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ZuoWei Xie 《中国科学:化学(英文版)》2014,57(8):1061-1063
<正>Carboranes are a class of boron hydride clusters in which one or more of the BH vertices are replaced by CH units.Unlike small boranes, carboranes are kinetically and thermodynamically very stable as well as relatively chemically inert, which are often called three-dimensional relatives of benzenes. They are finding many applications in medicine as boron neutron capture therapy(BNCT) agents, in nanomaterials/supramolecular design as building blocks, and as ligands for transition metals [1]. However, their unique structures make derivatization difficult, which limits their application scope. To this end, there is a need to develop 相似文献
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A novel Pd–C catalytic hydrodechlorination–hydrogenation was developed for a multi-step one-pot transformation of 4-acylpyridines. Under the selected conditions, 4-benzoylpyridines and 4-alkanoylpyridines were chemoselectively converted into the corresponding 4-benzylpiperidine hydrochlorides and α-alkyl-4-piperidinemethanol hydrochlorides, respectively. This catalytic method was performed simply by an addition of 1 equiv of ClCH2CHCl2 to the conventional hydrogenation system and directly gave the crystalline piperidine hydrochlorides in practical quantitative yields. 相似文献
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We focused on the effects of the inorganic acid HNO3 on the gas-sensing properties of nanometer SnO2 and prepared the powders via a dissolution-pyrolysis method. Furthermore, the powders were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectra (EDS). Several aspects were surveyed, including the calcining temperature, concentration of nitric acid and the working temperature. The results showed that the gas response of 3 wt% HNO3-doped SnO2 powders (calcined at 500 °C) to 10 ppm Cl2 reached 316.5, at the working temperature 175 °C. Compared with pure SnO2, appropriate HNO3 could increase the gas sensitivity to Cl2 gas more significantly. 相似文献
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碳硼烷和碳硼炔金属配合物中的金属-碳键具有不同于经典金属-碳键的化学性质.一方面,二十面体碳硼烷独特的电子和空间效应使得碳硼烷金属配合物中的金属-碳键不参与和不饱和分子的反应 另一方面,在一定条件下具有大空间位阻的碳硼笼可以诱导某些碳-碳偶联反应.然而,碳硼炔金属配合物中的金属-碳键能与多种不饱和分子发生反应,其反应模式取决于中心金属离子的电子构型.本文简要总结了我们近期在这方面的研究进展. 相似文献
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Transmetalation of carborane-fused zirconacycles to Cu(Ⅱ) induces the C-C coupling reaction to form four-membered rings. This serves as a new efficient and general methodology for the generation of a series of carborane-fused cyclobutenes and cyclobutanes. A reaction mechanism involving transmetalation to Cu(Ⅱ) and reductive elimination is proposed. 相似文献
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Density functional theory (DFT) combined with conductor-like solvent model (COSMO) have been performed to study the solvent effects of H2 adsorption on Cu(h k l) surface. The result shows H2 can not be parallel adsorbed on Cu(h k l) surface in gas phase and only vertical adsorbed. At this moment, the binding energies are small and H2 orientation with respect to Cu(h k l) surfaces is not a determining parameter. In liquid paraffin, when H2 adsorbs vertically on Cu(h k l) surface, solvent effects not only influences the adsorptive stability, but also improves the ability of H2 activation; When H2 vertical adsorption on Cu(h k l) surface at 1/4 and 1/2 coverage, H-H bond is broken by solvent effects. However, no stable structures at 3/4 and 1 ML coverage are found, indicating that it is impossible to get H2 parallel adsorption on Cu(h k l) surfaces at 3/4 and 1 ML coverages due to the repulsion between adsorbed H2 molecules. 相似文献
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ZhiWei Men XiuPing Sun WenHui Fang ZuoWei Li Biao Cao ShuQin Gao GuoHui Lu 《中国科学G辑(英文版)》2009,52(4):529-533
β-carotene with double fluorescence characteristics and large third-order optical nonlinearities, which is dissolved in the
carbon disulfide (CS2) as the core medium of a liquid core optical fiber (LCOF), is applied in the study of the CS2 stimulated Raman scattering (SRS). The results of this study show that when the concentrations of solution are more than
3.72×10−7 mol/L, the amplified spontaneous emission (ASE) of β-carotene is the main factor influencing the threshold and intensity
of Stokes lines; when the concentrations of solution are lower than 3.72×10−7 mol/L, the ASE disappears and the fluorescence plays the key role: The high-order Stokes lines may be observed at very low
input-laser power, and the Stokes thresholds decrease as the solution concentration increases. The result may be widely used
in the study of broadband stimulated radiation laser and seeding laser.
Supported by the National Natural Science Foundation of China (Grant No. 10774057) 相似文献
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ZuoWei Xie 《中国科学:化学(英文版)》2014,57(8):1058-1058
<正>As one of the most important five-member heterocyclic aromatic rings, pyrrole is widely distributed in numerous natural products and pharmaceutical agents. Asymmetric dearomatization of pyrroles is very attractive in organic synthesis given the fact that highly functionalized chira pyrrolines and pyrrolidines could be easily accessed from the readily available pyrroles. However, the reported asymmetric dearomatization reactions of pyrroles are limited to transition-metal-catalyzed [4+3] cycloaddition and hydrogenation reactions. The enantioselective intermolecular alkylative dearomatization of pyrroles is rare and challenging due to multiple selectivity issues including the 相似文献
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