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991.
Remote Construction of Chiral Vicinal Tertiary and Quaternary Centers by Catalytic Asymmetric 1,6‐Conjugate Addition of Prochiral Carbon Nucleophiles to Cyclic Dienones 下载免费PDF全文
Yuan Wei Zunwu Liu Xinxin Wu Jie Fei Xiaodong Gu Xiaoqian Yuan Prof. Dr. Jinxing Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18921-18924
An unprecedented remote construction of chiral vicinal tertiary and quaternary centers by a catalytic asymmetric 1,6‐conjugate addition of prochiral carbon nucleophiles to cyclic dienones has been developed. Both 5H‐oxazol‐4‐ones and 2‐oxindoles were found to be very efficient carbon nucleophiles in this reaction at a remote position, giving products with excellent enantio‐ and diastereoselectivities (up to 99 % ee and >19:1 d.r. for 5H‐oxazol‐4‐ones and up to 97 % ee and >19:1 d.r. for 2‐oxindoles). 相似文献
992.
Synthesized 2,5-diphenylethynyl thiophene based bent bolaamphiphiles can self-organize into square honeycomb LC phases with p4mm symmetries in the presence of water. UV and PL measurements indicate fl uorescent properties making them potential candidates for application in fl uorescence sensor devices 相似文献
993.
The rapid and reliable measurement of hydrogen peroxide (H2O2) is imperative for many areas of technology, including pharmaceutical, clinical, food industry and environmental applications. In this work, a novel multifunctional complex, [Ru(bpy)2(luminol-bpy)](PF6)2 (bpy: 2,20'-bipyridine), was designed and synthesized by incorporating a Ru(II) complex with a luminal group. In the presence of horseradish peroxidase (HRP), reaction of [Ru(bpy)2(luminol-bpy)]2+ with H2O2 can be monitored by three sensing channels including photoluminescence (PL), chemiluminiscence (CL) and eletrochemiluminiscence (ECL). The quantitative assays for H2O2 in aqueous solutions using [Ru(bpy)2(Luminalbpy)]( PF6)2 as a probe were established with PL, ECL and CL signal output modes, respectively. 相似文献
994.
995.
Development of a method using high‐performance liquid chromatographic fingerprint and multi‐ingredients quantitative analysis for the quality control of Yangxinshi Pian 下载免费PDF全文
Yerui Li Kai Yang Bowen Liu Ye Jin Xuesong Liu Zuolin Jiang Lianjun Luan Yongjiang Wu 《Journal of separation science》2015,38(17):2989-2994
A simple and reliable method of high‐performance liquid chromatography with diode array detection method was developed for fingerprint analysis and simultaneous determination of six compounds including puerarin, salvianolic acid B, berberine hydrochloride, palmatine chloride, dehydrocorydaline, and icariin in the Chinese medicine preparation Yangxinshi Pian. The separation was performed on an Agilent Eclipse XDB‐C18 reserved‐phase column (250 mm × 4.6mm I.D., 5 μm) using gradient elution with 50 mmol/L monopotassium phosphate aqueous solution and methanol as mobile phase at a flow rate of 1.0 mL/min. The column operating temperature was set at 30°C, and the detection wavelength was 280 nm. The method was validated by linearity, precision, accuracy, stability, and recovery. For fingerprint analysis, 25 peaks were selected as the common peaks, and four kinds of similarities including cosine similarity (S), ratio of similarity (S′), projection content similarity (C), and content similarity (P) were applied to evaluate the quality consistency of different batches of Yangxinshi Pian. The results showed that the developed method was an efficient tool for quality evaluation of Yangxinshi Pian. 相似文献
996.
Zheng-Feng Wu Han Bao Fa-Yang Zhou Jing-Xin Liu Fan-Cheng Meng Lu Feng Jin-Jian Lu Qing-Wen Zhang Yang Ye Li-Gen Lin 《中国化学快报》2017,28(8):1711-1715
Phytochemical investigation on the seeds of Caesalpinia sappan led to the isolation of five new cassanetype diterpenoids, named 11-oxo-phanginin A(1), caesalsappanins O–Q(2–4) and phanginin U(5),together with five known compounds. The structures of the new compounds were elucidated by extensive analysis of mass spectrometric and 1D and 2D NMR spectroscopic data. All the new compounds showed moderate cytotoxic effects on human breast cancer MCF-7 and human colon cancer HCT116 cell lines. 相似文献
997.
Tao Ye Xin-Yi Jin Liao Chen Chong Hu Jie Ren Yu-Jing Liu Gang Wu Lu-Jian Chen Hong-Zheng Chen Han-Ying Li 《中国化学快报》2017,28(4):857-862
Synthetic calcite single crystals,due to their strong crystal habit,tend to grow into characteristic rhombohedra.In the nature,biogenic calcite crystals form composites together with biomacromolecular materials,spurring investigations of how the growing calcite single crystals change their habit to satisfy the curvature of the organic phase.In this work,we examine calcite crystallization on a flat surface of glass slide and a curved surface of polystyrene(PS)sphere.The crystals exhibit tiny contact area onto the glass substrate that is averagely only 15% of their projected area on the substrate.In sharp contrast,the contact area greatly increase to above 75% of the projected area,once magnesium ions or agarose gel networks are introduced into the crystallization media.Furthermore,the calcite crystals form rough and step-like interfaces with a curved surface.However,the interfaces become smooth and curved as the crystals grow in presence of magnesium ions or agarose gel networks.The discrepancy between the interfacial structures implies kinetic effects of the additives on the crystallization around the surfaces. This work may provide implications for understanding the formation mechanisms of single-crystal composite materials. 相似文献
998.
Herein,we demonstrated that poly(ethylene oxide)(PEO),urea and thiourea can crystallize into novel ternary complex with the molar ratio of guest polymer and host small molecule as 3:2,and proved that the ternary complex behaves isomorphism phenomenon by varying the ratio between urea and thiourea for the first time.This observation gives a boost to prepare co-crystals of different small molecules that cannot be obtained by direct mixing without the aid of polymer chains. 相似文献
999.
Shengqiang Xu Qingming Huang Yanting Xu Zhuoliang Ye Xiaohui Chen 《Research on Chemical Intermediates》2017,43(12):7055-7071
The phosphorus (P) modified MoO3–Bi2SiO5/SiO2 catalyst was prepared by a simple co-impregnation method and investigated in the epoxidation of propylene by molecular oxygen. The catalyst was characterized by X-ray diffraction (XRD), N2 adsorption–desorption analysis, NH3-temperature-programmed desorption (NH3-TPD), transmission electron microscopy, and Raman spectroscopy. It was found that the P-modified MoO3–Bi2SiO5/SiO2 catalyst with a P/Mo molar ratio of 0.5 exhibits the best catalytic performance for epoxidation of propylene by O2, the TOFs for propylene oxide (PO) formation was four times higher than that of the unmodified one at 633 K. The modification by P could promote the dispersion of MoO3 nanoparticles and increase the number of weak and moderate acid sites with respect to the phosphorus-free MoO3–Bi2SiO5/SiO2 catalyst, which were beneficial to the formation of PO. Moreover, the introduction of P also could protect the mesoporous structure by inhibiting the formation of Bi2Mo3O12, which was beneficial to the dispersion of active species. We suppose that the phosphorus, bismuth and molybdenum species of P-modified MoO3–Bi2SiO5/SiO2 catalyst play important roles for propylene epoxidation by molecular oxygen. 相似文献
1000.
Xin-Lei WANG Kui MA Li-Hong GUO Tong DING Qing-Peng CHENG Ye TIAN Xin-Gang LI 《物理化学学报》2017,33(8):1699-1708
采用蒸氨法制备出不同Cu负载量的xCu/SiO_2-AE催化剂,并将其用于二甲醚水蒸气重整制氢反应。当Cu负载量为30%(w)时,30Cu/SiO_2-AE催化剂表现出最佳的催化性能。结果显示,该方法制备的催化剂表面具有高度分散的CuO和层状硅酸铜物相,经还原后分别形成Cu~0和Cu~+物种。与常规浸渍法制备的30Cu/SiO_2-IM催化剂相比,蒸氨法制备的30Cu/SiO_2-AE催化剂具有优异的催化稳定性和活性,这与其独特的层状结构和表面Cu~0与Cu~+之间的协同作用相关。 相似文献