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981.
Acetylene black paste electrode modified with molecularly imprinted polymers/graphene for the determination of bisphenol A 下载免费PDF全文
Wanzhen Xu Fei Yuan Chunyan Li Weihong Huang Xiangyang Wu Zhengqiao Yin Wenming Yang 《Journal of separation science》2016,39(24):4851-4857
A novel nanocomposite of molecularly imprinted polymers and graphene sheets was fabricated and used to obtain a highly conductive acetylene black paste electrode with high conductivity for the detection of bisphenol A. The two‐dimensional structure and the chemical functionality of graphene provide an excellent surface for the enhancement of the sensitivity of the electrochemical sensor and the specificity of molecularly imprinted polymers to improve detection of bisphenol A. The synergistic effect between graphene and molecularly imprinted polymers confers the nanocomposite with superior conductivity, broadened effective surface area and outstanding electrochemical performance. Factors affecting the performance of the imprinted sensor such as molecularly imprinted polymers concentration, foster time and scan rate are discussed. The sensor successfully detects bisphenol A with a wide linear range of 3.21 × 10?10 to 2.8 × 10?1 g/L (R = 0.995) and a detection limit of 9.63 × 10?11g/L. The fabricated sensor also possessed high selectivity and stability and exhibits potential for environmental detection of contaminants and food safety inspection. 相似文献
982.
Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone 下载免费PDF全文
Dr. Qifan Liu Hongmin Li Zhuang Wu Dingqing Li Dr. Helmut Beckers Dr. Guntram Rauhut Prof. Dr. Xiaoqing Zeng 《化学:亚洲杂志》2016,11(20):2953-2959
The stepwise decomposition of carbonyl diisocyanate, OC(NCO)2, has been studied by using IR spectroscopy in solid argon matrices at 16 K. Upon irradiation with an ArF laser (λ=193 nm), carbonyl diisocyanate split off CO and furnished a new carbonyl nitrene, OCNC(O)N, in its triplet ground state. Two conformers of the nitrene, syn and anti, that were derived from the two conformers of OC(NCO)2 (62 % syn–syn and 38 % syn–anti) were identified and characterized by combining IR spectroscopy and quantum chemical calculations. Subsequent irradiation with visible light (λ>395 nm) caused the Curtius rearrangement of the nitrene into OCNNCO. In addition to the expected decomposition products, N2 and CO, further photolysis of OCNNCO with the ArF laser yielded NOCN, through a diazomethanone (NNCO) intermediate. To further validate our proposed reaction mechanism, ArF‐laser photolysis of the closely related NNNNCO and cyclo‐N2CO in solid argon matrices were also studied. The observations of NOCN and in situ CO‐trapped product OCNNCO provided indirect evidence to support the initial generation of NNCO as a common intermediate during the laser photolysis of OCNNCO, NNNNCO, and cyclo‐N2CO. 相似文献
983.
984.
Structural and surface properties of different natural aluminosilicates (layered, chain and framework structural types) exposed of 20 kHz ultrasound irradiation (0–120 min) in aqueous and 35 wt%. aqueous H2O2 dispersions were studied by X-ray diffraction (XRD), dynamic light scattering (DLS), nitrogen adsorption–desorption, thermal analysis, and Fourier transform infrared spectroscopy (FTIR) techniques. It was confirmed that sonication caused slight changes in the structure of investigated minerals whereas their textural properties were significantly affected. The aqueous dispersions of montmorillonite (Mt), clinoptilolite (Zlt), glauconite (Glt) and palygorskite (Pal) were represented by several particles size fractions according to DLS-study. Ultrasound irradiation produced a decrease of the average particle diameter by 4–6 times in water and by 1.3–5 times in H2O2 dispersions except for Pal, which underwent strong agglomeration. A significant increase of total pore volume and pore diameter was observed for Glt sonicated in H2O2 dispersions whereas for Pal mainly micropore volume sharply increased in both aqueous and H2O2 dispersions. 相似文献
985.
A cationic palladium(II)-catalyzed enantioselective intramolecular addition of vinylpalladium species to ketones initiated by the carbopalladation of alkynoates under mild conditions without a Pd(II)/Pd(0) redox system was developed with high yield and enantioselectivity. This cascade reaction provides an efficient method for the construction of optically active hydroxylactones. 相似文献
986.
987.
A dendrite D in a metric space X is said to be free if there exists a connected open set U in X such that . In this paper, we prove that there is no expansive commutative group action on any Peano continuum having a free dendrite. In particular, no 1-dimensional compact ANR admits an expansive commutative group action. 相似文献
988.
The reaction of anhydrous YbCl3 with 1 equiv. of Li2Me2Si(NPh)2 in THF, after workup, yielded a ytterbium(III) chloride [{Me2Si(NPh)2Yb}(μ2‐Cl)(TMEDA)]2·3PhMe ( 1 ) (TMEDA=tetramethylethanediamine). The same reaction followed by treatment with Na‐K alloy afforded a new ytterbium(II) complex supported by a bridged diamide with four coordinated LiCl molecules, [{Me2Si(NPh)2Yb(THF)2}(μ3‐Cl)(μ4‐Cl){Li(THF)}2]2·2THF ( 2 ) in high yield. Both complexes were structurally characterized by X‐ray analysis to be dimers. Complex 1 was a chlorine‐bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me2Si(NPh)2Yb(THF)2]‐(μ3‐Cl)[Li(THF)]2 moieties were connected with each other by two μ4‐Cl bridges to form a "chair‐form" framework. 相似文献
989.
Wang Y Shen Z Li B Zhang Y Zhang Y 《Chemical communications (Cambridge, England)》2007,(12):1284-1286
The dynamic kinetic resolution of 2-oxo-3-arylsuccinates was achieved vial-proline-catalyzed addition of acetone in acetonitrile at room temperature, providing the desired adduct in good yield with up to 87 : 13 dr and high ee up to 99%. 相似文献
990.
The first divalent ytterbium complex supported by a diaminobis(phenolate) ligand, YbL(THF)2.0.5C7H8 (1; THF = tetrahydrofuran), was synthesized in good yield by the amine elimination reaction of Yb[N(SiMe3)2]2(THF)2 with H2L (L = [Me2NCH2CH2N(CH2-2-OC6H2-3,5-But2)2]) in a 1:1 molar ratio. X-ray structural determination shows complex 1 to be a THF-solvated monomer, which adopts a distorted octahedral coordination geometry around the Yb atom. Complex 1 can react with PhNCO and PhCCH, as a single electron-transfer reagent, to give the corresponding reduction coupling product [(YbLOCNPh)(THF)]2.4THF (2) and the alkynide complex YbLCCPh(DME) (3; DME = 1,2-dimethoxyethane). Complexes 2 and 3 have been characterized by X-ray crystal structural analysis. In complex 2, the dianionic oxamide ligand resulting from the reductive coupling of two phenyl isocyanate molecules coordinates to two Yb atoms in a mu,eta4 fashion. Complex 3 has a monomeric structure with a Yb-C(terminal phenylacetynide) bond length of 2.374(3) A. Complex 1 is also a highly efficient catalyst for ring-opening polymerization of epsilon-caprolactone. 相似文献