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991.
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
992.
Rong Zhang Qiao Bai Ling Xu Yan Hui Wang Department of Life Science Technology Beijing University of Chemical Technology Beijing China Institute of Materia Medica Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China 《中国化学快报》2007,18(6):656-658
2-Substituted-2,3-dihydro-4(1H)-quinazolinones were obtained in high yields by condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes or ketones in the refluxing 2,2,2-trifluoroethanol without any catalyst. 相似文献
993.
引言我们曾研究了金属镍,铜,钛,钨,铝,铁,银,铂,钼等和非金属硅与石墨及ⅢA—VA与ⅡB—ⅥA化合物晶体等的弛豫、重构和吸附表而的60多个表面结构。本文报道研究Ag(100)c(2×2)—C1表面的结果。Zanazzi和Jona观测了Ag(100)c(2×2)—C1表面结构的21束LEED谱,并采用层—KKR(Korring—Kohn—Rostocker)法,对清洁的Ag(100)表面吸附C1原子时假设了4种结构模型。经理论计算与观测值的比较,提出了C1原子的单层吸附和C1原子与Ag原子 相似文献
994.
本文采用XRD,NH_3-TPD,IR以及TEM等方法考察了Pt/BaKL沸石中Ba~(2+)的作用。NH_3-TPD结果表明,交换Ba~(2+)后的L型沸石的酸性,由于阳离子的作用仅在弱酸范围内有些改变,但与载铂的沸石的催化活性无明显的对应关系。IR及XRD谱线表明,BaKL沸石中Ba~(2+)在最佳交换度(26.3%)时,随预培烧温度的提高,使Ba~(2+)处于沸石孔道中B、C、D位置,接近于最佳分布,此时IR谱线上1421cm~(-1)处有一新峰。当沸石负载铂后,因铂与Ba~(2+)的相互作用,新峰消失,导致铂粒在沸石上分布更加均匀;铂粒在1.5—3.0nm之间占有最大比例,使得Pt/BaKL沸石呈现芳构化活性及选择性高于Pt/KL沸石,分别为~98%和~95%。 相似文献
995.
996.
Xu Z Gao N Chen H Dong S 《Langmuir : the ACS journal of surfaces and colloids》2005,21(23):10808-10813
Stable films of biopolymer chitosan and carbon nanotubes were prepared by a layer-by-layer self-assembly technique. Atomic force microscopy, scanning electron microscopy, cyclic voltammetry, and UV-vis spectroscopy were used to characterize the film assembly. Atomic force microscopy and scanning electron microscopy showed that an even, stable film was formed. The UV-vis spectroscopy and cyclic voltammetry study indicated the uniform growth of the film. The property of the self-assembled multilayer film in promoting protein electron transfer was demonstrated by incorporating microperoxidase-11 in the film. Microperoxidase-11 in the multilayer film could transfer electrons with the electrode indicating that carbon nanotubes could wire the protein to the electrode. The electrocatalytic activity of the microperoxidase-11 containing multilayer film-modified electrode toward H(2)O(2) and O(2) was investigated. The results showed that along with the increase in the assembled layers the electrocatalytic reduction potentials of H(2)O(2) and O(2) shifted positively. The prepared multilayer film of chitosan and carbon nanotubes containing protein was a sensitive interface for electrocatalytic study. 相似文献
997.
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
998.
电沉积AuInSe2半导体薄膜上的电化学振荡现象 总被引:1,自引:0,他引:1
研究了电沉积制得的AuInSe2半导体薄膜上过氧化氢阴极还原过程中产生的电化学振荡行为,对影响该振荡行为的一些因素如半导体薄膜的后处理、溶液组成、传质、光照、化学浸渍作用等进行了分析,同时采用外界周期性光照和外接小幅度正弦波电位来调节振荡频率,为金铟硒半导体薄膜发展成为光电传感器件提供了一定的理论与实践基础. 相似文献
999.
Mujie Yang Jinlong Xu Zhiquan Shen 《Journal of polymer science. Part A, Polymer chemistry》1990,28(12):3231-3240
The study on homogeneous rare earth coordination catalysts, LnL3-Al(i-Bu)3-CCl4, for the copolymerization of styrene with acrylonitrile has been successfully carried out for the first time. Some features and kinetic behavior of copolymerization of styrene with acrylonitrile by Nd(P204)3-Al(i-Bu)3-CCl4 system are described. The catalyst sites appear to possess both coordinate anionic and free radical characteristics. The catalytic activity of various rare earth elements in Ln(P204)3 and ligands in NdL3 for the copolymerization have the following order, respectively: Yb > Er > Tb ~ Tm > Ho > Ce > Lu ~ Sm ~ La > Pr > Nd, and Nd(naph)3 > Nd(P204)3 ~ Nd(P507)3 > Nd(acac)3·3H2O. An alternating-rich copolymer of styrene-acrylonitrile with a high softening point (195–230°C) was obtained by the LnL3-Al(i-Bu)3-CCl4 systems in toluene at 80°C. 相似文献
1000.
采用X射线衍射法测定二苯并噻吩亚砜单晶结构,发现晶体中二苯并噻吩亚砜分子以反平行三明治式的结构Ⅲ和反平行位移式的结构Ⅳ两种堆砌方式交替堆砌形成有序π-π堆积晶体。二苯并噻吩亚砜单晶结构属于三斜型,空间群为P1,晶体参数为:a=0.84712nm,b=0.94137nm,c=1.20380nm,α=97.866°,β=106.2630°,γ=96.437°,V=0.9014nm3,R1(全部数据)=0.0348和ωR2(全部数据)=0.0814。利用BHandH/6-31 G**方法计算了二苯并噻吩亚砜分子间的π-π堆积作用,Ⅲ和Ⅳ堆砌模式的π-π堆积效应作用能相当大,其计算值分别为-36.06kJ/mol和-39.83kJ/mol,电荷分布表明正负电荷匹配是稳定晶体π-π堆积体系的重要因素。 相似文献