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Angewandte Chemie

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https://www.readbyqxmd.com/read/30242949/molecular-engineering-of-carbon-nanotubes-with-cobalt-corroles-for-hydrogen-and-oxygen-evolution-in-ph-0-14-solutions
#1
Xialiang Li, Haitao Lei, Jieyu Liu, Xueli Zhao, Shuping Ding, Zongyao Zhang, Xixi Tao, Wei Zhang, Weichao Wang, Xiaohong Zheng, Rui Cao
Water splitting is promising to realize a hydrogen-based society. The practical use of molecular water splitting catalysts relies on their integration onto electrode materials. We describe here the immobilization of Co corroles on carbon nanotubes (CNTs) by four strategies and compare the performance of the resulted hybrids for H2 and O2 evolution. Co corroles can be covalently attached to CNTs with short conjugated linkers (the hybrid is denoted as H1) or with long alkane chains (H2), or can be grafted to CNTs via strong π-π interactions (H3) or via simple adsorption (H4)...
September 22, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30240522/a-metal-organic-framework-with-suitable-pore-size-and-specific-functional-site-for-record-removal-of-trace-propyne-from-propylene
#2
Banglin Chen, Libo Li, Huimin Wen, Chaohui He, Ruibiao Lin, Rajamani Krishna, Hui Wu, Wei Zhou, Jinping Li, Bin Li
Separation of propylene/propyne (C3H4/C3H6) is more difficult and challenging than that of acetylene/ethylene (C2H2/C2H4) because of their closer molecular sizes and has not been well explored. Herein, we carry out a comprehensive screening of a series of metal-organic frameworks with broad types of structures, pore sizes and functionalities, and identify UTSA-200 as the best separating material for the deep removal of trace C3H4 from C3H4/C3H6 mixtures. Gas sorption isotherms reveal that UTSA-200 exhibits by far the highest reported C3H4 adsorption capacity (95 cm3 cm-3 under 0...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30240496/design-of-a-multicompartment-hydrogel-that-facilitates-time-resolved-delivery-of-combination-therapy-and-synergized-killing-of-glioblastoma
#3
Poulami Majumder, Ulrich Baxa, Scott Tr Walsh, Joel P Schneider
There is significant current interest in identifying new combination therapies that synergize to treat disease, and it is becoming increasingly clear that the temporal resolution of their administration greatly impacts efficacy.To facilitate effective delivery, we developed a multicompartment hydrogel material composed of spherical vesicles interlaced within a self-assembled peptide-based network of physically crosslinked fibrils that allows time-resolved independent co-delivery of small molecules. Herein, we demonstrate that this material architecture effectively delivers the EGFR kinase inhibitor erlotinib (ERL) and doxorubicin (DOX, DNA intercalator) in an ERL_DOX sequential manner to synergistically kill glioblastoma, the most aggressive form of brain cancer...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30240115/modulating-self-assembly-of-dna-crystals-with-rationally-designed-agents
#4
Jiemin Zhao, Yue Zhao, Zhe Li, Yong Wang, Ruojie Sha, Nadrian Seeman, Chengde Mao
This manuscript reports a strategy for controlling the crystallization kinetics and improving the quality of engineered self-assembled 3D DNA crystals. Growing large, high-quality, biomacromolecule crystals is critically important for determining the 3D structures of biomacromolecules. It often presents a great challenge to structural biologists. Herein, we introduce a rationally designed agent to modulate the crystallization process. Under such conditions, fewer, but larger crystals with modestly higher resolutions are produced compared with the crystals from conditions without the modulating agent...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30240107/intercalation-enhanced-click-crosslinking-of-dna
#5
Masayuki Tera, Zahra Harati-Taji, Nathan William Luedtke
DNA-DNA cross-linking agents constitute an important family of chemotherapeutics that non-specifically react with endogenous nucleophiles and therefore exhibit undesirable side effects. Here we report a cationic Sondheimer diyne derivative "DiMOC" that exhibits weak, reversible intercalation into duplex DNA (Kd = 15 μM) where it undergoes tandem strain-promoted cross-linking of azide-containing DNA to give DNA-DNA interstrand crosslinks (ICLs) with an exceptionally high apparent rate constant = 2...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239084/aerobic-solid-state-red-phosphorescence-from-benzobismole-monomers-and-patternable-self-assembled-block-copolymers
#6
Sarah Parke, Emanuel Hupf, Gunwant Matharu, Inara de Aguiar, Letian Xu, Haoyang Yu, Michael Boone, Gabriel de Souza, Robert McDonald, Michael Ferguson, Gang He, Alex Brown, Eric Rivard
The synthesis of the first bismuth-containing macromolecules that exhibit phosphorescence in the solid state and in the presence of oxygen is reported. These red emissive high molecular weight polymers (> 300 kDa) feature benzobismoles appended to a hydrocarbon scaffold, and were built via an efficient ring-opening metathesis (ROMP) protocol. Moreover, our general procedure readily allows for the formation of cross-linked networks and block copolymers. Attaining stable red phosphorescence with non-toxic elements remains a challenge and thus our new class of soluble (processable) polymeric phosphor is of great interest...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239082/mechanically-responsive-crystalline-coordination-polymers-with-controllable-elasticity
#7
Marijana Dakovic, Mladen Borovina, Mateja Pisačić, Christer B Aakeröy, Željka Soldin, Boris-Marko Kukovec, Ivan Kodrin
Crystalline coordination polymers tend to be brittle and inelastic, however, we now describe a family of such compounds that are capable of displaying mechanical elasticity in response to external pressure. The design protocol successfully targets structural features that are critical for producing the desired mechanical output. The elastic crystals all comprise 1-D cadmium(II) halide polymeric chains with adjacent metal-centres bridged by two halide ions resulting in the required stacking interactions and short '4 Å' crystallographic axes...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239081/biomimetic-synthesis-of-aspergillin-pz
#8
Julius Reyes, Nils Winter, Lukas Spessert, Dirk Trauner
The cytochalasans are a large family of polyketide natural products with fascinating structures and potent bioactivities. To gain insight into their structural diversity and innate reactivity, we have developed a rapid synthesis of aspochalasin D, the central member of the family. It proceeds in 12 steps starting from divinyl carbinol and utilized a high pressure Diels-Alder reaction that proceeds with high regio- and stereoselectivity. So far, our work has cumulated in a biomimetic synthesis of aspergillin PZ, an intricate pentacyclic aspochalasan...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239080/a-charge-separated-state-that-lives-for-almost-a-second-at-a-conductive-metal-oxide-interface
#9
Renato N Sampaio, Ludovic Troian-Gautier, Gerald Meyer
Transparent conductive oxides (TCOs) are widely used, commercially available materials for opto-electronic applications yet have received very little attention for dye-sensitization applications. Here we report that mesoporous thin films of conductive indium-doped tin oxide (ITO) nanocrystallites support long-lived charge separation with first-order recombination kinetics (k = 1.5 s-1). A layer-by-layer technique was utilized to spatially arrange redox and/or chromophoric molecular components on ITO. Spectro-electrochemical measurements demonstrated that upon light absorption, each component provided a free energy gradient to direct electron transfer at the conductive oxide interface...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239079/cyclodextrin-based-3-rotaxane-crosslinked-fluorescent-polymer-synthesis-and-de-crosslinking-using-size-complementarity
#10
Yosuke Akae, Hiromitsu Sogawa, Toshikazu Takata
Vinyl group-substituted α-cyclodextrin (CD) based size-complementary [3]rotaxanes were synthesized as crosslinkers for rotaxane-crosslinked poly(methyl methacrylate) (RCP) via radical polymerization. The size-complementarity of the crosslinkers made it possible to de-crosslink RCP by heating, and the degree of decoupling could be monitored by fluorescence intensity depending on the state of the axle component of the rotaxane crosslink moiety.
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239078/stable-face-to-face-singlet-diradicaloids-doubly-%C3%A2%C2%B5-hydroxo-bridged-triply-linked-corrole-dimer-ga-iii-complexes
#11
Takayuki Tanaka, Shota Ooi, Daiki Shimizu, Ko Furukawa, Atsuhiro Osuka
In the known singlet diradicaloid molecules, two inherent radicals are interacted antiferromagnetically as a result of delicate energetic balances between closed-shell and open-shell states. Herein we report that the gallium(III) metalations of triply-linked corrole dimers provide doubly µ-hydroxo-bridged "face-to-face" dimers that display curved π-planes nearing each other at ca. 3.24 Å. On the basis of ESR and SQUID measurements and theoretical calculations, the dimers have been assigned as singlet diradicaloids that consist of two delocalized mono-radicals on the triply-linked corrole dimer planes...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30239076/observation-of-carbodicarbene-ligand-redox-noninnocence-in-highly-oxidized-iron-complexes
#12
Siu-Chung Chan, Puneet Gupta, Xenia Engelmann, Zhi Zhong Ang, Rakesh Ganguly, Eckhard Bill, Kallol Ray, Shengfa Ye, Jason England
To probe the possibility that carbodicarbenes (CDCs) ligands are redox active ligands, we synthesized all four members of the redox series [Fe(1)2]n+ (n = 2 - 5), where 1 is a neutral tridentate CDC. Through a combination of spectroscopy and DFT calculations, we show that the electronic structure of the pentacation is [FeIII(1•+)2]5+ (S = ½). That of [Fe(1)2]4+ is more ambiguous, but it has significant contributions from the open-shell singlet [FeIII(1)(1•+)]4+ (S = 0). The observed spin states derive from antiferromagnetic coupling of their constituent low-spin iron(III) centres and cation radical ligands...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30238677/palladium-phosphide-as-stable-and-efficient-electrocatalyst-for-overall-water-splitting
#13
Fang Luo, Quan Zhang, Xinxin Yu, Shenglin Xiao, Ying Ling, Hao Hu, Long Guo, Zehui Yang, Liang Huang, Weiwei Cai, Hansong Cheng
Efficient bifunctional electrocatalyst toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly desirable to substitute platinum and iridium oxide for water splitting. Herein, we report a novel palladium phosphide electrocatalyst supported on carbon black (PdP2@CB) for efficient water splitting in both alkaline and neutral electrolytes. Significantly lower overpotentials are required for PdP2@CB (27.5 mV in 0.5 M H2SO4; 35.4 mV in 1 M KOH; 84.6 mV in 1 M PBS) to achieve the HER electrocatalytic current density of 10 mA cm-2 compared to commercial Pt/CB (30...
September 21, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30238608/origin-of-the-chemiresistive-response-of-ultrathin-films-of-conductive-metal-organic-frameworks
#14
Victor Rubio-Gimenez, Neyvis Almora-Barrios, Garin Escorcia-Ariza, Marta Galbiati, Michele Sessolo, Sergio Tatay, Carlos Martí-Gastaldo
Conductive Metal-Organic Frameworks are opening new perspectives for the use of these porous materials for applications traditionally limited to more classical inorganic materials, like their integration into electronic devices. This has enabled the development of chemiresistive sensors capable of transducing the presence of specific guests into an electrical response with good selectivity and sensitivity. By combining experimental data with computational modelling, we describe a possible origin for the underlying mechanism of this phenomenon in ultrathin films (~30 nm) of Cu-CAT-1...
September 20, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30238596/new-nmr-avenues-to-characterize-the-interactions-of-extended-n-glycans-with-proteins-the-influenza-hemagglutinin-case
#15
Jesus Jimenez-Barbero, Beatriz Fernandez de Toro, Wenjie Peng, Andrew J Thompson, Gema Domínguez, Francisco Javier Cañada, Javier Pérez-Castells, James C Paulson, Angeles Canales
Long chain multiantenna N-glycans are extremely complex molecules from the structural perspective. Their inherent flexibility and the presence of repetitions of monosaccharide units in similar chemical environments hamper their full characterization by X-ray diffraction or standard NMR methodologies. Therefore, the exploration of their interaction properties in solution, especially with regard to branch specificity and molecular recognition features, remains a challenge. Herein, we report the successful conformational and interaction analysis of a sialylated tetradecasaccharide N-glycan presenting two LacNAc repetitions at each arm...
September 20, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30238593/redox-active-reagents-for-photocatalytic-generation-of-the-ocf-3-radical-and-hetero-aryl-c-h-trifluoromethoxylation
#16
Weijia Zheng, Johnny W Lee, Cristian A Morales-Rivera, Peng Liu, Ming-Yu Ngai
The trifluoromethoxy (OCF3 ) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF3 radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported. More importantly, the reagent allows catalytic, intermolecular C-H trifluoromethoxylation of a broad array of (hetero)arenes and biorelevant compounds...
September 20, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30238575/facile-synthesis-of-a-stable-dihydroboryl-bh2
#17
Merle Arrowsmith, James Mattock, Stephan Hagspiel, Ivo Krummenacher, Alfredo Vargas, Holger Braunschweig
While the one-electron reduction of (CAACMe)BH2Br (CAACMe = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) yields a tautomer of the corresponding tetrahydrodiborane, further reduction leads to the first stable parent boryl anion, [(CAACMe)BH2]-, which acts as a powerful boron nucleophile.
September 20, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30232833/diastereo-and-enantioselective-propargylations-of-5h-thiazol-4-ones-and-5h-oxazol-4-ones-as-enabled-by-cu-zn-and-cu-ti-catalysis
#18
Zhengyan Fu, Ning Deng, Sheng-Nan Su, Hongyang Li, Ren-Zhe Li, Xia Zhang, Jie Liu, Dawen Niu
We have achieved the asymmetric propargylic substitution (APS) reaction with 5H-thiazol-4-ones by Cu/Zn dual metal catalytic system and the APS reaction with 5H-oxazol-4-ones by Cu/Ti catalysis. These reactions furnish functional group-rich, terminal alkyne-containing products with two vicinal stereocenters in high yields and with good to excellent diastereo- and enantioselectivities. This study implies the use of dual metal catalytic systems as a viable approach to improve the selectivity profiles of the Cu-catalyzed APS reactions...
September 19, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30232826/positive-effect-of-polar-styrenes-on-copolymerization-with-ethylene-and-mechanism
#19
Bo Liu, Kening Qiao, Jian Fang, Tiantian Wang, Zichuan Wang, Dongtao Liu, Zhigang Xie, Laurent Maron, Dongmei Cui
Copolymerization of ethylene (E) and polar vinyl monomers remains a problem due to the fact that E propagation retards. Herein, for the first time, we reported that the copolymerization of E with polar styrenes (SR) by using the oxophilic scandium catalyst exhibited higher TOFs than both E and SR homopolymerzations when R is an electron withdrawing group. This positive comonomer effect was elucidated through computing reaction profiles of E/SF copolymerization at the DFT (B3PW91) level. It reveals that the secondary interaction between Sc3+ and phenyl of the last and penultimate inserted SF units leads to the decrease of the E insertion energy...
September 19, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30231186/chemoproteomic-profiling-of-phosphoaspartate-modifications-in-prokaryotes
#20
Jae Won Chang, Gihoon Lee, Jeffrey E Montgomery, Raymond Moellering
Phosphorylation at aspartic acid residues represents an abundant and critical posttranslational modification (PTM) in prokaryotes. In contrast to most characterized PTMs, such as phosphorylation at serine or threonine, the phosphoaspartate moiety is intrinsically labile, and therefore incompatible with common proteomic profiling methods. Here we report a nucleophilic, desthiobiotin-containing hydroxylamine (DBHA) chemical probe that covalently labels modified aspartic acid residues in native proteomes. DBHA treatment coupled with LC-MS/MS analysis enabled detection of known phosphoaspartate modifications, as well as novel aspartic acid sites in the E...
September 19, 2018: Angewandte Chemie
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