the partial reduction of LxCuFeS2 to Lx-wCuFe1-yS2-z and Fe; the complete reduction to a mixture of Cu and Fe, which can be magnetically separated. After the separation, pure Cu can be obtained by leaching out the residual Fe with acid. Electrolysis at a cell voltage of 2.4?V has led to a rapid reduction of CuFeS2. The current efficiency and energy consumption were 85% and 1.68 kWh/kg-CuFeS2, respectively.
- Tan, Mingsheng,He, Rui,Yuan, Yating,Wang, Zhiyong,Jin, Xianbo
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p. 148 - 154
(2016/07/27)
-
- Salt-Free Reduction of Nonprecious Transition-Metal Compounds: Generation of Amorphous Ni Nanoparticles for Catalytic C-C Bond Formation
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A salt-free procedure for the generation of a wide variety of metal(0) particles, including Fe, Co, Ni, and Cu, was achieved using 2,3,5,6-tetramethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene (1), which reduced the corresponding metal precursors under mild conditions. Notably, Ni particles formed in situ from the treatment of Ni(acac)2 (acac=acetylacetonate) with 1 in toluene exhibited significant catalytic activity for reductive C-C bond-forming reactions of aryl halides in the presence of excess amounts of 1. By examination of high-magnification transmission electron microscopy images and electron diffraction patterns, we concluded that amorphous Ni nanoparticles (Ni aNPs) were essential for the high catalytic activity.
- Yurino, Taiga,Ueda, Yohei,Shimizu, Yoshiki,Tanaka, Shinji,Nishiyama, Haruka,Tsurugi, Hayato,Sato, Kazuhiko,Mashima, Kazushi
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supporting information
p. 14437 - 14441
(2016/01/25)
-
- Reduction of metallic ions by molten gallium under ultrasonic irradiation and interactions between the formed metals and the gallium
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Metallic gallium can reduce ions of silver, copper or gold in a slow spontaneous reaction to form the free metals. However, when the reduction is performed with molten gallium under ultrasonic irradiation, the gallium is dispersed into micrometric spheres and the reduction rate is enhanced dramatically. This is due to the large surface area of unoxidized gallium that is formed, on which the heterogeneous reduction occurs. Each of these metals formed also a certain amount of an intermetallic compound with the gallium: Ag2Ga, CuGa2 and AuGa2. Zinc has a more negative reduction potential than gallium and therefore no reduction of zinc ions was expected. Nevertheless we conducted an experiment using a solution of zinc ions to check whether the extremely high temperature that develops near the surface of the particles during cavitation can overcome the energetic barrier for such reduction.
- Kumar, Vijay Bhooshan,Perelshtein, Ilana,Kimmel, Giora,Porat, Ze'Ev,Gedanken, Aharon
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p. 538 - 544
(2015/03/30)
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- TSV fillings and electrochemical measurements of the dialyl-amine additive with Cl- and Br-
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The TSV filling using the dialyl-amine and the Br- and Cl- halogen ions to a copper electrodeposition bath is reported. The TSV bottom acceleration and TSV outside inhibition have been measured by an electrochemical method using the rotating disk electrode and numerical computation of the fluid dynamics. A perfect TSV filling is achieved with 1 ppm P(DAMA[HBr]/SO2) + 1 ppm of Br- and the electrodeposited morphology is fine and bright. This shows acceleration at the lower rotation speeds of the rotating disk electrode and an inhibition at the higher speeds, if compared to 1 ppm P(DAMA[HCl]/SO2) + Cl-1 ppm. Br- 1 ppm shows a stronger inhibition at the higher rotation speeds, if compared to Cl-1 ppm. The addition of SPS in addition to Br- 1 ppm shows acceleration at the lower speeds. No voids formed at the higher current density of 3.5 mA/cm2 with SPS.
- Kondo,Yamada,Yokoi
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p. D397 - D400
(2015/06/22)
-
- Multiply-twinned intermetallic AuCu pentagonal nanorods
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Monodispersed intermetallic AuCu pentagonal nanorods with controlled size and composition have been developed by a seed-mediated growth route. The AuCu/C nanomaterial catalyzed the coupling reaction of sulfonamide with benzyl alcohol in good to excellent yields.
- Yang, Jinhua,Chng, Leng Leng,Yang, Xianfeng,Chen, Xiaojun,Ying, Jackie Y.
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supporting information
p. 1141 - 1143
(2014/01/17)
-
- Direct electroreduction of solid cuprous chloride to copper powder in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid
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Direct electroreduction of solid cuprous chloride to prepare copper powder in a neutral ambient-temperature ionic liquid, 1-butyl-3- methylimidazolium tetrafluoroborate ionic liquid (BMIMBF4) was investigated. Cyclic voltammetry of the CuCl powder in a Pt-powder cavity microelectrode exhibited that solid CuCl can be electrochemical reduced in the ionic liquid. Chronoamperometry of the salt powder filled Mo-cavity electrode (current collector) in the ionic liquid further demonstrated the conversion of chloride-to metal inside the cavity, as confirmed by scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction spectra.
- Zhang, Qibo,Hua, Yixin,Wang, Rui
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p. 397 - 401
(2014/04/03)
-
- Preparation of reduced iron powder using combined distribution of wood-charcoal by microwave heating
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In this paper, the influences of microwave heating with wood-charcoal as the reducing agent, on the reducing characterization of mill-scale were systematically investigated. The microstructures of the samples were characterized before and after microwave
- Ye, Qianxu,Zhu, Hongbo,Zhang, Libo,Ma, Ji,Zhou, Li,Liu, Peng,Chen, Jian,Chen, Guo,Peng, Jinhui
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p. 102 - 106
(2014/07/08)
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- Selective hydrogenolysis of glycerol to propylene glycol by using Cu:Zn:Cr:Zr mixed metal oxides catalyst
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Hydrogeneolysis of glycerol to propylene glycol has high interest due to cost and ease of availability of glycerol. In this study, Cu:Zn:Cr:Zr based catalyst was used for selective hydrogeneolysis of glycerol to propylene glycol. It was observed that incorporation of zinc and zirconium in Cu:Cr catalyst matrix improved glycerol conversion and propylene glycol selectivity. This improvement is due to increases in acidity which is confirmed by NH 3-TPD and Cu dispersion in the catalyst matrix which is measured by CO-chemisorption. XRD results confirmed the presence of active metallic Cu in the reduced catalyst. The liquid phase reaction was carried out with 80 wt% of glycerol solution at 240 °C, with 4 MPa of hydrogen pressure and 3 wt% catalyst loading. The novel catalyst Cu:Zn:Cr:Zr with the elemental molar ratio of 3:2:1:3 gave 100% of pure glycerol conversion and 97% of propylene glycol selectivity. The effects of temperature, hydrogen pressure, glycerol concentration and speed of agitation were studied for reaction optimization. A hydrogenolysis of crude glycerol obtained from biodiesel process, was also carried out under similar reaction condition to yield 90% of propylene glycol. Kinetic study was delineated and reaction followed the pseudo first order with respect to glycerol. The apparent activation energy was found to be 31.7 kcal/mol. The catalyst has good reusability up to four runs.
- Sharma, Rajesh V.,Kumar, Pardeep,Dalai, Ajay K.
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p. 147 - 156
(2014/05/06)
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- Fabrication of nanoporous copper by dealloying of amorphous Ti-Cu-Ag alloys
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Ternary TiCuAg amorphous alloys were used as the starting materials for fabricating nanoporous copper (NPC) in HF solutions. NPC with a pore size of 8-55 nm was fabricated through dealloying from an amorphous Ti 60Cu40-xAgx (x = 1, 2 at.%) ribbon alloy under free immersion conditions. A 3-dimensional bicontinuous NPC structure formed on Ti60Cu40, Ti60Cu 39Ag1, and Ti60Cu38Ag2 ribbon alloys with pore sizes of 130 nm, 48 nm, and 55 nm, respectively, after immersion in 0.13 M HF solution for 43.2 ks. The pore sizes of dealloyed ribbon alloys in 0.03 M HF solution were confirmed to be 71 nm, 41 nm and 39 nm, respectively. The pore size of NPCs dealloyed from Ag-added alloys was smaller than that of the Ti-Cu alloy. Smaller pores formed in the beginning of dealloying because even distributed Ag atoms in amorphous precursors suppressed the diffusion of Cu adatoms. The final characteristic pore size showed a weak dependence on the solution concentrations. Diffusivity decreased more than two orders due to the alloying of Ag. The dealloying residue was fcc Cu-Ag and Ag, with Ag adatoms concentrated at the grain boundary. The uneven distribution of Ag atoms caused the coarsening of nanoporous Cu after the prolonged dealloying.
- Dan, Zhenhua,Qin, Fengxiang,Makino, Akihiro,Sugawara,Muto, Izumi,Hara, Nobuyoshi
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p. S134-S138
(2014/01/06)
-
- Aqueous copper-mediated living polymerization: Exploiting rapid disproportionation of CuBr with Me6TREN
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A new approach to perform single-electron transfer living radical polymerization (SET-LRP) in water is described. The key step in this process is to allow full disproportionation of CuBr/Me6TREN (TREN = tris(dimethylamino)ethyl amine to Cu(0) powder and CuBr2 in water prior to addition of both monomer and initiator. This provides an extremely powerful tool for the synthesis of functional water-soluble polymers with controlled chain length and narrow molecular weight distributions (polydispersity index approximately 1.10), including poly(N-isopropylacrylamide) , N,N-dimethylacrylamide, poly(ethylene glycol) acrylate, 2-hydroxyethyl acrylate (HEA), and an acrylamido glyco monomer. The polymerizations are performed at or below ambient temperature with quantitative conversions attained in minutes. Polymers have high chain end fidelity capable of undergoing chain extensions to full conversion or multiblock copolymerization via iterative monomer addition after full conversion. Activator generated by electron transfer atom transfer radical polymerization of N-isopropylacrylamide in water was also conducted as a comparison with the SET-LRP system. This shows that the addition sequence of l-ascorbic acid is crucial in determining the onset of disproportionation, or otherwise. Finally, this robust technique was applied to polymerizations under biologically relevant conditions (PBS buffer) and a complex ethanol/water mixture (tequila).
- Zhang, Qiang,Wilson, Paul,Li, Zaidong,McHale, Ronan,Godfrey, Jamie,Anastasaki, Athina,Waldron, Christopher,Haddleton, David M.
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supporting information
p. 7355 - 7363
(2013/07/11)
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- Copper-mediated reaction of zirconacyclopentadienes with azides: A one-pot three-component synthesis of multiply substituted pyrroles from one azide and two alkynes
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A general method for the synthesis of multiply substituted pyrroles through zirconocene-mediated coupling of two alkynes and an azide in the presence of CuCl has been achieved.
- Zhou, Yiqing,Yan, Xiaoyu,Chen, Chao,Xi, Chanjuan
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p. 6182 - 6185
(2013/12/04)
-
- Dealloying behavior of amorphous binary Ti-Cu alloys in hydrofluoric acid solutions at various temperatures
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A nanoporous copper structure was fabricated from amorphous binary TixCu100-x (x = 40, 50 and 60 at.%) alloys in hydrofluoric acid solutions under a free corrosion condition. A bi-continuous nanoporous structure has a pore size of 25-75 nm and a ligament size of 46-79 nm in 0.03 M HF solution. In 0.13 M HF solution, a pore size of 85-380 nm and a ligament size of 80-338 nm were obtained. The dealloying process is thermal-activated and obeys the Arrhenius law. The surface diffusivity decreases with temperature and concentrations of dealloying solutions. The values of the activation energy of copper adatoms are estimated to be 40.3-78.1 kJ mol-1, which depend not only on the alloy composition but also on the dealloying electrolyte composition.
- Dan, Zhenhua,Qin, Fengxiang,Yamaura, Shin-Ichi,Sugawara, Yu,Muto, Izumi,Hara, Nobuyoshi
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p. 567 - 572
(2013/10/01)
-
- Topochemical fluorination of Sr3(M0.5Ru 0.5)2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-popper phases
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Reaction of the appropriate Sr3(M0.5Ru 0.5)2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-Popper oxide with CuF2 under flowing oxygen results in formation of the oxide-fluoride phases Sr3(Ti0.5Ru 0.5)2O7F2, Sr3(Mn 0.5Ru0.5)2O7F2, and Sr3(Fe0.5Ru0.5)2O 5.5F3.5 via a topochemical anion insertion/substitution process. Analysis indicates the titanium and manganese phases have Ti 4+, Ru6+ and Mn4+, Ru6+ oxidation state combinations, respectively, while Moessbauer spectra indicate an Fe3+, Ru5.5+ combination for the iron phase. Thus, it can be seen that the soft fluorination conditions employed lead to formation of highly oxidized Ru6+ centers in all three oxide-fluoride phases, while oxidation states of the other transition metal M cations remain unchanged. Fluorination of Sr3(Ti0.5Ru0.5) 2O7 to Sr3(Ti0.5Ru 0.5)2O7F2 leads to suppression of magnetic order as the fluorinated material approaches metallic behavior. In contrast, fluorination of Sr3(Mn0.5Ru0.5) 2O7 and Sr3(Fe0.5Ru 0.5)2O7 lifts the magnetic frustration present in the oxide phases, resulting in observation of long-range antiferromagnetic order at low temperature in Sr3(Mn0.5Ru 0.5)2O7F2 and Sr3(Fe 0.5Ru0.5)2O5.5F3.5. The influence of the topochemical fluorination on the magnetic behavior of the Sr3(M0.5Ru0.5)2OxF y phases is discussed on the basis of changes to the ruthenium oxidation state and structural distortions.
- Romero, Fabio Denis,Bingham, Paul A.,Forder, Susan D.,Hayward, Michael A.
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p. 3388 - 3398
(2013/05/08)
-
- Thermal tuning of advanced Cu sol-gels for mixed oxidation state Cu/Cu xOy materials
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In this report, we describe new conditions for the formation of copper gels and aerogels via epoxide addition to CuBr2 in dimethylformamide (DMF). These CuBr2-derived sols undergo a rapid gel transition and result in materials that have enhanced mechanical properties when compared with the gels derived from CuCl2. Additionally, upon air-annealing, they convert to nanoscopic CuO at temperatures much lower than the CuCl2 analogues. Moreover, annealing under nitrogen results in copper species with reduced oxidization states including Cu2O and metallic Cu. The ratio of copper oxidation states can be controlled by simple modification of the thermal program used to anneal the materials. The thermal reduction of the copper is attributed to retained DMF ligands in the as-prepared aerogels which was confirmed by FTIR spectroscopy. These aerogel materials were characterized by powder X-ray diffraction (PXRD), physisorption, thermogravimetric analysis (TGA), and temperature programmed reduction (TPR).
- Baghi, Roya,Peterson, Geneva R.,Hope-Weeks, Louisa J.
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p. 10898 - 10902
(2013/09/23)
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- Thermal tuning of advanced Cu sol-gels for mixed oxidation state Cu/Cu xOy materials
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In this report, we describe new conditions for the formation of copper gels and aerogels via epoxide addition to CuBr2 in dimethylformamide (DMF). These CuBr2-derived sols undergo a rapid gel transition and result in materials that have enhanced mechanical properties when compared with the gels derived from CuCl2. Additionally, upon air-annealing, they convert to nanoscopic CuO at temperatures much lower than the CuCl2 analogues. Moreover, annealing under nitrogen results in copper species with reduced oxidization states including Cu2O and metallic Cu. The ratio of copper oxidation states can be controlled by simple modification of the thermal program used to anneal the materials. The thermal reduction of the copper is attributed to retained DMF ligands in the as-prepared aerogels which was confirmed by FTIR spectroscopy. These aerogel materials were characterized by powder X-ray diffraction (PXRD), physisorption, thermogravimetric analysis (TGA), and temperature programmed reduction (TPR).
- Baghi, Roya,Peterson, Geneva R.,Hope-Weeks, Louisa J.
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p. 10898 - 10902
(2013/09/12)
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- PRECURSORS FOR ATOMIC LAYER DEPOSITION
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Atomic layer deposition (ALD) and chemical vapor deposition (CVD) precursors that are useful for forming metal-containing films are provided. These compounds include triazapentadienyl -imino enolate compounds and α-imino ketone compounds having formulae 1, 2, and 3, respectively. An ALD method using the precursors is also provided.
- -
-
Paragraph 0053
(2014/01/08)
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- Carbon monoxide oxidation by atmospheric oxygen on catalysts prepared by pyrolysis of transition metal β-diketonates on the synthetic foam ceramics
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The results of development of new catalytic systems for the carbon monoxide oxidation to dioxide are systematized. The catalysts were produced by gas-phase thermal decomposition of the transition metal acetylacetonates on the synthetic foam ceramics. The kinetic and activation parameters of the oxidation on the catalysts were studied and their relative activity was explored. The activity of catalysts at the oxidation with air oxygen were found to depend on the nature of the deposited metal and the carrier. A synergistic effect in the bimetallic copper catalysts was revealed.
- Didenkulova,Tsyganova,Shekunova,Aleksandrov
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p. 106 - 115
(2012/06/04)
-
- N-alkylation of amines with alcohols over alumina-entrapped Ag catalysts using the "borrowing hydrogen" methodology
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Ag/Al2O3 catalysts were found to be highly active and selective in the N-alkylation of aniline with a variety of aromatic and linear alcohols. In the presence of a base, for example, Cs2CO3 or K3PO4 as promoter, high yields of secondary amines were obtained. The highest activity was found with 2.4 wt.% Ag/Al2O 3. The reaction involves the transient catalytic dehydrogenation of the alkylating alcohol to the corresponding carbonyl compound which then reacts spontaneously with the amine. In the final step, the hydrogen from the alcohol dehydrogenation step is transferred back to the imine, giving the secondary amine as the final product. With secondary amines, piperidine and pyrrolidine, the hemiaminal intermediate can undergo dehydrogenation as well as dehydration to give amides and amines, respectively. The heterogeneous nature of Ag/Al 2O3 allows for easy recovery and regeneration, which makes it an attractive system in the context of green and sustainable synthesis.
- Liu, Huihui,Chuah, Gaik-Khuan,Jaenicke, Stephan
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p. 130 - 137
(2012/10/07)
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- Metal and alloy nanoparticles by amine-borane reduction of metal salts by solid-phase synthesis: Atom economy and green process
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A new solid state synthetic route has been developed toward metal and bimetallic alloy nanoparticles from metal salts employing amine-boranes as the reducing agent. During the reduction, amine-borane plays a dual role: acts as a reducing agent and reduces the metal salts to their elemental form and simultaneously generates a stabilizing agent in situ which controls the growth of the particles and stabilizes them in the nanosize regime. Employing different amine-boranes with differing reducing ability (ammonia borane (AB), dimethylamine borane (DMAB), and triethylamine borane (TMAB)) was found to have a profound effect on the particle size and the size distribution. Usage of AB as the reducing agent provided the smallest possible size with best size distribution. Employment of TMAB also afforded similar results; however, when DMAB was used as the reducing agent it resulted in larger sized nanoparticles that are polydisperse too. In the AB mediated reduction, BNHx polymer generated in situ acts as a capping agent whereas, the complexing amine of the other amine-boranes (DMAB and TMAB) play the same role. Employing the solid state route described herein, monometallic Au, Ag, Cu, Pd, and Ir and bimetallic CuAg and CuAu alloy nanoparticles of 10 nm were successfully prepared. Nucleation and growth processes that control the size and the size distribution of the resulting nanoparticles have been elucidated in these systems.
- Sanyal, Udishnu,Jagirdar, Balaji R.
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p. 13023 - 13033
(2013/02/22)
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- In situ STM study of Cu electrodeposition on TBPS-modified Au(111) electrodes
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The impact of 3,3′′-thiobis(1-propanesulfonic acid, sodium salt) (TBPS) on Cu/Au(111) electrodeposition has been investigated by electrochemical methods and scanning tunneling microscopy (STM). Cyclic voltammetry and galvanostatic experiments indicate that Cu growth on Au(111) - which is known to be strongly kinetically hindered in additive-free, aqueous perchloric acid solutions - proceeds significantly faster in the presence of TBPS. The TBPS molecules either float on top of the growing film or become incorporated into the deposit. Complementary in situ STM studies show that Cu underpotential deposition (UPD) proceeds via two distinct mechanisms. One-dimensional growth of Cu stripes was observed between 0.05 and 0.35 V RHE for TBPS-modified Au(111) electrodes. Each stripe is composed of two or three parallel rows of Cu atoms oriented along the main crystallographic directions of the Au(111) substrate. An increase of the TBPS concentration near the solid/liquid interface restricts the Cu stripe growth to a narrow potential regime between 0.3 and 0.35 VRHE and two-dimensional Cu island growth becomes the favored growth mechanism. The latter fully dominates in TBPS-containing electrolyte. Cu growth in the overpotential deposition (OPD) regime results in a smooth Cu film with low surface roughness, in contrast to defect-mediated 3D island growth in additive-free electrolytes.
- Liu, Yung-Fang,Krug, Klaus,Lin, Pin-Chun,Chiu, Yong-Da,Dow, Wei-Ping,Yau, Shueh-Lin,Lee, Yuh-Lang
-
-
- A controllable transformation in copper valence states and its applications
-
The present study revealed a surprising valence transformation of copper (Cu) in the sintering process of mixtures of copper chloride dihydrate (CuCl2·2H2O) with β-cyclodextrin (β-CD) in ambient atmosphere. Such a transformation in Cu valence states can be modulated by changing the initial molar ratio (IMR) of CuCl2· 2H2O to β-CD in the mixtures. Firstly, as the value of IMR decreased, the content of cuprous chloride (CuCl) decreased, while the content of cupric oxide (CuO) increased gradually. That is to say, there is an unambiguous IMR-dependence of the contents of CuCl and CuO formed. However, such a controllable valence transformation from Cu(II) to Cu(I) to Cu(II) did not happen in nitrogen atmosphere. Secondly, the in situ composite of CuCl and CuO produced a highly ordered structure of self-assembled nanowires, intertwined, with a diameter of 30 to 50 nm. Furthermore, electronic structural analysis provided direct evidence that the Cu-Cl and Cu-O bonds in this composite material were simultaneously impaired by self-assembled growth. Finally, we noticed that the photoluminescence property of CuCl was regulated through the formation of composites with CuO. In addition, this in situ composite synthesis technique was used to modify the magnetic property of CuO. Furthermore, the anomalous ferromagnetic behaviour of the CuO nanocrystal was observed and explained. In short, this work not only demonstrates a flexible and easily controllable valence transformation of Cu, but also provides a novel approach for constructing inorganic nanocomposite materials. We believe that the implications of these findings are important and make significant contributions to the development of inorganic chemistry and material science. The Royal Society of Chemistry 2012.
- Yang, Jing,Song, Le Xin,Yang, Jun,Dang, Zheng,Chen, Jie
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p. 2393 - 2398
(2012/03/22)
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- Electrochemical preparation of photoelectrochemically active CuI thin films from room temperature ionic liquid
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Cuprous iodide (CuI) thin films with photoelectrochemical activity were prepared by anodizing copper wire or copper-electrodeposited tungsten wire in the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6 RTIL) containing N-butyl-N- methylpyrrolidinium iodide (BMP-I). A copper coating was formed on the tungsten wire by potentiostatic electrodeposition in BMP-dicyanamide (BMP-DCA) RTIL containing copper chloride (CuCl). The CuI films formed using this method were compact, fine-grained and exhibited good adhesion. The characteristic diffraction signals of CuI were observed by powder X-ray diffractometry (XRD). X-ray photoelectron spectroscopy (XPS) also confirmed the formation of a CuI compound semiconductor. The CuI films demonstrated an apparent and stable photocurrent under white light illumination in aqueous solutions and in a RTIL. This method has enabled the electrochemical formation of CuI from a RTIL for the first time, and the first observation of a photocurrent produced from CuI in a RTIL. The coordinating strength of the anions of the RTIL is the key to the successful formation of the CuI thin film. If the coordinating strength of the anions of the RTIL is too strong, no CuI formation is observed.
- Huang, Hsin-Yi,Chien, Da-Jean,Huang, Genin-Gary,Chen, Po-Yu
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p. 204 - 209
(2012/04/17)
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- Hydrazine reduction of metal ions to porous submicro-structures of Ag, Pd, Cu, Ni, and Bi
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Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in glycerol-ethanol solution at room temperature or 120-180 °C. Phase purity, morphology, and specific surface area have been characterized. The reactions probably undergo three different mechanisms: simple reduction for Ag and Pd, coordination-then- reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. The reductant hydrazine also plays an important role to the formation of the porous submicro-structure. The reaction temperature influences the size of the constituent particles and the overall architecture of the submicro-structure so as to influence the surface area value. The as-prepared porous metals have shown the second largest surface area ever reported, which are smaller than those made by the reduction of NaBH4, but larger than those made by hard or soft template methods.
- Wang, Yue,Shi, Yong-Fang,Chen, Yu-Biao,Wu, Li-Ming
-
-
- POLYARYLENE POLYMERS AND PROCESSES FOR PREPARING
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Provided are sulfone-containing polyarylene polymers. Also provided are monomers and processes for preparing the polymers. The polyarylene polymers are suitable for use as engineering polymers.
- -
-
-
- Thermal and spectroscopic data to investigate the oxamic acid, sodium oxamate and its compounds with some bivalent transition metal ions
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Synthesis, characterization, and thermal behavior of transition metal oxamates, M(NH2C2O3)2?nH 2O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as the thermal behavior of oxamic acid and its sodium salt (NaNH2C 2O3) were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), experimental and theoretical infrared spectroscopy, TG-DSC coupled to FTIR, elemental analysis and complexometry. The results led to information about the composition, dehydration, thermal stability, thermal decomposition, as well as of the gaseous products evolved during the thermal decomposition of these compounds in dynamic air and N2 atmospheres.
- Caires, F. J.,Lima, L. S.,Carvalho, C. T.,Siqueira, A. B.,Treu-Filho, Oswaldo,Ionashiro, M.
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p. 335 - 344
(2012/03/12)
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- Plasma-assisted dissociation of organometallic vapors for continuous, gas-phase preparation of multimetallic nanoparticles
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Vapor-sized: In a plasma-based route to multimetallic nanoparticles (NPs), vapor mixtures of organometallic compounds are dissociated in an atmospheric-pressure microplasma (see picture). The size and composition of the particles is controlled by the relative vapor concentrations of the precursors.
- Lin, Pin Ann,Sankaran, R. Mohan
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p. 10953 - 10956
(2011/12/15)
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- Solution synthesis of nanoparticular binary transition metal antimonides
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The preparation of nanoengineered materials with controlled nanostructures, for example, with an anisotropic phase segregated structure or a regular periodicity rather than with a broad range of interparticle distances, has remained a synthetic challenge for intermetallics. Artificially structured materials, including multilayers, amorphous alloys, quasicrystals, metastable crystalline alloys, or granular metals, are mostly prepared using physical gas phase procedures. We report a novel, powerful solution-mediated approach for the formation of nanoparticular binary antimonides based on presynthesized antimony nanoparticles. The transition metal antimonides M-Sb (M = Co, Ni, Cu 2, Zn) were obtained with sizes ranging from 20 and 60 nm. Through careful control of the reaction conditions, single-phase nanoparticular antimonides were synthesized. The nanophases were investigated by powder X-ray diffraction and (high resolution) electron microscopy. The approach is based on activated metal nanoparticles as precursors for the synthesis of the intermetallic compounds. X-ray powder diffraction studies of reaction intermediates allowed monitoring of the reaction kinetics. The small particle size of the reactants ensures short diffusion paths, low activation barriers, and low reaction temperatures, thereby eliminating solid-solid diffusion as the rate-limiting step in conventional bulk-scale solid-state synthesis.
- Kieslich, Gregor,Birkel, Christina S.,Stewart, Andrew,Kolb, Ute,Tremel, Wolfgang
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p. 6938 - 6943
(2011/10/10)
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