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排序方式: 共有1421条查询结果,搜索用时 15 毫秒
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Prof. Allan J. Canty Prof. Alireza Ariafard Prof. Gerard van Koten 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15629-15635
Density Functional Theory studies of square-planar PtII pincer structures, (4-Z-NCN)PtCl ([4-Z-NCN]−=[4-Z-2,6-(Me2NCH2)2C6H2-N,C,N]−, Z=H, NO2, CF3, CO2H, CHO, Cl, Br, I, F, SMe, SiMe3, tBu, OH, NH2, NMe2), enable characterisation of mesomerism for the pincer-Pt interaction. Relationships between Hammett σp substituent parameters of Z and DFT data obtained from NBO6 and AOMix computation are used to probe the interaction of the 5dyz orbital of platinum with π-orbitals of the arene ring. Analogous computation for 2,6-(Me2CH2)2C6H3Z (Z=H, CF3, CHO, Cl, Br, I, F, SMe, SiMe3, tBu, OH, NH2) and (4-H-NCN)PtZ allows an estimation of the relative substituent effects of “(CH2NMe2)2PtZ” on π-delocalisation in the pincer system. 相似文献
3.
Bastiaan Kooij Paul Varava Farzaneh Fadaei-Tirani Rosario Scopelliti Dimitrios A. Pantazis Gerard P. Van Trieste III David C. Powers Kay Severin 《Angewandte Chemie (International ed. in English)》2023,62(4):e202214899
Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of CuI complexes with N-heterocyclic diazoolefin ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature. 相似文献
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Kesler Michael S. McGuire Michael A. Conner Ben Rios Orlando Murphy Bart Carter William Henderson Hunter B. Ludtka Gerard M. Kisner Roger A. 《Journal of Thermal Analysis and Calorimetry》2022,147(13):7449-7457
Journal of Thermal Analysis and Calorimetry - A new thermal analysis technique is described that allows measurements to be performed on bulk samples at extreme heating and cooling rates and in high... 相似文献
6.
Roos C. W. van Lier Dr. A. Dowine de Bruijn Prof. Dr. Gerard Roelfes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(4):1430-1437
Dehydroalanine (Dha) residues are attractive noncanonical amino acids that occur naturally in ribosomally synthesised and post-translationally modified peptides (RiPPs). Dha residues are attractive targets for selective late-stage modification of these complex biomolecules. In this work, we show the selective photocatalytic modification of dehydroalanine residues in the antimicrobial peptide nisin and in the proteins small ubiquitin-like modifier (SUMO) and superfolder green fluorescent protein (sfGFP). For this purpose, a new water-soluble iridium(III) photoredox catalyst was used. The design and synthesis of this new photocatalyst, [Ir(dF(CF3)ppy)2(dNMe3bpy)]Cl3, is presented. In contrast to commonly used iridium photocatalysts, this complex is highly water soluble and allows peptides and proteins to be modified in water and aqueous solvents under physiologically relevant conditions, with short reaction times and with low reagent and catalyst loadings. This work suggests that photoredox catalysis using this newly designed catalyst is a promising strategy to modify dehydroalanine-containing natural products and thus could have great potential for novel bioconjugation strategies. 相似文献
7.
Ahmad Fahim Habib Thomas Heinemann Grace G. Manahan Daniel Ullmann Paul Scherkl Alexander Knetsch Andrew Sutherland Andrew Beaton David Campbell Lorne Rutherford Lewis Boulton Alastair Nutter Adam Hewitt Alexander Dickson Oliver S. Karger Michael D. Litos Brendon D. O'Shea Gerard Andonian David L. Bruhwiler Georg Pretzler Thomas Wilson Zhengming Sheng Michael Stumpf Lars Reichwein Alexander Pukhov John R. Cary Mark J. Hogan Vitaly Yakimenko James B. Rosenzweig Bernhard Hidding 《Annalen der Physik》2023,535(10):2200655
Plasma wakefield accelerators offer accelerating and focusing electric fields three to four orders of magnitude larger than state-of-the-art radiofrequency cavity-based accelerators. Plasma photocathodes can release ultracold electron populations within such plasma waves and thus open a path toward tunable production of well-defined, compact electron beams with normalized emittance and brightness many orders of magnitude better than state-of-the-art. Such beams will have far-reaching impact for applications such as light sources, but also open up new vistas on high energy and high field physics. This paper reviews the innovation of plasma photocathodes, and reports on the experimental progress, challenges, and future prospects of the approach. Details of the proof-of-concept demonstration of a plasma photocathode in 90° geometry at SLAC FACET within the E-210: Trojan Horse program are described. Using this experience, alongside theoretical and simulation-supported advances, an outlook is given on future realizations of plasma photocathodes such as the upcoming E-310: Trojan Horse-II program at FACET-II with prospects toward excellent witness beam parameter quality, tunability, and stability. Future installations of plasma photocathodes also at compact, hybrid plasma wakefield accelerators, will then boost capacities and open up novel capabilities for experiments at the forefront of interaction of high brightness electron and photon beams. 相似文献
8.
Jeremy C. Mullins Dr. K. Yuvaraj Yixiao Jiang Dr. Gerard P. Van Trieste III Dr. Asim Maity Prof. David C. Powers Prof. Cameron Jones 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(65):e202202103
UV irradiation of solutions of a guanidinate coordinated dimagnesium(I) compound, [{(Priso)Mg}2] 3 (Priso=[(DipN)2CNPri2]−, Dip=2,6-diisopropylphenyl), in either benzene, toluene, the three isomers of xylene, or mesitylene, leads to facile activation of an aromatic C−H bond of the solvent in all cases, and formation of aryl/hydride bridged magnesium(II) products, [{(Priso)Mg}2(μ-H)(μ-Ar)] 4 – 9 . In contrast to similar reactions reported for β-diketiminate coordinated counterparts of 3 , these C−H activations proceed with little regioselectivity, though they are considerably faster. Reaction of 3 with an excess of the pyridine, p-NC5H4But (pyBut), gave [(Priso)Mg(pyButH)(pyBut)2] 10 , presumably via reduction of the pyridine to yield a radical intermediate, [(Priso)Mg(pyBut⋅)(pyBut)2] 11 , which then abstracts a proton from the reaction solvent or a reactant. DFT calculations suggest two possible pathways to the observed arene C−H activations. One of these involves photochemical cleavage of the Mg−Mg bond of 3 , generating magnesium(I) doublet radicals, (Priso)Mg⋅. These then doubly reduce the arene substrate to give “Birch-like” products, which subsequently rearrange via C−H activation of the arene. Circumstantial evidence for the photochemical generation of transient magnesium radical species includes the fact that irradiation of a cyclohexane solution of 3 leads to an intramolecular aliphatic C−H activation process and formation of an alkyl-bridged magnesium(II) species, [{Mg(μ-Priso−H)}2] 12 . Furthermore, irradiation of a 1 : 1 mixture of 3 and the β-diketiminato dimagnesium(I) compound, [{(DipNacnac)Mg}2] (DipNacnac=[HC(MeCNDip)2]−), effects a “scrambling” reaction, and the near quantitative formation of an unsymmetrical dimagnesium(I) compound, [(Priso)Mg−Mg(DipNacnac)] 13 . Finally, the EPR spectrum (77 K) of a glassed solution of UV irradiated 3 is dominated by a broad featureless signal, indicating the presence of a doublet radical species. 相似文献
9.
A simple one-dimensional model is used to simulate numerically the propagation oflinear and nonlinear waves in a deformable ceramic.The nummrical scheme used providesthe response in stress or strain and electric field within the sample and the voltage at aresistive external circuit connecting the two faces of the sample.Space-time diagrams of thepropagation are obtained for various mechanical loads.The voltage response obtainedagress well with experimental results in the linear regime.In the nonlinear one,thesteepening of the electromechanical wave yielding a shock wave is exhibited. 相似文献