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Angewandte Chemie

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https://www.readbyqxmd.com/read/28524602/elucidating-the-role-of-dissolution-in-ceo2-nanoparticle-plant-uptake-by-smart-radiolabeling
#1
Stefan Schymura, Thomas Fricke, Heike Hildebrand, Karsten Franke
The identification of major uptake pathways in plants is an important factor when evaluating the fate of manufactured nanoparticles in the environment and the associated risks. Using different radiolabeling techniques we were able to show a predominantly particulate uptake for CeO2 nanoparticles in contrast to a possible uptake in the form of ionic cerium.
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524544/enzymatic-engineering-of-live-bacterial-cell-surface-using-butelase-1
#2
Xiaobao Bi, Juan Yin, Giang K T Nguyen, Chang Rao, Nurashikin Bte Abdul Halim, Xinya Hemu, James P Tam, Chuan-Fa Liu
We show that butelase-mediated ligation (BML) can be used to modify live bacterial cell surfaces with diverse cargo molecules. Surface-displayed butelase recognition motif NHV was first introduced at the C-terminal end of the anchoring protein OmpA on E. coli cells. This then served as a handle of BML for the functionalization of E. coli cell surfaces with fluorescein and biotin tags, a tumor-associated monoglycosylated peptide and mCherry protein. The cell-surface ligation reaction was achieved at low concentrations of butelase and the labeling substrates...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524451/tris-perfluorotolyl-borane-a-boron-lewis-superacid
#3
Norbert Werner Mitzel, Jan Schwabedissen, Leif Körte, Marcel Soffner, Sebastian Blomeyer, Christian Reuter, Yury Vishnevskiy, Beate Neumann, Georg Stammler
Tris(tetrafluoro-4-(trifluoromethyl)phenyl)borane (BTolF) was prepared by reacting boron tribromide with tetrameric F3CC6F4-Cu(I). The latter was generated from F3CC6F4MgBr and copper(I) bromide. Lewis acidities of BTolF evaluated by the Gutmann-Beckett method and calculated fluoride ion affinities are 9 and 10%, respecttively, higher than that of tris(penta-fluorophenyl)borane (BCF) and even higher than that of SbF5. The molecular structures of BTolF and BCF were determined by gas electron diffraction, that of BTolF also by single crystal X-ray diffraction...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524450/methylammonium-mediated-evolution-of-mixed-organic-cation-perovskite-thin-films-a-dynamic-composition-tuning-process
#4
Chongwen Li, Yuanyuan Zhou, Li Wang, Yue Chang, Yingxia Zong, Lioz Etgar, Guanglei Cui, Nitin P Padture, Shuping Pang
Methylammonium-mediated phase-evolution behavior of FA1-x MAx PbI3 mixed-organic-cation perovskite (MOCP) is studied. It is found that by simply enriching the MOCP precursor solutions with excess methylammonium cations, the MOCPs form via a dynamic composition-tuning process that is key to obtaining MOCP thin films with superior properties. This simple chemical approach addresses several key challenges, such as control over phase purity, uniformity, grain size, composition, etc., associated with the solution-growth of MOCP thin films with targeted compositions...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524448/a-long-life-lithium-air-battery-in-ambient-air-with-a-polymer-electrolyte-containing-a-redox-mediator
#5
Ziyang Guo, Chao Li, Jingyuan Liu, Yonggang Wang, Yongyao Xia
Lithium-air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li2 O2 /LiOH/Li2 CO3 accumulation in the air electrode. Herein, we present a Li-air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I(-) /I2 conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524432/solution-nmr-structure-of-a-ligand-hybrid-2-g-quadruplex-complex-reveals-rearrangements-that-affect-ligand-binding
#6
Julia Wirmer-Bartoschek, Lars Erik Bendel, Hendrik R A Jonker, J Tassilo Grün, Francesco Papi, Carla Bazzicalupi, Luigi Messori, Paola Gratteri, Harald Schwalbe
Telomeric G-quadruplexes have recently emerged as drug targets in cancer research. Herein, we present the first NMR structure of a telomeric DNA G-quadruplex that adopts the biologically relevant hybrid-2 conformation in a ligand-bound state. We solved the complex with a metalorganic gold(III) ligand that stabilizes G-quadruplexes. Analysis of the free and bound structures reveals structural changes in the capping region of the G-quadruplex. The ligand is sandwiched between one terminal G-tetrad and a flanking nucleotide...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524364/biofunctional-microgel-based-fertilizers-for-controlled-foliar-delivery-of-nutrients-to-plants
#7
Richard A Meurer, Steffen Kemper, Sandra Knopp, Thomas Eichert, Felix Jakob, Heiner E Goldbach, Ulrich Schwaneberg, Andrij Pich
Foliar application of micronutrients (e.g. Fe(3+) ) onto plants over an extended time is challenging and often not possible due to insufficient rainfastness. Smart delivery systems which enable micronutrient release over several weeks would offer innovative and sustainable options to improve plant health and food production. Herein, we report a novel foliar fertilizer delivery system based on functional pH-responsive biohybrid microgels that have orthogonal functionality as carriers of micronutrients and employ peptides (termed anchor peptides) as foliar adhesion promoters...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524357/double-caging-linker-for-and-type-fluorogenic-construction-of-protein-antibody-bioconjugates-and-in-situ-quantification
#8
Shiyong Liu, Guhuan Liu, Guohai Shi, Haoyue Sheng, Yanyan Jiang, Haojun Liang
We report on in situ fluorescent quantification of the conjugation efficiency between azide-terminated synthetic polymers/ imaging probes and thiol-functionalized antibodies/proteins/peptides, by utilizing a doubly caged profluorescent and heterodifunctional core molecule (C1) as the self-sorting bridging unit. Orthogonal dual 'click' coupling of C1 with azide- and thiol-functionalized precursors leads to highly fluorescent bioconjugates, whereas single click products of C1 remain essentially nonfluorescent...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524354/an-aggregating-amphiphilic-squaraine-a-light-up-probe-that-discriminates-parallel-g-quadruplexes
#9
Vincenzo Grande, Filippo Doria, Mauro Freccero, Frank Würthner
G-quadruplexes (G4s) are peculiar DNA or RNA tertiary structures that are involved in the regulation of many biological events within mammalian cells, bacteria, and viruses. Although their role as versatile therapeutic targets has been emphasized for 35 years, G4 selectivity over ubiquitous double-stranded DNA/RNA, as well as G4 differentiation by small molecules, still remains challenging. Here, a new amphiphilic dicyanovinyl-substituted squaraine, SQgl, is reported to act as an NIR fluorescent light-up probe discriminating an extensive panel of parallel G4s while it is non-fluorescent in the aggregated state...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524343/synthesis-of-highly-substituted-pyridines-via-copper-catalyzed-condensation-of-oximes-and-%C3%AE-%C3%AE-unsaturated-imines
#10
Wei Wen Tan, Yew Jin Ong, Naohiko Yoshikai
A copper-catalyzed condensation reaction of oxime acetates and α,β-unsaturated ketimines into pyridine derivatives is reported. The reaction features mild conditions, high functional group compatibility, and high regioselectivity with respect to unsymmetrical oxime acetates, thus allowing for the preparation of a wide range of polysubstituted pyridines, many of which are not readily accessible by conventional condensation methods.
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523904/enantioselective-propargylation-of-polyols-and-desymmetrization-of-meso-1-2-diols-by-copper-borinic-acid-dual-catalysis
#11
Ren-Zhe Li, Hua Tang, Ke R Yang, Li-Qiang Wan, Xia Zhang, Jie Liu, Zhengyan Fu, Dawen Niu
A copper/borinic acid dual catalytic reaction enabled the enantioselective propargylation of aliphatic polyols. Readily available reagents and catalysts were used in this transformation, which displayed good to excellent chemo- and stereoselectivity for a broad array of substrates. The method was also applicable to the desymmetrization of meso 1,2-diols to furnish products with three stereogenic centers and a terminal alkyne group in one operation.
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523902/kinetically-controlled-layer-by-layer-stacking-of-metal-oxide-2d-nanosheets
#12
Joohyun Lim, Xiaoyan Jin, Yun Kyung Jo, Seul Lee, Seong-Ju Hwang
An efficient chemical way to finely control the layer-by-layer stacking of inorganic nanosheets (NS) is developed by tuning the type and composition of intercalant ion, and the reaction temperature for restacking process. The finely controlled stacking of NS relies on a kinetic control of the self-assembly of NS in the presence of coordinating organic cations. A critical role of organic cations in this assembly highlights the importance of the appropriate activation energy. Of prime importance is that a fine-control of the interstratification of 2D NS is highly effective not only in tailoring its pore structure but also in enhancing its electrode activity...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523865/the-interstitial-carbon-of-the-nitrogenase-femo-cofactor-is-far-better-stabilized-than-previously-assumed
#13
Jörg Grunenberg
The first quantum-mechanical calculations of all relevant potential constants in both the iron-molybdenum cofactor and the iron-vanadium cofactor of nitrogenase suggest that the carbide is bound to the center of the enzyme much more strongly than hitherto assumed. Previous studies seemed to indicate a dummy function of the interstitial carbon, with a weak force constant (ca. 0.32 N cm(-1) ). Our new investigations confirm a different picture: the central carbon atom binds the iron-sulfur cluster through six covalent C-Fe bonds...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523861/a-bifunctional-hybrid-electrocatalyst-for-oxygen-reduction-and-evolution-cobalt-oxide-nanoparticles-strongly-coupled-to-b-n-decorated-graphene
#14
Yun Tong, Pengzuo Chen, Tianpei Zhou, Kun Xu, Wangsheng Chu, Changzheng Wu, Yi Xie
The electrocatalyzed oxygen reduction and evolution reactions (ORR and OER, respectively) are the core components of many energy conversion systems, including water splitting, fuel cells, and metal-air batteries. Rational design of highly efficient non-noble materials as bifunctional ORR/OER electrocatalysts is of great importance for large-scale practical applications. A new strongly coupled hybrid material is presented, which comprises CoOx nanoparticles rich in oxygen vacancies grown on B,N-decorated graphene (CoOx NPs/BNG) and operates as an efficient bifunctional OER/ORR electrocatalyst...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523856/tunable-self-assembly-of-diblock-copolymers-into-colloidal-particles-with-triply-periodic-minimal-surfaces
#15
Zhixing Lin, Shaohua Liu, Wenting Mao, Hao Tian, Nan Wang, Ninghe Zhang, Feng Tian, Lu Han, Xinliang Feng, Yiyong Mai
We herein report the tunable self-assembly of simple block copolymers, namely polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers, into porous cubosomes with inverse Im3‾m or Pn3‾m mesophases of controlled unit cell parameters as well as hexasomes with an inverse hexagonal (p6mm) structure, which have been rarely observed in polymer self-assembly. A new morphological phase diagram was constructed for the solution self-assembly of PS-b-PEO based on the volume fraction of the PS block against the initial copolymer concentration...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523851/identification-of-multiple-druggable-secondary-sites-by-fragment-screening-against-dc-sign
#16
Jonas Aretz, Hannes Baukmann, Elena Shanina, Jonas Hanske, Robert Wawrzinek, Viktor A Zapol'skii, Peter H Seeberger, Dieter E Kaufmann, Christoph Rademacher
DC-SIGN is a cell-surface receptor for several pathogenic threats, such as HIV, Ebola virus, or Mycobacterium tuberculosis. Multiple attempts to develop inhibitors of the underlying carbohydrate-protein interactions have been undertaken in the past fifteen years. Still, drug-like DC-SIGN ligands are sparse, which is most likely due to its hydrophilic, solvent-exposed carbohydrate-binding site. Herein, we report on a parallel fragment screening against DC-SIGN applying SPR and a reporter displacement assay, which complements previous screenings using (19) F NMR spectroscopy and chemical fragment microarrays...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523838/an-unsaturated-quinolone-n-oxide-of-pseudomonas-aeruginosa-modulates-growth-and-virulence-of-staphylococcus-aureus
#17
Dávid Szamosvári, Thomas Böttcher
The pathogen Pseudomonas aeruginosa produces over 50 different quinolones, 16 of which belong to the class of 2-alkyl-4-quinolone N-oxides (AQNOs) with various chain lengths and degrees of saturation. We present the first synthesis of a previously proposed unsaturated compound that is confirmed to be present in culture extracts of P. aeruginosa, and its structure is shown to be trans-Δ(1) -2-(non-1-enyl)-4-quinolone N-oxide. This compound is the most active agent against S.  aureus, including MRSA strains, by more than one order of magnitude whereas its cis isomer is inactive...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523779/arylative-intramolecular-allylation-of-ketones-with-1-3-enynes-enabled-by-catalytic-alkenyl-to-allyl-1-4-rhodium-i-migration
#18
Benjamin M Partridge, Michael Callingham, William Lewis, Hon Wai Lam
Alkenyl-to-allyl 1,4-rhodium(I) migration enables the generation of nucleophilic allylrhodium(I) species by remote C-H activation. This new mode of reactivity was employed in the diastereoselective reaction of arylboron reagents with substrates containing a 1,3-enyne tethered to a ketone, to give products containing three contiguous stereocenters. The products can be obtained in high enantioselectivities using a chiral sulfur-alkene ligand.
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523729/competition-between-arene-perfluoroarene-and-charge-transfer-interactions-in-organic-light-harvesting-systems
#19
Yanqiu Sun, Yilong Lei, Liangsheng Liao, Wenping Hu
Two typical types of luminescent organic cocrystals comprising pyrene-octafluoronaphthalene (pyrene-OFN) and pyrene-1,2,4,5-tetracyanobezene (pyrene-TCNB) were developed by a simple supramolecular assembly strategy. The cocrystals exhibit distinct optical properties because of their different intermolecular interaction modes; that is, arene-perfluoroarene (AP) and charge-transfer (CT) interactions. Unexpectedly, a pyrene-TCNB system with strong CT interactions was incorporated into a pyrene-OFN host as a robust guest to generate white-light emission (WLE)...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523724/paul-hagenmuller
#20
Michel Pouchard
Paul Hagenmuller, honorary professor at the Université de Bordeaux, passed away at the age of 95 on January 7, 2017. Hagenmuller was one of the founders of solid-state chemistry at the interface between chemistry, physics, and material science, with contributions including high oxidation states in transition metal oxides, magnesium hydride for hydrogen-storage applications, and synthesis of copper perovskites.
May 19, 2017: Angewandte Chemie
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