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https://www.readbyqxmd.com/read/28646767/enhanced-photodegradation-of-2-4-dichlorophenoxyacetic-acid-using-a-novel-tio2-mgfe2o4-core-shell-structure
#1
Bui The Huy, Da-Som Jung, Nguyen Thi Kim Phuong, Yong-Ill Lee
A novel TiO2@MgO-Fe2O3 core-shell structure has been synthesized via a hydrolysis and co-precipitation method followed by calcination at 500 °C and has proven to be an efficient photocatalyst. The obtained TiO2@MgO-Fe2O3 core-shell was characterized by scanning electron microscopy, X-ray diffraction, and UV-Vis diffused reflectance techniques. Its photocatalytic activity toward 2,4-dichlorophenoxyacetic acid (2,4-D) was investigated in aqueous solutions with and without visible light irradiation in the presence and absence of hydrogen peroxide...
June 17, 2017: Chemosphere
https://www.readbyqxmd.com/read/28646755/bio-fabrication-of-catalytic-platinum-nanoparticles-and-their-in-vitro-efficacy-against-lungs-cancer-cells-line-a549
#2
Sadeeq Ullah, Aftab Ahmad, Aoke Wang, Muslim Raza, Amin Ullah Jan, Kamran Tahir, Aziz Ur Rahman, Yuan Qipeng
Platinum based drugs are considered as effective agents against various types of carcinoma; however, the severe toxicity associated with the chemically prepared platinum complexes limit their practical applications. Similarly, water pollution caused by various organic moieties is another serious health problem worldwide. Hence, an intense need exists to develop new, effective and biocompatible materials with catalytic and biomedical applications. In the present contribution, we prepared platinum nanoparticles (PtNPs) by a green route using phytochemicals as a source of reducing and stabilizing agents...
June 16, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28646193/fabrication-of-nitrogen-doped-nano-onions-and-their-electrocatalytic-activity-toward-the-oxygen-reduction-reaction
#3
E Y Choi, C K Kim
Nitrogen-doped nano-onions (NNO) were prepared as electrocatalytic materials for the oxygen reduction reaction (ORR). The nano-onions (NO), spherical graphitic material particles, were prepared by pyrolysis of nanodiamonds (ND). Oxidized NO (ONO) was prepared from NO by a modified Hummers' method, and this was mixed with urea, followed by pyrolysis, resulting in the formation of NNO. The nitrogen content and molar ratio of nitrogen-containing groups in the NNOs were varied by controlling the oxygen content of ONO to explore the effect of nitrogen content on the ORR activity...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645033/acetic-acid-assisted-fabrication-of-hierarchical-flower-like-bi2o3-for-photocatalytic-degradation-of-sulfamethoxazole-and-rhodamine-b-under-solar-irradiation
#4
Yueping Bao, Teik-Thye Lim, Ziyi Zhong, Rong Wang, Xiao Hu
With the assistance of acetic acid (CH3COOH), a novel 3D flower-like Bi2O3 was synthesized via hydrothermal process followed by calcination. For the first time, the role of CH3COOH as a capping agent in the formation of flower-like structure was investigated. The as-prepared flower-like Bi2O3 had a high activity on the degradation of sulfamethoxazole (SMX) under simulated solar light irradiation due to the narrow band gap of 2.69eV, high percentage of β-Bi2O3 as well as high intensity of polar facets (120) and (200)...
May 23, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28644918/heterogeneous-microtesla-sabre-enhancement-of-15n-nmr-signals
#5
Kirill V Kovtunov, Larisa M Kovtunova, Max E Gemeinhardt, Andrey V Bukhtiyarov, Jonathan Gesiorski, Valerii I Bukhtiyarov, Eduard Y Chekmenev, Igor V Koptyug, Boyd Goodson
The hyperpolarization of heteronuclei via Signal Amplification by Reversible Exchange (SABRE) was investigated under conditions of heterogeneous catalysis and microtesla magnetic fields. Immobilization of [IrCl(COD)(IMes)], [IMes = 1,3-bis(2,4,6-trimethylphenyl), imidazole-2-ylidene; COD = cyclooctadiene] catalyst onto silica particles modified with NH2(CH2)3- linkers engenders an effective heterogeneous SABRE (HET-SABRE) catalyst that was used to demonstrate ~102-fold enhancement of 15N NMR signals in pyridine at 9...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644915/mechanistic-insights-on-the-reduction-of-co2-to-silylformates-catalyzed-by-ir-nsin-species
#6
Luis A Oro, Alejandro Julián, Jefferson Guzmán, E A Jaseer, Francisco Fernández-Alvarez, Raquel Royo, Victor Polo, María Pilar García Orduña, Fernando Lahoz
The hydrosilylation of CO2 with different silanes such as HSiEt3, HSiMe2Ph, HSiMePh2, HSiMe(OSiMe3)2 and HSi(OSiMe3)3 in presence of catalytic ammounts of the iridium(III) complex [Ir(H)(CF3CO2)(NSiN*)(coe)] (1; NSiN* = fac-bis-(4-methylpyridine-2-yloxy); coe = cis-cyclooctene) has been comparatively studied. The activity of the hydrosilylation catalytic system based on 1 depends on the nature of the reducing agent, where HSiMe(OSiMe3)2 has proven to be the most active. The aforementioned reactions were found to be highly selective to the formation of the corresponding silylformate...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28644909/a-highly-efficient-synthesis-of-z-macrocycles-using-stereoretentive-ruthenium-based-metathesis-catalysts
#7
Tonia Sarah Ahmed, Robert H Grubbs
A highly efficient, Z-selective ring-closing metathesis system for the formation of macrocycles using a stereoretentive, ruthenium-based catalyst supported by a dithiolate ligand is reported. This catalyst is demonstrated to be remarkably active as observed in initiation experiments showing complete catalyst initiation at -20 °C within 10 min. Macrocyclization reactions generated Z-products from easily accessible diene starting materials bearing a Z-olefin moiety. This stereoretentive approach provides a more efficient and selective route to Z-macrocyles than in previously reported systems...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644864/overexpression-and-characterization-of-two-types-of-nitrile-hydratases-from-rhodococcus-rhodochrous-j1
#8
Yao Lan, Xiaohuan Zhang, Zhongmei Liu, Li Zhou, Ruihua Shen, Xianping Zhong, Wenjing Cui, Zhemin Zhou
Nitrile hydratase (NHase) from Rhodococcus rhodochrous J1 is widely used for industrial production of acrylamide and nicotinamide. However, the two types of NHases (L-NHase and H-NHase) from R. rhodochrous J1 were only slightly expressed in E. coli by routine methods, which limits the comprehensive and systematic characterization of the enzyme properties. We successfully expressed the two types of recombinant NHases in E. coli by codon-optimization, engineering of Ribosome Binding Site (RBS) and spacer sequences...
2017: PloS One
https://www.readbyqxmd.com/read/28644502/au3-%C3%AE-3-s-0e-elementary-block-new-insights-into-ligated-gold-clusters-with-%C3%AE-3-sulfido-motifs
#9
Wen Wu Xu, Xiao Cheng Zeng, Yi Gao
An understanding of the structural stability and formation mechanism of ligated gold nanoclusters with triply coordinated μ3-sulfido (μ3-S) motifs is important not only for gold chemistry but also for the design of more effective catalysts or drug carriers for various applications. In this article, a new elementary block Au3(μ3-S) with zero valence electrons [referred to as Au3(μ3-S)(0e)] has been identified, which describes all crystallized ligated gold clusters with μ3-S motifs, in conjunction with the previously reported Au3(2e) and Au4(2e) elementary blocks, in a grand unified model (GUM)...
June 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28644493/photoelectrochemical-devices-for-solar-water-splitting-materials-and-challenges
#10
Chaoran Jiang, Savio J A Moniz, Aiqin Wang, Tao Zhang, Junwang Tang
It is widely accepted within the community that to achieve a sustainable society with an energy mix primarily based on solar energy we need an efficient strategy to convert and store sunlight into chemical fuels. A photoelectrochemical (PEC) device would therefore play a key role in offering the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The past five years have seen a surge in the development of promising semiconductor materials. In addition, low-cost earth-abundant co-catalysts are ubiquitous in their employment in water splitting cells due to the sluggish kinetics of the oxygen evolution reaction (OER)...
June 23, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28644476/enantioselective-intermolecular-benzylic-c-h-amination-catalysed-by-an-engineered-iron-haem-enzyme
#11
Christopher K Prier, Ruijie K Zhang, Andrew R Buller, Sabine Brinkmann-Chen, Frances H Arnold
C-H bonds are ubiquitous structural units of organic molecules. Although these bonds are generally considered to be chemically inert, the recent emergence of methods for C-H functionalization promises to transform the way synthetic chemistry is performed. The intermolecular amination of C-H bonds represents a particularly desirable and challenging transformation for which no efficient, highly selective, and renewable catalysts exist. Here we report the directed evolution of an iron-containing enzymatic catalyst-based on a cytochrome P450 monooxygenase-for the highly enantioselective intermolecular amination of benzylic C-H bonds...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644470/rapid-heteroatom-transfer-to-arylmetals-utilizing-multifunctional-reagent-scaffolds
#12
Hongyin Gao, Zhe Zhou, Doo-Hyun Kwon, James Coombs, Steven Jones, Nicole Erin Behnke, Daniel H Ess, László Kürti
Arylmetals are highly valuable carbon nucleophiles that are readily and inexpensively prepared from aryl halides or arenes and widely used on both laboratory and industrial scales to react directly with a wide range of electrophiles. Although C-C bond formation has been a staple of organic synthesis, the direct transfer of primary amino (-NH2) and hydroxyl (-OH) groups to arylmetals in a scalable and environmentally friendly fashion remains a formidable synthetic challenge because of the absence of suitable heteroatom-transfer reagents...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644060/lytic-transglycosylases-concinnity-in-concision-of-the-bacterial-cell-wall
#13
David A Dik, Daniel R Marous, Jed F Fisher, Shahriar Mobashery
The lytic transglycosylases (LTs) are bacterial enzymes that catalyze the non-hydrolytic cleavage of the peptidoglycan structures of the bacterial cell wall. They are not catalysts of glycan synthesis as might be surmised from their name. Notwithstanding the seemingly mundane reaction catalyzed by the LTs, their lytic reactions serve bacteria for a series of astonishingly diverse purposes. These purposes include cell-wall synthesis, remodeling, and degradation; for the detection of cell-wall-acting antibiotics; for the expression of the mechanism of cell-wall-acting antibiotics; for the insertion of secretion systems and flagellar assemblies into the cell wall; as a virulence mechanism during infection by certain Gram-negative bacteria; and in the sporulation and germination of Gram-positive spores...
June 23, 2017: Critical Reviews in Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28644034/predicting-the-oxygen-binding-properties-of-platinum-nanoparticle-ensembles-by-combining-high-precision-electron-microscopy-dft
#14
Jolyon Aarons, Lewys Jones, Aakash Varambhia, Katherine E MacArthur, Dogan Ozkaya, Misbah Sarwar, Chris-Kriton Skylaris, Peter D Nellist
Many studies of heterogeneous catalysis, both experimental and computational, make use of idealised structures such as extended surfaces or regular polyhedral nanoparticles. This simplification neglects the morphological diversity in real commercial oxygen reduction reaction (ORR) catalysts used in fuel-cell cathodes. Here we introduce an approach that combines 3D nanoparticle structures obtained from high-throughput high-precision electron microscopy with density functional theory. Discrepancies between experimental observations and cuboctahedral/truncated-octahedral particles are revealed and discussed using a range of widely used descriptors, such as electron-density, d-band centres and generalised coordination numbers...
June 23, 2017: Nano Letters
https://www.readbyqxmd.com/read/28644031/tris-cyclopentadienyl-lanthanide-complexes-as-catalysts-for-hydroboration-reaction-toward-aldehydes-and-ketones
#15
Sufang Chen, Dandan Yan, Mingqiang Xue, Yubiao Hong, Yingming Yao, Qi Shen
It was found that homoleptic cyclopentadienyl lanthanide complexes Cp3Ln (Ln = Y (1), Yb (2), Sm (3), Nd (4), La (5), Cp = cyclopentadienyl) can be employed as excellent catalysts for the hydroboration of various aldehydes and ketones toward pinacolborane. These robust lanthanide catalysts exhibited high reactivity with low catalyst loadings (0.01-1 mol %) under mild conditions and good functional group tolerability. These complexes also demonstrated uniquely carbonyl-selective hydroboration in the presence of alkenes and alkynes...
June 23, 2017: Organic Letters
https://www.readbyqxmd.com/read/28643885/a-critical-assessment-of-the-direct-catalytic-oxidation-of-methane-to-methanol
#16
Manoj Ravi, Marco Ranocchiari, Jeroen A van Bokhoven
Despite the emerging number of disparate approaches for the direct selective partial oxidation of methane, none of them has translated into an industrial process. The oxidation of methane to methanol is a difficult yet intriguing and rewarding task as it has the potential to eliminate the prevalent natural gas flaring by providing novel routes to its valorisation. This review considers the synthesis of methanol and methanol derivatives from methane by homogeneous and heterogeneous pathways. In establishing the severe limitations related to the direct catalytic synthesis of methanol from methane, we highlight the vastly superior performance of systems, which produce methanol derivatives or incorporate specific measures such as the use of multi-component catalysts to stabilise methanol...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28643863/design-of-iron-ii-pthalocyanine-fepc-derived-oxygen-reduction-electrocatalysts-for-high-power-density-microbial-fuel-cells
#17
Carlo Santoro, Rohan Gokhale, Barbara Mecheri, Alessandra D'Epifanio, Silvia Licoccia, Alexey Serov, Kateryna Artyushkova, Plamen Atanassov
Iron(II) Phthalocyanine (FePc) deposited onto two different carbonaceous supports was synthesized by the non-conventional pyrolysis-free method, studied in the reaction of oxygen reduction (ORR) in neutral media, incorporated in an air-breathing cathode structure and tested in operating microbial fuel cell (MFC) configuration. Rotating ring disk electrode (RRDE) analysis revealed high performances of the Fe-based catalysts compared with activated carbon (AC). It was shown that Black Pearls supported FePc (Fe-BP(N)) exhibits the highest performance in term of more positive onset, positive shift of half-wave potential and higher limiting as well as highest power density in operating MFC (243±7 μWcm-2) that was 33% higher than Fe-CNT(N) (182±5 μWcm-2)...
June 23, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28643839/a-visible-light-activated-rhodium-complex-in-enantioselective-conjugate-addition-of-%C3%AE-amino-radicals-with-michael-acceptors
#18
Shao-Xia Lin, Gui-Jun Sun, Qiang Kang
We report an efficient enantioselective conjugate addition of photogenerated α-amino radicals to Michael acceptors catalyzed by a newly prepared chiral-at-metal rhodium complex. This protocol shows that a single Rh(iii) complex can serve not only as a Lewis acid but also as a photoredox catalyst to control the stereoselectivity during the bond formation.
June 23, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28643828/adaptability-of-the-metal-iii-iv-1-2-3-trioxobenzene-rod-secondary-building-unit-for-the-production-of-chemically-stable-and-catalytically-active-mofs
#19
Georges Mouchaham, Brian Abeykoon, Mónica Giménez-Marqués, Sergio Navalon, Andrea Santiago-Portillo, Maame Affram, Nathalie Guillou, Charlotte Martineau, Hermenegildo Garcia, Alexandra Fateeva, Thomas Devic
The use of a 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin has yielded a new MOF based on M-1,2,3-trioxobenzene chains that can be made of M = Zr(iv) or RE(iii) (RE = rare earth), showing a very high and limited chemical stability, respectively. The robust metallated Zr-analogue, Co-MIL-173(Zr), has proven to be a heme-like heterogeneous catalyst suitable for aerobic oxidation of hydrocarbons.
June 23, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28643556/catalytic-oxidation-of-toluene-comparative-study-over-powder-and-monolithic-manganese-nickel-mixed-oxide-catalysts
#20
Marina Duplančić, Vesna Tomašić, Zoran Gomzi
This paper is focused on development of the metal monolithic structure for total oxidation of toluene at low temperature. The well adhered catalyst, based on the mixed oxides of manganese and nickel, is washcoated on the Al/Al2O3 plates as metallic support. The influence of different reaction variables on the catalytic performance in the toluene oxidation is investigated. For the comparison purposes results observed for the manganese-nickel mixed oxide supported on the metallic monolith are compared with those obtained using powder type of the same catalyst...
June 23, 2017: Environmental Technology
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