Read by QxMD icon Read

Angewandte Chemie

Juan Alberto Varela, Margarida Rodrigues, Suman De, Patrick Flagmeier, Sonia Gandhi, Christopher M Dobson, David Klenerman, Steven Lee
Small aggregates of misfolded proteins play a key role in neurodegenerative disorders. Such species are difficult to study due to the lack of methods capable of resolving these heterogeneous aggregates, which are smaller than the optical diffraction limit. We demonstrate here an all-optical fluorescence microscopy method to characterise the structure of individual protein-aggregates based on the fluorescence anisotropy of dyes such as thioflavin-T, and show that this technology is capable of studying oligomers in human biofluids such as cerebrospinal fluid...
January 17, 2018: Angewandte Chemie
Fabien Hammerer, Leigh Loots, Jean-Louis Do, J P Daniel Therien, Christopher W Nickels, Tomislav Friscic, Karine Auclair
Mechanochemistry enables enzymatic cleavage of cellulose into glucose without bulk solvents, acids, other aggressive reagents or substrate pre-treatment. This clean mechano-enzymatic process is also directly applicable to biomass, avoids many limitations associated with the use of cellulases, and produces glucose concentrations >3 times the highest obtained by conventional methods.
January 17, 2018: Angewandte Chemie
Yong Sheng Zhao, Haiyun Dong, Chunhuan Zhang, Yuan Liu, Yongli Yan, Fengqin Hu
The very broad emission bands of organic semiconductor materials are, in theory, suitable for achieving versatile solid state lasers; however, most of organic materials only lase at short wavelength corresponding to the 0-1 transition governed by the Franck-Condon (FC) principle. Here we develop a strategy to overcome the limit of FC principle for tailoring the output of microlasers over a wide range based on the controlled vibronic emission of organic materials at microcrystal state. For the first time, the output wavelength of organic lasers is tailored across all vibronic (0-1, 0-2, 0-3, and even 0-4) bands spanning the entire emission spectrum...
January 17, 2018: Angewandte Chemie
Xin Ai, Yingxin Chen, Yuting Feng, Feng Li
There is only one family of room-temperature luminescent radicals, the triphenylmethyl radicals, to date. Herein, we synthesize a new stable room-temperature luminescent radical, (N-carbazolyl)bis(2,4,6-tirchlorophenyl)methyl radical (CzBTM), which has improved properties compared to the triphenylmethyl radicals. X-ray crystallography, electron paramagnetic resonance spectroscopy, and magnetic susceptibility measurements confirmed the radical structure. CzBTM shows room-temperature deep-red to near-infrared emission in various solutions...
January 17, 2018: Angewandte Chemie
Martin Andreas Robert George, Nguyen Xuan Truong, Marco Savoca, Otto Dopfer
We report the spectroscopic characterization of protonated monosilanol (SiH3OH2+) isolated in the gas phase, thus providing the first experimental determination of the structure and bonding of a member of the elusive silanole family. The SiH3OH2+ ion is generated in a silane/water plasma expansion, and its structure is derived from the IR photodissociation (IRPD) spectrum of its Ar cluster measured in a tandem mass spectrometer. The chemical bonding in SiH3OH2+ is analyzed by density functional theory (DFT) calculations, providing detailed insight into the nature of the dative H3Si+-OH2 bond...
January 17, 2018: Angewandte Chemie
Rudolf K Allemann, J Javier Ruiz-Pernia, Louis Luk, Inaki Tunon, Vicent Moliner, Enas Behiry
The origin of substrate preference in promiscuous enzymes was investigated by enzyme isotope labeling of the alcohol dehydrogenase from Geobacillus stearothermophilus (BsADH). At physiological temperature, protein dynamic coupling to the reaction coordinate was insignificant. However, the extent of dynamic coupling was highly substrate-dependent at lower temperatures. For benzyl alcohol, an enzyme isotope effect larger than unity was observed, whereas the enzyme isotope effect was close to unity for isopropanol...
January 17, 2018: Angewandte Chemie
Jeehye Byun, Wei Huang, Di Wang, Run Li, Kai A I Zhang
Water-compatibility of heterogeneous photocatalysts has been pursued for energy and environmental applications. However, there exists a trade-off between hydrophilicity and recyclability of the photocatalyst. Herein, we report a conjugated polymer photocatalyst with tertiary amine terminals that reversibly binds CO2 in water, generating a switchable hydrophilicity. The CO2-assisted hydrophilicity boosted up the photocatalytic efficiency in aqueous medium with minimum dosage. When CO2 was desorbed, the photocatalyst could be simply regenerated from reaction media, facilitating the repeated use of photocatalyst...
January 17, 2018: Angewandte Chemie
Zhong-Hua Xue, Jing-Tan Han, Wei-Jie Feng, Qiu-Ying Yu, Xin-Hao Li, Markus Antonietti, Jie-Sheng Chen
Engineering the adsorption of molecules on active sites is an integral and challenging part for the design of highly efficient transition-metal-based catalysts for methanol dehydrogenation. Here we report a Mott-Schottky catalyst composed of Ni nanoparticles and tailorable nitrogen-doped carbon-foam (Ni/NCF) and thus tunable adsorption energy for highly efficient and selective dehydrogenation of gas-phase methanol to hydrogen and CO even under relatively high weight hourly space velocities (WHSV). Both theoretical and experimental results reveal the key role of the rectifying contact at the Ni/NCF boundaries in tailoring the electron density of Ni species and enhancing the absorption energies of methanol molecules, which leads to a remarkably high turnover frequency (TOF) value (356 mol methanol mol-1 Ni h-1 at 350 °C), 10-fold outpacing the bench-marked transition-metal catalysts in the literature...
January 17, 2018: Angewandte Chemie
Ulrich S Schubert, Ronny Tepper
The halogen bond is a supramolecular interaction between a Lewis-acidic region of a covalently bound halogen and a Lewis base. It has been studied widely in silico and experimentally in the solid state; however, solution phase applications have attracted enormous interest in the last years. This Minireview highlights selected recent developments of halogen bond interactions in solution with focus on the use of halogen bond receptors in anion recognition and sensing, anion templated self-assembly as well as in organo-catalysis...
January 17, 2018: Angewandte Chemie
Tiago Rodrigues, Gonçalo J L Bernardes
Less is more: The efficacy of antibody-drug conjugates (ADCs) for cancer therapy is traditionally associated with cleavable linkers for payload release. Evidence now suggests that simpler constructs without cleavable moieties can afford more stable and effective ADCs.
January 17, 2018: Angewandte Chemie
Vladimir Gevorgyan, Maxim Ratushnyy, Marvin Parasram, Yang Wang
A novel mild, visible light-induced Pd-catalyzed hydrogen atom translocation/atom transfer radical cyclization (HAT/ATRC) cascade has been developed. This protocol involves a 1,5-HAT process of previously unknown hybrid vinyl Pd-radical intermediates leading to iodomethyl carbo- and heterocyclic structures.
January 16, 2018: Angewandte Chemie
Tatsuki Kurokawa, Shigeki Kiyonaka, Eiji Nakata, Masayuki Endo, Shohei Koyama, Emiko Mori, Nam Ha Tran, Huyen Dinh, Yuki Suzuki, Kumi Hidaka, Masaaki Kawata, Chikara Sato, Hiroshi Sugiyama, Takashi Morii, Yasuo Mori
In native systems, scaffolding proteins play important roles in assembling proteins into complexes to transduce signals. This concept is yet to be incorporated in assembling functional transmembrane protein complexes in artificial systems. To address this issue, DNA origami has potentiality to serve as scaffolds that arrange proteins at specific positions in complexes. Here, we report that Kir3 K+ channel proteins are assembled through zinc-finger protein (ZFP)-adaptors at specific locations on DNA origami scaffolds...
January 16, 2018: Angewandte Chemie
Takashi Kurogi, Manoj V Mane, Shuai Zheng, Patrick J Carroll, Mu-Hyun Baik, Daniel J Mindiola
The zirconium methylidene (PNP)Zr=CH2 (OAr) (1) reacts with N3 Ad to give two products (PNP)Zr=NAd(OAr) (2) and (PNP)Zr(η2 -N=NAd)(N=CH2 )(OAr) (3), both resulting from a common cycloaddition intermediate (PNP)Zr(CH2 N3 Ad)(OAr) (A). Using a series of control experiments in combination with DFT calculations, it was found that 2 results from a nitrene by a carbene metathesis reaction in which N2 acts as a delivery vehicle and forms N2 CH2 as a side product. In the case of 3, N-N bond splitting of the azide at the α-position allowed the isolation of a rare example of a parent ketimide complex of zirconium...
January 16, 2018: Angewandte Chemie
Lin Deng, Likun Jin, Guangbin Dong
Herein, we describe the development of a catalytic intramolecular "cut-and-sew" transformation between cyclobutanones and alkynes to construct cyclohexenone-fused rings. The challenge arises from the need for selective coupling at the more sterically hindered proximal position, which can be addressed using an electron-rich but less bulky phosphine ligand. The control experiment and 13C-labelling study suggest that the reaction may start with cleavage of the less hindered distal C-C bond of cyclobutanones, followed by decarbonylation and CO reinsertion to enable Rh insertion at the more hindered proximal position...
January 16, 2018: Angewandte Chemie
Dongyuan Zhao, Tiancong Zhao, Peiyuan Wang, Qin Li, Areej Abdulkareem Al-Khalaf, Wael N Hozzein, Fan Zhang, Xiaomin Li
Nanoparticle based diagnosis-therapy integrative systems represent an emerging approach to cancer treatment. However, a series of size-dependent biological barriers impede nanomedicine from clinical implementation, especially the contradiction on optimum sizes for long blood circulation and quick metabolization. Herein, we demonstrate a novel NIR induced decomposable nanocapsule. The nanocapsules are fabricated based on layer-by-layer assembly of azobenzene functionalized polymers and up/downconversion nanoparticles (U/DCNPs)...
January 16, 2018: Angewandte Chemie
Soichiro Ogi, Kentarou Matsumoto, Shigehiro Yamaguchi
Amino-acid-based diamides are widely used as a substructure in supramolecular polymers, and also represent key components of polypeptides that help to understand protein folding. Herein, we report that the interplay of folding and aggregation of a diamide can be used to achieve seed-initiated supramolecular polymerization. For that purpose, a pyrene-substituted diamide was synthesized, in which pyrene is used as a tracer to monitor the supramolecular polymerization. Thermodynamic and time-dependent studies revealed that the folding of the diamide moiety, via the formation of intramolecular hydrogen bonds, effectively prevents a spontaneous nucleation that leads to supramolecular polymerization...
January 16, 2018: Angewandte Chemie
Liuzhu Gong, Hong-Cheng Shen, Yu-Feng Wu, Ying Zhang, Lian-Feng Fan, Zhi-Yong Han
A Pd(II)-catalyzed asymmetric aminohydroxylation of 1,3-dienes with N-tosyl-2-aminophenols has been developed with a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides a direct and efficient approach to access chiral 3,4-dihydro-2H-1,4-benzoxazines in high levels of yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N-tosyl-2-aminophenols as a unique aminohydroxylation reagent complementary to known asymmetric aminohydroxylation methods.
January 16, 2018: Angewandte Chemie
Qinghua Zhang, Wenquan Zhang, Kangcai Wang, Juecheng Li, Zhien Lin, Siwei Song, Shiliang Huang, Yu Liu, Fude Nie
The experimental detection and synthesis of pentazole (HN5) and its anion (cyclo-N5-) have been actively pursued for the past hundred years in worldwide laboratories. In this study, we describe the synthesis of an aesthetical three-dimensional metal-pentazolate framework (denoted as MPF-1) consisting of sodium ions and cyclo-N5- anions, in which the isolated cyclo-N5- anions are preternaturally stabilized in this inorganic open-framework featuring two types of nanocages (Na20N60 and Na24N60) through strong metal coordination bonds...
January 16, 2018: Angewandte Chemie
Philipp Bielec, Oliver Janka, Theresa Block, Rainer Pöttgen, Wolfgang Schnick
Highly condensed nitridosilicates doped with Eu2+ or Ce3+ play an important role in saving energy by converting the blue light of (In,Ga)N-LEDs. Although nitridosilicates are known for great structural variety based on covalent anionic Si-N networks, elemental variety is restricted. Presenting a significant extension of the latter, this work describes a general access to open-shell transition metal nitridosilicates. As proof of principle the first iron nitridosilicate, namely Fe2Si5N8 was prepared by exchanging Ca2+ in α Ca2Si5N8 applying a FeCl2 melt (salt metathesis)...
January 16, 2018: Angewandte Chemie
Tsuyoshi Kato, Ricardo Rodriguez, Isabel Alvarado-Beltran, Jérémy Saouli, Antoine Baceiredo, Nathalie Saffon-Merceron, Vicenç Branchadell
The donor-stabilized sila--lactone reacts with CO2 via a [2+2]-cycloaddition to form the spiro-cyclic silicon carbonate derivative. Of particular interest, this process is reversible at room temperature. Furthermore, the photolysis of resulting CO2 adduct affords the first persistent SiO2-CO2 mixed dimer (SiCO4), presenting a Si2O4-like structure, which is stabilized by a Lewis donor-acceptor type ligand. As predicted by theoretical calculations, in marked contrast to Si2O4, the mixed dimer SiCO4 is labile and readily releases CO2...
January 15, 2018: Angewandte Chemie
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"