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991.
Three dinuclear copper(I) complexes, [Cu2(µ‐Cl)2(1,2‐(PPh2)2‐1,2‐C2B10H10)2]·2CH2Cl2 ( 1 ), [Cu2(µ‐Br)2(1,2‐(PPh2)2‐1,2‐C2B10H10)2]·2THF ( 2 ) and {Cu2(µ‐I)2[1,2‐(PPh2)2‐1,2‐C2B10H10]2} ( 3 ) have been synthesized by the reactions of CuX (X = Cl, Br and I) with the closo ligand 1,2‐(PPh2)2‐1,2‐C2B10H10. All these complexes were characterized by elemental analysis, FT‐IR, 1H and 13C NMR spectroscopy and X‐ray structure determination. Single crystal X‐ray structure determinations show that every complex contained di‐µ‐X‐bridged structure involving a crossed parallelogram plane formed by two Cu atoms and two X atoms (X = Cl, Br, I). The geometry at the Cu atom was a distorted tetrahedron, in which two positions were occupied by two P atoms of the PPh2 groups connected to the two C atoms of carborane (Cc), and the other two resulted from two X atoms which bridged the other Cu atom at the same time. To the best of our knowledge, this is the first example of copper(I) complexes with 1,2‐diphenylphosphino‐1,2‐dicarba‐closo‐dodecaborane as ligand characterized by X‐ray diffraction. The catalytic property of the complex 3 for the amination of iodobenzene with aniline was also investigated. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
992.
Diffraction fields in the focal space of some lens is investigated by using ray tracing and Stratton-Chu formulas. Two formulas are used. One is surface integration formula, and for another a line integration is added. Comparison of two calculation results is given. It is shown that for hyperbolic lens two calculations results are same and for extended hemi-ellipsoidal lens there are a lilt difference between them. 相似文献
993.
Yongmei Liu Wei Huang Yansheng Zhao Tao Dou 《Reaction Kinetics and Catalysis Letters》2009,96(1):157-163
Nano Cu-Zn-Al-ZSM-5 was directly synthesized in HCl solutions with the promotion of ultrasound. XRD results show that the
appropriate concentrations of HCl in the synthetic process were between 0.25 M and 1 M, and the optimal crystallization time
and temperature were 28 h and 200°C, respectively. The ultrasound irradiation can significantly increase the crystallization
of Cu-Zn-Al-ZSM-5 within 0.5 h. SEM photographs of Cu-Zn-Al-ZSM-5 zeolite showed the crystal size is about 50–60 nm. Results
of ICP/AES show that the weight% of Cu in 101(Cu-Zn-Al-SOD) and 202(Cu-Zn-Al-ZSM-5) were 4.42% and 2.30%, respectively. 相似文献
994.
Peng Dou Liang LiangJiangang He Zhen LiuHong-Yuan Chen 《Journal of chromatography. A》2009,1216(44):7558-7563
In recent years, functionalized magnetic nanoparticles (MNPs) have drawn continuously increasing attention due to their great potential for capturing biological molecules or species. However, functionalized MNPs as nanoextraction probes and the coupling with a separation platform for chemical analysis have not extensively investigated yet. In this study, boronate functionalized MNPs were synthesized and employed as extracting probes to capture and enrich cis-diol-containing biomolecules, and an off-line coupling method of the MNPs-based extraction with capillary electrophoresis (CE) was established by using pH junction, an on-line preconcentration technique in CE, as a bridge for the coupling. The prepared MNPs exhibited specific selectivity and sufficient capacity. The pH junction compressed a large injected sample volume into a much narrower sample zone and therefore significantly improved the detection sensitivity, solving the sensitivity mismatch between the MNPs-based extraction and CE. Experimental conditions for the pH junction and the desorption were optimized. Under the optimized conditions, the sensitivity was enhanced by 42-fold as compared with regular CE. N,N-dimethylformamide was found to be an effective desorption promoter, which reduced the desorption time to a few minutes. With the established method, riboflavin in a human urine sample was determined. 相似文献
995.
The remarkable differences between the infrared spectra of oxygen adsorption and nitrogen desorption in coal have been experimentally and theoretically investigated. Density functional theory calculations were performed to better explain the mechanism of oxygen adsorption using six different molecular models of coal. In addition, the remarkable differences of infrared spectra between oxygen adsorption and nitrogen desorption was defined as the index V, which was used to classify the spontaneous combustion tendency of coal. The experimental data indicated that the spectra in the 4000–2000 cm?1 and 1250–1050 cm?1 regions exhibited significant changes. These results suggest that the mechanism of oxygen adsorption is the alteration and transfer of charge density around the activated sites, which leads to the observed changes of the infrared spectra. The V, which is related to the alteration of spectral intensity, is found to decrease with the increase of adiabatic oxidation time and the relative spontaneous combustion period of coal. This observation solidifies the connection between sample spectral intensity and oxygen chemisorption. These data suggest that the hydroxy in hydroxy and carboxyl groups on the surface of coal particles is the site of oxygen chemisorption, and the V can be used to rapidly and accurately categorize the spontaneous combustion tendency of coal. 相似文献
996.
By using Fourier Optics, the general analytical expression of intensity distribution for the coherently combined beams positioned on the X-Y plane, which is applicable to both Gaussian and non-Gaussian beams, can be derived. Considering the fact that in many cases the array configuration can be regarded as composed of several regular polygons with a common center, an explicit analytical expression of the far-field intensity distribution for these cases has been derived. As an example, the above expression has been applied to study a 19 emitter array. Studies have also been done on the dark fringes of the far-field pattern for the specific emitters, whose numbers are 2 and 4, respectively. 相似文献
997.
Shi Sun Jingchun Liu Xiuxiu Sun Wenjun Zhu Fei Yang Lisa Felczak Q. Ping Dou Kequan Zhou 《Tetrahedron letters》2017,58(19):1895-1899
Five bioactive Annonaceous acetogenins, including three new compounds, annonamuricins A (1), B (2), and C (3), one registered but no spectral data reported compounds, annonamuricin D (4), and one known compound annonacin (5) were isolated from Graviola fruit (Annona muricata) and further determined through bioassay-guided fractionation. All five compounds are C35 Anonnonaceous acetogenins with a mono-tetrahydrofuran ring and four hydroxyls. Their structures were elucidated using spectral methods as well as chemical modification after isolation via chromatographic techniques and HPLC purification. These acetogenins demonstrated potent anti-proliferative activities against human prostate cancer PC-3 cells. 相似文献
998.
999.
The paper studies the 1-D piston problem of the relativistic Euler equations when the speed of the piston is a perturbation
of a constant. A sequence of approximate solutions constructed by a modified Glimm scheme is proved to be convergent to the
weak solution (which includes a strong leading shock) to the piston problem. In particular, we give the precise estimates
on the reflection of the perturbed waves on the piston and the leading shock.
The paper is supported by the National Natural Science Foundation of China (Grant 10626034) and the Special Research Fund
for Selecting Excellent Young Teachers of the Universities in Shanghai. 相似文献
1000.