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71.
A new method for the preparation of tetracyclic uracils (oxa-helicene) 4 was developed. The intramolecular hetero-Diels-Alder reaction of 1-oxa-1,3-butadiene 3 and an unactivated alkyne in the presence of CuI led to tetracyclic uracils 4 in aqueous media with good yields. The 1-oxa-1,3-butadiene 3 was prepared through Knoevenagel reaction of O-propargylated salicylaldehyde derivatives and barbituric acid or 1,3-dimethylbarbituric acid. 相似文献
72.
Nanocomposites with thermo and photo-switchable fluorescent properties were synthesized via mini-emulsion polymerization based on spiropyran and methyl methacrylate monomer. The photophysical behavior of fluorescence nanocomposites was investigated by fluorescence spectrophotometry in different temperature, UV-light and time of exposure. It was found that methyl methacrylate polymer is capable of acting as a protective layer and play a critical role in improving the photostability of colorants. The nanocomposites exhibited excellent fluorescent thermo-switching action with respect to the free spiro molecule. 相似文献
73.
The effect of 4,4′-diaminodiphenylsulfone (DADPS) as a co-additives in iodide/triiodide redox electrolyte on the performance of dye-sensitized solar cell based on the 2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid (TPA) and 2-cyano-3-(2΄-(5΄,10΄,15΄,20΄- tetraphenylporphyrinato Zinc (II)yl) acrylic acid (Zn-1) dyes have been investigated. Compared withstandard electrolyte (0.1 M LiI, 0.05 M I2, 0.6 M 1-butyl-2,3-dimethylimidazolium iodide (BDMII) and TBP (0.5, 1 M)), adding 0.5 M of DADPS, as a co-additive, into the electrolyte system has caused increasing short current density (Jsc) and open-circuit potential (Voc) consequently the energy conversion (η) improved. Electrochemical impedance results indicate adsorbing of DADPS on the titanium dioxide surface leads to an increase in the lifetime (τ). Adsorbing of DADPS on the semiconductor surface retards the interfacial charge recombination that has a beneficial effect on the Voc and Jsc. The results showed that amine groups of DADPS attach to the conduction band (CB) of TiO2 film and suppress the electron recombination process and as a result, it can be applied as a promising co-additive in DSSCs. 相似文献
74.
Firouz Matloubi Moghaddam Zohreh Mirjafary Hamdollah Saeidian Salman Taheri Malihe Doulabi Mostafa Kiamehr 《Tetrahedron》2010,66(1):134-5520
An efficient, single step synthesis of hitherto unknown indole-annulated pentacyclic indolylhydroquinolines via tandem C-alkylation and intramolecular S-alkylation of indolin-2-thiones with N-alkylquinolinium salts in excellent yields (83-95%) is reported. This facile approach provides a powerful entry into polycyclic structures containing nitrogen and sulfur related to alkaloids. The structure of the product was determined by Röntgen crystal structure analysis. 相似文献
75.
IntroductionIntheindustrialpractice ,manycontrolproblemofsystemscanbestudiedthroughinterconnectedsystems.Earlierresearchoninterconnectedsystemfocusedonpowersystem[1,2 ],controlofdistributedsystems (e .g .,regulationofseismiccables,vibrationcontrolinbeams,etc.) … 相似文献
76.
Activation analysis of some seaweed samples occurring off the coastline areas of Myanmar is described. Na, K and I were determined using Am(Be) radionuclide neutron source and low level -counting. 相似文献
77.
We classify Jordan G-tori, where G is any torsion-free abelian group. Using the Zelmanov prime structure theorem, such a class divides into three types, the Hermitian type, the Clifford type, and the Albert type. We concretely describe Jordan G-tori of each type. 相似文献
78.
Abstract The title compound containing two metal centers each complexes to one enantiopure chiral norephedrine-derived pyridyl-(bis)
oxazoline (pybox) ligand and linked by two hydroxide bridges, crystallizes to give rodlike form in the space group P21(# 4). Cell Parameters are a = 10.2344(18) ?, b = 13.952(3) ?, c = 23.371(4) ?, β = 94.586(4)°, V = 3326.6(10) ?3. The metal-hydroxide motif forms a square plane at the center of the structure with the scandium centers exhibiting a distorted
pentagonal bipyramid coordination sphere consisting of the chelating ligand and two additional triflouromethyl sulfonyloxy
species positioned anti to each other.
Graphical abstract The complex contains two metal centers each complexes to one enantiopure chiral norephedrine-derived pyridyl-(bis) oxazoline
(pybox) ligand and linked by two hydroxide bridges.
Structural report for Sc[(R,R)-norephedrine-pybox](OTf)3 dimeric complex
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
79.
The model of Ouchiyama and Tanaka 1 - 3 was successfully adapted to calculate the maximum packing fraction (ϕm) of polymer latexes with varying bimodal particle size distributions based upon rheological measurements performed on its constituent parts. The values of ϕm calculated from the model can be used to predict the rheological properties of the latices. The model was experimentally validated and used for the prediction the viscosity of studied bimodal latices of known concentration using the master curve of viscosity-reduced volume fraction (η vs. ϕ/ϕm). 相似文献
80.
Athermal silica-based interferometer-type planar light-wave circuits were realized by a newly developed multicore fabrication method. In this method, inductively coupled chemical-vapor deposition and polishing technologies are adopted on a silica substrate with a trench-type waveguide pattern prepared by reactive ion etching. Two kinds of deposited core material, 10GeO2-90SiO2 (mol. %) and 8GeO2-5B2O3-87SiO2 (mol. %), which show wavelength temperature dependence of 9.7 and 8.1 pm/degree C, respectively, were used to prepare the waveguide sections in a device. By adjustment of the lengths of waveguide sections with these two different core materials, athermal characteristics of less than 0.5 pm/degree C were achieved for Mach-Zehnder interferometer filter devices at the 1.55-microm wavelength range while the temperature varied from -20 to 80 degrees C. The new method is also applicable for the preparation of many other kinds of functional devices. 相似文献