Angewandte Chemie International Edition

Cover image for Vol. 56 Issue 10

Chefredakteur: Peter Gölitz, Stellvertreter: Neville Compton, Haymo Ross

Online ISSN: 1521-3773

Associated Title(s): Angewandte Chemie, Chemistry - A European Journal, Chemistry – An Asian Journal, ChemistryOpen, ChemPhotoChem, ChemPlusChem, Zeitschrift für Chemie

Upcoming Hot Papers

Hot Papers are chosen by the Editors for their importance in a rapidly evolving field of high current interest. Many of the "Very Important Papers" (VIPs) would certainly qualify to be included here, but such a duplication is avoided.

Palladium Catalysts

Detection of Palladium(I) in Aerobic Oxidation Catalysis

Jonathan N. Jaworski, Scott D. McCann, Dr. Ilia A. Guzei and Prof. Shannon S. Stahl

Detection of Palladium(I) in Aerobic Oxidation Catalysis

Catalyst entanglement: Catalyst dimerization is observed in both the aerobic palladium-catalyzed allylic C−H acetoxylation and aza-Wacker cyclization. A novel PdI species is rigorously characterized in catalysis which has implications for palladium catalyst design and presents insights into catalyst deactivation.

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Homogeneous Catalysis

Carbonyls as Latent Alkyl Carbanions for Conjugate Additions

Xi-Jie Dai, Dr. Haining Wang and Prof. Dr. Chao-Jun Li

Carbonyls as Latent Alkyl Carbanions for Conjugate Additions

Hidden talents: Carbonyls can act as latent carbon nucleophiles for conjugate additions through a ruthenium-catalyzed process. The reaction relies on homogeneous ruthenium(II) catalysis combined with phosphines as spectator ligands and hydrazine as the reducing agent. This method enables the incorporation of highly functionalized alkyl fragments into a vast array of electron-deficient olefins under mild reaction conditions.

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Interfacial Reaction Dynamics

Energy Transfer Dynamics of Formate Decomposition on Cu(110)

Jiamei Quan, Prof. Takahiro Kondo, Prof. Guichang Wang and Prof. Junji Nakamura

Energy Transfer Dynamics of Formate Decomposition on Cu(110)

CO2 desorption during formate decomposition in the steady-state reaction of HCOOH with O2 on Cu(110) is a thermal non-equilibrium process. During formate decomposition a large amount of released energy is transformed into the internal energies of CO2 molecules, which supports an Eley–Rideal-type mechanism for formate synthesis on copper catalysts.

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Fluorescent Labeling

In Vivo Gold Complex Catalysis within Live Mice

Kazuki Tsubokura, Dr. Kenward K. H. Vong, Dr. Ambara R. Pradipta, Dr. Akihiro Ogura, Sayaka Urano, Dr. Tsuyoshi Tahara, Dr. Satoshi Nozaki, Dr. Hirotaka Onoe, Dr. Yoichi Nakao, Regina Sibgatullina, Dr. Almira Kurbangalieva, Dr. Yasuyoshi Watanabe and Dr. Katsunori Tanaka

In Vivo Gold Complex Catalysis within Live Mice

The first metal-catalyzed reaction that proceeds within live mice is based on a targeting approach with glycans. Glycoalbumin–AuIII complexes can be accumulated in specific organs where they catalyze amide bond formation between a propargyl ester probe and amine groups on nearby proteins. The selective targeting was confirmed by whole body fluorescence imaging and analysis of dissected tissues.

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Interface Phenomena

Cation-Selective Channel Regulated by Anions According to Their Hofmeister Ranking

Dr. Philip A. Gurnev, Torri C. Roark, Dr. Horia I. Petrache, Dr. Alexander J. Sodt and Dr. Sergey M. Bezrukov

Cation-Selective Channel Regulated by Anions According to Their Hofmeister Ranking

Hofmeister effects: The conductance of a purely cation-selective peptide pore is regulated by anions in correlation with their position in the Hofmeister series (see picture). Moreover, the pore conformational dynamics are highly sensitive to the anion species. Both effects are related to preferential depletion of kosmotropic anions (accumulation of chaotropic anions) at the membrane–water interface.

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Polyoxometalate Self-Assembly

Photoresponsive Nanosheets of Polyoxometalates Formed by Controlled Self-Assembly Pathways

Keita Ishiba, Dr. Takao Noguchi, Dr. Hiroaki Iguchi, Dr. Masa-aki Morikawa, Prof. Dr. Kenji Kaneko and Prof. Dr. Nobuo Kimizuka

Photoresponsive Nanosheets of Polyoxometalates Formed by Controlled Self-Assembly Pathways

Controlling energy landscapes: Polyoxometalates and ether linkage-enriched ammonium ions spontaneously self-assemble into rectangular, ultrathin nanosheets under controlled conditions in water. These nanosheets are reduced by photoillumination. Site-specific photoetching and photodeposition of silver nanoparticles is demonstrated.

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Photocatalysis

Photocatalysis with Quantum Dots and Visible Light: Selective and Efficient Oxidation of Alcohols to Carbonyl Compounds through a Radical Relay Process in Water

Lei-Min Zhao, Dr. Qing-Yuan Meng, Xiang-Bing Fan, Chen Ye, Dr. Xu-Bing Li, Dr. Bin Chen, Prof. Dr. Vaidhyanathan Ramamurthy, Prof. Dr. Chen-Ho Tung and Prof. Dr. Li-Zhu Wu

Photocatalysis with Quantum Dots and Visible Light: Selective and Efficient Oxidation of Alcohols to Carbonyl Compounds through a Radical Relay Process in Water

Selective oxidation of alcohols to aldehydes/ketones has been achieved with 3-mercaptopropionic acid-capped CdSe quantum dots (QDs) and visible light. A visible-light-prompted electron-transfer reaction initiated the oxidation. The thiyl radical generated from the thiolate anion adsorbed on a CdSe QD plays a key role by abstracting the hydrogen atom of C−H bond from the alcohol.

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Radiopharmaceuticals

Chelator-Free Radiolabeling of Nanographene: Breaking the Stereotype of Chelation

Sixiang Shi, Cheng Xu, Dr. Kai Yang, Shreya Goel, Hector F. Valdovinos, Dr. Haiming Luo, Emily B. Ehlerding, Dr. Christopher G. England, Dr. Liang Cheng, Dr. Feng Chen, Prof. Robert J. Nickles, Prof. Zhuang Liu and Prof. Weibo Cai

Chelator-Free Radiolabeling of Nanographene: Breaking the Stereotype of Chelation

Chelator-free radiolabeling based on interactions between Cu and the π electrons of nanographene was shown, which can potentially substitute chelator-assisted labeling. The reliability of in vivo positron emission tomography imaging is enhanced while bypassing the inherent drawbacks of conventional chelator-based labeling.

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Phosphorylation

Combined Phosphoramidite-Phosphodiester Reagents for the Synthesis of Methylene Bisphosphonates

Sander B. Engelsma, Nico J. Meeuwenoord, Prof. Dr. Hermen S. Overkleeft, Prof. Dr. Gijsbert A. van der Marel and Dr. Dmitri V. Filippov

Combined Phosphoramidite-Phosphodiester Reagents for the Synthesis of Methylene Bisphosphonates

The condensation of novel phosphanylmethylphosphonate reagents with an alcohol of choice followed by oxidation provides orthogonally protected methylene bisphosphonate tetraesters. Global deprotection of the tetraester leads to terminal methylene bisphosphonates whereas selective deprotection at the terminal phosphonate followed by condensation with a second alcohol yields methylene bisphosphonate diesters.

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Biocatalysis

Catalytic Alkylation Using a Cyclic S-Adenosylmethionine Regeneration System

Silja Mordhorst, Dr. Jutta Siegrist, Prof. Dr. Michael Müller, Dr. Michael Richter and Jun. Prof. Dr. Jennifer N. Andexer

Catalytic Alkylation Using a Cyclic S-Adenosylmethionine Regeneration System

Play it again, SAM: Biocatalytic alkylation is an emerging field in biotechnology. In addition to the discovery and engineering of highly efficient and selective methyltransferases, the development of an efficient regeneration system for the cofactor S-adenosylmethionine (SAM) is a prerequisite for their economic application. The development of a biomimetic in vitro SAM regeneration cycle is presented with different methyltransferases as a model system.

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Polymers

Automated Synthesis of Well-Defined Polymers and Biohybrids by Atom Transfer Radical Polymerization Using a DNA Synthesizer

Dr. Xiangcheng Pan, Sushil Lathwal, Stephanie Mack, Jiajun Yan, Prof. Subha R. Das and Prof. Krzysztof Matyjaszewski

Automated Synthesis of Well-Defined Polymers and Biohybrids by Atom Transfer Radical Polymerization Using a DNA Synthesizer

Autorad: Photoinduced atom transfer radical polymerization is conducted in an automated DNA synthesizer to prepare well-defined homopolymers, diblock copolymers, and biohybrids. This technique provides a clean polymerization system under ambient temperature with oxygen tolerance.

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Heterogeneous Catalysis

Production of Primary Amines by Reductive Amination of Biomass-Derived Aldehydes/Ketones

Dr. Guanfeng Liang, Prof. Aiqin Wang, Dr. Lin Li, Dr. Gang Xu, Prof. Ning Yan and Prof. Tao Zhang

Production of Primary Amines by Reductive Amination of Biomass-Derived Aldehydes/Ketones

Amines from biomass: Ru/ZrO2 works as a highly efficient, bifunctional catalyst for the reductive amination of a variety of biomass-based aliphatic and aromatic aldehydes/ketones in aqueous ammonia for the production of primary amines under mild reaction conditions. A broad spectrum of renewable primary amines is produced in good to excellent yields.

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Acetonitrile Ions

The Triply Deprotonated Acetonitrile Anion CCN3− Stabilized in a Solid

Franziska Jach, Stephan Ingmar Brückner, Alexander Ovchinnikov, Dr. Anna Isaeva, Dr. Matej Bobnar, Dr. Matthias Friedrich Groh, Prof. Dr. Eike Brunner, Dr. Peter Höhn and Prof. Dr. Michael Ruck

The Triply Deprotonated Acetonitrile Anion CCN3− Stabilized in a Solid

Just C, C, and N: A one-pot synthesis from the elements gives the fully deprotonated acetonitrile anion CCN3− stabilized in the bulk host framework of the Ba5[TaN4][C2N] nitridometalate. The anion is isoelectronic to CO2, and, in contrast to acetonitrile (H3C−C≡N), the electron pairs are shifted towards two double bonds, that is, [C=C=N]3−.

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Catalysis in MOFs

Mapping-Out Catalytic Processes in a Metal–Organic Framework with Single-Crystal X-ray Crystallography

Dr. Alexandre Burgun, Dr. Campbell J. Coghlan, Dr. David M. Huang, Dr. Wenqian Chen, Dr. Satoshi Horike, Prof. Susumu Kitagawa, Dr. Jason F. Alvino, Prof. Gregory F. Metha, Prof. Christopher J. Sumby and Prof. Christian J. Doonan

Mapping-Out Catalytic Processes in a Metal–Organic Framework with Single-Crystal X-ray Crystallography

Crystallization not needed. A MnII-based MOF is used as a matrix to isolate and structurally elucidate the chemistry of a single-site rhodium(I) catalyst that carries out the carbonylation of methyl halides. X-ray crystal structures of catalytic intermediates were obtained and explain why carbonylation occurs with MeBr but not MeI.

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Supramolecular Chemistry

Strain-Promoted Thiol-Mediated Cellular Uptake of Giant Substrates: Liposomes and Polymersomes

Nicolas Chuard, Dr. Giulio Gasparini, Dr. Dimitri Moreau, Samuel Lörcher, Prof. Cornelia Palivan, Prof. Wolfgang Meier, Dr. Naomi Sakai and Prof. Stefan Matile

Strain-Promoted Thiol-Mediated Cellular Uptake of Giant Substrates: Liposomes and Polymersomes

Giant Substrates, High Tension: Realized with liposomes and polymersomes, strain-promoted thiol-mediated cellular uptake of giant substrates is characterized by increasing activity with disulfide ring tension, inactivity of cationic charges and maleimides, inhibition by Ellman's reagent, self-activation in microdomains, and self-inhibition by micelle formation.

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Proteomics

Enrichment of Specifically Labeled Proteins by an Immobilized Host Molecule

Dr. James Murray, Jaehwan Sim, Kyunghoon Oh, Gihyun Sung, Ara Lee, Dr. Annadka Shrinidhi, Dr. Ayyavu Thirunarayanan, Dr. Dinesh Shetty and Prof. Dr. Kimoon Kim

Enrichment of Specifically Labeled Proteins by an Immobilized Host Molecule

Supramolecular fishing with molecular bait: Intracellular proteins can be enriched using the synthetic host–guest pair cucurbit[7]uril and ammonium-adamantane. Specific proteins were labeled with an affinity-based probe that transfers an ammonium-adamantane group to the protein so that it can be selectively enriched by a cucurbit[7]uril bead.

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Photovoltaic Materials

Design, Synthesis, and Photovoltaic Characterization of a Small Molecular Acceptor with an Ultra-Narrow Band Gap

Huifeng Yao, Yong Cui, Runnan Yu, Bowei Gao, Hao Zhang and Prof. Jianhui Hou

Design, Synthesis, and Photovoltaic Characterization of a Small Molecular Acceptor with an Ultra-Narrow Band Gap

Mind the gap: A non-fullerene electron acceptor with an ultra-narrow optical band gap of 1.24 eV was prepared. Despite a low energy loss of 0.509 eV, the organic solar cell (OSC) device demonstrated a high power conversion efficiency of 10.9 % with an impressive short-circuit current density of 25.3 mA cm−2.

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BN Compounds

Poly(p-phenylene iminoborane): A Boron–Nitrogen Analogue of Poly(p-phenylene vinylene)

Thomas Lorenz, Merian Crumbach, Dr. Thomas Eckert, Artur Lik and Dr. Holger Helten

Poly(p-phenylene iminoborane): A Boron–Nitrogen Analogue of Poly(p-phenylene vinylene)

Très BN: A BN analogue of the well-known semiconducting organic polymer poly(p-phenylene vinylene) (PPV) was synthesized through a facile Si/B exchange polycondensation. The novel inorganic–organic hybrid polymer and monodisperse oligomers of this type show some π-conjugation across the B=N units along the backbone and extension of the conjugation path with increasing chain length.

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Drug Delivery

Anaerobe-Inspired Anticancer Nanovesicles

Chenggen Qian, Peijian Feng, Jicheng Yu, Dr. Yulei Chen, Quanyin Hu, Wujin Sun, Xuanzhong Xiao, Dr. Xiuli Hu, Adriano Bellotti, Prof. Dr. Qun-Dong Shen and Prof. Dr. Zhen Gu

Anaerobe-Inspired Anticancer Nanovesicles

A biomimetic vesicle mimics the natural mode of tumor targeting and therapeutic drug delivery of anaerobic bacteria. The nanovesicle is stable in cells with normal physiological redox and oxygen balance; however, once disrupted by external light stimuli, it shows dual synergistic anticancer actions with enhanced therapeutic efficacy.

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Electrocatalysis

Efficient Hydrogen Evolution Electrocatalysis Using Cobalt Nanotubes Decorated with Titanium Dioxide Nanodots

Jin-Xian Feng, Han Xu, Yu-Tao Dong, Xue-Feng Lu, Ye-Xiang Tong and Prof. Gao-Ren Li

Efficient Hydrogen Evolution Electrocatalysis Using Cobalt Nanotubes Decorated with Titanium Dioxide Nanodots

Electrolysis of water: Carbon-fiber-supported nanotubes from TiO2 nanodot-decorated Co nanosheets were fabricated for the electrocatalytic hydrogen evolution reaction (HER). The electronic interaction between TiO2 and Co can effectively activate the absorbed water molecules and optimize the free energy of H adsorption. The catalysts show an excellent electrocatalytic performance for the HER.

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Borophene

The Role of Holes in Borophenes: An Ab Initio Study of Their Structure and Stability with and without Metal Templates

Naiwrit Karmodak and Prof. Eluvathingal D. Jemmis

The Role of Holes in Borophenes: An Ab Initio Study of Their Structure and Stability with and without Metal Templates

On a silver template: The dependence of the stability of two-dimensional boron sheets on the density of hexagonal holes is reversed on silver templates. This trend is less pronounced at higher temperatures.

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Fluorescence Enhancement

Turn-On Fluorescence in Tetra-NHC Ligands by Rigidification through Metal Complexation: An Alternative to Aggregation-Induced Emission

Dr. Narayan Sinha, Dr. Linda Stegemann, Tristan T. Y. Tan, Prof. Dr. Nikos L. Doltsinis, Priv.-Doz. Dr. Cristian A. Strassert and Prof. Dr. F. Ekkehardt Hahn

Turn-On Fluorescence in Tetra-NHC Ligands by Rigidification through Metal Complexation: An Alternative to Aggregation-Induced Emission

Stop rotating! Tetraphenylethylene (TPE) bridged tetrakis-NHC precursors display fluorescence turn-on in dilute solution upon formation of organometallic chelate complexes. The fluorescence enhancement can be attributed to the rigidification of the TPE moiety, caused by restriction of its intramolecular rotation. This ridigification method for the fluorescence turn-on constitutes an alternative approach to aggregation-induced emission.

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Biomass

Catalysis Meets Nonthermal Separation for the Production of (Alkyl)phenols and Hydrocarbons from Pyrolysis Oil

Dr. Zhengwen Cao, Jan Engelhardt, Michael Dierks, Dr. Matthew T. Clough, Dr. Guang-Hui Wang, Dr. Eleni Heracleous, Dr. Angelos Lappas, Dr. Roberto Rinaldi and Prof. Dr. Ferdi Schüth

Catalysis Meets Nonthermal Separation for the Production of (Alkyl)phenols and Hydrocarbons from Pyrolysis Oil

Out of the woods: Selective hydrodeoxygenation of lignocellulose-derived pyrolysis bio-oil, catalyzed by MoCx/C, affords value-added alkylphenol (and phenol) products and hydrocarbons. The strategy requires no prior fractionation of the lignocellulosic biomass, no further synthetic steps, and no input of additional petrochemical platform molecules.

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Organocatalysis

NHC-Organocatalyzed CAr−O Bond Cleavage: Mild Access to 2-Hydroxybenzophenones

Daniel Janssen-Müller, Santanu Singha, Fabian Lied, Karin Gottschalk and Prof. Dr. Frank Glorius

NHC-Organocatalyzed CAr−O Bond Cleavage: Mild Access to 2-Hydroxybenzophenones

Catalysis with Smiles: A Truce–Smiles rearrangement of acyl-anion equivalents generated by N-heterocyclic carbene (NHC) catalysis has been achieved. The developed method includes CAr−O, CAr−S, or CAr−N bond cleavage for the formation of a CAr−C bond and enables access to 2-hydroxybenzophenones, an important structural motif present in several bioactive natural products.

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Fluorescent Probes

Highly Multiplexed Single-Cell In Situ Protein Analysis with Cleavable Fluorescent Antibodies

Manas Mondal, Renjie Liao, Lu Xiao, Taylor Eno and Dr. Jia Guo

Highly Multiplexed Single-Cell In Situ Protein Analysis with Cleavable Fluorescent Antibodies

Reiterative staining: Protein targets were stained with antibodies that had been tethered to fluorophores via a chemically cleavable linker. Through continuous cycles of target staining, fluorescence imaging, and fluorophore cleavage, a large number of different protein targets could be detected in individual cells in situ.

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Heterogeneous Catalysis

Electrocatalytic Synthesis of Ammonia at Room Temperature and Atmospheric Pressure from Water and Nitrogen on a Carbon-Nanotube-Based Electrocatalyst

Shiming Chen, Prof. Siglinda Perathoner, Prof. Claudio Ampelli, Chalachew Mebrahtu, Prof. Dangsheng Su and Prof. Gabriele Centi

Electrocatalytic Synthesis of Ammonia at Room Temperature and Atmospheric Pressure from Water and Nitrogen on a Carbon-Nanotube-Based Electrocatalyst

Sustainable industrial chemistry: Ammonia is synthesized directly from water and N2 at room temperature and atmospheric pressure in an electrochemical flow cell operating in the gas phase (half-cell for NH3 synthesis). Iron supported on carbon nanotubes was used as the electrocatalyst in this half-cell.

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Intermetalloid Clusters

Retention of the Zn−Zn bond in [Ge9Zn−ZnGe9]6− and Formation of [(Ge9Zn)−(Ge9)−(ZnGe9)]8− and Polymeric 1∞ [−(Ge9Zn)2−−]1

Kerstin Mayer, Laura-Alice Jantke, Prof. Dr. Stephan Schulz and Prof. Dr. Thomas F. Fässler

Retention of the Zn−Zn bond in [Ge9Zn−ZnGe9]6− and Formation of [(Ge9Zn)−(Ge9)−(ZnGe9)]8− and Polymeric 1∞ [−(Ge9Zn)2−−]1

Zn atoms serve for both: Covalent coupling of two clusters through zinc vertex atoms or Lewis acid/base interactions lead to novel intermetalloid clusters with zinc.

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C−H Activation

General Enantioselective C−H Activation with Efficiently Tunable Cyclopentadienyl Ligands

Zhi-Jun Jia, Dr. Christian Merten, Dr. Rajesh Gontla, Dr. Constantin G. Daniliuc, Dr. Andrey P. Antonchick and Prof. Dr. Herbert Waldmann

General Enantioselective C−H Activation with Efficiently Tunable Cyclopentadienyl Ligands

The discovery of chiral Cp ligands that unite the advantages of previously developed ligand classes is enabled by a novel approach. They can be readily synthesized on gram scale, and both their structures and configurations can be efficiently adjusted by means of flexible enantioselective [6+3] cycloaddition reactions. With these ligands, three rhodium(III)-catalyzed C−H activation reactions were rendered highly enantioselective.

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Biocatalytic Photosynthesis

Photoelectrochemical Reduction of Carbon Dioxide to Methanol through a Highly Efficient Enzyme Cascade

Su Keun Kuk, Dr. Raushan K Singh, Dr. Dong Heon Nam, Ranjitha Singh, Prof. Dr. Jung-Kul Lee and Prof. Dr. Chan Beum Park

Photoelectrochemical Reduction of Carbon Dioxide to Methanol through a Highly Efficient Enzyme Cascade

In synergy: A tandem photoelectrochemical (PEC) cell with an integrated enzyme cascade has been developed to transfer photogenerated electrons to a multienzyme cascade for the biocatalyzed reduction of CO2 to methanol in high yield. The approach makes use of water as an electron donor, a hematite photoanode and a bismuth ferrite photocathode for the regeneration of NADH with visible light, as well as a three-dehydrogenase cascade system.

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Copper Catalysis

Enantioselective Copper-Catalyzed Intermolecular Amino- and Azidocyanation of Alkenes in a Radical Process

Dinghai Wang, Fei Wang, Dr. Pinghong Chen, Prof. Dr. Zhenyang Lin and Prof. Dr. Guosheng Liu

Enantioselective Copper-Catalyzed Intermolecular Amino- and Azidocyanation of Alkenes in a Radical Process

A radical process is involved in the asymmetric copper-catalyzed intermolecular amino- and azidocyanation of alkenes developed herein. A variety of enantiomerically enriched β-amino/azido alkylnitriles were efficiently synthesized. The azidocyanation products were further converted into a series of optically active building blocks and bioactive compounds.

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Charge Transfer

Accessing the Intrinsic Nature of Electronic Transitions from Gas-Phase Spectroscopy of Molecular Ion/Zwitterion Complexes

Dr. Mark H. Stockett, Mikkel Boesen, Jørgen Houmøller and Prof. Steen Brøndsted Nielsen

Accessing the Intrinsic Nature of Electronic Transitions from Gas-Phase Spectroscopy of Molecular Ion/Zwitterion Complexes

Pulling back the curtain on charge transfer: The electronic absorption by molecular ions is often affected by a microenvironment, especially if the transitions have charge-transfer (CT) character. An excellent indicator of CT is a large change in absorption caused by a single betaine molecule attached to the bare ion. Such shifts are evidenced from gas-phase ion spectroscopy of mass-selected complexes readily made by electrospray ionization.

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Nanoparticle Assembly

Real-Time Monitoring of Nanoparticle Formation by FRET Imaging

Dr. Brenda L. Sanchez-Gaytan, Dr. François Fay, Dr. Sjoerd Hak, Amr Alaarg, Prof. Zahi A. Fayad, Dr. Carlos Pérez-Medina, Prof. Willem J. M. Mulder and Dr. Yiming Zhao

Real-Time Monitoring of Nanoparticle Formation by FRET Imaging

Watching them form: A new technology is described that combines microfluidic-based nanoparticle synthesis and Förster resonance energy transfer (FRET) microscopy imaging to visualize nanoparticle self-assembly in real time. The FRET pair dyes DiO and DiI are incorporated during mixing and nanoparticle assembly to provide a spatial and temporal read-out.

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Peptide Folding

Peptide N-Amination Supports β-Sheet Conformations

Matthew P. Sarnowski, Dr. Chang Won Kang, Yassin M. Elbatrawi, Dr. Lukasz Wojtas and Prof. Dr. Juan R. Del Valle

Peptide N-Amination Supports β-Sheet Conformations

Growing a backbone: The conformational heterogeneity of Nα-substituted peptides limits their ability to adopt stable secondary structures. Here, a practical synthesis of backbone aminated peptides that readily adopt β-sheet folds is described. Data derived from model N-amino peptides suggest that extended conformations are stabilized through steric, electrostatic, and hydrogen-bonding interactions.

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Drug Delivery

Micromotors Spontaneously Neutralize Gastric Acid for pH-Responsive Payload Release

Jinxing Li, Pavimol Angsantikul, Dr. Wenjuan Liu, Dr. Berta Esteban-Fernández de Ávila, Dr. Soracha Thamphiwatana, Prof. Mingli Xu, Elodie Sandraz, Dr. Xiaolei Wang, Dr. Jorge Delezuk, Dr. Weiwei Gao, Prof. Liangfang Zhang and Prof. Joseph Wang

Micromotors Spontaneously Neutralize Gastric Acid for pH-Responsive Payload Release

Magnesium-based micromotors can autonomously and temporally neutralize gastric acid through efficient chemical propulsion in the gastric fluid by rapidly depleting the localized protons. The in vivo results demonstrate that these motors can safely and quickly neutralize gastric acid and simultaneously release a payload without causing noticeable acute toxicity or affecting the stomach function, and the normal stomach pH is restored within 24 hours post motor administration.

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Helical Structures

Plasmonic Chirality Imprinting on Nucleobase-Displaying Supramolecular Nanohelices by Metal–Nucleobase Recognition

Dr. Yiyang Lin, Dr. E. Thomas Pashuck, Dr. Michael R. Thomas, Dr. Nadav Amdursky, Shih-Ting Wang, Dr. Lesley W. Chow and Prof. Molly M. Stevens

Plasmonic Chirality Imprinting on Nucleobase-Displaying Supramolecular Nanohelices by Metal–Nucleobase Recognition

Amyloid fibrils were constructed through the self-assembly of nucleobase–peptide conjugates that were designed to repeatedly organize achiral nucleobases into helical patterns on the surface. The fibrils were utilized for the in situ nucleation and assembly of metallic nanoparticles through metal–nucleobase recognition.

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Organocatalysis

Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers

Jae Hun Sim and Prof. Choong Eui Song

Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers

Hydrophobic hydration: Under aqueous reaction conditions, extremely unreactive β,β-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of the highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers.

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Biosynthesis

Biosynthesis of the Carbonylmethylene Structure Found in the Ketomemicin Class of Pseudotripeptides

Junpei Kawata, Taiki Naoe, Dr. Yasushi Ogasawara and Prof.Dr. Tohru Dairi

Biosynthesis of the Carbonylmethylene Structure Found in the Ketomemicin Class of Pseudotripeptides

Off the beaten path: The biosynthetic pathway of the carbonylmethylene-containing pseudopeptide in ketomemicins was fully elucidated in vitro. The pathway involves two unique C−C bond formations. KtmA catalyzes an aldol reaction concomitant with decarboxylation starting from malonyl-CoA and phenylpyruvate, and a Claisen-type condensation is catalyzed by the PLP-dependent amino acid C-acyltransferase homologue KtmB.

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Self-Sorting

Social Self-Sorting of Colloidal Families in Co-Assembling Microgel Systems

Kang Han, Dennis Go, Thomas Tigges, Khosrow Rahimi, Alexander J. C. Kuehne and Prof. Dr. Andreas Walther

Social Self-Sorting of Colloidal Families in Co-Assembling Microgel Systems

Finding their partners: In multicomponent systems, colloids bearing molecular recognition units can self-sort in a social manner into their respective families. Additionally, the self-assemblies and their interactions are switchable using orthogonal triggers, such as light and redox chemistry.

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Medicinal Chemistry

In Vivo Dearomatization of the Potent Antituberculosis Agent BTZ043 via Meisenheimer Complex Formation

Dr. Florian Kloss, Prof. Dr. Viktor Krchnak, Anna Krchnakova, Dr. Sebastian Schieferdecker, Dr. Julia Dreisbach, Dr. Volker Krone, Dr. Ute Möllmann, Prof. Dr. Michael Hoelscher and Prof. Dr. Marvin J. Miller

In Vivo Dearomatization of the Potent Antituberculosis Agent BTZ043 via Meisenheimer Complex Formation

Transient metabolite: The nitrobenzothiazinone BTZ043 is extensively reduced in vivo to form a transient hydride Meisenheimer complex, which is readily re-oxidized under atmospheric conditions. Separate chemical generation and stabilization methods enabled the full characterization of this highly unusual metabolite, which provides new opportunities for rational lead optimization of highly active benzothiazinones.

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Heterogeneous Catalysis

Palladium-Catalyzed Hydrolytic Cleavage of Aromatic C−O Bonds

Meng Wang, Dr. Hui Shi, Dr. Donald M. Camaioni and Prof. Dr. Johannes A. Lercher

Palladium-Catalyzed Hydrolytic Cleavage of Aromatic C−O Bonds

Selective hydrolysis: Palladium catalyzes the reductive hydrolytic cleavage of aromatic ether C−O bonds with high selectivities by a hitherto unconsidered mechanism involving partial hydrogenation of the phenyl group to an enol ether. Rapid water addition provides the corresponding hemiacetal, which then undergoes elimination to cyclohexanone and phenol/alkanol products.

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Peptide Cyclization

Diversity-Oriented Synthesis of Cyclic Azapeptides by A3-Macrocyclization Provides High-Affinity CD36-Modulating Peptidomimetics

Jinqiang Zhang, Mukandila Mulumba, Dr. Huy Ong and Prof. William D. Lubell

Diversity-Oriented Synthesis of Cyclic Azapeptides by A3-Macrocyclization Provides High-Affinity CD36-Modulating Peptidomimetics

Building bridges: A solid-phase peptide cyclization method was developed and used to synthesize fifteen cyclic aza-GHRP-6 analogs with ring sizes from 16 to 25 atoms. The cyclic azapeptides exhibit unprecedented affinity for the CD36 receptor, and suppress Toll-like receptor agonist-induced signalling in macrophages.

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Electrochemical Graphitization

Electrochemically Driven Transformation of Amorphous Carbons to Crystalline Graphite Nanoflakes: A Facile and Mild Graphitization Method

Dr. Junjun Peng, Nanqing Chen, Rui He, Dr. Zhiyong Wang, Prof. Sheng Dai and Prof. Xianbo Jin

Electrochemically Driven Transformation of Amorphous Carbons to Crystalline Graphite Nanoflakes: A Facile and Mild Graphitization Method

Graphitize me: The graphitization of various kinds of amorphous carbons can be realized through a cathodic polarization in molten calcium chloride at about 1100 K, generating porous graphite composed of petal-like nanoflakes. This nanostructured graphite allows fast and reversible intercalation/deintercalation of anions. In a Pyr14TFSI ionic liquid, promising a superior cathode material for batteries.

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