43,319 results match your criteria Angewandte Chemie International Edition [Journal]


Intramolecular Reaction of Transient Phosphenium and Arsenium Ions Giving Rise to Isolable 9-Phospha- and 9-Arsena-Fluorenium Ions.

Angew Chem Int Ed Engl 2020 May 27. Epub 2020 May 27.

Universität Bremen, Institut fuer Biologie und Chemie, Leobener Str., 28359, Bremen, GERMANY.

Transient phosphenium and arsenium ions, generated by fluoride abstraction of bis( m -terphenyl)fluoropnictogens, underwent intramolecular electrophilic attack prior to methyl group migration and gave rise to isolable 9-phospha- and 9-arsena-fluorenium ions. Read More

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http://dx.doi.org/10.1002/anie.202006728DOI Listing

Sulfur-Preloaded Double-shelled C@MoS2 Structures As an Additive Reservoir for Stable Lithium Metal Anodes.

Angew Chem Int Ed Engl 2020 May 27. Epub 2020 May 27.

Nanyang Technological University, School of Chemical and Biomedical Eng, 62 Nanyang Drive, #N1.2-B1-09, 637459, Singapore, SINGAPORE.

The notorious growth of Li dendrites is one of the main hindrances for the practical application of the lithium metal anode (LMA). In this work, a sulfur-preloaded hollow nanostructure based on hierarchical MoS 2 coated hollow carbon particles (C@MoS 2 /S) was designed to modify the LMA. The C@MoS 2 hollow nanostructures serve as a good scaffold for repeated Li plating/stripping. Read More

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http://dx.doi.org/10.1002/anie.202001989DOI Listing

Improved access to organo-soluble di- and tetrafluoridochlorate(I)/(III) salts.

Angew Chem Int Ed Engl 2020 May 27. Epub 2020 May 27.

Freie Universitat Berlin Fachbereich Biologie Chemie Pharmazie, Institut für Chemie und Biochemie, GERMANY.

A facile one-pot gram-scale synthesis of tetraalkylammonium tetrafluoridochlorate(III) [cat][ClF 4 ] ([cat] = [NEt 3 Me] + , [NEt 4 ] + ) is described. An acetonitrile solution of the corresponding alkylammonium chloride salt is fluorinated with diluted fluorine at low temperatures. The reaction proceed via the [ClF 2 ] - anion which is structurally characterized for the first time. Read More

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http://dx.doi.org/10.1002/anie.202006268DOI Listing

Co-based Single Atom Site Catalysts with High Stability for Selective Dehydrogenation of Formic Acid.

Angew Chem Int Ed Engl 2020 May 27. Epub 2020 May 27.

Leibniz-Institut für Katalyse, Homogeneous Catalysis, Albert-Einstein-Straße 29a, 18059, Rostock, GERMANY.

MOF-derived Co-N-C catalysts with isolated single cobalt atoms have been synthesized and compared with cobalt nanoparticles for formic acid dehydrogenation. The atomically dispersed Co-N-C catalyst achieves superior activity, better acid resistance and improved long-term stability compared with nanoparticles synthesized by a similar route. HAADF-STEM, XPS, EPR and XAFS characterizations reveal the formation of Co(II)Nx centers as active sites. Read More

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http://dx.doi.org/10.1002/anie.202004125DOI Listing

Chemistry of Soft Porous Crystals - Structural Dynamics and Gas Adsorption Properties.

Angew Chem Int Ed Engl 2020 May 27. Epub 2020 May 27.

Kyoto University, Institute for Integrated Cell-Material Sciences, Yoshida, Sakyo-ku, 606-8501, Kyoto, JAPAN.

Since their prediction in 1998 , guest-induced structural transitions in 3 rd generation porous coordination polymers (PCPs) have changed common understanding on the adsorption properties of porous solids. By 2009, the chemistry of local and global dynamic behavior in crystalline porous solids received tremendous interest, with the studies linked under soft porous crystals (SPCs) . Since then, another decade has passed and novel phenomena in SPCs have emerged that require evaluation, particularly regarding their host-guest chemistry. Read More

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http://dx.doi.org/10.1002/anie.202004535DOI Listing

Water-Soluble Polymers with Appending Porphyrins as Bioinspired Catalysts for the Hydrogen Evolution Reaction.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Renmin University of China, Department of Chemistry, 59 Zhongguancun Street, 100872, Beijing, CHINA.

Molecular design to improve catalyst performance is significant but challenging. In enzymes, residue groups that are close to reaction centers play critical roles in regulating activities. Using this bioinspired strategy, we designed three water-soluble polymers with appending Co porphyrins and different side-chain groups to mimic enzyme reaction centers and activity-controlling residue groups, respectively. Read More

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http://dx.doi.org/10.1002/anie.202003836DOI Listing

Fullerene-Based Molecular Torsion Balance for Investigating Noncovalent Interactions at C60 Surface.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Tokyo Gakugei University, Department of Chemistry, Nukuikitamachi 4-1-1, 184-8501, Koganei, JAPAN.

In order to investigate the nature and strength of noncovalent interactions at the fullerene surface, molecular torsion balances consisting of C60 and organic moieties connected through a biphenyl linkage were designed, synthesized, and characterized. NMR spectroscopy combined with computational studies showed that the unimolecular system remains in equilibrium between well-defined folded and unfolded conformers owing to restricted rotation around the biphenyl C-C bond. The measured energy differences between the two conformers depend on the substituents and can, in turn, be ascribed to the differences in the intramolecular noncovalent interactions between the organic moieties and the fullerene surface. Read More

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http://dx.doi.org/10.1002/anie.202005888DOI Listing

Methanol synthesis at a wide range of H2/CO2 ratios over Rh-In bimetallic catalyst.

Angew Chem Int Ed Engl 2020 May 27. Epub 2020 May 27.

University of Oxford, Chemistry, South Parks Road, University of Oxford, OX1 3QR, Oxford, UNITED KINGDOM.

Recent years have seen an increasing interest in capturing hydrogen generated from renewables with CO 2 to produce methanol. However, renewable hydrogen production is currently expensive and in limited quantity as compared to CO 2 . Excess CO 2 and limited H 2 in the feedstock gas mixture is not favourable for the CO 2 hydrogenation to methanol reaction, which causes low activity and poor methanol selectivity. Read More

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http://dx.doi.org/10.1002/anie.202000841DOI Listing

Cationic Oligomer as an Organic Template for Direct Synthesis of Aluminosilicate ITH Zeolite.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Universitat Politechnica de Valencia, Instituto de Techologia Quimica, SPAIN.

Despite great progress in the synthesis of aluminosilicate zeolites, there are still a large number of zeolites that could not be prepared in the aluminosilicate form. One of typical examples is ITH zeolite, where direct synthesis of aluminosilicate ITH is currently still challenging. Herein, for the first time we demonstrate the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template. Read More

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http://dx.doi.org/10.1002/anie.202003282DOI Listing

Enantioselective Intramolecular Allylic Substitution via Synergistic Palladium/Chiral Phosphoric Acid Catalysis: Insight into Stereoinduction through Statistical Modeling.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

University of Utah, Chemistry, UNITED STATES.

The mode of asymmetric induction in an enantioselective intramolecular allylic substitution reaction catalyzed by a combination of palladium and a chiral phosphoric acid was investigated by a combined experimental and statistical modeling approach. Experiments to probe nonlinear effects, the reactivity of deuterium-labeled substrates, and control experiments revealed that the nucleophilic attack to the π -allylpalladium intermediate is the enantio-determining step, in which the chiral phosphate anion is involved in stereoinduction. Using multivariable linear regression analysis, we identified that the presence of multiple noncovalent interactions with the chiral environment of the phosphate anion are integral to enantiocontrol in the transition state. Read More

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http://dx.doi.org/10.1002/anie.202006237DOI Listing

CuPd Nanoparticles as a Robust Catalyst for Electrochemical Allylic Alkylation.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Brown University, Department of Chemistry, 324 Brook St., Box H, 2912, Providence, UNITED STATES.

We report an efficient CuPd nanoparticle (NP) catalyst (3 nm CuPd NPs deposited on carbon support) for catalyzing electrochemical allylic alkylation in water/isopropanol (v/v 1/1) and 0.2 M KHCO 3 solution at room temperature. The Pd-catalysis was Pd/Cu composition dependent and CuPd NPs with Pd/Cu ratio close to 1 are the most efficient catalyst for the selective cross-coupling of alkyl halides and allylic halides to form C-C hydrocarbons with product yields reaching up to 99%. Read More

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http://dx.doi.org/10.1002/anie.202006293DOI Listing

Overriding Intrinsic Reactivity in Aliphatic C-H Oxidation: Preferential C3/C4 Oxidation of Aliphatic Ammonium Substrates.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Universitat Basel, Department Chemie, Mattenstrasse 24a, 4058, Basel, SWITZERLAND.

The site-selective C-H oxidation of unactivated positions in aliphatic ammonium chains poses a tremendous synthetic challenge for which a solution has not been found yet. Here, we report preferential oxidation of the strongly deactivated C3/C4 positions of aliphatic ammonium substrates by employing a novel supramolecular catalyst. This chimeric catalyst was synthesized by linking the well-explored catalytic moiety Fe(pdp) to an alkyl ammonium binding molecular tweezer. Read More

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http://dx.doi.org/10.1002/anie.202004242DOI Listing

Tackling N-Alkyl Imines with 3d Metal Catalysis: Highly Enantioselective Iron-Catalyzed Synthesis of α-Chiral Amines.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Ruprecht Karls Universitat Heidelberg, Anorganisch-Chemisches Institut, GERMANY.

A readily activated iron alkyl precatalyst effectively catalyzes the highly enantioselective hydroboration of N- alkyl imines. Employing a chiral bis(oxazolinylmethylidene)isoindoline pincer ligand, the asymmetric reduction of various acyclic N -alkyl imines provided the corresponding α-chiral amines in excellent yields and with up to greater than 99% ee . The applicability of this base metal catalytic system was further demonstrated at the synthesis of the pharmaceuticals Fendiline and Tecalcet. Read More

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http://dx.doi.org/10.1002/anie.202006557DOI Listing

What's Hot, What's Not: The Trends of the Past 20 Years in the Chemistry of Odorants.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Givaudan S&T, Fragrance Research, Kemptpark 50, 8310, Kemptthal, SWITZERLAND.

This review is the sequel to the 2000 report on the recent advances in the chemistry of odorants and it summarizes the developments in fragrance chemistry over the past 20 years. Following the olfactory spectrum set out in that report, trendsetting so-called captive odorants (patent-protected ingredients unavailable to the market) are presented according to the main odor families: "fruity", "marine", "green", "floral", "spicy", "woody", "amber", and "musky". The design of odorants, their chemical synthesis, and their use in modern perfumery are illustrated with prominent examples. Read More

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http://dx.doi.org/10.1002/anie.202005719DOI Listing

Partially Pyrolyzed Binary Metal-Organic Framework Nanosheets for Efficient Electrochemical Hydrogen Peroxide Synthesis.

Authors:
Xiaoqing Huang

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Soochow University, College of Chemistry, Chemical Engineering and Materials Science, 199 Renai Road, 215123, Suzhou, CHINA.

Metal-organic frameworks (MOFs) are a class of versatile materials for fabricating functional heterogeneous catalysts, but the most routine method is through carbonization to form porous carbon materials, which however inevitably losses their inherent MOFs characteristics. Herein, we developed a partially-controlled pyrolysis strategy to create evenly distributed NiO nanoparticles within NiFe-MOF nanosheets (MOF NSs) for electrochemical synthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (ORR). The elemental Ni can be partially transformed to NiO and uniformly distributed on the surface of the MOF NSs, which is crucial for the formation of the particular structure. Read More

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http://dx.doi.org/10.1002/anie.202006422DOI Listing

Synthesis and characterization of the highly unstable metalloid cluster Ag64(PnBu3)16Cl6.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Eberhard Karls Universitat Tubingen Mathematisch-Naturwissenschaftliche Fakultat, Anorganische Chemie, GERMANY.

The reduction of (nBu3P)AgCl with LBH(sec-Bu)3 in toluene gives the metalloid silver cluster Ag64(PnBu3)16Cl61 as dark red, temperature and light sensitive single crystals in high yield. 1 is the largest structurally characterized metalloid silver cluster exhibiting chlorine and phosphine substituents only. The silver atoms in 1 show an overall brick-shape arrangement, where structural resemblance to the close packed fcc- and hcp-structures is realized. Read More

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http://dx.doi.org/10.1002/anie.202006454DOI Listing

Cyrille Boyer.

Authors:

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

"My favorite drink is good red wine. I can never resist chocolate …" Find out more about Cyrille Boyer in his Author Profile. Read More

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http://dx.doi.org/10.1002/anie.202006181DOI Listing

Holey Lamellar High Entropy Oxide as Ultra-Highly Active Heterogeneous Catalyst for Solvent-free Aerobic Oxidation of Benzyl Alcohol.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Jilin University, Department of Chemistry, 2699 Qianjin Street, 130012, Changchun, CHINA.

The development of noble metal free heterogeneous catalysts is promising for selective oxidation of aromatic alcohols; however, the relatively low conversion of non-noble metal catalysts under solvent-free atmospheric condition greatly restricts their industrial application. Herein, we design ed synthesize a novel holey lamellar high entropy oxide (HEO) Co 0.2 Ni 0. Read More

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http://dx.doi.org/10.1002/anie.202004892DOI Listing

Covalent Assembly of MoS2 Nanosheets with SnS Nanodots as Linkages for Lithium/Sodium-Ion Batteries.

Angew Chem Int Ed Engl 2020 May 26. Epub 2020 May 26.

Tongji University, School of Chemical Science and Engineering, Siping Road 1239, 200092, Shanghai, CHINA.

Weak Van der Waals' interactions between interlayers of two-dimensional layered materials have rendered intrinsic problems of disabled across-interlayer electron transfer and poor layered structural stability, seriously deteriorating their performance in energy applications. Herein, we propose a novel covalent assembly strategy for MoS 2 nanosheets to realize unique MoS 2 /SnS hollow superassemblies (HSs) by using SnS nanodots as covalent linkages. The covalent assembly based on all-inorganic and carbon-free concept enables effective across-interlayer electron transfer, facilitated ion diffusion kinetics and outstanding mechanical stability, which are evidenced by substantial characterizations, density functional theory calculations and mechanical simulations. Read More

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http://dx.doi.org/10.1002/anie.202005840DOI Listing

Silica-grafted Tris(neopentyl)aluminum: A Monomeric Aluminum Solid Co-Catalyst for Efficient Nickel-Catalyzed Ethene Dimerization.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Ecole normale superieure de Lyon, CRMN, FRANCE.

A silica-supported monomeric alkylaluminum co-catalyst was prepared via Surface Organometallic Chemistry by contacting tris-(neopentyl)aluminum and partially dehydroxylated silica . This system, fully characterized by solid-state  27 Al NMR augmented by computational studies, efficiently activates ( n Bu 3 P) 2 NiCl 2  towards dimerization of ethene demonstrating comparable activity to previously reported dimeric diethylaluminum chloride supported on silica.  Three types of aluminum surface species have been identified: monografted tetracoordinated Al species as well as two types of bis-grafted Al species - tetra- and pentacoordinated. Read More

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http://dx.doi.org/10.1002/anie.202006285DOI Listing

Nickel-Mediated Trifluoromethylation of Phenol Derivatives via Aryl C-O Bond Activation.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Lehigh University, Department of Chemistry, UNITED STATES.

The increasing pharmaceutical importance of trifluoromethylarenes has stimulated the development of more efficient trifluoromethylation reaction. Tremendous efforts have focused on copper- and palladium-mediated/catalyzed trifluoromethylation of aryl halides. In contrast, no general method exists for the conversion of widely available inert electrophiles, such as phenol derivatives, into the corresponding trifluoromethylated arenes. Read More

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http://dx.doi.org/10.1002/anie.202004116DOI Listing

Atomic-Scale Insight into Exsolution of CoFe Alloy Nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3-δ with Efficient CO2 Electrolysis.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Chinese Academy of Sciences, Dalian Institute of Chemical Physics, CHINA.

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere has been employed to generate highly active metal-oxide interface for CO 2 electrolysis in solid oxide electrolysis cell. Herein, we provide atomic-scale insight into the exsolution of CoFe alloy nanoparticles in La 0.4 Sr 0. Read More

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http://dx.doi.org/10.1002/anie.202006536DOI Listing

Revisiting the Polymerization of Diphenylacetylenes with Tungsten(VI) Chloride and Tetraphenyltin: An Alternative Mechanism by a Metathesis Catalytic System.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Kanazawa University, Graduate School of Natural Science and Technology, JAPAN.

An alternative reaction mechanism of the polymerization of diphenylacetylelnes using a catalytic system composed of tungsten(VI) chloride and tetraphenyltin has been proposed through the optimization of reaction conditions and investigation of the effect of the electronic nature of diphenylacetylene monomers on the polymerizability. The detailed structures of the polymers have been suggested by mass spectrometric analysis of the obtained polymers and oligomers, which suggested that a phenyl group of tetraphenyltin has been introduced to an initiating end of the polymer chain. Mass spectrometric analysis also provided information about the termination processes of the polymerization. Read More

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http://dx.doi.org/10.1002/anie.202005964DOI Listing

Carbon Dots in Porous Materials: Host-Guest Synergy for Enhanced Performance.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Jilin University, College of Chemistry, CHINA.

Carbon dots (CDs) are emerging as a new class of carbon nanomaterials, which have inspired growing interest for their widespread applications in anti-counterfeiting, sensing, bioimaging, optoelectronic and energy-related fields . In terms of the concept of host-guest assembly, i mmobilizing CDs into porous materials (PMs) ha s proven to be an eff ective strategy to avoid the ag gregation of bare CDs in solid state, in particular, the host-guest synergy with both merits of CDs and PMs afford composites promising properties in afterglow and tunable emissions, as well as optimize their performance in optics, catalysis, and energy storage. This minireview summarizes the recent progress in the research of CDs@PM s, and highlights synthetic strategies of constructing composites and roles of porous matrices in boosting the applications of CDs in diverse areas. Read More

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http://dx.doi.org/10.1002/anie.202006545DOI Listing

Three-step Spin State Transition and Hysteretic Proton Transfer in the Crystal of an Iron(II) Hydrazone Complex.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Kyushu University, Institute for Materials Chemistry and Engineering, 744, Motooka, Nishi-ku, 819-0395, Fukuoka, JAPAN.

A proton-electron coupling system, exhibiting unique bistability or multistability of the protonated state, is an attractive target for developing new switchable materials on the basis of proton dynamics. In this paper, we present an iron(II) hydrazone crystalline compound, which displays the stepwise transition and bistability of proton transfer at the crystal level. These phenomena are realized through the coupling with spin transition. Read More

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http://dx.doi.org/10.1002/anie.202006763DOI Listing

2D Conductive Metal-Organic Frameworks: An Emerging Platform for Electrochemical Energy Storage.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Tianjin University, Department of Chemistry, Weijin Road 92, 300072, Tianjin, CHINA.

Two-dimensional conductive metal-organic frameworks (2D c -MOFs) as an emerging class of multifunctional materials have attracted extensive attention thanks to their predictable and diverse structures, intrinsic permanent porosity, high charge mobility and excellent electrical conductivity. These unique inherent characteristics render them as a promising new platform for electrical related devices. This minireview highlights the recent key progress of 2D c -MOFs with emphasis on the design strategies, unique electrical properties, and potential applications in electrochemical energy storage. Read More

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http://dx.doi.org/10.1002/anie.202006102DOI Listing

A 2-Tyr-1-Carboxylate Mononuclear Iron Center is the Active Site of Dimethylformamidase.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Purdue University, Biological Sciences, 1203 W STATE ST, 47907, WEST LAFAYETTE, UNITED STATES.

N, N-dimethyl formamide(DMF) was first synthesized in 1893 and is used extensively in the industry [1] . Yet, certain bacterial species such as Paracoccus, Pseudomonas, and Alcaligenes have evolved metabolic pathways to use the human-made DMF as a sole carbon and nitrogen source for growth [2-4] . Dimethylformamidase (DMFase) is the enzyme that breaks down DMF in this pathway. Read More

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http://dx.doi.org/10.1002/anie.202005332DOI Listing

Molecular spring-like triple-helix coordination polymers as dual stress and thermally responsive crystalline metal-organic materials.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Institute of High Energy Physics, Chinese Academy of Sciences, Laboratory of Nuclear Energy Chemistry, No.19B Yuquan Road, Shijingshan District, 100049, Beijing, CHINA.

Herein we present a new kind of elastic metal-organic materials (MOMs) that are capable of multiple stimuli-responsiveness based on dual stress and thermally responsive triple-helix coordination polymers. The strong metal-coordination linkage in combination with the flexibility of organic linkers in these MOMs,  rather than the '4 Å' stacking interactions observed in organic crystals, renders the helical chain to be act like a molecular spring and thus accounts for their intriguing macroscopic elasticity. Moreover, the thermosalient effect of elastic MOMs is reported for the first time here. Read More

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http://dx.doi.org/10.1002/anie.202003808DOI Listing

Catalytic, Enantioselective Sulfenofunctionalization of Alkenes- Development and Recent Advances.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

University of Illinois at Urbana-Champaign, Chemistry, 600 S. Mathews Ave., 245 Roger Adams Laboratory, 61801, Urbana, UNITED STATES.

The last decade has witnessed a burgeoning of new methods for the enantioselective vicinal difunctionalization of alkenes initiated by electrophilic sulfenyl group transfer. The addition of sulfenium ions to alkenes results in the generation of chiral, non-racemic thiiranium ions. These highly reactive intermediates are susceptible to attack by a myriad of nucleophiles in a stereospecific ring-opening event to afford anti 1,2-sulfenofunctionalized products. Read More

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http://dx.doi.org/10.1002/anie.202005920DOI Listing

A New Facet of the Pseudo-Element Concept: The Arachno-Zintl Ion (Sn5Sb3)3- and the Effects of Element Composition on the Structures of Isoelectronic Clusters.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Philipps-Universität Marburg, Fachbereich Chemie, Hans-Meerwein-Strasse 4, 35032, Marburg, GERMANY.

Zintl anions are excellent examples of the application of isoelectronic considerations, also referred to as the pseudo -element concept. In its most general formulation, this concept states that isoelectronic atoms tend to form equal numbers of bonds. Hence, clusters such as Zintl ions usually retain their structure upon isoelectronic replacement of some or all atoms. Read More

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http://dx.doi.org/10.1002/anie.202002863DOI Listing

Nickel-Catalyzed Allylmethylation of Alkynes Using Allylic Alcohols and AlMe3: A Facile Access to Skipped Dienes and Trienes.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

University of Shanghai for Science and Technology, College of Science, CHINA.

We present herein an unprecedented allylative dicarbofunctionalization of alkynes using allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD) 2 , triphenylphosphine and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all-carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes. Read More

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http://dx.doi.org/10.1002/anie.202006322DOI Listing

Faceted Branched Nickel Nanoparticles with Tunable Branch Length for High Activity Biomass Oxidation Electrocatalysis.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

University of New South Wales, School of Chemsitry, AUSTRALIA.

Controlling the formation of nanosized branched nano-particles with high uniformity is one of the major synthetic challenges to achieve nanocatalysts with improved activity and stability. Using a cubic-core hexagonal-branch mechanism to form highly monodis-perse branched nanoparticles we vary the length of the nickel bran-ches. Lengthening the nickel branches, with their high coverage of active facets, is shown to improve activity for electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) as an example for biomass conver-sion. Read More

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http://dx.doi.org/10.1002/anie.202005489DOI Listing

Gem-diols-type intermediate of Ketone Activation on Sn-β Zeolite as Studied by Solid-state NMR Spectroscopy.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences, state key laboratory of magnetic resonance and atomic and molecular physics, CHINA.

Lewis acid zeolites have found an increasing application in the field of biomass conversion, in which the selective transformation of carbonyl-containing molecule is of particular importance due to its relevance in organic synthesis. Mechanistic insight into the activation of carbonyl group on Lewis acid sites is challenging and critical for the understanding of the catalytic process, which requires the identification of reaction intermediates. Here we report the observation of a stable surface gem -diols-type species in the activation of acetone on Sn-β zeolite. Read More

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http://dx.doi.org/10.1002/anie.202005589DOI Listing

Copper 1,19-Diaza-21,24-Dicarbacorrole: A Corrole Analog with an N-N Linkage Stabilizes Ground-State Singlet Organocopper.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Kyushu University, Dept. of Chemistry and Biochemistry, Grad School Engineering, 744 Motooka, Nishi-ku, 819-0395, Fukuoka, JAPAN.

A copper complex of a heterocorrole analog with an N-N linkage, 1,19-diaza-21,24-dicarba-dibenzocorrole ( Cu-5 ), was successfully synthesized via oxidative metalation-cyclization of a tetrapyrrolic precursor. The N-N linkage in the skeleton of Cu-5 , which serves as a mediator of π-electron delocalization, features an 18π aromatic system. The electronic structure of Cu-5 is best described as a ground-state singlet species stabilized by the distinct NNCC coordination core. Read More

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http://dx.doi.org/10.1002/anie.202005167DOI Listing

A Stable Integrated Photoelectrochemical Reactor for H2 Production from Water Attains a Solar-to-Hydrogen Efficiency of 18% at 15 Suns and 13% at 207 Suns.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

SABIC, Catalysis, KAUST, 23955, KAUST, SAUDI ARABIA.

The major challenge, in solar water splitting to H 2 and O 2 , is in making a stable and affordable system for large-scale applications. We have designed, fabricated and tested a photoelectrochemical reactor composed of (i) an integrated device, to reduce the balance of system cost, (ii) concentrated sunlight, to reduce the photo-absorber cost, and (iii) alkaline electrolyte, to reduce catalyst cost and eliminate external thermal management needs. The system consists of an III-V-based photovoltaic cell integrated with Ni foil as an O 2 evolution catalyst that also protects the cell from corrosion. Read More

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http://dx.doi.org/10.1002/anie.202002240DOI Listing

A Novel Side-Chain Liquid Crystal Elastomer Exhibiting Anomalous Reversible Shape Change.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

University of Sherbrooke, Department of Chemistry, Blvd. Universite, J1K 2R1, Sherbrooke, CANADA.

Liquid crystalline elastomers (LCEs) have been actively investigated as stimuli-controlled actuators and soft robots. The basis of these applications is the ability of LCEs to undergo a reversible shape change upon a liquid crystalline (LC)-isotropic phase transition. When a mechanically stretched LCE strip with uniaxially aligned mesogens (i. Read More

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http://dx.doi.org/10.1002/anie.202003904DOI Listing

Ultramicropore engineering by dehydration to enable molecular sieving of H2 by calcium trimesate.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

University of South Florida College of Arts & Sciences, Chemistry, UNITED STATES.

The high energy footprint of commodity gas purification and ever-increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable "ideal" separation through molecular size or shape exclusion. Physisorbents must exhibit just the right pore diameter to enable such ideal separation, but the 0. Read More

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http://dx.doi.org/10.1002/anie.202006414DOI Listing

Boosting Low Valent Al(I) Reactivity with a Potassium Reagent.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Friedrich-Alexander-Universitat Erlangen-Nurnberg, chemistry, GERMANY.

It was anticipated that the potassium reagent RK (R = CH(SiMe3)2 or N(SiMe3)2) reacts with the low-valent Al(I) complex (DIPPBDI)Al (DIPPBDI = HC[C(Me)N(DIPP)]2, DIPP = 2,6-iPr-phenyl) to the anionic Al complex [(DIPPBDI)AlR]-K+. However, instead deprotonation of the Me group in the ligand backbone was observed and the Al(I) complex [H2C=C(N-DIPP)-C(H)=C(Me)-N-DIPP]Al-K+ crystallized as a bright-yellow product (1, 73%). Like most anionic Al(I) complexes, also 1 forms a dimer in which formally negatively charged Al centers are bridged by K+ ions that show strong K+···DIPP interactions. Read More

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http://dx.doi.org/10.1002/anie.202006693DOI Listing

Manganese-Catalyzed anti-Selective Asymmetric Hydrogenation of α-Substituted β-Ketoamides.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Shanghai Institute of Organic Chemistry, state key laboratory of organometallic chemistry, 345 Lingling Road, 200032, Shanghai, CHINA.

A Mn-catalyzed diastereo- and enantioselective hydrogenation of α-substituted β-ketoamides has been realized for the first time under dynamic kinetic resolution conditions. The anti-α-substituted β-hydroxy amides, a type of useful building blocks for synthesis of bioactive molecules and chiral drugs, have been prepared in high yields with excellent selectivities (up to >99% dr and >99% ee) and unprecedentedly high activity (TON up to 10000). The origin of excellent stereoselectivities has been clarified by DFT calculation study on the structures and the corresponding energies of the transition states possibly involved in the catalysis. Read More

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http://dx.doi.org/10.1002/anie.202006383DOI Listing

Perylene-fused, Aggregation-free Polycyclic Aromatic Hydrocarbons for Solution-processed Distributed Feedback Lasers.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

National University of Singapore, 3 Science Drive 3, 117543, Singapore, SINGAPORE.

Perylene-fused, aggregation-free polycyclic aromatic hydrocarbons with partial zigzag periphery (ZY-01, ZY-02, and ZY-03) were synthesized. X-ray crystallographic analysis reveals that there is no intermolecular π-π stacking in all three molecules, and as a result, they show moderate-to-high photoluminescence quantum yield in both solution and solid state. They also display characteristic absorption and emission spectra of perylene dyes. Read More

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http://dx.doi.org/10.1002/anie.202004789DOI Listing

Oxidation, Coordination and Nickel-Mediated Deconstruction of a Highly Electron-Rich Diboron Analogue of 1,3,5-Hexatriene.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Julius-Maximilians-Universitat Wurzburg, Department of Chemistry, Am Hubland, 97074, Würzburg, GERMANY.

The reductive coupling of a N-heterocyclic carbene (NHC)-stabilized (dibromo)vinylborane yields a 1,2-divinyldiborene, which, although isoelectronic to a 1,3,5-triene, displays no extended π conjugation due to twisting of the C2B2C2 chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in a η2-B2 and η4-C2B2 fashion, respectively, it undergoes a complex rearrangement to a η4-1,3-diborete upon complexation with nickel(0). Read More

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http://dx.doi.org/10.1002/anie.202006131DOI Listing

Three-Dimensional Chemically Stable Covalent Organic Frameworks via Hydrophobic Engineering.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Jilin University, College of Chemistry, 2699 Qianjin Street, 130012, Changchun, CHINA.

The development of three-dimensional (3D) covalent organic frameworks (COFs) with high chemical stability is of critical importance for their practical uses. In this work, we for the first time demonstrate the stability of 3D COFs can be improved by periodic decoration of isopropyl groups on their backbones. Owing to the strong hydrophobicity of the alkyl groups, the resultant COFs show high crystallinity, permanent pores, and exceptional stability in harsh environments, such as strong acids (3 M HCl or 3 M H2SO4 for one week), a strong base (20 M NaOH for one week) and boiling water (100 ºC for one month). Read More

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http://dx.doi.org/10.1002/anie.202005277DOI Listing

Shuangyin Wang.

Authors:

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

"The secret of being a successful scientist is to do your own and labeled research … In my first experiment I unintentionally functionalized carbon nanotubes, on which Pt nanoparticles were deposited uniformly. Luck is part of research …" Find out more about Shuangyin Wang in his Author Profile. Read More

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http://dx.doi.org/10.1002/anie.202005830DOI Listing

Site-selective oxidation of monolayered liquid-exfoliated WS2 by shielding the basal plane through adsorption of a facial amphiphile.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Heidelberg University, Phys. Chem. Institute, Chair of Applied Physical Chemistry, Im Neuenheimer Feld 253, 69120, Heidelberg, GERMANY.

In recent years, various functionalization strategies for transition metal dichalcogenides have been explored to tailor the materials' properties and to provide anchor points for the fabrication of hybrid structures. In this report, new insights into the role of the surfactant in functionalization reactions are described. Using the spontaneous reaction of WS 2 with chloroauric acid as a model reaction, the regioselective formation of gold nanoparticles on WS 2 is shown to be heavily dependent on the surfactant employed. Read More

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http://dx.doi.org/10.1002/anie.202005730DOI Listing

Aggregation-Induced Emission: More Is Different.

Angew Chem Int Ed Engl 2020 May 25. Epub 2020 May 25.

Department of Chemistry, Hong Kong Branch of Chinese National Engineering, Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science & Technology, Clear Water Bay Kowloon, Hong Kong, China.

"Aggregation-induced emission research has brought us to the meso territory, where the synergy and cooperation between many molecules in the aggregate make it different from its elementary components. … Let's enthusiastically embrace the opportunity to develop meso science and to innovate meso technology, and make our planet a brighter place to live!" Read more in the Guest Editorial by B. Liu and B. Read More

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http://dx.doi.org/10.1002/anie.202005345DOI Listing

Deciphering the Intersystem Crossing in a Helical BODIPY for Recorded Low Dose Photodynamic Therapy.

Angew Chem Int Ed Engl 2020 May 24. Epub 2020 May 24.

University of Massachusetts-Medical School, 364 plantation street Lrb806, 01605, Worcester, UNITED STATES.

Intersystem crossing (ISC) of triplet photosensitizers is a vital process for fundamental photochemistry and photodynamic therapy (PDT). However, the currently effective long wavelength operating photosensitizers have to rely on heavy atoms to enhance ISC. Unfortunately, the heavy atoms, besides their toxicity, can also cause significant reduction in the triplet lifetime of the photosensitizers, which is fundamentally detrimental to their applications. Read More

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http://dx.doi.org/10.1002/anie.202005269DOI Listing

Beyond Frameworks: Structuring Reticular Materials across Nano, Meso, and Bulk Regimes.

Angew Chem Int Ed Engl 2020 May 24. Epub 2020 May 24.

Ludwig-Maximilians Universität München, Department Chemie, Butenandtstr. 11, Haus E, E 3.039, 81377, Munich, GERMANY.

Reticular materials are of high interest for diverse applications ranging from catalysis and separation to gas storage and drug delivery. These open, extended frameworks can be tailored to the intended application through crystal structure design. Implementing these materials in application settings, however, requires structuring beyond their lattices, in order to interface the functionality at the molecular level effectively with the macroscopic world. Read More

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http://dx.doi.org/10.1002/anie.201914461DOI Listing

A Diselenide turn-on Fluorescent Probe for the Detection of Thioredoxin Reductase.

Angew Chem Int Ed Engl 2020 May 24. Epub 2020 May 24.

Portland State University, Department of Chemistry, 1719 SW 10th Ave, SB2, Department of Chemistry, 97217, Portland, UNITED STATES.

We report the first diselenide-based probe for the selective detection of thioredoxin reductase (TrxR), an enzyme commonly overexpressed in melanomas. The probe design involves conjugation of a seminaphthorhodafluor dye with a diselenide moiety. TrxR reduces the diselenide bond, triggering a fluorescence turn-on response of the probe. Read More

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http://dx.doi.org/10.1002/anie.202004094DOI Listing

A Blinking Mesoporous TiO2-x Composed of Nanosized Anatase with Unusually Long-Lived Trapped Charge Carriers.

Angew Chem Int Ed Engl 2020 May 22. Epub 2020 May 22.

Akademie ved Ceske republiky, Instiute of Scientific Instruments, Královopolská 147, 612 64, Brno, CZECH REPUBLIC.

A novel mesoporous TiO2-x material that is comprised of small, crystalline, vacancy-rich anatase nanoparticles that show unique optical, thermal and electronic properties is synthesized using polymer-derived mesoporous carbon (PDMC) as a template. The PDMC pores serve as physical barriers during the condensation and pyrolysis of a titania precursor, preventing the titania nanoparticles from growing beyond 10 nm in size. Unlike most titania nanomaterials, the particles remain in anatase phase and undergo no transition to rutile phase, and also become catalytically-active reduced TiO2-x, during pyrolysis. Read More

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http://dx.doi.org/10.1002/anie.202005143DOI Listing