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Stereoretentive Manipulations of Anomeric Nucleophiles: Applications in the Synthesis of Selenoglycosides.
We report a stereospecific cross-coupling of anomeric stannanes with symmetrical diselenides resulting in the synthesis of selenoglycosides with exclusive anomeric control without directing groups. This reaction is compatible with free hydroxyl groups and was demonstrated in the preparation of glycoconjugates derived from mono-, di- and trisaccharides and peptides (35 examples). Given the generality and a broad substrate scope, the glycosyl cross-coupling method can find use in the synthesis of glycomimetics and glycoconjugates. PMID: 29671931 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Zhu F, O'Neill S, Rodriguez J, Walczak MA Tags: Angew Chem Int Ed Engl Source Type: research

A Desulfurative Strategy for the Generation of Alkyl Radicals Enabled by Visible-Light Photoredox Catalysis.
Abstract Herein, we present a new desulfurative protocol for generating primary, secondary and tertiary alkyl radicals via visible-light photoredox catalysis. A process that involves the generation of N-centered radicals from sulfinamide intermediates, followed by subsequent fragmentation, is critical to forming the corresponding alkyl radical species. This strategy has been successfully applied to conjugate addition reactions that features mild reaction conditions, broad substrate scope (>60 examples), and good functional-group tolerance. PMID: 29671934 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Qin Y, Xue F, Wang F, Liu J, Di J, Liao Q, Lu H, Zhu M, He L, He H, Zhang D, Song H, Liu XY Tags: Angew Chem Int Ed Engl Source Type: research

Nanohelicoidal Nematic Liquid Crystal Formed by a Non-Linear Duplexed Hexamer.
Abstract The twist-bend modulated nematic liquid crystal phase exhibits phenomena of fundamental importance to science; the formation of a helical pitch of nanometre scale in a fluid and the spontaneous breaking of mirror symmetry leading to a quasi-fluid state composed of chiral domains despite being composed of an achiral material. We note that this phase has only been observed for materials with two or more mesogenic units, the manner of attachment between which is always linear. In this communication we report on non-linear oligomers, with a H-shaped hexamesogen found to exhibit both nematic and twist-bend mod...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Mandle RJ, Goodby JW Tags: Angew Chem Int Ed Engl Source Type: research

Instant Locking of Molecular Ordering in Liquid Crystal Elastomers by Oxygen-Mediated Thiol-Acrylate Click Reactions.
Abstract Liquid crystal elastomers (LCEs) with intrinsic anisotropic strains are reversible shape-memory polymers of interest in sensor, actuator, and soft robotics applications. Rapid gelation of LCEs is required to fix molecular ordering within the elastomer network, which is essential for directed shape transformation. A highly efficient photo-cross-linking chemistry, based on two-step oxygen-mediated thiol-acrylate click reactions, allows for nearly instant gelation of the main-chain LCE network upon exposure to UV light. Molecular orientation from the pre-aligned liquid crystal oligomers can be faithfully tra...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Xia Y, Zhang X, Yang S Tags: Angew Chem Int Ed Engl Source Type: research

Cucurbit[7]uril-Dimethyllysine Recognition in a Model Protein.
Abstract Here, we provide the first structural characterization of host-guest complexation between cucurbit[7]uril (Q7) and dimethyl-lysine (KMe2) in a model protein. Binding was dominated by complete encapsulation of the dimethylammonium functional group. While selectivity for the most sterically accessible dimethyllysine was observed both in solution and in the solid state, three different modes of Q7-KMe2 complexation were revealed by X-ray crystallography. The crystal structures revealed also entrapped water molecules that persisted in solvating the ammonium group within the Q7 cavity. Remarkable Q7-protein as...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Guagnini F, Antonik P, Rennie M, O'Byrne P, Khan A, Pinalli R, Dalcanale E, Crowley PB Tags: Angew Chem Int Ed Engl Source Type: research

Bottom-up Synthesis and Self-Assembly of Copper Clusters into Permanent Excimer Supramolecular Nanostructures.
Abstract Metal cluster are promising nontoxic candidates in optoelectronics and photonics. Recently, clusters with appropriate molecular ligands have been demonstrated to be uniquely suitable as subnanometer building blocks for supramolecular architectures with controlled secondary interactions, providing access to physical regimes not achievable with conventional intermolecular motifs. A compelling example of this is the excimer photophysics exhibited by individual cluster-based superstructures produced by top-down etching of gold nanoparticles. The generalization of the strategy to other metals and its extension...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Santiago-Gonzalez B, Monguzzi A, Capitani C, Prato M, Santambrogio C, Meinardi F, Brovelli S Tags: Angew Chem Int Ed Engl Source Type: research

"Precipitation on Nanoparticles": Attractive Intermolecular Interactions Stabilize Specific Ligand Ratios on the Surfaces of Nanoparticles.
"Precipitation on Nanoparticles": Attractive Intermolecular Interactions Stabilize Specific Ligand Ratios on the Surfaces of Nanoparticles. Angew Chem Int Ed Engl. 2018 Apr 19;: Authors: Chu Z, Han Y, Kral P, Klajn R Abstract Confining organic molecules to the surfaces of inorganic nanoparticles can induce intermolecular interactions between them, which can affect the composition of the mixed self-assembled monolayers obtained by co-adsorption from solution of two different molecules. Here, we study co-adsorption of two thiolated ligands-a dialkylviologen and a zwitterionic sulfobetaine-that...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Chu Z, Han Y, Kral P, Klajn R Tags: Angew Chem Int Ed Engl Source Type: research

Thoughts on Chemistry and Scientific Truth in Post-Factual Times.
Abstract "… The value and meaning of scientific truth has not been overcome by postmodernism or post-factual tendencies. Just because politics is mostly a representation of opinions, this does not imply that truth has become irrelevant. Quite the opposite, the value of truth is growing in turbulent times and for scientists it constitutes the currency of credibility and accountability …" Read more in the Guest Editorial by Peter R. Schreiner. PMID: 29673023 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Schreiner PR Tags: Angew Chem Int Ed Engl Source Type: research

Japan Prize / Merck-Banyu Lectureship for Naoya Kumagai / DECHEMA Prize for Timothy No ël.
Japan Prize / Merck-Banyu Lectureship for Naoya Kumagai / DECHEMA Prize for Timothy Noël. Angew Chem Int Ed Engl. 2018 Apr 19;: Authors: PMID: 29673024 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Tags: Angew Chem Int Ed Engl Source Type: research

Enantioselective Rhodium-Catalyzed Dimerization of ω-Allenyl Carboxylic Acids: Straightforward Synthesis of C2-Symmetric Macrodiolides.
Enantioselective Rhodium-Catalyzed Dimerization of ω-Allenyl Carboxylic Acids: Straightforward Synthesis of C2-Symmetric Macrodiolides. Angew Chem Int Ed Engl. 2018 Apr 19;: Authors: Breit B, Steib P Abstract Herein, we report on the first enantioselective and atom-efficient, catalytic one-step dimerization methodology to selectively transform ω allenyl carboxylic acids into C2-symmetric, 14- to 28-membered bismacrolactones (macrodiolides). This convenient asymmetric access serves as an attractive route towards multiple naturally occuring homodimeric, macrocyclic scaffolds and demonstrates...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Breit B, Steib P Tags: Angew Chem Int Ed Engl Source Type: research

Polycyclic Indoline-Benzodiazepines by Electrophilic Additions of α-Imino Carbenes to Tröger Bases.
Polycyclic Indoline-Benzodiazepines by Electrophilic Additions of α-Imino Carbenes to Tröger Bases. Angew Chem Int Ed Engl. 2018 Apr 19;: Authors: Bosmani A, Guarnieri-Ibáñez A, Goudedranche S, Besnard C, Lacour J Abstract Polycyclic indoline-benzodiazepines are afforded by the intermolecular reaction of Tröger bases with N-sulfonyl-1,2,3-triazoles. Under Rh(II)-catalysis, α-imino carbenes are generated and a subsequent cascade of [1,2]-Stevens, Friedel-Crafts, Grob and aminal formation reactions yield the polycyclic heterocycles as single isomers (d.r.>49:1, fou...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Bosmani A, Guarnieri-Ibáñez A, Goudedranche S, Besnard C, Lacour J Tags: Angew Chem Int Ed Engl Source Type: research

The Functionality of Surface Hydroxyls on Selectivity and Activity of CO2 Reduction over Cu2O in Aqueous Solutions.
Abstract CO2 reduction in aqueous solutions is an attractive strategy for carbon capture and utilization. Cuprous oxide (Cu2O) is a promising catalyst for CO2 reduction as it can not only convert CO2 into valuable hydrocarbons but also suppress the side H2 evolution reaction (HER). However, the nature of the active sites is still under debate due to the complex surface structure of Cu2O under reducing conditions, leading to limited guidance in designing improved Cu2O catalysts. This paper describes the functionality of surface bounded hydroxyls on over partially reduced Cu2O(111) for CO2 reduction reaction (CO2RR)...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Gong J, Yang P, Zhao ZJ, Chang X, Zha S, Zhang G, Mu R Tags: Angew Chem Int Ed Engl Source Type: research

Synthesis of 1,4-Cyclohexanedimethanol, 1,4-Cyclohexanedicarboxylic Acid and 1,2-Cyclohexanedicarboxylates from Formaldehyde, Crotonaldehyde and Acrylate.
Abstract 1,4-Cyclohexanedimethanol (CHDM), 1,4-cyclohexanedicarboxylic acid (CHDA), and 1,2-cyclohexanedicarboxylates are valuable polyester monomers and plasticizers. In this work, we propose a new strategy for the synthesis of these compounds via a proline-catalyzed formal [3+1+2] cycloaddition of formaldehyde, crotonaldehyde, and acrylate (or fumarate), followed by a hydrogenation over commercially available Cu/Zn/Al catalyst, a one-pot hydrogenation/oxidation/hydrolysis process, or a Pd/C-catalyzed tandem decarbonylation/hydrogenation step, respectively. PMID: 29673054 [PubMed - as supplied by publisher] ...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Hu Y, Zhao Z, Liu Y, Li G, Wang A, Cong Y, Zhang T, Wang F, Li N Tags: Angew Chem Int Ed Engl Source Type: research

Trifluoromethanesulfonic Anhydride as a Low-Cost and Versatile Trifluoromethylation Reagent.
We report herein the unprecedented direct trifluoromethylation of (hetero)arenes using trifluoromethanesulfonic anhydride as a radical trifluoromethylation reagent by merging photoredox catalysis and pyridine activation. Furthermore, the introduction of both of the CF3 and OTf groups of trifluoromethanesulfonic anhydride into internal alkynes to access tetrasubstituted trifluoromethylated alkenes is developed. As trifluoromethanesulfonic anhydride is a low-cost and abundant chemical, this protocol provides a cost-efficient and practical route to trifluoromethylated compounds. PMID: 29673060 [PubMed - as supplied by pu...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Qing FL, Ouyang Y, Xu XH Tags: Angew Chem Int Ed Engl Source Type: research

From Open-shell Singlet Diradicaloid to Closed-shell Global Anti-aromatic Macrocycles.
Abstract A dithieno[a,h]-s-indacene (DTI) based diradicaloid DTI-2Br was synthesized and its open-shell singlet diradical character was validated by magnetic measurements. On the other hand, its macrocyclic trimer DTI-MC3 and tetramer DTI-MC4 turned out to be closed-shell compounds with global anti-aromaticity, which was supported by X-ray crystallographic analysis and NMR spectra, assisted by ACID and 2D-NICS calculations. Such change can be explained by a subtle balance between two types of anti-ferromagnetic spin-spin coupling along the π-conjugated macrocycles. The dications of DTI-MC3 and DTI-MC4 turned ou...
Source: Angewandte Chemie - April 19, 2018 Category: Chemistry Authors: Wu J, Li G, Gopalakrishna TY, Phan H, Tun Seng Herng TS, Ding J Tags: Angew Chem Int Ed Engl Source Type: research

Molecular Vise Approach to Create Metal-Binding Sites in MOFs and Detection of Biomarker.
We report a new approach to create metal-binding site in a series of metal-organic frameworks (MOFs), where tetra-topic carboxylate linker, 4',4'',4''',4''''-methanetetrayltetrabiphenyl-4-carboxylic acid, is partially replaced by a tri-topic carbox-ylate linker, tris(4-carboxybiphenyl)amine, in combination with mono-topic linkers, formic acid, trifluoroacetic acid, ben-zoic acid, isonicotinic acid, 4-chlorobenzoic acid, and 4-nitrobenzoic acid, respectively. The distance between these paired-up linkers can be precisely controlled, ranging from 5.4 to 10.8 Å, where a variety of metals, Mg2+, Al3+, Cr3+, Mn2+, Fe3+, Co...
Source: Angewandte Chemie - April 18, 2018 Category: Chemistry Authors: Wang Y, Liu Q, Zhang Q, Peng B, Deng H Tags: Angew Chem Int Ed Engl Source Type: research

Self-Assembled Cyclic Structures from Copper (II)-Peptoids.
Abstract Metal-ligand coordination is a key interaction in the self-assembly of biopolymers. Although binding of metal ions to synthetic proteins and peptides is known to yield high-order structures, self-assembly of peptidomimetic molecules upon metal binding is still challenging. Herein we explore the self-assembly of three peptoid trimers 3, 3A and 3B, bearing a bipyridine ligand at their C-terminus, a benzyl group at their N-terminus and a polar group (N-ethyl-R) in the middle position (R = OH, OCH3 and NH2, respectively) by Cu2+ coordination. X-ray diffraction analysis revealed unique, highly symmetric, dinuc...
Source: Angewandte Chemie - April 18, 2018 Category: Chemistry Authors: Ghosh T, Fridman N, Kosa M, Maayan G Tags: Angew Chem Int Ed Engl Source Type: research

Chiral DNA origami nanotubes with well-defined and addressable inside and outside surfaces.
We report the design and assembly of chiral DNA nanotubes with well-defined and addressable inside and outside surfaces. We demonstrate that the outside surface can be functionalised with a chiral arrangement of gold nanoparticles to create a plasmonic device and that the inside surface can be functionalised with a track for a molecular motor allowing transport of a cargo within the central cavity. PMID: 29668118 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - April 18, 2018 Category: Chemistry Authors: Benn F, Haley NEC, Lucas AE, Silvester E, Helmi S, Schreiber R, Bath J, Turberfield AJ Tags: Angew Chem Int Ed Engl Source Type: research

N-Heterocyclic Carbene Analogues of Thiele and Chichibabin Hydrocarbons.
RS Abstract Stable N-heterocyclic carbene analogues of Thiele and Chichibabin hydrocarbons, [(IPr)(C6 H4 )(IPr)] and [(IPr)(C6 H4 )2 (IPr)] (4 and 5, respectively; IPr=C{N(2,6-iPr2 C6 H3 )}2 CHCH), are reported. In a nickel-catalyzed double carbenylation of 1,4-Br2 C6 H4 and 4,4'-Br2 (C6 H4 )2 with IPr (1), [(IPr)(C6 H4 )(IPr)](Br)2 (2) and [(IPr)(C6 H4 )2 (IPr)](Br)2 (3) were generated, which respectively afforded 4 and 5 as crystalline solids upon reduction with KC8 . Experimental and computational studies support the semiquinoidal nature of 5 with a small singlet-triplet energy gap ΔES-T of 10.7 kcal&t...
Source: Angewandte Chemie - April 18, 2018 Category: Chemistry Authors: Rottschäfer D, Ho NKT, Neumann B, Stammler HG, van Gastel M, Andrada DM, Ghadwal RS Tags: Angew Chem Int Ed Engl Source Type: research

Nanosecond Dynamics Regulate the MIF-Induced Activity of CD74.
Abstract Macrophage migration inhibitory factor (MIF) activates CD74, which leads to severe disorders including inflammation, autoimmune diseases and cancer under pathological conditions. Molecular dynamics (MD) simulations up to one microsecond revealed dynamical correlation between a residue located at the opening of one end of the MIF solvent channel, previously thought to be a consequence of homotrimerization, and residues in a distal region responsible for CD74 activation. Experiments verified the allosteric regulatory site and identified a pathway to this site via the MIF β-strands. The reported finding...
Source: Angewandte Chemie - April 18, 2018 Category: Chemistry Authors: Pantouris G, Ho J, Shah D, Syed MA, Leng L, Bhandari V, Bucala R, Batista VS, Loria JP, Lolis E Tags: Angew Chem Int Ed Engl Source Type: research

A Bulky Diamine Ligand Promoted Cross-Coupling with Difluoroalkyl Bromides via Iron Catalysis.
Abstract Although iron-catalyzed cross-coupling of Grignard reagents with alkyl halides has been well established, the adoption of the reaction for fluoroalkylations has not been reported because traditional catalytic systems often lead to defluorination reactions. Here, we describe our investigation of an iron-catalyzed cross-coupling between arylmagnesium and difluoroalkyl bromides with steric modified N,N,N',N'-tetramethyl-ethane-1,2-diamine (TMEDA) (L4) as a ligand. The use of a bulky diamine ligand (L4), in which a butylene is substituted at one carbon atom of ethylene backbone in TMEDA, enables the iron-cata...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Zhang X, An L, Xiao YL, Zhang S Tags: Angew Chem Int Ed Engl Source Type: research

Divergent Synthesis of CF3-Substituted Allenyl Nitriles by Ligand-Controlled Radical 1,2- and 1,4-Addition of 1,3-Enynes.
Abstract A ligand-controlled system that enables regioselective trifluoromethylcyanation of 1,3-enynes has been identified, which provides an access to a variety of CF3-containing tri- and tetra-substituted allenyl nitriles. We disclose that the involved propargylic radicals can be selectively trapped by (Box)Cu(II) cyanide, while the tautomerized allenyl radicals are trapped by (phen)Cu(II) cyanide. In addition, the reaction features broad substrate scope and excellent functional group compatibility. Moreover, this protocol represents a novel regioselectivity-tunable functionalization of 1,3-enynes via radicals, ...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Liu G, Wang F, Wang D, Liang L, Lu R, Chen P, Lin Z, Zhou Y Tags: Angew Chem Int Ed Engl Source Type: research

Long-Lasting Efficacy of Coatings for Bronze Artworks Conservation: the Key Role of Layered Double Hydroxide Nanocarriers in Protecting Corrosion Inhibitors from Photodegradation.
Abstract The photodegradation kinetics of 2-mercaptobenzothiazole (MBT), a corrosion inhibitor for copper-based alloys, is studied for the first time in high amorphous polyvinyl alcohol coatings subjected to either UV irradiation or indoor light exposure. The photodegradation process proceeds rapidly, thus compromising the anticorrosion ability of the coating. We prove that the encapsulation of MBT into layered double hydroxide (LDH) nanocarriers slows down its decomposition kinetics by a factor 3. Besides preserving the corrosion inhibitor, such a strategy allows a controlled release of MBT triggered by corrosion...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Salzano de Luna M, Buonocore GG, Giuliani C, Messina E, Di Carlo G, Lavorgna M, Ambrosio L, Ingo GM Tags: Angew Chem Int Ed Engl Source Type: research

Distinct Electron Conductance Regimes in Bacterial Decaheme Cytochromes.
Abstract Shewanella oneidensis MR-1 can gain energy by extracellular electron transfer to solid surfaces. They employ c-type cytochromes in two Mtr transmembrane complexes, forming a multiheme wire for electron transport across the cellular outer membrane. It is unclear whether the dominant mechanism entails electron or hole transfer, and why two Mtr pathways exist. We investigated electron and hole transfer mechanisms in the external terminal of the two complexes, MtrC and MtrF. Comparison of computed redox potentials with previous voltammetry experiments in distinct environments, i.e. isolated and electrode-boun...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Barrozo A, El-Naggar MY, Krylov A Tags: Angew Chem Int Ed Engl Source Type: research

Engineering Proteins at Interfaces: From Complementary Characterization to Material Surfaces with Designed Functions.
r K Abstract Once materials come in contact with a biological fluid containing proteins, proteins are generally - so desired or not - attracted by a material's surface and adsorb onto it. The aim of this review is to give an overview of the most commonly used characterization methods employed to obtain a better understanding of the adsorption processes on either planar or curved surfaces. We continue to illustrate the benefit of combining different methods to different surface geometries of the material. The thus obtained insights ideally pave the way for engineering functional materials interacting in a predeterm...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Morsbach S, Gonella G, Mailänder V, Wegner S, Wu S, Weidner T, Berger R, Koynov K, Vollmer D, Encinas N, Kuan SL, Bereau T, Kremer K, Weil T, Bonn M, Butt HJ, Landfester K Tags: Angew Chem Int Ed Engl Source Type: research

Polar Fluorooxoborate NaB4O6F: A Promising Material for Ionic Conduction and Nonlinear Optics.
Abstract The search of new borates with improved functional properties has attracted considerable attention. Here, a new polar fluorooxoborate, NaB4O6F (NBF) was prepared by high-temperature solid-state reaction. NBF belongs to the AB4O6F family (A = alkali metal or ammonium)-a series of compounds undergo significant cation-dependent structural changes, and NBF is of particular interest in the family due to the special cation position. Temperature-dependent ionic conductivity measurement indicates that NBF is a new solid ionic conductor, and it shows the lowest active energy of 32.5 kJ·mol-1 in fluorooxobor...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Zhang Z, Wang Y, Zhang B, Yang Z, Pan S Tags: Angew Chem Int Ed Engl Source Type: research

Bottom-up Construction of Graphene Segments Based on a Palladium-Catalyzed Annulative Dimerization of o-Iodobiaryl Compounds.
Abstract A straightforward method based on a Pd-catalyzed annulative dimerization of o-iodobiaryl compounds via a double C-I and C-H bond cleavage for the construction of aromatic compounds with a triphenylene core has been developed. The protocol features simple reaction conditions that require neither a ligand nor an oxidant, and it tolerates a wide scope of coupling partners without compromising its efficiency or scalability. More importantly, the generated TCCT synthon can be used to prepare a series of fully fused, small graphene nanoribbons by a late-stage arylation with arylboronic acids and subsequent Scho...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Shi Z, Zhu C, Wang D, Wang D, Zhao Y, Sun WY Tags: Angew Chem Int Ed Engl Source Type: research

Direct Access to Aryl Bis(trifluoromethyl)carbinols from Aryl Bromides or Fluorosulfates via a Pd-Catalyzed Carbonylation.
Abstract A Pd-catalyzed carbonylative approach for the direct conversion of (hetero)aryl bromides into their α,α-bis(trifluoromethyl)carbinols is described, applying only stoichiometric amounts of carbon monoxide and trifluoromethyltrimethyl-silane. In addition, aryl fluorosulfates proved highly compatible to these reaction conditions. The method is tolerant of a diverse set of functional groups, and it is adaptable to late-stage carbon isotope labeling. PMID: 29663685 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Skrydstrup T, Domino K, Veryser C, Wahlqvist B, Gaardbo C, Neumann KT, Daasbjerg K, De Borggraeve W Tags: Angew Chem Int Ed Engl Source Type: research

Affinity-driven Covalent Modulator of Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH) Cascade.
Abstract Traditional medicines provide a fertile ground to explore potent lead compounds; yet, their transformation into modern drugs is fraught with challenges in deciphering the target that is mechanistically valid for its biological activity. Herein we revealed Z-(+)-isochaihulactone 1 exhibited significant inhibition against MDR cancer cell lines and mice xenografts. By NMR spectroscopy, 1 was shown to resist to an off-targeting thiolate, thus giving 1 a target covalent inhibitor-like (TCI) property. By identifying the pharmacophore of 1 (α,β-unsaturated moiety), a 1-derived probe was designed and s...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Chern J, Lu CP, Fang Z, Chang CM, Hua KF, Chen YT, Yang Ng C, Chen YS, Lam Y, Wu SH Tags: Angew Chem Int Ed Engl Source Type: research

Ultrathin Chiral Metal-Organic Frameworks Nanosheets for Efficient Enantioselective Separation.
In this report, the first example of ultrathin CMOFs nanosheets is successfully fabricated via the confinement growth of two-dimensional (2D) chiral layers, which are assembled by helical metal-organic chains within microemulsion. Impressively, this convenient and easily scaled up inverse microemulsion protocol is capable of fabricating a series of 2D CMOFs nanosheets composed of variable metal node or alternative chiral ligand. More significantly, thanks to the exceptionally large number of chiral sites exposed on surfaces, as-obtained CMOFs nanosheets exhibit much higher enantioselectivity in chiral separation compared w...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Guo J, Zhang Y, Zhu Y, Long C, Zhao M, He M, Zhang X, Lv J, Han B, Tang Z Tags: Angew Chem Int Ed Engl Source Type: research

An O3-type Oxide with Low Sodium Content as the Phase-Transition-Free Anode for Sodium-Ion Batteries.
Abstract Layered transition metal oxides NaxMeO2 (Me = transition metal) with P2 or O3 structure have attracted extensive attention in sodium-ion batteries (NIBs). Herein, we find a universal law to distinguish structural competition between P2 and O3 types based on the ratio of interlayer distances of alkali metal layer d(O-Na-O) and transition-metal layer d(O-Me-O). It is demonstrated that the ratio of ~1.62 can be used as an indicator. O3-type Na0.66Mg0.34Ti0.66O2 oxide is prepared as stable an anode for NIBs, in which the low Na-content (≈0.66) usually undergoes a P2-type structure with respect to NaxMeO...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Zhao C, Avdeev M, Chen L, Hu YS Tags: Angew Chem Int Ed Engl Source Type: research

Application of in situ techniques for the characterization of NiFe based oxygen evolution reaction (OER) electrocatalysts.
Abstract Developing high-efficiency and affordable electrocatalysts for the sluggish oxygen evolution reaction (OER) remains a crucial bottleneck on the way to the practical applications of rechargeable energy storage technologies and water splitting for producing clean fuel (H2). In recent years, NiFe based materials have demonstrated to be excellent electrocatalysts for OER. Understanding the characteristics that affect OER activity and determining the OER mechanism are of vital importance for the development of OER electrocatalysts. Therefore, in situ characterization techniques performed under OER conditions a...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Yang W, Zhu K, Zhu X Tags: Angew Chem Int Ed Engl Source Type: research

Oxidation Catalysis via an Aerobically Generated Dess-Martin Periodinane Analogue.
Abstract Hypervalent iodine(V) reagents, such as Dess-Martin periodinane (DMP) and 2-iodoxybenzoic acid (IBX), are broadly useful oxidants in chemical synthesis. Development of strategies to access these reagents from O₂ would immediately enable use of O₂ as a terminal oxidant in a broad array of substrate oxidation reactions. Recently we disclosed the aerobic synthesis of I(III) reagents by intercepting reactive oxidants generated during aldehyde autoxidation. Here, we couple aerobic oxidation of iodobenzenes with disproportionation of the initially generated I(III) compounds to generate I(V) reagents. The ae...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Maity A, Hyun SM, Wortman AK, Powers DC Tags: Angew Chem Int Ed Engl Source Type: research

Thermal-Responsive Phosphorescent Nanoamplifiers Assembled from Two Metallophosphors.
Abstract Thermal-responsive phosphorescent nanotubes have been fabricated from the co-assembly of two neutral iridium complexes, which behave as the antenna chromophores and energy acceptors respectively in these highly-ordered crystalline superstructures. By tuning the acceptor doping ratio in a range of 0 - 0.5%, these tubes display color-tunable phosphorescence from green to red at room temperature, attributed to the highly efficient light-harvesting and energy transfer in these materials. For the same reason, the acceptor emission in the nanotubes is amplified more than 800 times with respect to its pure nonem...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Sun MJ, Zhong YW, Yao J Tags: Angew Chem Int Ed Engl Source Type: research

A Very Short Uranium(IV)-Rhodium(I) Bond with Net Double-Dative Bonding Character.
Abstract Reaction of the uranium silyl-phosphino-carbene complex [U{C(SiMe3)(PPh2)}(BIPM)(μ-Cl)Li(TMEDA)(μ-TMEDA)0.5]2 (1, BIPM = C(PPh2NSiMe3)2; TMEDA = Me2NCH2CH2NMe2) with the rhodium chloride compound [Rh(μ-Cl)(COD)]2 (COD = cyclo-octadiene) affords the unprecedented heterotrimetallic UIV-RhI2 complex [U(Cl)2{C(PPh2NSiMe3)(PPh[C6H4]NSiMe3)}{Rh(COD)}{Rh(CH(SiMe3)(PPh2)}] (2). Complex 2 exhibits one, very short, uranium-rhodium distance that is by some margin the shortest uranium-rhodium bond on record, one of the shortest absolute uranium-metal distances generally, and the shortest actinide-transition ...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Liddle S, Lu E, Wooles A, Gregson M, Cobb P Tags: Angew Chem Int Ed Engl Source Type: research

Block-Stereoblock Copolymers of Poly( ε-Caprolactone) and Poly(Lactic Acid).
Block-Stereoblock Copolymers of Poly(ε-Caprolactone) and Poly(Lactic Acid). Angew Chem Int Ed Engl. 2018 Apr 17;: Authors: Rosen T, Goldberg I, Navarra W, Venditto V, Kol M Abstract A magnesium complex of the type {ONNN}Mg-HMDS wherein {ONNN} is a sequential tetradentate monoanionic ligand is introduced. In the presence of an alcohol initiator this complex catalyzes the living and immortal homopolymerization of the lactide enantiomers and ε-caprolactone at room-temperature with exceptionally high activities, as well as the precise block copolymerization of these monomers in a one-pot s...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Rosen T, Goldberg I, Navarra W, Venditto V, Kol M Tags: Angew Chem Int Ed Engl Source Type: research

Spectral imaging and archival data in analyzing the Madonna of the Rabbit painting by Manet and Titian.
Abstract A concise insight into the outputs provided by the latest prototype of visible-near infrared (VIS-NIR) multispectral scanner (National Research Council-National Institute of Optics, CNR-INO, Italy) is presented. The analytical data acquired on an oil painting Madonna of the Rabbit by É. Manet are described. In this work, the VIS-NIR data were complemented with X-ray fluorescence (XRF) mapping for the chemical and spatial characterization of several pigments. The spatially registered VIS-NIR data facilitated their processing with spectral correlation mapping (SCM) and artificial neural network (ANN)...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Striova J, Ruberto C, Barucci M, Blažek J, Kuzman D, Dal Fovo A, Pampaloni E, Fontana R Tags: Angew Chem Int Ed Engl Source Type: research

Salvaging Reactive Fullerenes from Soot by Exohedral Derivatization.
Abstract The awesome allotropy of carbon yields innumerable, topologically possible cage structures of molecular carbon. This field is also related to endohedral metallofullerenes constructed by metal-atom encapsulation. Pure form of stable and soluble empty fullerenes and endohedral metallofullerenes are available in macroscopic amounts from carbon arc production or other physical processes followed by extraction and subsequent chromatographic separation. However, many other unidentified fullerene species, which must be reactive and insoluble in their pristine forms, remain in soot. Such "missing" speci...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Yamada M, Akasaka T, Nagase S Tags: Angew Chem Int Ed Engl Source Type: research

Hairy Graphenes: Wrapping Nanocellulose Nets around Graphene Oxide Sheets.
Abstract Constructing advanced functional nanomaterials with pre-designed organized morphologies from low-dimension synthetic and biological components is extremely challenging because of complex inter-component interactions, high-aspect ratios, flexible shapes, crumpling instabilities and limited common wet-chemistry processing conditions. Herein, we report an efficient and universal amphiphilicity-driven assembly strategy to construct "hairy" flexible hybrid nanosheets with the net of 1D cellulose nanofibers (CNFs) conformally wrapped around 2D graphene oxide (GO) monolayers. This interface-driven bio-...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Xiong R, Kim HS, Korolovych VF, Zhang S, Yingling Y, Tsukruk VV Tags: Angew Chem Int Ed Engl Source Type: research

Macrotheranostic Probe with Disease-activated Near-infrared Fluorescence, Photoacoustic and Photothermal Signals for Imaging-guided Therapy.
Abstract Theranostics provides opportunities for precision cancer therapy. However, theranostic systems that simultaneously turn on their diagnostic signal and pharmacological action only in respond to targeted biomarker have been less exploited. We herein report the synthesis of a smart macrotheranostic probe that specifically turns on near-infrared fluorescence, photoacoustic and photothermal signals in the presence of cancer-overexpressed enzyme for imaging-guided cancer therapy. Supervisor to the small-molecule counterpart probe, the macrotheranostic probe has an ideal biodistribution and renal clearance, perm...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Pu K, Zhen X, Zhang J, Huang J, Xie C, Miao Q Tags: Angew Chem Int Ed Engl Source Type: research

Control of the Spin Dynamics of Single-Molecule Magnets using a Quasi One-Dimensional Arrangement.
Abstract Magnetic dipole interactions are dominate in quasi one-dimensional (1D) molecular magnetic materials, in which TbNcPc units (Tb3+ = terbium(III) ion, Nc = naphthalocyaninato, Pc = phthalocyaninato) adopt a structure similar to TbPc₂ single-molecule magnets (SMMs). The magnetic properties of the [TbNcPc]0/+ (neutral 1 and cationic 2) with 1D structures are significantly different than those of a magnetically diluted sample (3). In particular, the magnetic relaxation time (τ) of 2 in the low temperature region is five orders of magnitude slower than that of 3. Furthermore, the coercivity (HC) of 2 rem...
Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Katoh K, Yamashita S, Yasuda N, Kitagawa Y, Breedlove BK, Nakazawa Y, Yamashita M Tags: Angew Chem Int Ed Engl Source Type: research

Divergent Couplings of Anilines and Enones via Integration of C-H Activation and Transfer Hydrogenation.
Abstract Ideally, in catalytic reactions the catalyst fulfills several intrinsically different duties in one-shot. This requires integration of more than one distinct transformations in a catalytic cycle. Cp*Rh(III)/Ir(III) complexes are known to play important roles in both C-H activation and transfer hydrogenation (TH). However, these two areas evolved separately. They are integrated in redox- and chemo-divergent couplings of N-pyridylanilines with enones. The Ir-catalyzed coupling with enones leads to efficient synthesis of tetrahydroquinolines via TH from iPrOH. Counterintuitively, iPrOH does not serve as the ...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Li X, Zhou X, Zheng G, Xia J, Kong L Tags: Angew Chem Int Ed Engl Source Type: research

Water formation below silica thin films: Real time observation of a chemical reaction in a physically confined space.
Abstract Using low energy electron microscopy and local photoelectron spectroscopy, we investigated the water formation from adsorbed O and H₂ on a Ru(0001) surface covered with a vitreous SiO₂ bilayer (BL) and compared it to the same reaction on bare Ru(0001). In both cases the reaction is characterized by moving reaction fronts. The reason for this might be related with the requirement of site release by O adatoms for further H₂ dissociative adsorption. We find apparent activation energies (E_a^app) for the front motion of 0.59 eV without cover and 0.27 eV under cover. We suggest that the smaller activatio...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Prieto MJ, Klemm H, Xiong F, Gottlob D, Menzel D, Schmidt T, Freund HJ Tags: Angew Chem Int Ed Engl Source Type: research

Tunneling Mode of Scanning Electrochemical Microscopy (SECM): Probing Electrochemical Processes at Single Nanoparticles.
Abstract Electrochemical experiments at individual nanoparticles (NP) can provide new insights into their structure-activity relationships. By using small nanoelectrodes as tips in the scanning electrochemical microscope (SECM), we recently imaged individual surface-bound 10-50 nm metal NPs. Herein, we introduce a new mode of the SECM operation based on tunneling between the tip and a nanoparticle immobilized on the insulating surface. The obtained current vs. distance curves show the transition from the conventional feedback response to electron tunneling between the tip and the NP at separation distances ≤ ~3...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Sun T, Wang D, Mirkin MV Tags: Angew Chem Int Ed Engl Source Type: research

Development of the Vinylogous Pictet-Spengler Cyclization and Total Synthesis of ( ±)-Lundurine A.
Development of the Vinylogous Pictet-Spengler Cyclization and Total Synthesis of (±)-Lundurine A. Angew Chem Int Ed Engl. 2018 Apr 16;: Authors: Nash A, Qi X, Maity P, Owens K, Tambar UK Abstract A novel vinylogous Pictet-Spengler cyclization has been developed for the generation of indole annulated medium sized rings. The method enables synthesis of tetrahydro-azocinoindoles with a fully substituted carbon center, which is prevalent in many biologically active alkaloids. The strategy has been applied to the total synthesis of (±)-lundurine A. PMID: 29663602 [PubMed - as supplied by...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Nash A, Qi X, Maity P, Owens K, Tambar UK Tags: Angew Chem Int Ed Engl Source Type: research

Crowding Shifts the FMN Recognition Mechanism of Riboswitch Aptamer from Conformational Selection to Induced Fit.
Abstract In bacteria, the binding between riboswitch aptamer domain and ligand is regulated by environmental cues, such as low Mg2+ in macrophages during pathogenesis to ensure spatiotemporal expression of virulence genes. We investigated binding between the flavin mononucleotide (FMN) riboswitch aptamer and its anionic ligand in the presence of molecular crowding agent without Mg2+ ion, which mimics pathogenic conditions. Structural, kinetic, and thermodynamic analyses under the crowding revealed more dynamic conformational rearrangements of the FMN riboswitch aptamer compared to dilute Mg2+-containing solution. ...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Rode A, Endoh T, Sugimoto N Tags: Angew Chem Int Ed Engl Source Type: research

Dynamic Interfacial Adhesion through Cucurbit[n]uril Molecular Recognition.
Abstract Supramolecular building block, such as cucurbit[n]uril (CB[n])-based host-guest complexes, have been extensively studied at the nano- and microscale as adhesion promoters. Herein, we exploit a new class of CB[n]-threaded highly-branched polyrotaxanes (HBP-CB[n]) as aqueous adhesives to macroscopically bond two wet surfaces, including biological tissue, through the formation of CB[8] heteroternary complexes. The dynamic nature of these complexes gives rise to adhesion with remarkable self-healing, displaying recovery and re-adhesion after mechanical failure at the interface. Incorporation of functional gue...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Liu J, Tan CSY, Scherman OA Tags: Angew Chem Int Ed Engl Source Type: research

Genetically engineered supercharged polypeptide fluids: fast and persistent self-ordering induced by a touch.
Abstract Mechanically induced disorder-order transitions have been studied in fluid surfactant solutions or polymer thermotropic liquid crystals. However, the isothermally induced ordered phases do not persist after cessation of shear, which limits their technological applicability to a great extent. Moreover, no such stimuli-responsive materials involving biomacromolecules have been reported although biopolymer liquids are gaining a lot of attention. Here we introduce a new type of biological fluid system in which anionic polypeptides are complexed with cationic surfactants. The resulting fluids exhibited very se...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Zhang L, Ma C, Sun J, Shao B, Portale G, Chen D, Liu K, Herrmann A Tags: Angew Chem Int Ed Engl Source Type: research

Highly Efficient and Stereoselective Thioallylation of Alkynes: Possible Gold Redox Catalysis with No Need of a Strong Oxidant.
Abstract A possible gold redox-catalyzed stereoselective thioallylation of alkynes was achieved. The reaction was accomplished with high efficiency (as low as 0.1% catalyst loading, up to 99% yield) and broad substrate scope (various alkynes, inter- and intramolecular fashion). The gold(I) catalyst acts as both pi-acid for alkyne activation and redox catalyst for Au(I/III) coupling, while the in-situ generated sulfonium cation functions as a mild oxidant. This novel methodology provides an exciting system for gold redox catalysis without the need of a strong oxidant. PMID: 29663659 [PubMed - as supplied by pu...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Shi X, Wang J, Zhang S, Wojtas L, Akhmedov N, Chen H, Xu C Tags: Angew Chem Int Ed Engl Source Type: research

Exposing the Origins of Irreproducibility in Fluorine NMR Spectroscopy.
Abstract Fluorine chemistry has taken a pivotal role in chemical reaction discovery, drug development, and chemical biology. NMR spectroscopy, arguably the most important technique for characterization of fluorinated compounds, is rife with highly inconsistent referencing of fluorine NMR chemical shifts, producing deviations larger than 1 ppm. Herein, we provide unprecedented evidence that both spectrometer design and the current unified scale system underpinning the calibration of heteronuclear NMR spectra has unintentionally led to widespread variation in the standardization of 19F NMR spectral data. We demonstr...
Source: Angewandte Chemie - April 16, 2018 Category: Chemistry Authors: Togni A, Rosenau CP, Jelier BJ, Gossert AD Tags: Angew Chem Int Ed Engl Source Type: research