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排序方式: 共有870条查询结果,搜索用时 271 毫秒
281.
Meriem Toumi Noureddine Raouafi Khaled Boujlel Issa Tapsoba Jean-Paul Picard Michel Bordeau 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2477-2490
Electrogenerated cyanomethyl anion promotes the reaction between primary or secondary amines, carbon disulfide, and alkyl or benzyl halide. Secondary amines are converted to alkyl or benzyl dithiocarbamates, whereas primary amines give N-substituted alkyl or benzyl 3-amino-2-cyanodithiocrotonates. The mechanisms are discussed. 相似文献
282.
Bi‐channel Surface Acoustic Wave Gas Sensor for Carbon Disulfide and Methanol Vapors in Polymer Plants
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A C60‐polyphenylacetylene (C60‐PPA) and polyvinylpyrrolidone (PVP) coated two‐channel surface acoustic wave (SAW) crystal gas sensor with a homemade computer interface for data acquisition and data processing was developed and employed to detect carbon disulfide (CS2) and methanol (CH3OH) vapors in polymer plants. The frequency of surface acoustic wave oscillator decreases due to the adsorption of gas molecules on the coated materials of the SAW sensor. Six coating materials (C60‐PPA, nafion, PPA, crytand [2,2], polyethene glycol and PVP) were used to adsorb and detect carbon disulfide and methanol gases. Adsorption of all the six coating materials to CS2 and CH3OH was found to be physical adsorption. The C60‐PPA coated SAW detector exhibited more sensitive to CS2 than the other coating materials. In contrast, the PVP coated SAW detector was more sensitive to CH3OH than the other coating materials. With the two‐channel SAW sensor, the C60‐PPA coated SAW showed a good detection limit of 0.4 ppm and good reproducibility with RSD of 3.37 % (n=10) for CS2. Similarly, the PVP coated SAW also showed a good detection limit of 0.05 ppm and good reproducibility, with RSD of 0.86 % (n=10) for CH3OH. The interference effect of other organic molecules on the SAW detection system was negligible, except for the irreversible adsorption of C60‐PPA to propylamine. The frequency signals from the two‐channel SAW sensor array C60‐PPA and PVP coatings were processed by a back‐propagation artificial neural network (BPN) and multiple regression analysis (MRA). Thus a two‐channel SAW sensor array with BPN and MRA has been successfully applied for the qualitative and quantitative analyses of CS2 and CH3OH in mixtures. 相似文献
283.
D. Depenheuer M. Sinther J. Kohl-Landgraf Th. Walther 《Journal of Molecular Spectroscopy》2011,269(1):86-91
We report on our measurements of the Landé g-factors for rovibrational states in the 10V-band of carbon disulfide. Our improved accuracy enabled us to increase the measurements precision of previous studies and additionally determine the Landé g-factors for nearly all previously assigned transitions. 相似文献
284.
Anirban Bhandari Saikat Mishra Ram Chandra Maji Akhilesh Kumar Marilyn M. Olmstead Apurba K. Patra 《Angewandte Chemie (International ed. in English)》2020,59(23):9177-9185
According to the well‐accepted mechanism, methyl‐coenzyme M reductase (MCR) involves Ni‐mediated thiolate‐to‐disulfide conversion that sustains its catalytic cycle of methane formation in the energy saving pathways of methanotrophic microbes. Model complexes that illustrate Ni‐ion mediated reversible thiolate/disulfide transformation are unknown. In this paper we report the synthesis, crystal structure, spectroscopic properties and redox interconversions of a set of NiII complexes comprising a tridentate N2S donor thiol and its analogous N4S2 donor disulfide ligands. These complexes demonstrate reversible NiII‐thiolate/NiII‐disulfide (both bound and unbound disulfide‐S to NiII) transformations via thiyl and disulfide monoradical anions that resemble a primary step of MCR's catalytic cycle. 相似文献
285.
Andrew M. White Simon J. de Veer Guojie Wu Peta J. Harvey Kuok Yap Gordon J. King Joakim E. Swedberg Conan K. Wang Ruby H. P. Law Thomas Durek David J. Craik 《Angewandte Chemie (International ed. in English)》2020,59(28):11273-11277
Ruthenium‐catalysed azide–alkyne cycloaddition (RuAAC) provides access to 1,5‐disubstituted 1,2,3‐triazole motifs in peptide engineering applications. However, investigation of this motif as a disulfide mimetic in cyclic peptides has been limited, and the structural consequences remain to be studied. We report synthetic strategies to install various triazole linkages into cyclic peptides through backbone cyclisation and RuAAC cross‐linking reactions. These linkages were evaluated in four serine protease inhibitors based on sunflower trypsin inhibitor‐1. NMR and X‐ray crystallography revealed exceptional consensus of bridging distance and backbone conformations (RMSD<0.5 Å) of the triazole linkages compared to the parent disulfide molecules. The triazole‐bridged peptides also displayed superior half‐lives in liver S9 stability assays compared to disulfide‐bridged peptides. This work establishes a foundation for the application of 1,5‐disubstituted 1,2,3‐triazoles as disulfide mimetics. 相似文献
286.
Kun Zhou Yihao Zhou Hongchao Yang Huile Jin Yonggang Ke Qiangbin Wang 《Angewandte Chemie (International ed. in English)》2020,59(41):18249-18255
We present a strategy of interfacially bridging covalent network within tobacco mosaic virus (TMV) virus‐like particles (VLPs). We arranged T103C cysteine to laterally conjugate adjacent subunits. In the axis direction, we set A74C mutation and systematically investigated candidate from E50C to P54C as the other thiol function site, for forming longitudinal disulfide bond chains. Significantly, the T103C‐TMV‐E50C‐A74C shows the highest robustness in assembly capability and structural stability with the largest length, for TMV VLP to date. The fibers with lengths from several to a dozen of micrometers even survive under pH 13. The robust nature of this TMV VLP allows for reducer‐free synthesis of excellent electrocatalysts for application in harshly alkaline hydrogen evolution. 相似文献
287.
Dr. Daniel H. Scharf Prof. Dr. Michael Groll Dr. Andreas Habel Dr. Thorsten Heinekamp Prof. Dr. Christian Hertweck Prof. Dr. Axel A. Brakhage Dr. Eva M. Huber 《Angewandte Chemie (International ed. in English)》2014,53(8):2221-2224
Nature provides a rich source of compounds with diverse chemical structures and biological activities, among them, sulfur‐containing metabolites from bacteria and fungi. Some of these compounds bear a disulfide moiety that is indispensable for their bioactivity. Specialized oxidoreductases such as GliT, HlmI, and DepH catalyze the formation of this disulfide bridge in the virulence factor gliotoxin, the antibiotic holomycin, and the anticancer drug romidepsin, respectively. We have examined all three enzymes by X‐ray crystallography and activity assays. Despite their differently sized substrate binding clefts and hence, their diverse substrate preferences, a unifying reaction mechanism is proposed based on the obtained crystal structures and further supported by mutagenesis experiments. 相似文献
288.
Precise Tuning of the Charge Transfer Kinetics and Catalytic Properties of MoS2 Materials via Electrochemical Methods
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Xinyi Chia Dr. Adriano Ambrosi Prof. David Sedmidubský Prof. Zdeněk Sofer Prof. Martin Pumera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17426-17432
MoS2 has become particularly popular for its catalytic properties towards the hydrogen evolution reaction (HER). It has been shown that the metallic 1T phase of MoS2, obtained by chemical exfoliation after lithium intercalation, possesses enhanced catalytic activity over the semiconducting 2H phase due to the improved conductivity properties which facilitate charge‐transfer kinetics. Here we demonstrate a simple electrochemical method to precisely tune the electron‐transfer kinetics as well as the catalytic properties of both exfoliated and bulk MoS2‐based films. A controlled reductive or oxidative electrochemical treatment can alter the surface properties of the film with consequently improved or hampered electrochemical and catalytic properties compared to the untreated film. Density functional theory calculations were used to explain the electrochemical activation of MoS2. The electrochemical tuning of electrocatalytic properties of MoS2 opens the doors to scalable and facile tailoring of MoS2‐based electrochemical devices. 相似文献
289.
《Journal of Energy Chemistry》2014,23(2):221-226
In this work, a series of coal-based active carbon(CAC) catalysts loaded by Al2O3were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide(COS) and carbon disulfide(CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2concentration, gas hourly space velocity(GHSV) and relative humidity(RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3calcined at 300 ℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2decrease. A small amount of O2introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2. 相似文献
290.
Kang Bing Zou Xian Hong Yin Wen Qi Liu Ren Hua Qiu Ruo Xin Li Ling Ling Shao 《合成通讯》2013,43(14):2464-2471
In the presence of a catalytic amount of cesium hydroxide under a nitrogen atmosphere, terminal alkynes reacted with diaryl disulfides at room temperature in dimethylformamide to give almost exclusively (Z)-1,2-diarylthio-1-alkene in good yields, but under an air atmosphere, the reaction gave a mixture of alkynyl sulfide and (Z)-1,2-diarylthio-1-alkene. 相似文献