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73.
l‐Proline‐functionalized Fe3O4 nanoparticles as a novel magnetic chiral catalyst for the direct asymmetric Mannich reaction 下载免费PDF全文
l ‐Proline has been successfully anchored on the surface of magnetic nanoparticles and characterized using powder X‐ray diffraction, scanning electron microscopy, vibrating sample magnetometry and Fourier transform infrared spectroscopy. These nanoparticles as a chiral catalyst have been employed to promote the direct asymmetric Mannich reaction. The corresponding products are obtained in high yields with high level of diastereoselectivity (up to 99:1 dr) in the presence of Fe3O4– l ‐proline. Also this heterogeneous catalyst can be recovered easily and reused many times without significant loss of its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
74.
“(Diphosphine)Nickel”‐Catalyzed Negishi Cross‐Coupling: An Experimental and Theoretical Study 下载免费PDF全文
Dr. Emmanuel Nicolas Alexia Ohleier Florian D'Accriscio Dr. Anne‐Frédérique Pécharman Dr. Matthieu Demange Dr. Philippe Ribagnac Dr. Jorge Ballester Dr. Corinne Gosmini Dr. Nicolas Mézailles 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7690-7694
The use of a strongly donating “(bis‐dialkylphosphine)Ni” fragment promotes the catalytic coupling of a large range of ArCl and ArZnCl derivatives under mild conditions. Stoichiometric mechanistic investigations and DFT calculations prove that a Ni0/NiII cycle is operative in this system. 相似文献
75.
Conjugated polymer nanoparticles with aggregation induced emission characteristics for intracellular Fe3+ sensing 下载免费PDF全文
Dongliang Yang Fei Li Zhimin Luo Biqing Bao Yanling Hu Lixing Weng Yixiang Cheng Lianhui Wang 《Journal of polymer science. Part A, Polymer chemistry》2016,54(12):1686-1693
In this article, a novel zwitterionic conjugated polyelectrolyte containing tetraphenylethene unit was synthesized via Pd‐catalyzed Sonogashira reaction. The resulting polymer (P2), which exhibited typical aggregation‐induced emission (AIE) properties, was weakly fluorescent in dilute DMSO solution and showed bright fluorescence emissions when aggregated in DMSO/water mixtures or fabricated into conjugated polymer nanoparticles (CPNs). The nanoparticles from P2 could be prepared by reprecipitation method with an average diameter around 23 nm. Notably, the cell‐staining efficiencies of lipid‐P2 nanoparticles could be enhanced with lipid encapsulation and these nanoparticles were endocytosed via caveolae‐mediated and clathrin‐mediated endocytosis pathways. Furthermore, the lipid‐P2 nanoparticles with low cytotoxicity, high photostability and efficient cell staining ability could be employed for in vitro detection of Fe3+ ions in A549 cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1686–1693 相似文献
76.
Donor-acceptor type copolymers have wide applications in organic field-effect transistors and organic photovoltaic devices. Thieno[3,4-c]pyrrole-4,6-dione (TPD), as an electron-withdrawing unit, has been widely used in D-A type copolymers recently. Till now, the highest power conversion efficiency and mobility of TPD-based copolymers are over 8% and 1.0 cm2 V-1 s-1 respectively. In this review, the recent progress of TPD-based copolymers in organic solar cells and organic transistors is summarized. 相似文献
77.
Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R(R = F, OH, NH2) have been systematically carried out by combined density functional theory(DFT) and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex(Q), one transition state(TS), and one intermediate(IM) which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order: GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation. 相似文献
78.
Silver(I)‐Catalyzed Enantioselective [3+2]‐Cycloaddition Reaction of α‐Silylimines: A Facile Route to Quaternary‐Carbon‐Rich Scaffolds 下载免费PDF全文
Dr. Naredla Kesava‐Reddy Christopher Golz Prof. Dr. Carsten Strohmann Dr. Kamal Kumar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18373-18377
A silver‐catalyzed highly enantioselective 1,3‐dipolar cycloaddition reaction of α‐silylimines with pyrone‐based trisubstituted olefins was developed affording bi‐ and tricyclic α‐quaternary‐carbon‐rich pyrano‐pyrrolidines in excellent yields. The tricyclic benzopyrone adducts thus obtained were efficiently transformed into highly complex tetracyclic scaffolds supporting four consecutive stereogenic centers with three quaternary carbons. 相似文献
79.
Is PdII‐Promoted σ‐Bond Metathesis Mechanism Operative for the PdPEPPSI Complex‐Catalyzed Amination of Chlorobenzene with Aniline? Experiment and Theory 下载免费PDF全文
Feiqun Wang Lei Zhu Yunfei Zhou Prof. Xiaoguang Bao Prof. Henry F. Schaefer III 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):4153-4161
Reduction of the Pd?PEPPSI precatalyst to a Pd0 species is generally thought to be essential to drive Buchwald–Hartwig amination reactions through the well‐ documented Pd0/PdII catalytic cycle and little attention has been paid to other possible mechanisms. Considered here is the Pd?PEPPSI‐catalyzed aryl amination of chlorobenzene with aniline. A neat reaction system was used in new experiments, from which the potentially reductive roles of the solvent and labile ligand of the PEPPSI complex in leading to Pd0 species are ruled out. Computational results demonstrate that anilido‐containing PdII intermediates involving σ‐bond metathesis in pathways leading to the diphenylamine product have relatively low barriers. Such pathways are more favorable energetically than the corresponding reductive elimination reactions resulting in Pd0 species and other putative routes, such as the PdII/PdIV mechanism, single electron transfer mechanism, and halide atom transfer mechanism. In some special cases, if reactants/additives are inadequate to reduce a PdII precatalyst, a PdII‐involved σ‐bond metathesis mechanism might be feasible to drive the Buchwald–Hartwig amination reactions. 相似文献
80.
Fen Yu Dr. Xuan Fang Huimin Jia Miaoxing Liu Xiaotong Shi Chaowen Xue Dr. Tingtao Chen Prof. Zhipeng Wei Prof. Fang Fang Prof. Hui Zhu Prof. Hongbo Xin Prof. Jing Feng Prof. Xiaolei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8053-8058
For the first time, the influence of different types of atoms (Zn and O) on the antibacterial activities of nanosized ZnO was quantitatively evaluated with the aid of a 3D‐printing‐manufactured evaluation system. Two different outermost atomic layers were manufactured separately by using an ALD (atomic layer deposition) method. Interestingly, we found that each outermost atomic layer exhibited certain differences against gram‐positive or gram‐negative bacterial species. Zinc atoms as outermost layer (ZnO?Zn) showed a more pronounced antibacterial effect towards gram‐negative E. coli (Escherichia coli), whereas oxygen atoms (ZnO?O) showed a stronger antibacterial activity against gram‐positive S. aureus (Staphylococcus aureus). A possible antibacterial mechanism has been comprehensively discussed from different perspectives, including Zn2+ concentrations, oxygen vacancies, photocatalytic activities and the DNA structural characteristics of different bacterial species. 相似文献