156,858 results match your criteria Catalysis Surveys From Asia[Journal]


Enzyme Instructed Self-assembly of Naphthalimide-dipeptide: Spontaneous Transformation from Nanosphere to Nanotubular Structures that Induces Hydrogelation.

Chem Asian J 2020 Jul 11. Epub 2020 Jul 11.

National Chiao Tung University, Materials Science and Engineering, 1001 University Rd., 30010, Hsinchu, TAIWAN.

Understanding the structure-morphology relationships of the self-assembled nanostructures is very crucial for developing the materials with the desired chemical and biological functions. Here, phosphate-based naphthalimide (NI) derivatives have been developed for the first time to study the enzyme instructed self-assembly process. Self-assembly of simple amino acid derivative NI-Y p resulted in non-specific amorphous aggregates in the presence of alkaline phosphatase enzyme. Read More

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http://dx.doi.org/10.1002/asia.202000575DOI Listing

Merging Electrosynthesis and Bifunctional Squaramide Catalysis in the Asymmetric Detrifluoroacetylative Alkylation Reactions.

Angew Chem Int Ed Engl 2020 Jul 11. Epub 2020 Jul 11.

University of Science and Technology of China, Hefei National Laboratory for Physical Sciences at the Microscale, No.96, JinZhai Road Baohe District, 230026, Hefei, CHINA.

An enantioselective bifunctional squaramide-catalyzed detrifluoroacetylative alkylation reaction under electrochemical conditions has been developed. The unified strategy based on this key tandem methodology has been divergently explored for the asymmetric synthesis of fluorine-containing target molecules with good stereocontrol (up to 95% ee ). Furthermore, this catalytic asymmetric detrifluoroacetylative alkylation reaction demonstrated the benefits of combining electrosynthesis and organocatalysis for the preparation of biologically relevant products containing C-F tertiary stereogenic center. Read More

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http://dx.doi.org/10.1002/anie.202006903DOI Listing

Structure-based mechanistic insights into catalysis by tRNA thiolation enzymes.

Curr Opin Struct Biol 2020 Jul 8;65:69-78. Epub 2020 Jul 8.

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Université Paris Sciences et Lettres, 11 Place Marcelin Berthelot, 75231 Paris cedex 05, France. Electronic address:

In all domains of life, ribonucleic acid (RNA) maturation includes post-transcriptional chemical modifications of nucleosides. Many sulfur-containing nucleosides have been identified in transfer RNAs (tRNAs), such as the derivatives of 2-thiouridine (sU), 4-thiouridine (sU), 2-thiocytidine (sC), 2-methylthioadenosine (msA). These modifications are essential for accurate and efficient translation of the genetic code from messenger RNA (mRNA) for protein synthesis. Read More

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http://dx.doi.org/10.1016/j.sbi.2020.06.002DOI Listing

Synergistic effects, gaseous products, and evolutions of NO precursors during (co-)pyrolysis of textile dyeing sludge and bamboo residues.

J Hazard Mater 2020 Jun 29;401:123331. Epub 2020 Jun 29.

Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China.

This study aimed to investigate the synergistic influences of the textile dyeing sludge (TDS) and bamboo residues (BR) co-pyrolysis, and its effects on the formation mechanisms of NH and HCN. The mass loss rate was lower for TDS than BR, with the co-pyrolysis with 50% BR exerting the strongest synergistic effect. The pyrolysis stages 1 (< 400 °C) and 2 (400-800 °C) were best described using the diffusion and third-order reaction mechanisms, respectively. Read More

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http://dx.doi.org/10.1016/j.jhazmat.2020.123331DOI Listing

Dialdehyde cellulose nanocrystals act as multi-role for the formation of ultra-fine gold nanoparticles with high efficiency.

Int J Biol Macromol 2020 Jul 9. Epub 2020 Jul 9.

State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China. Electronic address:

Gold nanoparticles (AuNPs) within 10 nm prepared and stabilized by environmentally friendly reducing and supporting agents are highly desired to obtain excellent catalytic properties for organic transformation. In this paper, a rapid and mild strategy for synthesizing ultra-fine AuNPs is reported by using dialdehyde cellulose nanocrystals (DACNCs) as both efficient reductant, dispersant and template for the first time. DACNCs with higher content of aldehyde groups, acting as multi-role player, are crucial to limit the size of AuNPs within 10 nm. Read More

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http://dx.doi.org/10.1016/j.ijbiomac.2020.07.057DOI Listing

Non-thermal plasma-enhanced low-temperature catalytic desulfurization of electrolytic aluminum flue gas by CuO-ZrSnO: experimental and numerical analysis.

Environ Sci Pollut Res Int 2020 Jul 10. Epub 2020 Jul 10.

Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Jingmingnan Road 727, Kunming, 650000, China.

Catalytic desulfurization is favored for its ability to desulfurize low concentrations of SO by generating sulfur without the need for flue gas conditioning or additives. Maintaining reaction efficiency at a low temperature would justify the industrial scale use of this method. To that end, in this study, we modified a previously reported highly efficient CuO-ZrSnO catalyst and investigated its desulfurization performance. Read More

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http://dx.doi.org/10.1007/s11356-020-09602-6DOI Listing

Highly Active Gas Phase Organometallic Catalysis Supported Within Metal-organic Framework Pores.

J Am Chem Soc 2020 Jul 10. Epub 2020 Jul 10.

Metal-organic Frameworks (MOFs) can act as a platform for the heterogenization of molecular catalysts, providing im-proved stability, allowing easy catalyst recovery and a route towards structural elucidation of the active catalyst. We have developed a MOF, 1, possessing vacant N,N-chelating sites which are accessible via the porous channels that penetrate the structure. In the present work, cationic Rhodium(I) norbornadiene (NBD) and bis(ethylene) complexes paired with both non-coordinating and coordinating anions have been incorporated into the N,N-chelation sites of 1 via post-synthetic metalation and facile anion exchange. Read More

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http://dx.doi.org/10.1021/jacs.0c05286DOI Listing

Covalently Functionalized DNA Duplexes and Quadruplexes as Hybrid Catalysts in an Enantioselective Friedel-Crafts Reaction.

Molecules 2020 Jul 8;25(14). Epub 2020 Jul 8.

Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany.

The precise site-specific positioning of metal-ligand complexes on various DNA structures through covalent linkages has gained importance in the development of hybrid catalysts for aqueous-phase homogeneous catalysis. Covalently modified double-stranded and G-quadruplex DNA-based hybrid catalysts have been investigated separately. To understand the role of different DNA secondary structures in enantioselective Friedel-Crafts alkylation, a well-known G-quadruplex-forming sequence was covalently modified at different positions. Read More

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http://dx.doi.org/10.3390/molecules25143121DOI Listing

Sustainable Carbon as Efficient Support for Metal-Based Nanocatalyst: Applications in Energy Harvesting and Storage.

Molecules 2020 Jul 8;25(14). Epub 2020 Jul 8.

Universitat Politècnica de València, Camino de Vera s/n Edificio 6C, 46022 Valencia, Spain.

Sustainable activated carbon can be obtained from the pyrolysis/activation of biomass wastes coming from different origins. Carbon obtained in this way shows interesting properties, such as high surface area, electrical conductivity, thermal and chemical stability, and porosity. These characteristics among others, such as a tailored pore size distribution and the possibility of functionalization, lead to an increased use of activated carbons in catalysis. Read More

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http://dx.doi.org/10.3390/molecules25143123DOI Listing

Ameliorated Mechanical and Dielectric Properties of Heat-Resistant Radome Cyanate Composites.

Molecules 2020 Jul 8;25(14). Epub 2020 Jul 8.

Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China.

In order to improve the mechanical and dielectric properties of radome cyanate, a synergistic reinforcement method is employed to develop a resin-based ternary-composite with high heat-resistance and preferable radar-band transmission, which is expected to be applied to fabricate radomes capable of resisting high temperature and strong electric field. According to copolymerization characteristics and self-curing mechanism, epoxy resin (EP) and bismaleimide (BMI) are employed as reinforcements mixed into a cyanate ester (CE) matrix to prepare CE/BMI/EP composites of a heat-resistant radome material by high-temperature viscous-flow blending methods under the catalysis of aluminum acetylpyruvate. The crystallization temperature, transition heat, and reaction rate of cured polymers were tested to analyze heat-resistance characteristics and evaluate material synthesis processes. Read More

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http://dx.doi.org/10.3390/molecules25143117DOI Listing

Biomimetic self-assembled nanofibers.

Soft Matter 2006 Feb;2(3):177-181

Department of Chemistry and Bioengineering, Rice University, 6100 Main street, MS 60, Houston, Texas, USA77005.

Peptide-amphiphiles, peptides to which a non-peptidic hydrophobic moiety has been added to the N or C terminal end, have been demonstrated to be a versatile method for simultaneously controlling nanostructure and chemical functionality. These amphiphiles are able to self-assemble, in a controlled fashion, into nanofibers with diameter between 6-10 nm and with length in excess of 1000 nm. At proper concentration these nanofibers form a viscoelastic gel capable of entrapping living cells and eliciting specific responses from them. Read More

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http://dx.doi.org/10.1039/b516805hDOI Listing
February 2006

Macroscopic samples of polystyrene with ordered three-dimensional nanochannels.

Soft Matter 2006 Dec;2(1):57-59

Department of Chemistry, University of Minnesota, Minneapolis, MN 55455-0431, USA.

Block copolymers containing a chemically degradable block are versatile precursors to nanoporous organic materials. Most work in this area has been accomplished in thin films. However, high surface area catalysis, separations, and nanotemplating can require monolithic samples with macroscopic pore volumes. Read More

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http://dx.doi.org/10.1039/b513958aDOI Listing
December 2006

It takes two to tango - The case of thebaine 6-O-demethylase.

Int J Biol Macromol 2020 Jul 7. Epub 2020 Jul 7.

Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. Electronic address:

Thebaine 6-O-demethylase (T6ODM) is an Fe(II)/2-oxoglutarate-dependent dioxygenase catalysing two oxidative O-demethylation reactions in morphine biosynthesis. Its crystal structure revealed a large active site pocket which is at least two times larger than necessary to accommodate a substrate (thebaine or oripavine) molecule. Since so far no crystal structures have been obtained for enzyme-substrate complex, which is necessary to explain the enzyme regiospecificity towards the C6-bound methoxy group, in this work we used computational methods and multi-parametric surface plasmon resonance measurements to elucidate the most likely structure of this complex and the reaction mechanism starting therefrom. Read More

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http://dx.doi.org/10.1016/j.ijbiomac.2020.07.030DOI Listing

Cobalt-Catalyzed Cross-Couplings between Alkyl Halides and Grignard Reagents.

Acc Chem Res 2020 Jul 10. Epub 2020 Jul 10.

Molecular, Macromolecular Chemistry and Materials, ESPCI Paris, CNRS, PSL University, 10 rue Vauquelin, 75005 Paris, France.

ConspectusMetal-catalyzed cross-couplings have emerged as essential tools for the construction of C-C bonds. The identification of efficient catalytic systems as well as large substrate scope made these cross-couplings key reactions to access valuable molecules ranging from materials, agrochemicals to active pharmaceutical ingredients. They have been increasingly integrated in retrosynthetic plans, allowing shorter and original route development. Read More

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http://dx.doi.org/10.1021/acs.accounts.0c00238DOI Listing

Human riboflavin kinase: Species-specific traits in the biosynthesis of the FMN cofactor.

FASEB J 2020 Jul 10. Epub 2020 Jul 10.

Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain.

Human riboflavin kinase (HsRFK) catalyzes vitamin B (riboflavin) phosphorylation to flavin mononucleotide (FMN), obligatory step in flavin cofactor synthesis. HsRFK expression is related to protection from oxidative stress, amyloid-β toxicity, and some malignant cancers progression. Its downregulation alters expression profiles of clock-controlled metabolic-genes and destroys flavins protection on stroke treatments, while its activity reduction links to protein-energy malnutrition and thyroid hormones decrease. Read More

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http://dx.doi.org/10.1096/fj.202000566RDOI Listing

Redox-Neutral P(O)-N Coupling between P(O)-H Compounds and Azides via Dual Copper and Photoredox Catalysis.

Org Lett 2020 Jul 10. Epub 2020 Jul 10.

Institute of Chemistry and BioMedical Sciences, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China.

We report a redox-neutral P(O)-N coupling reaction of P(O)-H compounds with azides via photoredox and copper catalysis, providing new access to useful phosphinamides, phosphonamides, and phosphoramides. This transformation tolerates a wide range of nucleophilic functionalities including alcohol and amine nucleophiles, which makes up for the deficiency of classical nitrogen nucleophilic substitution reactions. As a demonstration of the broad potential applications of this new methodology, late-stage functionalization of a diverse array of azido-bearing natural products and drug molecules, a preliminary asymmetric reaction, and a continuous visible-light photoflow process have been developed. Read More

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http://dx.doi.org/10.1021/acs.orglett.0c02207DOI Listing

Preparation of lipase-electrospun SiO2 nanofiber membrane bioreactors and their targeted catalytic ability at macroscopic oil-water interface.

J Agric Food Chem 2020 Jul 10. Epub 2020 Jul 10.

Lipase is one of the most widely used enzymes in biocatalysis. Due to the special structure of the catalytic active center, lipases show high catalytic activity at oil-water interfaces. Hence, the interface plays a key role in activating and modulating lipase biocatalysis. Read More

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http://dx.doi.org/10.1021/acs.jafc.0c02801DOI Listing

Surface Engineering of Liquid Metal Nanodroplets by Attachable Diblock Copolymers.

ACS Nano 2020 Jul 10. Epub 2020 Jul 10.

Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.

Liquid metal (LM) micro/nano droplets have promising applications in various fields such as flexible electronics, catalysis, and soft composites as well as biomedicines. However, the preparation of highly stable LM nanodroplets suspension based on eutectic gallium/indium (EGaIn) alloys is still challenging. Herein, we report a general and robust strategy to fabricate EGaIn nanodroplets stabilized by polymer brushes (polymer brushes/EGaIn nanodroplets) attachment of well-defined diblock copolymers with short poly(acrylic acid) (PAA) anchoring segments. Read More

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http://dx.doi.org/10.1021/acsnano.0c02720DOI Listing

Surface engineering of magnetic iron oxide nanoparticles by polymer grafting: synthesis progress and biomedical applications.

Nanoscale 2020 Jul 10. Epub 2020 Jul 10.

Key Laboratory of Materials Chemistry for Energy Conversion and Storage of Ministry of Education (HUST), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.

Magnetic iron oxide nanoparticles (IONPs) have wide applications in magnetic resonance imaging (MRI), biomedicine, drug delivery, hyperthermia therapy, catalysis, magnetic separation, and others. However, these applications are usually limited by irreversible agglomeration of IONPs in aqueous media because of their dipole-dipole interactions, and their poor stability. A protecting polymeric shell provides IONPs with not only enhanced long-term stability, but also the functionality of polymer shells. Read More

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http://dx.doi.org/10.1039/d0nr03346dDOI Listing

Atomic-precision engineering of metal nanoclusters.

Dalton Trans 2020 Jul 10. Epub 2020 Jul 10.

Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.

Ultrasmall metal nanoparticles (below 2.2 nm core diameter) start to show discrete electronic energy levels due to strong quantum confinement effects and thus behave much like molecules. The size and structure dependent quantization induces a plethora of new phenomena, including multi-band optical absorption, enhanced luminescence, single-electron magnetism, and catalytic reactivity. Read More

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http://dx.doi.org/10.1039/d0dt01853hDOI Listing

Operando potassium K-edge X-ray absorption spectroscopy: investigating potassium catalysts during soot oxidation.

Phys Chem Chem Phys 2020 Jul 10. Epub 2020 Jul 10.

Department of Chemistry, Loughborough University, Loughborough, Leicestershire LE113TU, UK.

The chemical and structural nature of potassium compounds involved in catalytic soot oxidation have been studied by a combination of temperature programmed oxidation and operando potassium K-edge X-ray absorption spectroscopy experiments. These experiments are the first known operando studies using tender X-rays (∼3.6 keV) under high temperature oxidation reaction conditions. Read More

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http://dx.doi.org/10.1039/d0cp01227kDOI Listing

Probing the design rationale of a high-performing faujasitic zeotype engineered with hierarchical porosity and moderated acidity.

Angew Chem Int Ed Engl 2020 Jul 10. Epub 2020 Jul 10.

University of Southampton, Chemistry, University Road, Highfield, SO171BJ, Southampton, UNITED KINGDOM.

Porosity and acidity are influential properties in the rational design of solid-acid catalysts. Probing the physicochemical characteristics of an acidic zeotype framework at the molecular level can provide valuable insights in understanding intrinsic reaction pathways, for affording structure-activity relationships. Herein, we employ a variety of probe-based techniques (including positron annihilation lifetime spectroscopy (PALS), FTIR and solid-state NMR) to demonstrate how a hierarchical design strategy for a faujasitic (FAU) zeotype (synthesized for the first time, via a soft-templating approach, with high phase-purity) can be used to simultaneously modify the porosity and modulate the acidity for an industrially-significant catalytic process (Beckmann rearrangement). Read More

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http://dx.doi.org/10.1002/anie.202005108DOI Listing

Novel reversibly switchable fluorescent molecular systems based on metallacarborane-perylenediimide conjugates.

Chemistry 2020 Jul 10. Epub 2020 Jul 10.

Universitat Autonoma de Barcelona, Chemistry, Edifici C/n, Campus Bellaterra, 08153, Cerdanyola del Valles, SPAIN.

Icosahedral metallacarboranes are θ-shaped anionic molecules in which two icosahedra share one vertex that is a metal center. The most remarkable of these compounds is the anionic cobalt-based metallacarborane [Co(C2B9H11)2]- , whose oxidation-reduction processes occur via an outer sphere electron process. This, along with its low density negative charge, makes [Co(C2B9H11)2]- very appealing to participate in electron-transfer processes. Read More

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http://dx.doi.org/10.1002/chem.202002419DOI Listing

An Ultrastable, Small {Ag } Nanocluster within a Triangular Hollow Polyoxometalate Framework.

Angew Chem Int Ed Engl 2020 Jul 10. Epub 2020 Jul 10.

Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.

Small Ag nanoclusters (n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face-centered-cubic-type small {Ag } nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si W O ] . Read More

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http://dx.doi.org/10.1002/anie.202008402DOI Listing

Axial modification of cobalt complexes on heterogeneous surface with enhanced electron transfer for carbon dioxide reduction.

Angew Chem Int Ed Engl 2020 Jul 9. Epub 2020 Jul 9.

Southern University of Science and Technology, Department of Physics, CHINA.

Efficient electron communication between molecular catalyst and support is critical for heterogeneous molecular electrocatalysis and yet it is often overlooked during the catalyst design. Taking CO 2 electro-reduction on tetraphenylporphyrin cobalt (PCo) immobilized onto graphene as an example, we demonstrate that adding a relay molecule improves the interfacial electron communication. While the directly immobilized PCo on graphene exhibits relatively poor electron communications, it is found that diphenyl sulfide serves as an axial ligand for PCo and it improves the redox activity of PCo on the graphene surface to facilitate the generation of [PCo] • ‾ active sites for CO 2 reduction. Read More

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http://dx.doi.org/10.1002/anie.202008759DOI Listing

Heterogeneous photocatalysis in flow chemical reactors.

Beilstein J Org Chem 2020 26;16:1495-1549. Epub 2020 Jun 26.

Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS Scotland, United Kingdom.

The synergy between photocatalysis and continuous flow chemical reactors has shifted the paradigms of photochemistry, opening new avenues of research with safer and scalable processes that can be readily implemented in academia and industry. Current state-of-the-art photocatalysts are homogeneous transition metal complexes that have favourable photophysical properties, wide electrochemical redox potentials, and photostability. However, these photocatalysts present serious drawbacks, such as toxicity, limited availability, and the overall cost of rare transition metal elements. Read More

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http://dx.doi.org/10.3762/bjoc.16.125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7323633PMC

An overview on disulfide-catalyzed and -cocatalyzed photoreactions.

Beilstein J Org Chem 2020 23;16:1418-1435. Epub 2020 Jun 23.

School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.

Disulfides are versatile catalysts. They can be photocatalysts, hydrogen atom transfer (HAT) catalysts, cocatalysts, or initiators in photocatalytic reactions. Under photoirradiation, organic disulfides can be easily cleaved into free thiyl radicals (RS) and can reversibly add to unsaturated multiple bonds to catalyze a variety of functionalization reactions under mild conditions. Read More

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http://dx.doi.org/10.3762/bjoc.16.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7323623PMC

Molecular Features and Metal Ions That Influence 10-23 DNAzyme Activity.

Molecules 2020 Jul 7;25(13). Epub 2020 Jul 7.

Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Duesseldorf, Germany.

Deoxyribozymes (DNAzymes) with RNA hydrolysis activity have a tremendous potential as gene suppression agents for therapeutic applications. The most extensively studied representative is the 10-23 DNAzyme consisting of a catalytic loop and two substrate binding arms that can be designed to bind and cleave the RNA sequence of interest. The RNA substrate is cleaved between central purine and pyrimidine nucleotides. Read More

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http://dx.doi.org/10.3390/molecules25133100DOI Listing

Accelerating high-resolution NMR of half-integer quadrupolar nuclei in solids: SPAM-MQMAS and SPAM-STMAS.

Solid State Nucl Magn Reson 2020 May 13;108:101668. Epub 2020 May 13.

Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unit of Catalysis and Chemistry of Solids, F-59000, Lille, France; Bruker Biospin, 34 rue de l'industrie, F-67166, Wissembourg, France; RIKEN RSC NMR Science and Development Division, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa, 230-0045, Japan. Electronic address:

In solid-state NMR, multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments are well-established techniques to obtain high-resolution spectra of half-integer quadrupolar nuclei. In 2004 and 2005, a soft-pulse-added-mixing (SPAM) concept was introduced by Gan and Amoureux to enhance the S/N ratio of MQMAS and STMAS experiments. Despite their robustness and simplicity, SPAM approaches have not yet been widely applied. Read More

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http://dx.doi.org/10.1016/j.ssnmr.2020.101668DOI Listing

Pollution profiles of antibiotic resistance genes associated with airborne opportunistic pathogens from typical area, Pearl River Estuary and their exposure risk to human.

Environ Int 2020 Jul 6;143:105934. Epub 2020 Jul 6.

Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

To reveal the selective pressures of near-shore human activities on marine and continental bioaerosols, the pollution profile and potential exposure risk of airborne pathogens and antibiotic-resistance genes (ARGs) in Pearl River Estuaries (113.52 E, 22.69 N), a transitional zone between marine and continental environments, were fully explored. Read More

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http://dx.doi.org/10.1016/j.envint.2020.105934DOI Listing

Mechanism of Nucleotidyltransfer Reaction and Role of Mg Ion in Sugar Nucleotidyltransferases.

Biophys J 2020 Jun 24. Epub 2020 Jun 24.

Department of Chemistry, Indian Institute of Technology, Kanpur, India. Electronic address:

Sugar nucleotidyl transferases (SNTs) catalyze nucleotidyltransfer reactions to form sugar-nucleotides and pyrophosphate in the presence of two Mg ions (Mg and Mg). We unveil the mechanism and free energetics of nucleotidyl transfer reaction in an SNT called GlmU through hybrid quantum mechanics-molecular mechanics molecular dynamics simulations and free energy calculations. The study identifies the roles of the active site residues and the Mg ions in catalyzing the reaction. Read More

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http://dx.doi.org/10.1016/j.bpj.2020.06.017DOI Listing

Mechanistic characterization of UDP-glucuronic acid 4-epimerase.

FEBS J 2020 Jul 9. Epub 2020 Jul 9.

Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, 8010, Graz, Austria.

UDP-glucuronic acid (UDP-GlcA) is a central precursor in sugar nucleotide biosynthesis and common substrate for C4-epimerases and decarboxylases releasing UDP-galacturonic acid (UDP-GalA) and UDP-pentose products, respectively. Despite the different reactions catalyzed, the enzymes are believed to share mechanistic analogy rooted in their joint membership to the short-chain dehydrogenase/reductase (SDR) protein superfamily: oxidation at the substrate C4 by enzyme-bound NAD initiates the catalytic pathway. Here, we present mechanistic characterization of the C4-epimerization of UDP-GlcA, which in comparison to the corresponding decarboxylation has been largely unexplored. Read More

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http://dx.doi.org/10.1111/febs.15478DOI Listing

3D Printing of an Grown MOF Hydrogel with Tunable Mechanical Properties.

ACS Appl Mater Interfaces 2020 Jul 9. Epub 2020 Jul 9.

Department of Chemical & Biomolecular Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States.

Due to their precisely modifiable microporosity and chemical functionality, Metal-Organic Frameworks (MOFs) have revolutionized catalysis, separations, gas storage, drug delivery, and sensors. However, because of their rigid and brittle powder morphology, it is challenging to build customizable MOF shapes with tunable mechanical properties. Here, we describe a new three-dimensional (3D) printing approach to create stretchable and tough MOF hydrogel structures with tunable mechanical properties. Read More

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http://dx.doi.org/10.1021/acsami.0c08880DOI Listing

Mechanical Insights into the Enzymatic Cleavage of Double C-C Bond in Poly(-1,4-isoprene) by the Latex Clearing Protein.

Inorg Chem 2020 Jul 9. Epub 2020 Jul 9.

Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China.

The b-type cytochrome Lcp is a latex clearing protein (Lcp), which acts as an endotype dioxygenase to catalyze the extracellular cleavage of the chemically inert aliphatic polymer poly(-1,4-isoprene), producing oligo-isoprenoids with different terminal carbonyl groups (aldehyde and ketone, -CH-CHO and -CH-COCH). On the basis of the fact that the muteins of E148A, E148Q, and E148H have substantially reduced reactivity, and the E148-initiated reaction mechanism has been previously proposed, in which a cyclic dioxetane intermediate or an epoxide intermediate may be involved, however, open questions still remain. In this paper, on the basis of the crystal structure of Lcp the enzyme-substrate reactant model was constructed, and the cleavage mechanism of the central double bond of poly(-1,4-isoprene) was elucidated by performing quantum mechanics/molecular mechanics calculations. Read More

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http://dx.doi.org/10.1021/acs.inorgchem.0c00726DOI Listing

N-Heterocyclic Carbenes: A Door Open to Supramolecular Organometallic Chemistry.

Acc Chem Res 2020 Jul 9. Epub 2020 Jul 9.

Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Av. Vicente Sos Baynat s/n, E-12071 Castellón, Spain.

ConspectusThe field of metallosupramolecular chemistry is clearly dominated by the use of O-, N-, and P-donor Werner-type polydentate ligands. These molecular architectures are of high interest because of their wide range of applications, which include molecular encapsulation, stabilization of reactive species, supramolecular catalysis, and drug delivery, among others. Only recently, organometallic ligands have allowed the preparation of a variety of supramolecular coordination complexes, and the term supramolecular organometallic complexes (SOCs) is gaining space within the field of metallosupramolecular chemistry. Read More

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http://dx.doi.org/10.1021/acs.accounts.0c00312DOI Listing

Unidimensional Approximation of the Diffuse Electrical Layer in the Inner Volume of Solid Electrolyte Grains in Absence of Background Ions.

Chemphyschem 2020 Jul 9. Epub 2020 Jul 9.

Institute of Chemistry and Chemical Technology SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Laboratory for Catalytic Conversion of Renewable Resources, Akademgorodok 50/24, 660036, Krasnoyarsk, RUSSIAN FEDERATION.

In this paper we continue working on our theory of electrical double layers resulting exclusively from dissociation of a solid electrolyte, which we previously proposed as a medium for catalytic interaction between solid cellulose and solid acid catalysts of hydrolysis. Two theoretical unidimensional models of the inner grain volume are considered: an infinitely long cylindrical pore, and a gel electrolyte near a grain outer surface. Despite the model simplicity, the predictions for the cylindrical pore case are in semi-quantitative agreement with literature data on electroosmotic experiments, adequately explaining high proton selectivity of sulfonic membranes, and decline of such selectivity at high background acid concentration. Read More

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http://dx.doi.org/10.1002/cphc.202000455DOI Listing

A Woven Supramolecular Metal-Organic Framework Comprising a Ruthenium Bis(terpyridine) Complex and Cucurbit[8]uril: Enhanced Catalytic Activity toward Alcohol Oxidation.

Chempluschem 2020 Jul;85(7):1498-1503

Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, 2205 Songhu Road, Shanghai, 200438, P. R. China.

The self-assembly of a diamondoid woven supramolecular metal-organic framework wSMOF-1 has been achieved from intertwined [Ru(tpy) ] (tpy=2,2',6',2''-terpyridine) complex M1 and cucurbit[8]uril (CB[8]) in water, where the intermolecular dimers formed by the appended aromatic arms of M1 are encapsulated in CB[8]. wSMOF-1 exhibits ordered pore periodicity in both water and the solid state, as confirmed by a combination of H NMR spectroscopy, UV-vis absorption, isothermal titration calorimetry, dynamic light scattering, small angle X-ray scattering and selected area electron diffraction experiments. The woven framework has a pore aperture of 2. Read More

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http://dx.doi.org/10.1002/cplu.202000391DOI Listing

Perspective on theoretical methods and modeling relating to electro-catalysis processes.

Chem Commun (Camb) 2020 Jul 9. Epub 2020 Jul 9.

School of Physics, Southeast University, Nanjing 211189, China.

Electro-catalysis is expected to be a promising clean alternative for energy conversion, and the search for effective and stable electro-catalysts is fundamental. Theoretical calculations play an important role in the rational design and optimization of the performance of electro-catalysts by revealing active sites for reactions and corresponding reaction mechanisms. However, the simulation of electrochemical processes under realistic conditions, for instance, electrode-electrolyte interface structures and the dynamic movement of species around the interface, is still limited. Read More

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http://dx.doi.org/10.1039/d0cc02998jDOI Listing

Hydrophilic/Aerophobic Hydrogen-Evolving Electrode: NiRu-Based Metal-Organic Framework Nanosheets In-situ Grown on Conductive Substrates.

ACS Appl Mater Interfaces 2020 Jul 9. Epub 2020 Jul 9.

Electrocatalytic reduction of water via hydrogen evolution reaction (HER) is considered one of the most ideal avenues to produce high-purity hydrogen (H2) in large quantities, which always requires active electrocatalysts to overcome the high energy barrier. It is of significance yet challenging to design and construct effective HER electrocatalysts of an acceptable cost. In this study, a highly efficient metal-organic framework (MOF)-based electrochemical HER system based on NiRu-based binary MOF (Ru-doped Ni2(BDC)2TED MOF, BDC = 1,4-benzenedicarboxylic acid; TED = triethylenediamine) nanosheets grown on conductive substrates (e. Read More

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http://dx.doi.org/10.1021/acsami.0c03333DOI Listing

A Reductive Supramolecular Hydrogel: A Platform for Facile Fabrication of Diverse Metal-Nanoparticle-Decorated Conductive Networks with Spatiotemporal Control.

Chempluschem 2020 Jul 1. Epub 2020 Jul 1.

Department of Chemistry, Key Lab of Organic Optoelectronics & Molecular Engineering, Tsinghua University, Beijing, 100084, P. R. China.

Nanoparticle-hydrogel hybrid composites have a great potential for a broad range of applications, such as antibacterial materials, stimuli-responsive materials and catalysis. A novel supramolecular hydrogel system was developed using an amino acid based amphiphile containing a terminal pyrrole moiety as a gelator. The pyrrole moiety could serve as both reducing agent and monomer, and a variety of metal precursors penetrating into the hydrogel could be reduced in situ into metal nanoparticles while the pyrrole moieties preorganized in hydrogel were oxidized into polyprroles, affording metal-nanoparticle-decorated covalent conductive networks. Read More

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http://dx.doi.org/10.1002/cplu.202000468DOI Listing

Continuous Synthesis of Aryl Amines from Phenols Utilizing Integrated Packed-Bed Flow Systems.

Angew Chem Int Ed Engl 2020 Jul 9. Epub 2020 Jul 9.

Interdisciplinary Research Center for Catalytic Chemistry (IRC3), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, Higashi 1-1-1, Tsukuba, Ibaraki, 305-8565, Japan.

Aryl amines are important pharmaceutical intermediates among other numerous applications. Herein, an environmentally benign route and novel approach to aryl amine synthesis using dehydrative amination of phenols with amines and styrene under continuous-flow conditions was developed. Inexpensive and readily available phenols were efficiently converted into the corresponding aryl amines, with small amounts of easily removable co-products (i. Read More

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http://dx.doi.org/10.1002/anie.202005109DOI Listing

Effect of alkali metal cations on length and strength of hydrogen bonds in DNA base pairs.

Chemphyschem 2020 Jul 9. Epub 2020 Jul 9.

Politechnika Warszawska, Faculty of Chemistry, POLAND.

For many years non-covalently bonded complexes of nucleobases have attracted considerable interest. However, there is a lack of information about the nature of hydrogen bonding between nucleobases when the bonding is affected by metal coordination to one of the nucleobases and how the individual hydrogen bonds and aromaticity of nucleobases respond to the presence of the metal cation. Here we report a DFT computational study of nucleobase pairs interacting with alkali metal cations. Read More

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http://dx.doi.org/10.1002/cphc.202000434DOI Listing

Hydrogen adsorption on InO(111) and InO(110).

Phys Chem Chem Phys 2020 Jul 9. Epub 2020 Jul 9.

Department of Physics and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.

In2O3-Based catalysts have been measured to have a high activity for CO2 hydrogenation to H3COH. Here, we use density functional theory calculations with and without Hubbard-U corrections in combination with ab initio thermodynamics to investigate the dissociative adsorption of H2 over In2O3(111) and In2O3(110). H2 is found to dissociate heterolytically with a moderate barrier on both facets. Read More

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http://dx.doi.org/10.1039/d0cp01749cDOI Listing

Electron transfer in the confined environments of metal-organic coordination supramolecular systems.

Chem Soc Rev 2020 Jul 9. Epub 2020 Jul 9.

State Key Laboratory of Fine Chemicals, Zhang Dayu School of Chemistry, Dalian University of Technology, Dalian 116024, China.

The incorporation of electron transfer pairs in both ground and excited states (including electron transfer pairs in excited states and hydrogen or oxygen transfer pairs in ground states) into redox-active hosts with electronic acceptor or donor guests has led to development of a novel method of mimicking the photophysical properties and redox reactions of naturally occurring enzymatic systems. This occurs within the confined microenvironments of metal-organic capsules and metal-organic frameworks. These two types of coordination supramolecular host-guest systems can dock and separate electronic donor-acceptor pairs via closed through-space separation. Read More

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http://dx.doi.org/10.1039/c9cs00917eDOI Listing

Electrical conductivity and magnetic bistability in metal-organic frameworks and coordination polymers: charge transport and spin crossover at the nanoscale.

Chem Soc Rev 2020 Jul 9. Epub 2020 Jul 9.

Instituto de Ciencia Molecular, Universitat de València, Catedrático José Beltrán 2, 46980 Paterna, Spain.

Materials scientists are currently shifting from purely inorganic, organic and silicon-based materials towards hybrid organic-inorganic materials to develop increasingly complex and powerful electronic devices. In this context, it is undeniable that conductive metal-organic frameworks (MOFs) and bistable coordination polymers (CPs) are carving a niche for themselves in the electronics world. The tunability and processability of these materials alongside the combination of electrical conductivity with porosity or spin transition offers unprecedented technological opportunities for their integration into functional devices. Read More

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http://dx.doi.org/10.1039/c9cs00594cDOI Listing

Unravelling the Enigma of Nonoxidative Conversion of Methane on Iron Single-Atom Catalysts.

Angew Chem Int Ed Engl 2020 Jul 9. Epub 2020 Jul 9.

Xi'an Jiaotong University, school of mechanical engineering, CHINA.

The direct, nonoxidative conversion of methane on silica-confined single-atom iron catalyst (Fe 1 ©SiO 2 ) by Bao et al . ( Science , 2014, 344 , 616) is a landmark discovery in catalysis science. However, the initially proposed gas-phase reaction mechanism has been much debated. Read More

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http://dx.doi.org/10.1002/anie.202003908DOI Listing

trans-Selective Aryldifluoroalkylation of Endocyclic Enecarbamates and Enamides via Nickel Catalysis.

Angew Chem Int Ed Engl 2020 Jul 8. Epub 2020 Jul 8.

Shanghai Institute of Organic Chemistry Chinese Academy of Science, Key Laboratory of Organofluorine Chemistry, 345 Lingling Lu, 200032, Shanghai, CHINA.

2-Pyrroline and 2-azetine are useful synthons for the synthesis of pyrrolidines and azetidines that widely exist in natural products, pharmaceuticals, and agrochemicals. But efficient methods for dicarbofuntionalization of these cyclic alkenes are limited. Particularly, the dicarbofunctionalization of endocyclic enecarbamates to achieve fluorinated compounds remains an unsolved issue, despite of the wide applications of organofluorinated molecules in life and materials science. Read More

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http://dx.doi.org/10.1002/anie.202008498DOI Listing

Tailoring Polymer Colloids Derived Porous Carbon Spheres Based on Specific Chemical Reactions.

Adv Mater 2020 Jul 9:e2002475. Epub 2020 Jul 9.

Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA.

Porous carbon spheres derived from polymer colloids with regular geometry, monodispersed morphology, well-controlled contents and structures play important roles in many areas of application, such as energy storage/conversion, gas adsorption/separation, catalysis, and chemo-photothermal therapy. Suitable polymerization reaction and synthetic strategy are both critical for the obtainment of stable polymer colloids as carbon precursors. Basic polymerization reactions are the cornerstones of synthetic strategies, which directly provides the direct molecular-based design of functionalized polymer/carbon spheres. Read More

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http://dx.doi.org/10.1002/adma.202002475DOI Listing

Comparative Study of Selenides and Tellurides of Transition Metals (Nb and Ta) with Respect to its Catalytic, Antimicrobial, and Molecular Docking Performance.

Nanoscale Res Lett 2020 Jul 8;15(1):144. Epub 2020 Jul 8.

Solar Cell Applications Research Lab, Department of Physics, Government College University, Lahore, Punjab, 54000, Pakistan.

The present research is a comparative study that reports an economical and accessible method to synthesize niobium (Nb) and Tantalum (Ta) selenides and tellurides with useful application in the removal of pollutants in textile, paper, and dyeing industries as well as in medical field. In this study, solid-state process was used to generate nanocomposites and various characterization techniques were employed to compare two groups of materials under investigation. Structure, morphology, elemental constitution, and functional groups of synthesized materials were analyzed with XRD, FESEM coupled with EDS, FTIR, and Raman spectroscopy, respectively. Read More

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http://dx.doi.org/10.1186/s11671-020-03375-0DOI Listing

Structure Elucidation and Mechanistic Study of a New Dimeric Degradant in Ropinirole Hydrochloride Extended-Release Tablets.

Pharm Res 2020 Jul 8;37(7):136. Epub 2020 Jul 8.

Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, 210009, People's Republic of China.

Purpose: The goal of the study was to elucidate the structure of a new degradant (1,3'-Dimer), generated in the stability testing of ropinirole extended-release tablets, and the formation mechanism of 1,3'-Dimer and its isomer (3,3'-Dimer).

Methods: The strategy of combining LC-PDA/UV-MS (n = 1, 2) and NMR in conjunction with mechanism-based forced degradation study was employed to identify the structure of the unknown degradant and the formation mechanism of this dimeric degradant as well as its isomer, 3,3'-Dimer. The forced degradation was conducted by treating ropinirole API with formaldehyde under alkaline catalysis. Read More

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http://dx.doi.org/10.1007/s11095-020-02863-3DOI Listing