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91.
The reaction of ninhydrin with 1,2,3- and 1,2,4-trimethylbenzene in the presence of H2SO4 or AlCl3 afforded 2-monoaryl and 2,2-diaryl-1,3-indanedione derivatives as the major products. With 1,3,5-trimethylbenzene as the arene nucleophile, either a reduction product or an indenoindanone derivative was obtained depending upon the catalyst employed in the reaction. 相似文献
92.
Catalytic asymmetric Reformatsky reactions of benzaldehyde with optically active menthyl bromoacetates in the presence of Zn-Cu couple were performed using 0.25 equiv. of (1R,2S) or (1S,2R)-dimethyl-2-amino-1,2-diphenyl ethanol as chiral ligand to obtain β - hydroxy esters with enantioselectivities up to 60.2%. The obvious double chiral induction effect was observed while chiral ligands matched with optically active substrates. 相似文献
93.
94.
Alginate beads were coated with copolymers of N-isopropylacrylamide and dimethylaminoethylmethacrylate (P(NIPAM-co-DMAEMA)s) by taking advantage of electrostatic interaction between alginate and the copolymer. The copolymers, of which DMAEMA contents in the feed for the copolymerization were 5.0% (PND 5) and 15.0% (PND 15), were employed for the coatings of alginate beads. The adsorption curve of PND 5 and PND 15 on the surface of alginate beads seemed to be Langmuir isotherm. The beads were coated in the PND solutions (2%, pH 5.0 or pH 7.0) and the amounts of adsorption (g PND/g alginate) were about 1.3 with PND 5 solution (pH 5.0), 1.2 with PND 15 solution (pH 5.0), and 0.75 with PND 15 (pH 7.0). The release from the beads coated with PNDs were observed at 30°C, 37°C, and 45°C using amaranth or FITC-dextran as a dye. The degrees of release were significantly suppressed due to the coating layers of PNDs. However, the coating layers could hardly act as a controller for the temperature-sensitive release. 相似文献
95.
Martin Danko Matej Mi?u?ík Mária Omastová Juraj Bujdák Du?an Chorvát Jr. 《Chemical Papers》2013,67(1):18-28
New fluorescence dyes with an alkoxysilane moiety were synthesised by the condensation of 3-(triethoxysilyl)-1-propanamine (3-aminopropyltriethoxysilane) with 4,10-benzothioxanthene-3,1′-dicarboxylic acid anhydride (BTXA) and N,N-dimethylaminonaphthalene-1,8-dicarboxylic acid anhydride (DMANA), which was accompanied by the formation of an imidic bridge. The compounds N-(3-(triethoxysilyl)propyl)-thioxantheno[2,1,9-dej]isoquinoline-1,3-dione (BTX-S) and 4-(N′, N′-dimethyl)-N-(triethoxysilyl)propyl-1,8-naphthalene dicarboxylic acid imide (DMAN-S) were characterised by steady-state and time-resolved fluorescence spectroscopy in chloroform and ethanol. Both conjugates (BTX-S and DMAN-S) exhibited absorption and emission bands in the same region as the un-substituted BTXA and DMANA. An important Stokes shift was observed for DMAN-S in ethanol. A high fluorescence quantum yield was observed for BTX-S in both solvents and for DMAN-S in chloroform. In addition, the newly developed fluorescent silane dyes were covalently attached to the microscopic particles of layered silicates and on the surface of SiO2 wafers as a proof of concept for fluorescence particle (surface) visualisation. The surface wafer modification was precisely characterised by X-ray photoelectron spectroscopy (XPS). Successful covalent linkage onto the particles of layered silicates was proved by confocal laser scanning microscopy technique. 相似文献
96.
A new simple receptor 1 based on aminosalicylimine was prepared. It exhibited an ‘off–on fluorescence type’ mode with high sensitivity in the presence of Zn2+. In particular, this chemosensor could clearly distinguish Zn2+ from Cd2+. Also, it could be a reusable chemosensor because the addition of EDTA quenched the fluorescence of the Zn2+-2·1 complex. Furthermore, receptor 1 had a sufficiently low detection limit (68 nM) in aqueous solutions, which implies that 1 could sense the nanomolar concentration of Zn2+. Therefore, this sensor has the ability to be a practical system for the monitoring of Zn2+ concentrations in aqueous samples. 相似文献
97.
Shao‐Bo Mi 《Surface and interface analysis : SIA》2014,46(2):102-105
Structural properties of YBa2Cu3O7‐δ/PrBa2Cu3O7‐δ heterointerfaces have been investigated by aberration‐corrected electron microscopy. Experimental evidence shows that c‐axis‐oriented YBa2Cu3O7‐δ/PrBa2Cu3O7‐δ heterostructures with atomically sharp interface epitaxially grow on SrTiO3(001) substrates. In terms of the contrast analysis, no apparent interdiffusion between YBa2Cu3O7‐δ and PrBa2Cu3O7‐δ occurs at the interface. In addition, stand‐off misfit dislocations and planar faults appear within PrBa2Cu3O7‐δ layer near the interface. Both misfit dislocations and interfacial dislocations resulting from the termination of planar faults contribute to misfit relaxation at the YBa2Cu3O7‐δ/PrBa2Cu3O7‐δ interface. The defect configuration of planar faults and stand‐off misfit dislocations is explored. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
98.
Nucleophile‐Dependent Regio‐ and Stereoselective Ring Opening of 1‐Azoniabicyclo[3.1.0]hexane Tosylate 下载免费PDF全文
Mi‐Kyung Ji Dietmar Hertsen Doo‐Ha Yoon Heesung Eum Hannelore Goossens Prof. Dr. Michel Waroquier Prof. Dr. Veronique Van Speybroeck Prof. Dr. Matthias D'hooghe Prof. Dr. Norbert De Kimpe Prof. Dr. Hyun‐Joon Ha 《化学:亚洲杂志》2014,9(4):1060-1067
1‐[(1R)‐(1‐Phenylethyl)]‐1‐azoniabicyclo[3.1.0]hexane tosylate was generated as a stable bicyclic aziridinium salt from the corresponding 2‐(3‐hydroxypropyl)aziridine upon reaction with p‐toluenesulfonyl anhydride. This bicyclic aziridinium ion was then treated with various nucleophiles including halides, azide, acetate, and cyanide in CH3CN to afford either piperidines or pyrrolidines through regio‐ and stereoselective ring opening, mediated by the characteristics of the applied nucleophile. On the basis of DFT calculations, ring‐opening reactions under thermodynamic control yield piperidines, whereas reactions under kinetic control can yield both piperidines and pyrrolidines depending on the activation energies for both pathways. 相似文献
100.
Cancer is a global issue and a serious threat to human health, one approach to treatment is starvation therapy. Recently, three-dimensional (3D) bioprinted tumor tissue models have been developed; however, whether 3D bioprinted models are good for in vitro study of starvation therapy is unclear. In this study, we studied the state of cells with serum-free medium in both 3D bioprinted scaffold and 2D cell cultures and found that 3D bioprinted cancer cells (3D cells) were more tolerant to serum starvation than 2D cells in terms of cell viability, cell proliferation, and M2 macrophage polarization. Moreover, the ratio of LC3II/I, an index of autophagy, increased much more in 3D cells, and 3D cells showed more autophagosomes than 2D cells after serum starvation, which indicated that the autophagy levels were higher in 3D cells. These results suggested that 3D cells are more tolerant to serum starvation than 2D cells, and autophagy may play an important role in this process. 相似文献