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1.
Pan Pei Min Zhao Dengkai Lin Dr. Zhan Dong Dr. Liangliang Song Prof. Dr. Liang-An Chen 《Angewandte Chemie (International ed. in English)》2023,62(33):e202305510
Transition metal-catalyzed C−S cross-coupling has emerged as an important strategy to furnish thioethers; however, the dominant utilization of noble metal catalysts as well as the construction of challenging C(sp3)−S bonds by transition metal-catalysis remain highly problematic. Earth-abundant manganese has gathered increasing interest as an attractive catalyst for new reaction development; nevertheless, C(sp3)−S cross-coupling reaction by manganese catalysis has not been reported. Herein, we disclose a highly efficient manganese-catalyzed redox-neutral thiolation of a broad range of alkyl halides with thioformates as practical sulfuration agents. Strategically, employing easily synthesized thioformates as thiyl radical precursors allows access to various aryl and alkyl thioethers in good to excellent yields. Notably, this redox-neutral method avoids the utilization of strong bases, external ligands, forcing reaction conditions, and stoichiometric manganese, thus presenting apparent advantages, such as broad substrate scope, excellent functional group compatibility, and mild reaction conditions. Finally, the utilities of this method are also illustrated by downstream transformations and late-stage thiolation of structurally complex natural products and pharmaceuticals. 相似文献
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Influence of velocity in nanoscale friction processes 总被引：3，自引：0，他引：3
R. Prioli A.M.F. Rivas F.L. Freire Jr. A.O. Caride 《Applied Physics A: Materials Science & Processing》2003,76(4):565-569
Force-microscopy images of boric acid crystals were obtained experimentally and simulated with the use of a two-dimensional
mechanical model. An analysis of the stick and slip movement of the microscope tip shows that the energy-dissipation mechanism
is strongly influenced by the non-linear dynamics of the sliding system. The contributions of stick and viscous forces on
the energy dissipation (or friction forces) are studied as a function of the relative scanning velocity. At low relative velocities,
the stick forces are shown to be responsible for the energy dissipation. This energy is velocity-dependent, due to the coupling
between the two degrees of freedom of the sliding system. As the scanning velocity increases the stick forces are damped;
the viscous force is then predominant in the energy-dissipation process.
Received: 30 October 2001 / Accepted: 17 May 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +55-21/2295-9397, E-mail: prioli@vdg.fis.puc-rio.br 相似文献
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S. Preciado‐Flores R. Melndrez V. Chernov D. Soto‐Puebla M. Pedroza‐Montero M. Barboza‐Flores 《physica status solidi (a)》2007,204(9):3041-3046
It is known that room temperature beta‐irradiated Ib type diamond generates a non‐reproducible TL glow curve shape, due to mobility of the impurity‐vacancy (I –V) and interstitials (I) defects in the 30–800 °C temperature range. This situation may hinder the use of this type of diamond material in dose assessment applications. The recurring heating of the Ib type diamond sample changes the defects concentration and consequently the intensity of the TL glow peaks associated to the characteristic temperature annealing stages. In the present work we have performed thermal annealing (TA) treatment on an Ib type diamond in the 100–800 °C range previous to beta irradiation. It was observed that after the 800 °C annealing treatment the TL glow curve showed 3–5% reproducibility, in contrast to the non‐reproducible TL observed in non‐annealed diamond, and remained the same after two months of successive TL read outs. Moreover, the 800 °C annealing treatment assured a linear integrated TL dose behavior, a significant improvement over non‐annealed samples that could facilitate the employment of Ib type synthetic diamond in dosimetric applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Using multiple q-integrals and a determinant evaluation, we establish a nonterminating 8φ7 summation for the root system Cr. We also give some important specializations explicitly. 相似文献
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M. Tariq Riaz Ivanna Pohorilets Jackson J. Hernandez Jeovanna Rios Nancy I. Totah 《Tetrahedron letters》2018,59(29):2809-2812
A practical, operationally simple preparation of 2-(trimethylsilyl)methyl-2-propen-1-ol derivatives is described. The cobalt catalyzed coupling of a protected vinyl halide with trimethylsilylmethylmagnesium chloride shows excellent functional group tolerance and provides these synthetically useful allyl silanes in good overall yield. By this method, the use of highly concentrated organolithium reagents, complex reaction protocols, and expensive starting materials is avoided. 相似文献
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H. G. Ganev 《中国物理C(英文版)》2023,47(10):104101-104101-13
The recently proposed microscopic shell-model version of the Bohr-Mottelson (BM) collective model is considered in more detail in the coordinate representation. The latter possesses a clear and transparent physical meaning, which reveals several features of the new version of the collective model missed in the previous formulation. The relationship to the original BM model is considered, along with the relationships between the different limiting submodels of the microscopic version of the BM model, which closely resemble the relationships of the original Wilets-Jean and rotor models. The kinematically correct many-particle wave functions of the microscopic version of the BM model, conserving the experimentally observed integrals of motion, are shown to consist of collective irrotational-flow and intrinsic components begin{document}$ - $end{document} ![]()
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10.
F. Bonelli N. Manini E. Cadelano L. Colombo 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(4):449-459
Using a tight-binding atomistic simulation, we simulate the recent
atomic-force microscopy experiments probing the slipperiness of graphene
flakes made slide against a graphite surface.
Compared to previous theoretical models, where the flake was assumed to be
geometrically perfect and rigid, while the substrate is represented by a
static periodic potential, our fully-atomistic model includes quantum
mechanics with the chemistry of bond breaking and bond formation, and the
flexibility of the flake.
These realistic features, include in particular the crucial role of the
flake rotation in determining the static friction, in qualitative agreement
with experimental observations. 相似文献