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181.
Lei Chen Fang Li Bei Zhang Xiaozhi Li Shan Jin Sheng-Hua Liu 《Journal of organometallic chemistry》2010,695(14):1768-1775
2-Phenylindenyl phosphine ligand can be changed into anionic phosphine ligand in situ and utilized in the palladium-catalyzed Buchwald/Hartwig amination reactions in DME, providing good to excellent yields of amination products from aryl chlorides, bromides and iodides. 31P NMR studies show that the resonance for the anionic phosphine appeared between those of the (2-phenylindenyl)-dicyclohexyl phosphonium salt and (2-phenylindenyl)dicyclohexylphosphine. The calculated results were consistent with the experimental results. 相似文献
182.
A method was developed for the determination of silver ion (Ag) by combining dispersive liquid-liquid microextraction preconcentration with graphite furnace atomic absorption spectrometry. Diethyldithiocarbamate was used as a chelating agent, and carbon tetrachloride and methanol as extraction and dispersive solvent. Factors influencing the extraction efficiency of Ag and its subsequent determination were studied and optimized. The detection limit is 12 ng L?1 (3 s) with an enrichment factor of 132, and the relative standard deviation is 3.5% (n?=?7, at 1.0 ng mL?1). The method was successfully applied to the determination of trace amounts of Ag in water samples. 相似文献
183.
Dispersive liquid–liquid microextraction (DLLME) based on the solidification of floating organic droplets (DLLME-SFO) combined with gas chromatography-electron-capture detection (GC–ECD) has been developed for extraction and analysis of three dinitrobenzenes. The extraction conditions including extraction solvent, disperser solvent, extraction time, salt effect and temperature were investigated and optimized systematically. The limits of detection were 0.019 μg L?1 for 1,4-dinitrobenzene, 0.079 μg L?1 for 1,3-dinitrobenzene and 0.034 μg L?1 for 1,2-dinitrobenzene. Moreover, it offered good repeatability and high recovery. This method was successfully applied to monitor DNBs in different water samples. 相似文献
184.
Phenyltriazolinones are one of the most important classes of herbicides targeting the protoporphyrinogen oxidase enzyme. A series of triazolinone derivatives containing a strobilurin pharmacophore were designed and synthesized with the aim of discovering new phenyltriazolinone analogues with high activity. The herbicidal activity of the synthesized compounds was assayed and some of the test compounds displayed moderate herbicidal activity at 150 g ai/ha. 相似文献
185.
“Host” molecules, containing a binding site that is highly specific for an analyte “guest,” are used as sensors to register
analyte binding through a variety of mechanisms such as colorimetric, fluorescent, or electrochemical signals. There is increasing
interest in the host–guest chemistry on the surface of quantum dots (QDs) and in the changes that it produces in the luminescent
properties of QDs. The bulk of this study focuses on those QDs with bound host molecules (crown ether, cyclodextrin, calixarene,
and porphyrin) and the selectivity they display toward metal ions and small organic molecules. 相似文献
186.
187.
The synthesis and X-ray crystal structure of a methylene-bridged glycoluril dimer 2 was reported.The methylene-bridged glycoluril dimer 2(C38H36Br4N8O12,Mr=1116.35) crystallizes in space group P1 with a=10.5802(6),b=16.8469(9),c=24.7673(14) ,α=98.00,β=96.263(1),γ=101.606(1)o,V=4239.3(4)3,Z=4,Dc=1.749 g/cm3,μ=3.869 mm-1 and F(000)=2224.It crystallizes in an S-shaped conformation that displays two ethoxycarbonyl groups on each face of the molecule. 相似文献
188.
《Physica E: Low-dimensional Systems and Nanostructures》2007,36(2):241-245
Lattice-type mismatched heteroepitaxy is demonstrated as a novel concept for the fabrication of almost ideal, highly luminescent nanocrystal quantum dots that are coherently embedded in a single-crystalline matrix. In this approach, the formation of quantum dots is induced by transformation of a metastable epitaxial 2D quantum well into an array of isolated nanocrystals with-highly symmetric shape. This process is driven by the lattice-type mismatch between the constituent materials and the resulting miscibility gap. The investigated PbTe/CdTe heterosystem has a model character because it combines two compounds with different cubic lattice types but almost identical lattice constants. The obtained epitaxial nanocrystals exhibit outstanding properties such as a well-defined symmetric shape, the absence of strain, intermixing and a wetting layer, which is in contrast to the conventional Stranski–Krastanow quantum dots. The small-rhomboedric-cubo-octahedron PbTe/CdTe nanocrystals on GaAs substrates display intense room temperature mid-infrared luminescence as is crucial for device applications. Ab initio density functional theory is used to clarify the interface structure, indicating that the covalent and ionic bonding character of CdTe and PbTe is maintained across the interface. 相似文献
189.
Rui Zheng 《Journal of Molecular Spectroscopy》2011,265(2):102-105
The rovibrational spectrum of the N2-N2O van der Waals complex has been recorded in the N2O ν1 region (∼1285 cm−1) using a tunable diode laser spectrometer to probe a pulsed supersonic slit jet. The observed transitions together with the data observed previously in the N2O ν3 region are analyzed using a Watson S-reduced asymmetric rotor Hamiltonian. The rotational and centrifugal distortion constants for the ground and excited vibrational states are accurately determined. The band-origin of the spectrum is determined to be 1285.73964(14) cm−1. A restricted two-dimensional intermolecular potential energy surface for a planar structure of N2-N2O has been calculated at the CCSD(T) level of theory with the aug-cc-pVDZ basis sets and a set of mid-bond functions. With the intermolecular distance fixed at the ground state value R = 3.6926 Å, the potential has a global minimum with a well depth of 326.64 cm−1 at θN2 = 11.0° and θN2O = 84.3° and has a saddle point with a barrier height of 204.61 cm−1 at θN2 = 97.4° and θN2O = 92.2°, where θN2(θN2O) is the enclosed angle between the N-N axis (N-N-O axis) and the intermolecular axis. 相似文献
190.
光谱相似性测度是高光谱遥感影像定量化分析和精细地物直接识别的基础,光谱特征的选择和刻画方式是光谱相似性测度的关键.研究表明,利用光谱的单一特征无法全面反应地物光谱间的相似性,光谱识别时需要综合考虑光谱的多种特征.本文在几何距离、相关系数和相对熵的基础上提出了一种结合多种光谱特征的新型光谱相似性测度,即光谱泛相似测度(s... 相似文献