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191.
Yong Qiang TU 《中国化学快报》1992,3(8):625-628
Three new β-dihydroagarofuran sesquiterpene polyol esters,one alkaloid andtwo non-alkaloids,were isolated from the MeOH extract of seed oil of Celastrus angulatus.Their structures were elucidated on the basis of UV,IR,mass,NOE difference,~1H-NMR,~(13)C-NMR and ~1H-~(13)C long-range correlation spectroscopy. 相似文献
192.
研究了环磷酰的示波极谱法。环磷酰胺经亚硝化反应后,其产物在0.1mol/L HCl介质中于-0.490V附近出现一清晰的阴极还原波。在1.0×1-^-4mol/L范围内,浓度与波高有良好的线性关系,检测下限可达5×10^-8mol/L.用于针剂,注剂和尿液中环磷酰胺的测定均获满意的结果。 相似文献
193.
Wang M Wang BM Shi L Tu YQ Fan CA Wang SH Hu XD Zhang SY 《Chemical communications (Cambridge, England)》2005,(44):5580-5582
A quinine/Selectfluor combination inducing rearrangement reaction of allylic alcohols was discovered, which involved a moderate yield with good enantioselective construction of alpha-quaternary carbon center and beta-fluoro aldehyde under base condition. 相似文献
194.
Laser-ablated Au atoms have been co-deposited with CO molecules in solid argon to produce gold carbonyls. In addition to the previously reported Au(CO)n (n = 1, 2) and Au2(CO)2 molecules, small gold cluster monocarbonyls Au(n)CO (n = 2-5) are formed on sample annealing and characterized using infrared spectroscopy on the basis of the results of the isotopic substitution and CO concentration change and comparison with theoretical predictions. Of particular interest is that the mononuclear gold carbonyls, Au(CO)n (n = 1, 2), are favored under the experimental conditions of higher CO concentration and lower laser energy, whereas the yields of the gold cluster carbonyls, Au(n)CO (n = 2-5) and Au2(CO)2, remarkably increase with lower CO concentration and higher laser power. Density functional theory (DFT) calculations have been performed on these molecules and the corresponding small naked gold clusters. The identities of these gold carbonyls Au(n)CO (n = 1-5) and Au(n)(CO)2 (n = 1, 2) are confirmed by the good agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts. 相似文献
195.
Shouzhi Pu Jingkun Xu Liang Shen Qiang Xiao Tianshe Yang Gang Liu 《Tetrahedron letters》2005,46(5):871-875
The photochromic diarylethene, 1,2-bis(2-methyl-5-(2-(1,3-dithiolpentane))-thien-3-yl)perfluorocyclopentene (BMDTP), has been synthesized in high yield and its structure was determined by X-ray crystallographic analysis. The compound undergoes a photochromic reaction both in solution and in the single crystalline phase. In addition, its fluorescence property in solution is discussed. 相似文献
196.
计算了43种不对称变色酸双偶氮膦酸型显色剂的Am拓扑指数,并将其与结构选择性因子相结合,用于偶氮类显色剂结构与铈显色反应对比度的相关性研究,讨论了显色剂结构对拓扑指数有译比度的影响。 相似文献
197.
We report the synthesis of open-ended MoS2 nanotubes and their application as the catalyst for methanation of carbon monoxide with hydrogen. Because the catalysis of the methanation reaction occurs at relatively low temperatures, such nanotubes may provide new solutions toward harnessing the environmental load caused by CO emission. 相似文献
198.
The importance of accurately treating van der Waals interactions between the quantum mechanical (QM) and molecular mechanical (MM) atoms in hybrid QM/MM simulations has been investigated systematically. First, a set of van der Waals (vdW) parameters was optimized for an approximate density functional method, the self-consistent charge-tight binding density functional (SCC-DFTB) approach, based on small hydrogen-bonding clusters. The sensitivity of condensed phase observables to the SCC-DFTB vdW parameters was then quantitatively investigated by SCC-DFTB/MM simulations of several model systems using the optimized set and two sets of extreme vdW parameters selected from the CHARMM22 forcefield. The model systems include a model FAD molecule in solution and a solvated enediolate, and the properties studied include the radial distribution functions of water molecules around the solute (model FAD and enediolate), the reduction potential of the model FAD and the potential of mean force for an intramolecular proton transfer in the enediolate. Although there are noticeable differences between parameter sets for gas-phase clusters and solvent structures around the solute, thermodynamic quantities in the condensed phase (e.g., reduction potential and potential of mean force) were found to be less sensitive to the numerical values of vdW parameters. The differences between SCC-DFTB/MM results with the three vdW parameter sets for SCC-DFTB atoms were explained in terms of the effects of the parameter set on solvation. The current study has made it clear that efforts in improving the reliability of QM/MM methods for energetical properties in the condensed phase should focus on components other than van der Waals interactions between QM and MM atoms. 相似文献
199.
The reactions of the cationic, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(8)-C(8)H(8))]BF(4) (1, Ar=C(6)H(5); 2, Ar=p-CH(3)C(6)H(4); 3, Ar=p-CF(3)C(6)H(4)) with LiN(C(6)H(5))(2) in THF at low temperature gave novel N-nucleophilic-addition products, namely, the neutral, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(7)-C(8)H(8)N(C(6)H(5))(2))] (4, Ar=C(6)H(5); 5, Ar=p-CH(3)C(6)H(4); 6, Ar=p-CF(3)C(6)H(4))). Cationic bridging carbyne complexes 1-3 react with (C(2)H(5))(2)NH, (iC(3)H(7))(2)NH, and (C(6)H(11))(2)NH under the same conditions with ring cleavage of the COT ligand to produce the novel diiron-bridging carbene inner salts [Fe(2)[mu-C(Ar)C(8)H(8)NR(2)](CO)(4)] (7, Ar=C(6)H(5), R=C(2)H(5); 8, Ar=p-CH(3)C(6)H(4), R=C(2)H(5); 9, Ar=p-CF(3)C(6)H(4), R=C(2)H(5); 10, Ar=C(6)H(5), R=iC(3)H(7); 11, Ar=p-CH(3)C(6)H(4), R=iC(3)H(7); 12, Ar=p-CF(3)C(6)H(4), R=iC(3)H(7); 13, Ar=C(6)H(5), R=C(6)H(11); 14, Ar=p-CH(3)C(6)H(4), R=C(6)H(11), 15, Ar=p-CF(3)C(6)H(4), R=C(6)H(11)). Piperidine reacts similarly with cationic carbyne complex 3 to afford the corresponding bridging carbene inner salt [Fe(2)[mu-C(Ar)C(8)H(8)N(CH(2))(5)](CO)(4)] (16). Compound 9 was transformed into a new diiron-bridging carbene inner salt 17, the trans isomer of 9, by heating in benzene. Unexpectedly, the reaction of C(6)H(5)NH(2) with 2 gave a novel COT iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NHC(6)H(5)](mu-CO)(CO)(3)(eta(8)-C(8)H(8))] (18). However, the analogous reactions of 2-naphthylamine with 2 and of p-CF(3)C(6)H(4)NH(2) with 3 produce novel chelated iron-carbene complexes [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(10)H(7)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (19) and [Fe(2)[=C(C(6)H(4)CF(3)-p)NC(6)H(4)CF(3)-p](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (20), respectively. Compound 18 can also be transformed into the analogous chelated iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(6)H(5)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (21). The structures of complexes 6, 9, 15, 17, 18, and 21 have been established by X-ray diffraction studies. 相似文献
200.
Changmei Sun Rongjun Qu Qiang Xu Chunnuan Ji Yanzhi Sun 《European Polymer Journal》2007,43(4):1501-1509
Two novel chelating resins were prepared by anchoring ethylenediamine to crosslinked polystyrene via a spacer containing sulfide. Their structures were characterized by Fourier transform-infrared spectra (FTIR) and scanning electron microscopy (SEM). Porous structure parameters of the resins were measured by ASAP 2020 using BET and BJH methods. Their adsorption capacities for several heavy metal ions especially Hg2+ were investigated. The results showed that for the two resins, the more N contents did not mean the better adsorption capacity and the saturated adsorption capacity of poly(2-ethylenediamidomercaptomethylstyrene) (PSM-EDA) for Hg2+ could reach to 3.0 mmol/g at room temperature. Isothermal adsorptions of the resins for Hg2+ could be described by Langmuir formula. The adsorption mechanism of the resins for Hg2+, Cu2+ and Ag+ was confirmed by X-ray photoelectron spectroscopy (XPS) and FTIR. 相似文献