43,406 results match your criteria Angewandte Chemie International ed. in English[Journal]


Halogen bonding between anions: association of anion-radicals of tetraiodo-p-benzoquinone with iodide anions.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Ball State University, Department of Chemistry, 2000 W. University Avenue, 47306, Muncie, UNITED STATES.

Halogen bonding between two negatively charged species, tetraiodo- p -benzoquinone anion-radicals (I 4 Q -• ) and iodide anions was observed and characterized for the first time. X-ray structural and EPR/UV-VIS spectral studies revealed that the anion-anion bonding led to the formation of crystals comprising 2D layers of I 4 Q -• anion-radicals linked by iodides and separated by Et 4 N + counter-ions. Computational analysis suggested that the seemin-gly antielectrostatic halogen bonds in these systems were formed via a combination of several factors. Read More

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http://dx.doi.org/10.1002/anie.202004384DOI Listing

Hierarchically Structured Allotropes of Phosphorus from Data-Driven Exploration.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Universita degli Studi di Milano, Dipartimento di Chimia, ITALY.

The discovery of materials is increasingly guided by quantum-mechanical crystal-structure prediction, but the structural complexity in bulk and nanoscale materials remains a bottleneck. Here we demonstrate how data-driven approaches can vastly accelerate the search for complex structures, combining a machine-learning (ML) model for the potential-energy surface with efficient, fragment-based searching. We use the characteristic building units observed in Hittorf's and fibrous phosphorus to seed stochastic ("random") structures searches over hundreds of thousands of runs. Read More

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http://dx.doi.org/10.1002/anie.202005031DOI Listing

Irreversible amide-linked covalent organic framework for selective and ultrafast gold recovery.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Jiangnan University, School of Food Science and Technology, 1800 Lihu Ave, 214122, Wuxi, CHINA.

Design of stable adsorbents for selective gold recovery with large capacity and fast kinetics is of great challenge, but significant for economy and environment. Here, we show the design and preparation of an irreversible amide-linked covalent organic framework (COF) JNU-1 via a building block exchange strategy for efficient recovery of gold. JNU-1 was synthesized through the exchange of 4,4'-biphenyldicarboxaldehyde (BA) in mother COF TzBA consisting of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline (Tz) and BA with terephthaloyl chloride. Read More

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http://dx.doi.org/10.1002/anie.202006535DOI Listing

"Organic synthesis-Where now?" is thirty years old. A reflection on the current state of affairs.

Authors:
Tomas Hudlicky

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Brock University, Department of Chemistry, 1812 Sir Isaac Brock Way St., L2S 3A1, St. Catharines, CANADA.

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http://dx.doi.org/10.1002/anie.202006717DOI Listing

Unexpected Acetylation of Endogenous Aliphatic Amines by Arylamine N-Acetyltransferase NAT2.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Uppsala University, Department of Medicinal Chemistry, Husaragatan 3, Biomedical Center, Box 574, 75123, Uppsala, SWEDEN.

N-Acetyltransferases play critical roles in the deactivation and clearance of xenobiotics, including clinical drugs. NAT2 has previously been classified as an arylamine N-acetyltransferase that mainly converts aromatic amines, hydroxylamines and hydrazines. Here, we demonstrate that the human arylamine N-acetyltransferase NAT2 also acetylates a series of aliphatic endogenous amines. Read More

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http://dx.doi.org/10.1002/anie.202005915DOI Listing

A Simple Strategy to Eliminate Hexosylation Bias in the Relative Quantification of N-glycosylation in Biopharmaceuticals.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

University of Salzburg, Department of Molecular Biology, Division of Chemistry and Bioanalytics, Hellbrunner Strasse 34, 5020, Salzburg, AUSTRIA.

N -glycosylation may affect the safety and efficacy of biopharmaceuticals and is thus monitored during manufacturing. Mass spectrometry of the intact protein is increasingly used to reveal co-existing glycosylation variants. However, quantification of N -glycoforms via this approach may be biased by single hexose residues as introduced by glycation or O -glycosylation. Read More

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http://dx.doi.org/10.1002/anie.202002147DOI Listing

Xiaohua Liu.

Authors:

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

"In a spare hour, I walk my dog … My favorite time of day is when I enjoy my walks in the garden …" Find out more about Xiaohua Liu in her Author Profile. Read More

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http://dx.doi.org/10.1002/anie.202007547DOI Listing

Ørsted and Bunsen: Voltaic Batteries, Electric Arcs, Electromagnetism, and Electrolysis.

Authors:
Curt Wentrup

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

The University of Queensland, School of Chemistry and Molecular Biosciences, Coopers Road, 4072, Brisbane, AUSTRALIA.

200 years ago Ørsted laid the foundation of electromagnetism in his famous experiment deflecting a magnetic needle in the electrical field of a platinum wire. For this he used his own Cu-Zn trough battery, which was among the best then available, but 21 years later it was surpassed by the coal-zinc battery invented by Bunsen, which became highly successful and acclaimed. That year, 1841, Bunsen made his first direct contact with Scandinavia when he visited Berzelius in Stockholm, Palmstedt in Gothenburg, and Ørsted, Scharling and Zeise in Copenhagen. Read More

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http://dx.doi.org/10.1002/anie.202006761DOI Listing

Zinc-organic Battery with a Wide Operation-temperature Window from -70 to 150 °C.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Fudan University School of Basic Medical Sciences, Department of Chemistry, CHINA.

Aqueous zinc (Zn) battery has been considered as a promising candidate for grid-scale energy storage. However, their cycle stability is generally limited by the structure collapse of cathode materials and the dendrite formation coupled with undesired hydrogen evolution on Zn anode. Here we propose a Zn-organic battery, which involves a phenanthrenequinone macrocyclic trimer (PQ-MCT) cathode, a Zn foil anode and a nonaqueous electrolyte of N, N-dimethylformamide (DMF) solution containing Zn2+. Read More

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http://dx.doi.org/10.1002/anie.202005603DOI Listing

Deuteriodifluoromethylation and gem-Difluoroalkenylation of Aldehydes Using ClCF H in Continuous Flow.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.

The deuteriodifluoromethyl group (CF D) represents a challenging functional group due to difficult deuterium incorporation and unavailability of precursor reagents. Herein, we report the use of chlorodifluoromethane (ClCF H) gas in the continuous flow deuteriodifluoromethylation and gem-difluoroalkenylation of aldehydes. Mechanistic studies revealed that the difluorinated oxaphosphetane (OPA) intermediate can proceed via alkaline hydrolysis in the presence of D O to provide α-deuteriodifluoromethylated benzyl alcohols or undergo a retro [2+2] cycloaddition under thermal conditions to provide the gem-difluoroalkenylated product. Read More

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http://dx.doi.org/10.1002/anie.202004260DOI Listing

A Single-Atom Manipulation Approach for Synthesis of Atomically Mixed Nanoalloys as Efficient Catalysts.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.

Synthesis of well-defined atomically mixed alloy nanoparticles on desired substrates is an ultimate goal for their practical application. Herein we report a general approach for preparing atomically mixed AuPt, AuPd, PtPd, AuPtPd NAs(nanoalloys) through single-atom level manipulation. By utilizing the ubiquitous tendency of aggregation of single atoms into nanoparticles at elevated temperatures, we have synthesized nanoalloys on a solid solvent with CeO as a carrier and transition-metal single atoms as an intermediate state. Read More

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http://dx.doi.org/10.1002/anie.202004945DOI Listing

Dongmei Cui.

Authors:

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

"The most important future application of my research is making environmentally benign tyres … My favorite way to spend a holiday is climbing a mountain …" Find out more about Dongmei Cui in her Author Profile. Read More

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http://dx.doi.org/10.1002/anie.202007394DOI Listing

In-situ Scanning Tunneling Microscopy of Cobalt Phthalocyanine Catalyzed CO2 Reduction Reaction.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Institute of Chemistry, Chinese Academy of Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology, 2, North 1st Street, Zhongguancun, 100190, Beijing, CHINA.

We report a molecular investigation of cobalt phthalocyanine (CoPc) catalyzed CO 2 reduction reaction by electrochemical scanning tunneling microscopy (ECSTM). An ordered adlayer of CoPc is prepared on Au(111). Approximately 14% of the adsorbed species appear with high contrast in CO 2 purged electrolyte environment. Read More

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http://dx.doi.org/10.1002/anie.202005242DOI Listing

Polyesters by a Radical Pathway: Rationalization of the Cyclic Ketene Acetal Efficiency.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Aix-Marseille Université, Institut de Chimie Radicalaire UMR 7273, Av. Esc. Normandie-Niemen, 13393, Marseille, FRANCE.

Radical Ring-Opening polymerization (rROP) of Cyclic Ketene Acetals (CKAs) combines the advantages of both ring-opening polymerization and radical polymerization thereby allowing the robust production of polyesters coupled with the mild polymerization conditions of a radical process. rROP was recently rejuvenated by the possibility to copolymerize CKAs with classic vinyl monomers leading to the insertion of cleavable functionality into a vinyl-based copolymer backbone and thus imparting (bio)degradability. Such materials are suitable for a large scope of applications, particularly within the biomedical field. Read More

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http://dx.doi.org/10.1002/anie.202005114DOI Listing

A Mixed-Valence {Fe13} Cluster Exhibiting Metal-to-Metal Charge Transfer-Switched Spin Crossover.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Dalian University of Technology, State Key Laboratory of Fine Chemicals, CHINA.

It is promising and challenging to manipulate the electronic structures and functions of materials utilizing both metal-to-metal charge transfer (MMCT) and spin-crossover (SCO) to tune the valence and spin states of metal ions. Here, metallocyanate building block is utilized to link with a ferrous-triazole moiety and generates a mixed-valence complex {[(Tp 4-Me )Fe III (CN) 3 ] 9 [Fe II 4 (trz-ph) 6 ]}⋅[Ph 3 PMe] 2 ⋅[(Tp 4-Me )Fe III (CN) 3 ] ( 1 ; trz-ph = 4-phenyl-4H-1,2,4-tirazole). Moreover, MMCT occurs between Fe III and one of the Fe II sites after heat treatment, resulting in the generation of a new phase, {[(Tp 4-Me )Fe II (CN) 3 ][(Tp 4-Me )Fe III (CN) 3 ] 8 [Fe III Fe II 3 (trz-ph) 6 ]}⋅[Ph 3 PMe] 2 ·[(Tp 4-Me )Fe III (CN) 3 ] ( 1a ). Read More

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http://dx.doi.org/10.1002/anie.202005998DOI Listing

Copper-Catalyzed Deaminative Difluoromethylation.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Miami University, Chemistry and Biochemistry, 246 Hughes Lab, 45056, Oxford, UNITED STATES.

A difluoromethyl group (CF 2 H) is considered to be a lipophilic and metabolically stable bioisostere of an amino (NH 2 ) group. Therefore, methods that can rapidly convert an NH 2 group into a CF 2 H group would be of great value to medicinal chemistry. We report herein an efficient Cu-catalyzed approach for the conversion of alkyl pyridinium salts, which can be readily synthesized from the corresponding alkyl amines, to their alkyl difluoromethane analogues. Read More

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http://dx.doi.org/10.1002/anie.202006048DOI Listing

"Phenalenannulations: Three-Point Double Annulation Reactions that Convert Benzenes into Pyrenes".

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Florida State University, Department of Chemistry and Biochemistry, Dittmer Chemistry Building, r. 614, 32306-4390, Tallahassee, UNITED STATES.

"3-Point annulations", or ''phenalenannulations" transform a benzene ring directly into a substituted pyrene by "wrapping" two new cycles around the perimeter of the central ring at three consecutive carbon atoms. This efficient, modular, and general method for p-extension opens access to non- symmetric pyrenes and their expanded analogues. Potentially, this approach can convert any aromatic ring bearing a -CH 2 Br or a -CHO group into a pyrene moiety. Read More

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http://dx.doi.org/10.1002/anie.202006087DOI Listing

S-modified oxygen vacancies in iron-cobalt oxide nanosheets: Enabling extremely high activity of oxygen evolution reaction for achieving industrial water splitting benchmark.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

University of Queensland, School of Chemical Engineering, AUSTRALIA.

Water electrolysis is a promising strategy for high-purity hydrogen production but restrained by the high electricity cost. Developing an oxygen evolution reaction (OER) electrocatalyst with excellent activity and low price is indispensable for reducing water electrolysis cost. The modulation of electronic structure of catalysts can be an efficient strategy to boost their activities. Read More

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http://dx.doi.org/10.1002/anie.202006546DOI Listing

Solar-Assisted eBiorefinery: Photoelectrochemical Pairing of Oxyfunctionalization and Hydrogenation Reactions.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Korea Advanced Institute of Science and Technology, Department of Materials Science & Engineering, 373-1 Guseong-dong Yuseong-gu, 305-701, Daejeon, KOREA, REPUBLIC OF.

Inspired by natural photosynthesis, biocatalytic photoelectrochemical (PEC) platforms are gaining prominence for the conversion of solar energy into useful chemicals by combining redox biocatalysis and photoelectrocatalysis. Here, we report a dual biocatalytic PEC platform consisting of a molybdeneum (Mo)-doped BiVO4 (Mo:BiVO4) photoanode and an inverse opal ITO (IO-ITO) cathode that gives rise to the coupling of peroxygenase and ene-reductase-mediated catalysis, respectively. In the PEC cell, the photoexcited electrons generated from the Mo:BiVO4 are transferred to the IO-ITO and regenerate reduced flavin mononucleotide to drive ene-reductase-catalyzed trans-hydrogenation of ketoisophrone to (R)-levodione. Read More

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http://dx.doi.org/10.1002/anie.202006893DOI Listing

Synthesis of A Stable N-Hetero-Rh(I)-Metallacyclic Silanone.

Angew Chem Int Ed Engl 2020 Jun 4. Epub 2020 Jun 4.

Universite Toulouse III Paul Sabatier, Chemistry, FRANCE.

A novel N-hetero-Rh(I)-metallacyclic silanone has been synthesized. This silanone, showing an extremely large dimerization energy (ΔG = +86.2 kcal/mol), displays considerable stability and persists in solution up to 60 °C. Read More

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http://dx.doi.org/10.1002/anie.202006088DOI Listing

Quantitative Supramolecular Hetero-dimerization for Efficient Energy Transfer.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Univesity of Cambridge, Melville Laboratory for Polymer Synthesis, Department of Chemistry, Lensfield Road, CB2 1EW, Cambridge, UNITED KINGDOM.

The challenge of quantitatively forming self-assembled hetero-dimers without other equilibrium by-products is overcome through self-sorting favored by the introduction of designed shape-complementary moieties. Such a supramolecular strategy based on CB[8]-directed dimerization is further applied to generate hetero-chromophore dimers quantitatively, leading to efficient energy transfer (> 85 %) upon photoexcitation. Read More

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http://dx.doi.org/10.1002/anie.202006530DOI Listing

Heterostructured Inter-Doped Ruthenium-Cobalt Oxide Hollow Nanosheet Arrays for Highly Efficient Overall Water Splitting.

Authors:
Cheng Wang Limin Qi

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Peking University, College of Chemistry, Peking University, 100871, Beijing, CHINA.

The development of transition metal oxides (TMOs)-based bifunctional catalysts toward efficient overall water splitting through delicate control of composition and structure is a challenging task. Herein, we report rational design and controllable fabrication of unique heterostructured inter-doped ruthenium-cobalt oxide ((Ru-Co)O x ) hollow nanosheet arrays on carbon cloth. Benefiting from the desirable compositional and structural advantages of more exposed active sites, optimized electronic structure, and interfacial synergy effect, the (Ru-Co)O x nanoarrays exhibited outstanding performance as a bifunctional catalyst. Read More

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http://dx.doi.org/10.1002/anie.202005436DOI Listing

Stringing the PDI Bow.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Columbia University, Chemistry, UNITED STATES.

This study explores a new mode of contortion in perylene diimides where the molecule is bent, like a bow along its long axis. We synthesize these bowed PDIs through a facile 4-fold Suzuki macrocyclization with aromatic linkers and a tetraborylated perylene diimide that introduces strain and results in a bowed structure. By -altering the strings of the bow, the degree of bending can be controlled from flat to highly bent. Read More

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http://dx.doi.org/10.1002/anie.202004989DOI Listing

How to Make Nitroaromatics Glow: Next Generation Large, χ-Shaped, Centrosymmetric Diketopyrrolopyrroles.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Institute of Organic Chemistry, Polish Academy of Sciences, Institute of Organic Chemistry, Kasprzaka 44/52, 01-224, Warsaw, POLAND.

This article describes a synthetic approach to a new structurally diverse family of π-expanded diketopyrrolopyrroles (DPPs). These red-emissive dyes, based on a previously unknown skeleton, can be easily synthesized via a three-step strategy involving the preparation of diketopyrrolopyrrole followed by N-arylation and subsequent intramolecular palladium-catalyzed direct arylation. A careful selection of the aryl substituents on DPP gives access to a π-extended DPP derivative with intense fluorescence reaching 750 nm. Read More

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http://dx.doi.org/10.1002/anie.202005244DOI Listing

Enantiomeric discrimination through tip-enhanced Raman scattering using a chemically modified silver tip with an asymmetric atomic arrangement.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Kwansei Gakuin University, School of Science and Technology, 2-1 Gakuen, 669-1337, Sanda, Hyogo, JAPAN.

Enantiomeric discrimination is achieved by tip-enhanced Raman scattering (TERS) using a silver tip chemically modified by an achiral para -mercaptopyridine ( p MPY) probe molecule. Differences in the relative intensities of the p MPY spectra were monitored for three pairs of enantiomers containing hydroxyl (-OH) and/or amino (-NH 2 ) groups. The N: or N + -H functionality of the p MPY-modified tip participates in hydrogen bond interactions with a particular molecular orientation of each chiral isomer. Read More

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http://dx.doi.org/10.1002/anie.202005446DOI Listing

Compressing Double [7]Helicene by Successive Charging with Electrons.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

University of Albany, Department of Chemistry, State University of New York, 1400 Washington Avenue, 12222, Albany, UNITED STATES.

Chemical reduction of a benzo-fused double [7]helicene ( 1 ) with two alkali metals, K and Rb, provided access to three different reduced states of 1 . The doubly-reduced helicene 1 2- has been characterized by single-crystal X-ray diffraction as a solvent-separated ion triplet with two potassium counterions. The triply- and tetra-reduced helicenes, 1 3- and 1 4- , have been crystallized together in an equimolar ratio and both form the contact-ion complexes with two Rb + ions each, leaving three remaining Rb + ions wrapped by crown ether and THF molecules. Read More

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http://dx.doi.org/10.1002/anie.202005852DOI Listing

Isothiourea-Catalyzed Acylative Kinetic Resolution of Tertiary α-Hydroxy Esters.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

University of St Andrews, School of Chemistry, North Haugh, FIFE, KY10 3TH, St. Andrews, UNITED KINGDOM.

A highly enantioselective isothiourea-catalyzed acylative kinetic resolution (KR) of acyclic tertiary alcohols has been developed. Selectivity factors of up to 200 were achieved for the KR of tertiary alcohols bearing an adjacent ester substituent, with both reaction conversion and enantioselectivity found to be sensitive to the steric and electronic environment at the stereogenic tertiary carbinol centre. For more sterically-congested alcohols, the use of a recently-developed isoselenourea catalyst was optimal, with equivalent enantioselectivity but higher conversion achieved in comparison to the isothiourea HyperBTM. Read More

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http://dx.doi.org/10.1002/anie.202004354DOI Listing

Glycoconjugated Metallohelices have Improved Nuclear Delivery and Suppress Tumour Growth In Vivo.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

University of Huddersfield School of Applied Sciences, School of Applied Sciences, UNITED KINGDOM.

Monosaccharides are added to the hydrophilic face of a self-assembled asymmetric Fe(II) metallohelix, using CuAAC chemistry. The sixteen resulting architectures are water-stable and optically pure, and exhibit improved antiproliferative selectivity against colon cancer cells (HCT116 p53 +/+ ) with respect to the non-cancerous ARPE-19 cell line. While the most selective compound is a glucose-appended enantiomer, its cellular entry is not mainly glucose transporter-mediated. Read More

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http://dx.doi.org/10.1002/anie.202006814DOI Listing

Scalable Photoelectrochemical Dehydrogenative Cross-Coupling of Heteroarenes with Aliphatic C-H Bonds.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Xiamen University, Chemistry, 422 South Siming Road, 361005, Xiamen, CHINA.

Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross-coupling of heteroarenes with aliphatic C-H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. Read More

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http://dx.doi.org/10.1002/anie.202005724DOI Listing

Anisotropic Poisson's Effect and Deformation-induced Fluorescence Change of Elastic 9,10-Dibromoanthrathene Single Crystals.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Waseda Daigaku, Waseda Research Institute for Science and Engineering, JAPAN.

Elastic organic crystals have attracted considerable attention as next-generation flexible smart materials. However, the detailed information on both molecular packing change and macroscopic mechanical crystal deformations upon applied stress are still insufficient. Here we report that fluorescent single crystals of 9,10-dibromoanthracene are elastically bendable and stretchable, which allows a detailed investigation of the deformation behavior. Read More

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http://dx.doi.org/10.1002/anie.202006474DOI Listing

Caught in the Hinact: Crystal Structure and Spectroscopy Reveal a Sulfur Bound to the Active Site of an O2-stable State of [FeFe] Hydrogenase.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Max Planck Institute for Chemical Energy Conversion, Inorganic Spectroscopy, Stiftstrasse 34-36, 45470, Muelheim an der Ruhr, GERMANY.

[FeFe] hydrogenases are the most active H 2 converting catalysts in nature but their extreme oxygen sensitivity limits their use in technological applications. The [FeFe] hydrogenases from sulfate reducing bacteria can be purified in an O 2 -stable state called H inact . To date, the structure and mechanism of formation of H inact remain unknown. Read More

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http://dx.doi.org/10.1002/anie.202005208DOI Listing

Atroposelective Synthesis of Axially Chiral N-Arylpyrroles by Chiral-at-Rhodium Catalysis.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043, Marburg, Germany.

A transformation of fluxional into configurationally stable axially chiral N-arylpyrroles was achieved with a highly atroposelective electrophilic aromatic substitution catalyzed by a chiral-at-metal rhodium Lewis acid. Specifically, N-arylpyrroles were alkylated with N-acryloyl-1H-pyrazole electrophiles in up to 93 % yield and with up to >99.5 % ee, and follow-up conversions reveal the synthetic utility of this new method. Read More

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http://dx.doi.org/10.1002/anie.202004799DOI Listing

Design of Bowl-ShapedN-Hydroxyimide Derivatives as New Organoradical Catalysts for Site-Selective C(sp3)-H Bond Functionalization Reactions.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Kyoto University, Department of Chemistry, Graduate School of Science, Sakyo, 606-8502, Kyoto, JAPAN.

A series of new bowl-shaped N -hydroxyimide derivatives has been designed and used as selective organoradical catalysts. A number of these bowl-shaped N -hydroxyimide derivatives exhibit excellent site-selectivity in the amination of benzylic C(sp 3 )-H bonds in aromatic hydrocarbon substrates. Read More

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http://dx.doi.org/10.1002/anie.202003982DOI Listing

30 Years of Safe Genetic Engineering in Germany.

Angew Chem Int Ed Engl 2020 Jun 3. Epub 2020 Jun 3.

Institut für Technische Biokatalyse, Technische Universitat Hamburg, Hamburg, Germany.

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http://dx.doi.org/10.1002/anie.202006430DOI Listing

Free Radical Chemistry of Phosphasilenes.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Simon Fraser University, Chemistry, 8888 University Drive, V5A 1S6, Burnaby, CANADA.

Understanding the characteristics of radicals formed from silicon-containing heavy analogues of alkenes is of great importance for their application in radical polymerization. Bulky and electronic substituent effects in such compounds as phosphasilenes not only stabilize the Si=P double bond, but also influence the structure and species of the formed radicals. Herein we report our first investigations of radicals derived from phosphasilenes with Mes (2,4,6-trimethylphenyl), Tip (2,4,6-triisopropylphenyl), Dur (2,3,5,6-tetramethylphenyl) and NMe 2 (dimethylamino) substituents on the P atom, using muon spin spectroscopy and DFT calculations. Read More

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http://dx.doi.org/10.1002/anie.202006289DOI Listing

Cation-Controlled Assembly of Polyoxotungstate-Based Coordination Networks.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

University of California San Diego, Chemistry and Biochemistry, 9500 Gilman Dr, 92093, La Jolla, UNITED STATES.

We use the Preyssler polyoxoanion, [NaP5W30O110 ]14- ({P5W30}), as a platform for evaluating the role of non-bridging cations in the formation of transition-metal-bridged polyoxometalate coordination frameworks. Specifically, we show that the assembly architecture of Co2+-bridged  frameworks is dependent on the identity and amount of alkali or alkaline earth cations present during crystallization. The inclusion of Li+ , Na+ , K+ , Mg2+ or Ca2+ in the framework synthesis is used to selectively synthesize five different Co 2+-bridged {P5W30} structures. Read More

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http://dx.doi.org/10.1002/anie.202005627DOI Listing

Ineffective OH-pinning of the flipping dynamics of a spherical guest within a tight-fitting tube.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

The University of Tokyo, Department of Chemistry, Hongo 7-3-1, 113-0033, Bunkyo-ku, JAPAN.

A supramolecular/synthetic method was devised to affix a sterically hindered substituent onto a fullerene guest encapsulated in a tubular host. A two-wheeled complex of (C 59 N)-(C 59 N) with a tubular host was oxidatively bisected to afford the C 59 N +  cation captured in the tube. The C 59 N +  cation in the tube was then trapped by ethanol or water, which led to an oxy substituent pinned on the guest. Read More

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http://dx.doi.org/10.1002/anie.202005538DOI Listing

Quantitative assessment of tip effects in single-molecule high-speed atomic force microscopy using DNA origami substrates.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Paderborn University, Technical and Macromolecular Chemistry, Warburger Str. 100, 33098, Paderborn, GERMANY.

High-speed atomic force microscopy (HS-AFM) is widely employed in the investigation of dynamic biomolecular processes at a single-molecule level. However, it remains an open and somewhat controversial question, how these processes are affected by the rapidly scanned AFM tip. While tip effects are commonly believed to be of minor importance in strongly binding systems, weaker interactions may significantly be disturbed. Read More

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http://dx.doi.org/10.1002/anie.202005884DOI Listing

Three-Dimensional Cuprous Lead Bromide Framework with Highly Efficient and Stable Blue Photoluminescence Emission.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Jining University, Department of Chemistry and Chemical Engineering, Xingtan Road, 273155, Qufu, CHINA.

Recently, it is still challenging and attractive to construct single crystalline hybrid lead halides with highly stable and efficient blue light emissions through accurate structural design strategy considering the instability and low photoluminescence quantum yield (PLQY) of blue- emitting perovskites. Herein, by rationally introducing d 10 transition metal into single lead halide as new structural building unit and optical emitting center, we prepared a bimetallic halide of [(NH 4 ) 2 ]CuPbBr 5 with new type of three-dimensional (3D) anionic framework. Remarkably, [(NH 4 ) 2 ]CuPbBr 5 exhibits strong band-edge blue emission (441 nm) with high PLQY of 32% upon UV light excitation. Read More

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http://dx.doi.org/10.1002/anie.202006990DOI Listing

Multifunctional Active-Center-Transferable Platinum/Lithium Cobalt Oxide Heterostructured Electrocatalysts towards Superior Water Splitting.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Zhejiang University, School of Materials Science and Engineering, Hangzhou, 310027, Hangzhou, CHINA.

Designing cost-effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active-center-transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO2) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO2 nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Read More

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http://dx.doi.org/10.1002/anie.202005241DOI Listing

Optimization of Active Sites via Crystal Phase, Composition and Morphology for Efficient Low-Iridium Oxygen Evolution Catalysts.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Jilin University, State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, 2699 Qianjin Street, 130012, Changchun, CHINA.

Reducing the amount of iridium in oxygen evolution electrocatalysts without compromising their catalytic performances is one of the major requirements in proton exchange membrane water electrolyzers. Here, with the help of theoretical studies, we show that anatase-type TiO 2 -IrO 2 solid solutions possess more active iridium catalytic sites for the oxygen evolution reaction (OER) than IrO 2 , the benchmark OER catalyst. It is worth adding that the same is not observed for their rutile-type counterparts. Read More

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http://dx.doi.org/10.1002/anie.202006756DOI Listing

Reconciling Electrostatic and n→π* Orbital Contributions in Carbonyl Interactions.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

University of Edinburgh, EaStCHEM School of Chemistry, Joseph Black Building, David Brewster Road, EH9 3FJ, Edinburgh, UNITED KINGDOM.

Attractive interactions between carbonyl groups have been studied extensively, primarily due to their prevalence in protein structure. However, prior investigations have pointed to conflicting origins; earlier investigations identified dominant electrostatic dipolar interactions, while others have implicated lone pair n→π* orbital delocalisation. Here we reconcile these observations. Read More

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http://dx.doi.org/10.1002/anie.202005739DOI Listing

Reversibly Switching the Charge State and Adsorption Location of Single Potassium Atom on Ultrathin CuO Film.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Peking university, College of Chemistry and Molecular Engineering, Haidian District, 100871, Beijing, CHINA.

Potassium (K) cations are spontaneously formed upon thermal deposition of low-coverage K onto an ultrathin CuO monolayer grown on Cu(110) and explored by low-temperature scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy. The formed K cations are highly immobile and thermally stable. The local work function around an individual K cation decreases by 1. Read More

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http://dx.doi.org/10.1002/anie.202005370DOI Listing

Triarylborane Catalysed Alkenylation Reaction of Aryl Esters with Diazo-Compounds.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Cardiff University, Chemistry, Main Building, Park Place, CF10 3AT, Cardiff, UNITED KINGDOM.

Herein we report a facile, mild reaction protocol to form carbon-carbon bonds in the absence of transition metal catalysts. We demonstrate the metal-free alkenylation reactions of aryl esters with α-diazoesters to give highly functionalized enyne products. Catalytic amounts of tris(pentafluorophenyl)borane (10-20 mol%) are employed to afford the C=C coupled products (31 examples) in good to excellent yields (36-87%). Read More

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http://dx.doi.org/10.1002/anie.202007176DOI Listing

Prediction of CO2/N2 Selectivity in Porous Carbons from N2 Adsorption Isotherm at 77 K via Convolutional Neural Networks.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

University of California, Riverside, Department of Chemistry, 501 Big Springs Road, 92521, Riverside, UNITED STATES.

Porous carbons are an important class of porous materials with many applications including gas separation, while N 2 adsorption isotherm at 77 K is the most widely used approach to characterize porosity. Conventionally, textual properties such as surface area and pore volumes are derived from the N 2 adsorption isotherm at 77 K via fitting to an adsorption theory and then correlated to gas separation performance (uptake and selectivity). Here we use the N 2 isotherm at 77 K directly as input (representing feature descriptors for the porosity) to train convolutional neural networks that predict gas separation performance (using CO 2 /N 2 as a test case) for porous carbons more accurately. Read More

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http://dx.doi.org/10.1002/anie.202005931DOI Listing

Twisted Surfaces in Mesoporous Single Crystals Deliver Enhanced Catalytic activity and Stability.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Chinese Academy of Science, Fujian Institute of Research on the Structure of Matter, CHINA.

Porous single crystals which combine ordered lattice structures and disordered inter-connected pores would provide an alternative to create twisted surface in porous microstructures. Here we grow transition metal nitrides Nb4N5 and MoN single crystals at 2 cm scale to create well-defined active structures at twisted surfaces and we present high catalytic activity and stability toward non-oxidative dehydrogenation of ethane to ethylene. Unsaturated metal-nitrogen coordination structures including Nb-N1/5, Nb-N2/5, Mo-N1/3 and Mo-N1/6 at twisted surface mainly account for the C-H activation with chemisorption of H in molecular ethane at twisted surface, which not only improves dehydrogenation performance but also avoids the deep cracking of ethane to enhance coking resistance. Read More

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http://dx.doi.org/10.1002/anie.202006299DOI Listing

Metal-Free Photocatalytic Hydrogenation Using Covalent Triazine Polymers.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Soochow University, College of Nano Science & Technology, 199 Ren'ai Rd, Suzhou Industrial Park, 215123, Suzhou, CHINA.

Photocatalytic hydrogenation of biomass-derived organic molecules transforms solar energy to high-energy-density chemical bonds, and may enable the production of industrial building-block chemicals with great economical values. Despite its great potential, photocatalytic hydrogenation remains poorly explored up to now. Existing researches are mostly based on broad bandgap inorganic semiconductors and require the assistance of noble metal based cocatalysts. Read More

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http://dx.doi.org/10.1002/anie.202006618DOI Listing

C7-Indole Amidations and Alkenylations by Ruthenium(II) Catalysis.

Angew Chem Int Ed Engl 2020 Jun 2. Epub 2020 Jun 2.

Georg-August-Universitaet Goettingen, Institut fuer Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Goettingen, GERMANY.

C7-H functionalized indoles are ubiquitous structural units of biological and pharmaceutical compounds for numerous antiviral agents against SARS-CoV or HIV-1. Thus, achieving site-selective functionalizations of C7-H of indoles, while discriminating among other bonds, is highly demand. Herein, we disclose site-selective C7-H activations of indoles accomplished by ruthenium(II)biscarboxylate catalysis under mild conditions. Read More

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http://dx.doi.org/10.1002/anie.202006164DOI Listing