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991.
Metallacyclobutadienes are analogues of cyclobutadienes in which one of the cyclobutadiene CR groups has been formally replaced by a transition‐metal fragment. These metallacycles are interesting because they can play an important role in catalysis and can serve as starting materials for the syntheses of organometallic compounds such as metallabenzene, η5‐cyclopentadienyl, and η3‐cyclopropenyl complexes. Unlike cyclobutadienes, metallacyclobutadienes can be significantly more stable. A number of metallacyclobutadienes have now been isolated and thoroughly characterized, especially for those that contain transition metals of groups 5–9. Their properties have also been actively investigated. This article highlights the chemistry of metallacyclobutadienes with reference to their syntheses, reactivity, and structural properties. 相似文献
992.
The Origin of the Photoluminescence Enhancement of Gold‐Doped Silver Nanoclusters: The Importance of Relativistic Effects and Heteronuclear Gold–Silver Bonds 下载免费PDF全文
Dr. Xiao‐Ying Xie Dr. Pin Xiao Dr. Xiaoyan Cao Prof. Dr. Wei‐Hai Fang Prof. Dr. Ganglong Cui Prof. Dr. Michael Dolg 《Angewandte Chemie (International ed. in English)》2018,57(31):9965-9969
The weak photoluminescence of silver nanoclusters prevents their broad application as luminescent nanomaterials. Recent experiments, however, have shown that gold doping can significantly enhance the photoluminescence intensity of Ag29 nanoclusters but the molecular and physical origins of this effect remain unknown. Therefore, we have computationally explored the geometric and electronic structures of Ag29 and gold‐doped Ag29?xAux (x=1–5) nanoclusters in the S0 and S1 states. We found that 1) relativistic effects that are mainly due to the Au atoms play an important role in enhancing the fluorescence intensity, especially for highly doped Ag26Au3, Ag25Au4, and Ag24Au5, and that 2) heteronuclear Au?Ag bonds can increase the stability and regulate the fluorescence intensity of isomers of these gold‐doped nanoclusters. These novel findings could help design doped silver nanoclusters with excellent luminescence properties. 相似文献
993.
Wentao Qi Haoshan Wei Yong Zhang Jiaqin Liu Qi Zhou Wenfang Wang Jiewu Cui Yan Wang Chuansheng Chen Yucheng Wu 《Journal of Solid State Electrochemistry》2018,22(8):2367-2374
Novel NiCo2O4 nanoarrays have been in-situ grown on a La0.8Sr0.2MnO3-δ(LSM) cathode through a hydrothermal method, which presents the enhanced electrochemical performances of the LSM cathode for the intermediate temperature solid oxide fuel cells. XRD and SEM have been used to characterize phase structure and morphology of NiCo2O4 nanoarrays. The LSM cathode, modified by the NiCo2O4 nanoarrays, exhibits excellent electrochemical performances compared with the bare LSM cathode. The maximum peak power density of single cell, based on the NiCo2O4 nanoarrays modified the LSM cathode, reaches 957 mW cm?2 at 800 °C, which is almost two times higher than that for the cell based on the bare LSM cathode. 相似文献
994.
Synthesis of Higher Alcohols via Syngas on Cu/Zn/Si Catalysts. Effect of Polyethylene Glycol Content
Rong-Ji Cui Xing Yan Jin-Chuan Fan Wei Huang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(5):884-888
Cu/Zn/Si catalysts with different polyethylene glycol (PEG) content were prepared by a complete liquid-phase method, and characterized by XRD, H2-TPR, N2-adsorption, and XPS. The influence of PEG content on the higher alcohols synthesis from syngas was investigated. The results showed that addition of PEG can influence the texture and surface properties of the catalysts, and therefore affect their activity and product distribution. With an increase in PEG content, BET surface area, Cu crystallite size and surface active ingredient content of the catalysts first increased and then decreased, the CO conversion had similar variation tendency. However, the pore volume and pore diameter of the catalyst increased, and the binding energy of the active component and the content of Cu2O decreased, which resulted in higher catalyst selectivity towards higher alcohols. The highest C2+OH selectivity in total alcohols was 60.6 wt %. 相似文献
995.
Shi-hua Sang Xiao-ping Li Da-wei Li Rui-zhi Cui Cui Wei 《Russian Journal of Inorganic Chemistry》2018,63(12):1644-1650
Solid-liquid equilibria in the quaternary systems KCl–MgCl2–SrCl2–H2O and NaCl–KCl–SrCl2–H2O at 348 K were measured by the isothermal solution saturation method. The composition of the equilibrium solid phase, solubilities of salts, and densities of saturated solution in the two systems were determined. Phase diagrams, water content diagrams and solution density diagrams of quaternary systems were plotted according to experimental data. The phase diagram of the quaternary system NaCl–KCl–SrCl2–H2O has one invariant point, three univariant curves as the boundary of NaCl, KCl and SrCl2 · 2H2O. This phase diagrams were simple co-saturation type without complex salt and solid solution. For the quaternary system KCl–MgCl2–SrCl2–H2O, one complex salt KCl · MgCl2 · 6H2O (Car) had been found in this system, consisted of five univariant curves, two invariant points and four crystallization regions of MgCl2 · 6H2O (Bis), KCl, SrCl2 · 2H2O and KCl · MgCl2 · 6H2O. And the densities transformation rules were simply discussed. Simultaneously, the solubilities and densities data in invariant point of the quaternary system NaCl–KCl–SrCl2–H2O had been compared with the experimental data of previous researchers. 相似文献
996.
The synthesis of a novel class of phosphorus amidines via a copper-catalyzed multicomponent reaction of sulfonyl azides, alkynes and iminophosphoranes is described. The protocol is efficient and general. 相似文献
997.
Chlorosulfonyl-containing naphthol azo compounds were prepared by reaction of the corresponding sulfonate-containing naphthol
azo dyes with thionyl chloride in the presence of a catalytic quantity of N,N-dimethylformamide and various solvents. The yields and reaction selectivity of chlorosulfonyl-containing naphthol azo compounds
were discussed according to the properties of solvents. It was demonstrated that high chemical selectivity and high yield
were achieved by using benzene, toluene or thionyl chloride as solvent. Additionally, on account of unstable properties of
sulfonyl chloride compounds in MS and 1H-NMR analyses, a new analytical method using stable sulfonamide is put forward to verify the chemical structures of the corresponding
sulfonyl chloride compounds indirectly.
__________
Translated from Journal of Dalian University of Technology, 2008, 48(1): 26–32 相似文献
998.
In this paper, some improvements on Darvishi and Hessari [On convergence of the generalized AOR method for linear systems with diagonally dominant coefficient matrices, Appl. Math. Comput. 176 (2006) 128–133] are presented for bounds of the spectral radius of lω,r, which is the iterative matrix of the generalized AOR (GAOR) method. Subsequently, some new sufficient conditions for convergence of GAOR method will be given, which improve some results of Darvishi and Hessari [On convergence of the generalized AOR method for linear systems with diagonally dominant coefficient matrices, Appl. Math. Comput. 176 (2006) 128–133]. 相似文献
999.
Mengjun Cui Jingya Li Ajuan Yu Jinli Zhang Yangjie Wu 《Journal of molecular catalysis. A, Chemical》2008,290(1-2):67-71
One-pot synthesis of the N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) adduct of cyclopalladated ferrocenylimine complex 1 has been described. This complex has been successfully applied to Suzuki coupling reaction. Various aryl chlorides and boronic acids can be coupled efficiently with a mild base K3PO4·7H2O and low catalyst loadings. This system has been proven to be compatible with the sterically hindered aryl chlorides and some boronic acids leading to form di- and tri-ortho-substituted biaryls in high yields. 相似文献
1000.
Zhu X Koenig P Gellman SH Yethiraj A Cui Q 《The journal of physical chemistry. B》2008,112(17):5439-5448
All-atom molecular mechanical (MM) force field parameters are developed for a cyclic beta-amino acid, amino-cyclo-pentane-carboxylic acid (ACPC), using a multi-objective evolutionary algorithm. The MM model is benchmarked using several short, ACPC-containing alpha/beta-peptides in water and methanol with SCC-DFTB (self consistent charge-density functional tight binding)/MM simulations as the reference. Satisfactory agreements are found between the MM and SCC-DFTB/MM results regarding the distribution of key dihedral angles for the tetra-alpha/beta-peptide in water. For the octa-alpha/beta-peptide in methanol, the MM and SCC-DFTB/MM simulations predict the 11- and 14/15-helical form as the more stable conformation, respectively; however, the two helical forms are very close in energy (2-4 kcal/mol) at both theoretical levels, which is also the conclusion from recent NMR experiments. As the first application, the MM model is applied to an alpha/beta-pentadeca-peptide in water with both explicit and implicit solvent models. The stability of the peptide is sensitive to the starting configuration in the explicit solvent simulations due to their limited length ( approximately 10-40 ns). Multiple ( approximately 20 x 20 ns) implicit solvent simulations consistently show that the 14/15-helix is the predominant conformation of this peptide, although substantially different conformations are also accessible. The calculated nuclear Overhauser effect (NOE) values averaged over different trajectories are consistent with experimental data, which emphasizes the importance of considering conformational heterogeneity in such comparisons for highly dynamical peptides. 相似文献