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Angewandte Chemie

Chao Luo, Xiao Ji, Ji Chen, Karen Gaskell, Xinzi He, Yujia Liang, Jianjun Jiang, Chunsheng Wang
Organic electrode materials are promising for green and sustainable lithium ion batteries. However, the high solubility of organic materials in the liquid electrolyte results in the shuttle reaction and fast capacity decay. Herein, azo compounds are firstly applied in all solid-state lithium batteries (ASSLB) to suppress the dissolution challenge. Due to the high compatibility of azobenzene (AB) based compounds to Li3PS4 (LPS) solid electrolyte, the LPS solid electrolyte is used to prevent the dissolution and shuttle reaction of AB...
May 23, 2018: Angewandte Chemie
Ki-Young Yoon, Guangbin Dong
Herein, we report the palladium/norbornene cooperatively catalyzed polymerization, which simplifies synthesis of functional aromatic polymers, including conjugated polymers. Specifically, an A2B2C-type multicomponent polymerization is developed using ortho-amination/ipso-alkynylation reaction for preparing various amine-functionalized arylacetylene-containing polymers. Within a single catalytic cycle, the amine side-chains are site-selectively installed in situ via C-H activation during the polymerization process, which represents a major difference from conventional cross-coupling polymerizations...
May 23, 2018: Angewandte Chemie
Matthew Bennett, Mark Thompson, Sarah Shepherd, Mark Dunstan, Abigail Herbert, Duncan Smith, Victoria Cronin, Binuraj Menon, Colin Levy, Jason Micklefield
Benzylisoquinoline alkaloids (BIAs) are a structurally diverse family of plant secondary metabolites which have been exploited to develop analgesics, antibiotics, antitumor agents and other therapeutic agents. Biosynthesis of BIAs proceeds via a common pathway from tyrosine to (S)-reticulene at which point the pathway diverges. Coclaurine N-methyltransferase (CNMT) is a key enzyme in the pathway to (S)-reticulene, installing the N-methyl substituent that is essential for the bioactivity of many BIAs. In this paper, we describe the first crystal structure of CNMT which, along with mutagenesis studies, defines the enzymes active site architecture...
May 23, 2018: Angewandte Chemie
Antonio M Echavarren, Rafal Zuzak, Ruth Dorel, Marek Kolmer, Marek Szymonski, Szymon Godlewski
A unified approach to the synthesis of the series of higher acenes up to previously unreported undecacene has been developed through the on-surface dehydrogenation of partially saturated precursors. These molecules could be converted into the parent acenes by atomic manipulation with the tip of a scanning tunneling and atomic force microscope (STM/AFM) as well as by on-surface annealing. The structure of the generated acenes has been visualized by high resolution non-contact AFM imaging and the evolution of the transport gap with the increase of the number of fused benzene rings has been determined on the basis of scanning tunneling spectroscopy (STS) measurements...
May 23, 2018: Angewandte Chemie
Andreas Speicher, Daniel Meidlinger, Lisa Marx, Catalina Bordeianu, Sabine Choppin, Françoise Colobert
The macrocyclization uses to be the key step in the syntheses of cyclophane type natural products. Considering cyclophanes with axially chiral biaryl moieties, the control of atroposelectivity is - referring to synthesis and biological activities - essential and challenging. We report on an atroposelective approach involving Heck cyclization, allowing for the first time the total synthesis of an enantiopure macrocyclic bis(bibenzyl), namely isoplagiochin D. An enantiopure sulfinyl auxiliary in ortho-position of a biaryl axis (still flexible) was used to induce an atropo-diastereoselective Heck coupling (up to 98 % de)...
May 23, 2018: Angewandte Chemie
Mario Wiesenfeldt, Tobias Knecht, Christoph Schlepphorst, Frank Glorius
Any[Si]ng but flat! We report a method to convert readily available silylated arenes into silylated saturated carbo- and heterocycles by arene hydrogenation. The scope includes alkoxy and halosilyl substituents. Silyl groups can be derivatized into a plethora of functionalities and find application in organic synthesis, materials science, pharmaceutical, agrochemical, and fragrance research. Yet, silylated saturated (hetero- ) cycles are difficult to access with current technologies. The yield of the hydrogenation depends on the amount of the silica gel additive...
May 23, 2018: Angewandte Chemie
Anna Sib, Tobias Alexander Marius Gulder
The sorbicillinoids are a large family of fungal natural products, many of which possessing highly challenging molecular architectures. Depending on their individual structures they exhibit strong biological activities ranging from radical scavenging and anti-infective properties to cytotoxicity. Despite the resulting strong biomedical potential of these natural products and the interest of the total synthetic community owing to their fascinating structures, many sorbicillinoids are currently not synthetically accessible, thus hampering in depth biological characterization and structural diversification...
May 23, 2018: Angewandte Chemie
Bartosz Marzec, David Green, Mark Holden, Alexander Cote, Johannes Ihli, Alexander Kulak, Daniel Walker, Saba Khalid, Chiu Tang, Dorothy Duffy, Yi-Yeoun Kim, Fiona Meldrum
Biomineralisation processes invariably occur in the presence of multiple organic additives, which act in combination to give exceptional control over structures and properties. However, few synthetic studies have investigated the cooperative effectives of soluble additives. This work addresses this challenge and focuses on the combined effects of amino acids and coloured dye molecules. The experiments demonstrate that strongly coloured calcite crystals only form in the presence of Brilliant Blue R (BBR) and four of the seventeen soluble amino acids, as compared with almost colourless crystals using the dye alone...
May 23, 2018: Angewandte Chemie
Nicholas Stephanopoulos, Minghui Liu, Shuoxing Jiang, Omar Loza, Petr Šulc, Nour Eddine Fahmi
We describe a reconfigurable DNA nano-tweezer that can be switched between a close and open state with a brief pulse of UV light. In its initial state, the tweezer is held shut using a hairpin with a single-stranded poly-A loop. Also incorporated in the structure is a poly-T trigger strand bearing seven photocaged residues. Upon illumination with 365 nm light, the cages are removed and the trigger strand hybridizes to the loop, opening the tweezer and increasing the distance between its arms from 4 to 18 nm...
May 23, 2018: Angewandte Chemie
Shigeyoshi Inoue, Prasenjit Bag, Catherine Weetman
Synthesis and isolation of stable main group compounds featuring multiple bonds has been of keen interest for the last several decades. Multiply bonded complexes were obtained using sterically demanding substituents that provide kinetic and thermodynamic stability. Many of these compounds have unusual structural and electronic properties that challenges the classical concept of covalent multiple bonding. In contrast, analogous aluminium compounds are scarce in spite of its high natural abundance. The parent dialumene (Al2H2) has been calculated to be extremely weak, thus making Al multiple bonds a challenging synthetic target...
May 23, 2018: Angewandte Chemie
Shigekazu Ito, Yasuhiro Ueta, Kota Koshino, Kenji M Kojima, Iain McKenzie, Koichi Mikami
A 1,3-diphosphacyclobutane-2,4-diyl contains a unique unsaturated cyclic unit, and the presence of radical-type centres have been expected as a source of functionalities. This study demonstrates that the P-heterocyclic singlet biradical captures muonium (Mu = [µ+e-]) of the light isotope of hydrogen radical to generate an observable P-heterocyclic paramagnetic species. Investigation of a powder sample of 2,4-bis(2,4,6-tri-t-butylphenyl)-1-t-butyl-3-benzyl-1,3-diphosphacyclobutane-2,4-diyl by muon avoided level-crossing resonance (µLCR) spectroscopy revealed that muonium adds to the cyclic P2C2 unit...
May 22, 2018: Angewandte Chemie
Pengju Yang, Ruirui Wang, Min Zhou, Xinchen Wang
Metal-free carbonitride(CN) semiconductors are appealing light-transducers for photocatalytic redox reactions due to the unique bandgap and chemical/thermal stability. To harness solar energy efficiently, CN catalysts that are active over a wider range of the visible spectrum are highly desired. Herein, we report a photochemical approach to prepare a new-type triazine-based CN superstructure. The obtained CN shows extraordinary light-harvesting characteristics, with suitable semiconductor-redox potentials. The light absorption edge of the CN reaches up to 735 nm, which is significantly longer than that of the conventional CN semiconductor at ~460 nm...
May 22, 2018: Angewandte Chemie
Xinhua Wan, Xichong Ye, Jiaxi Cui, Bowen Li, Na Li, Jie Zhang
Collection of two optically pure enantiomers in a single crystallization process can significantly increase the chiral separation efficiency but it's hard to realize nowadays. Herein we describe, for the first time, a self-reporting strategy for visualizing the crystallization process by a kind of dyed self-assembled inhibitors made from the copolymers with tri(ethylene glycol)-grafting polymethylsiloxane as main chains and poly(N6-methacryloyl-L-lysine) as side chains. When applied with seeds together for the fractional crystallization of conglomerates, the inhibitors can label the formation of the secondary crystals and guide us to completely separate the crystallization process of two enantiomers with colorless crystals as the first product and red crystals as the secondary product...
May 22, 2018: Angewandte Chemie
Verònica Postils, Carlos Delgado-Alonso, Josep M Luis, Pedro Salvador
The IUPAC has recently clarified the term Oxidation State (OS), and provided algorithms for its determination based on the ionic approximation (IA) of the bonds supported by atomic electronegativities (EN). Unfortunately, there are a number of exceptions and ambiguities in IUPAC's algorithms when it comes to practical applications. Our comprehensive study reveals the critical role of the chemical environment on establishing the OS, which cannot always be properly predicted using fix atomic EN values. By identifying what we define here as subsystems of enhanced stability within the molecular system, OS can be safely assigned in many cases without invoking exceptions...
May 22, 2018: Angewandte Chemie
Honggen Peng, Cheng Rao, Ning Zhang, Xiang Wang, Wenming Liu, Wenting Mao, Lu Han, Pengfei Zhang, Sheng Dai
Pd-CeOx solid solutions have demonstrated promising performance in industrial and environmental catalysis. However, challenges such as severe growth and aggregation of Pd and thermal-, vapor- or SO2-induced poisoning still obstruct their path toward real-world applica-tions. Herein we develop an efficient strategy (enhanced metal-oxide interaction and core-shell confinement to inhibit the sintering of noble metal) for design and synthesis of confined ultrathin Pd-CeOx nan-owire (2.4 nm) catalysts for methane combustion, which enable CH4 total oxidation at a low temperature of 350C, much lower than that (425C) of a commercial Pd/Al2O3 catalyst...
May 22, 2018: Angewandte Chemie
Martin R L Paine, Berwyck L J Poad, Gert B Eijkel, David L Marshall, Stephen J Blanksby, Ron M A Heeren, Shane R Ellis
Mass spectrometry imaging (MSI) enables the spatial distributions of molecules possessing different mass-to-charge ratios to be mapped within complex environments revealing regional changes at the molecular level. Even at high mass resolving power however, these images often reflect the summed distribution of multiple isomeric molecules, each potentially possessing a unique distribution coinciding with distinct biological function(s) and metabolic origin. Here, this chemical ambiguity is addressed through an innovative combination of ozone-induced dissociation reactions with MSI, enabling the differential imaging of isomeric lipid molecules directly from biological tissues...
May 22, 2018: Angewandte Chemie
Poonam Gupta, Durga Prasad Karothu, Ejaz Ahmed, Pance Naumov, Naba Kamal Nath
The first example of a smart crystalline material, the 2:1 cocrystal of probenecid and 4,4'-azopyridine, which responds reversibly to multiple external stimuli (heat, UV light, and mechanical pressure) by twisting, bending and elastic deformation without fracture is reported. This material is also able to self-heal on heating and cooling, thereby overcoming the main setbacks of molecular crystals for future applications as crystal actuators. The photo- and thermomechanical effects and self-healing capabilities of the material are rooted in reversible trans-cis isomerization of the azopyridine unit and crystal-to-crystal phase transition...
May 22, 2018: Angewandte Chemie
Neng Xiao, Gerald Gourdin, Yiying Wu
In the superoxide batteries based on O2/O2- redox chemistry, identifying an electrolyte to stabilize both alkali metal and superoxide remains challenging due to their reactivity towards electrolyte components. Bis(fluorosulfonyl)imide (FSI-) has been recognized as a "magical anion" for passivating alkali metals. Herein, we illustrate the chemical reactions between FSI- and superoxide, and the resultant dilemma when considering an anode-compatible electrolyte vs. a cathode-compatible one in K-O2 batteries...
May 22, 2018: Angewandte Chemie
Alexander Lipp, Dorota Ferenc, Christoph Gütz, Mario Geffe, Nina Vierengel, Dieter Schollmeyer, Hans Jürgen Schäfer, Siegfried R Waldvogel, Till Opatz
The biosynthesis of thebaine is based on the regioselective, intramolecular, oxidative coupling of (R)-reticuline. For decades, chemists have sought to mimic this coupling using stoichiometric oxidants. However, all approaches suffered from low yields or the formation of undesired regioisomers. Electrochemistry would represent a sustainable alternative in this respect but all attempts to accomplish an electrochemical synthesis of thebaine have failed so far. Herein, a regioselective and diastereoselective anodic coupling of 3',4',5'-trioxygenated laudanosine derivatives is presented, which finally enabled an electrochemical access to (-)-thebaine...
May 22, 2018: Angewandte Chemie
Ksenia S Egorova, Philip V Toukach
Glycoinformatics is a young scientific branch, which assists the scientific community in carbohydrate research. In spite of fundamental roles of glycans in living organisms, the informatization of the field is significantly hindered by the lack of standards, data indices, protocols and tools widely recognized by researchers and publishers. The connection of the existing glycoinformatics projects with each other and with global life-science projects is far from complete. Moreover, in contrast to genes and proteins, there is no obligatory unique identifier for each natural carbohydrate structure...
May 22, 2018: Angewandte Chemie
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