含茂基、烷氧墓及乙酰氧基混合配位镧系金属有机化合物的合成及表征

本文通过二茂基镧系金属氯化物Ｃｐ２ＬｎＣｌ（Ｃｐ＝Ｃ５Ｈ５；Ｌｎ＝Ｄｙ，Ｈｏ，Ｙｂ）与等摩尔的ＮａＯＡｃ（Ａｃ＝ＣＨ３ＣＯ）及烷基醇ＨＯＲ（Ｒ＝－ＣＨ２ＣＨ２ＣＨ３，－ＣＨ２ＣＨ—ＣＨ２）在四氢呋喃溶剂中混合一步反应，合成了六种新的含三种不同配位基的镧系金属有机化合物．化合物的元素分析结果符合通式ＣＰＬｎ（ＯＲ）（ＯＡｃ），红外光谱显示了η５－ＣＰ、ＯＲ及ＯＡｃ基团的特征吸收峰，质谱显示了化合物的三聚碎片离子峰．基于元素分析、红外光谱及质谱数据，建议化合物可能为三聚体结构，即：［ＣｐＬｎ（ＯＲ）（ＯＡｃ）］３．     

Single-crystalline and monodisperse LaF3 triangular nanoplates from a single-source precursor

Single-crystalline and monodisperse LaF3 triangular nanoplates (2.0 x 16.0 nm) in trigonal tysonite structure were synthesized by the thermolysis of a single-source precursor (SSP), La(CF3COO)3, in a hot oleic acid/octadecene solution. The combined use of SSP and coordinating and noncoordinating solvents was demonstrated to have played key roles in the formation of such high-quality nanoplates, which could spontaneously organize into two types of superlattices (edge-to-edge and face-to-face) on a large area. This SSP approach has advantages of one-step, mass production, and easy operation, and may represent a rather general route toward metal fluoride nanocrystals.     

内-α-取代-α-甲基双环[2,2,1]庚烷-2-基甲醇的合成及其结构与香气的关系

合成了18种内-α-取代-α-甲基双环[2,2,1]庚烷-2-基甲醇(Ⅰ)。测定了所有化合物的折光率(或熔点)、质谱、红外光谱、~1H核磁共振谱、气相色谱的保留时间和薄层色谱的比移值。评定了它们的香气,并与相应的内-α-取代-α-甲基双环[2,2,1]-5-庚烯-2-基甲醇(Ⅱ)系列化合物的香气进行了比较,初步探讨了结构与香气的关系。     

Synthesis and characterization of organophosphoryl polyoxotungstates [RP(O)]2X n+W11O39 (8−n)− (X n+ = P5+, Si4+, Ge4+, Ga3+)

In the presence of n-Bu₄NBr acting as phase-transfer reagent, n-Bu₄N⁺ salts of organophosphoryl polyoxotungstate derivatives [RP(O)]₂X ⁿ⁺W₁₁O₃₉ ^(8–n)– [R = PhCH₂CH₂P(O), X = P, Si; R = C₆H₁₁P(O); X = Ge, Ga] have been prepared and characterized by elemental analysis, i.r., ³¹P- and ¹⁸³W-n.m.r. spectroscopy. According to the elemental analysis and spectroscopic data, the hybrid anions consist of an -[XW₁₁O₃₉] framework on which are grafted two equivalent organophosphoryl groups through P—O—W bridges; these new species still retain the Keggin structure. The six-line ¹⁸³W spectrum indicates that hybrid anions possess C _s symmetry in MeCN.     

Synthesis,characterization, and theoretical studies of group 4 amido hydrotris(pyrazolyl)borate complexes

Titanium and zirconium amido complexes containing a hydrotris(pyrazolyl)borate (Tp) or hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) ligand TpM(NMe(2))(3) (M = Ti, 1; M = Zr, 2) and Tp*M(NMe(2))(3) (M = Ti, 3; M = Zr, 4) were prepared by the reactions of M(NMe(2))(3)Cl (M = Ti, Zr) with sodium hydridotris(pyrazol-1-yl)borate and potassium hydridotris(3,5-dimethylpyrazol-1-yl)borate, respectively. The structures of 1, 2, and 4.CH(2)Cl(2) were determined by X-ray diffraction and show octahedral coordination geometry around the metal centers. Density functional theory calculations at the B3PW91 level were performed to understand the orientations and the rotational behavior of amido ligands in these metal complexes.     

Structural Features of a Polysaccharide from Centella asiatica

Centella asiatica has been used as remedy for sodation, stabilization and against lepra, anabrosis1 in the oriental countries. The low-molecular-weight constituents in Centella asiatica have been investigated1. However, no polysaccharides have been reported. 1BI was the first polysaccharide isolated from C. asiatica, which had immunostimulating activity in vitro. In present study, we report the structural features of 1BI. Experimental Extraction, isolation and purification Dried C.…     

Crystallization of binary carboxylic acids characterized with streaming potential measurement

The streaming potential of supersaturated solution of binary carboxylic acids, which have even carbon atoms, was determined to characterize crystallization under different temperatures. The value of the streaming potential was related to the type and solubility of the acids and the starting temperature of crystallization, and was easily influenced by the pressure difference of the liquid or the rate of temperature decline. When the temperature was declined to the point where a crystal nucleus appeared, the streaming potential reached the minimum. Thereafter, as the temperature was sequentially lowered, some minicrystals grew, and the streaming potential presented an ascendant tendency. The higher the starting temperature of the acids saturated solution, the higher is the temperature corresponding to the streaming potential minimum. The less the carbon atoms in the acids and the greater the solubility of the acids are, the higher is the temperature of the streaming potential minimum. Copyright © 2007 John Wiley & Sons, Ltd.     

安培检测芯片毛细管电泳及其初步应用

An end-channel amperometric detector with a guide tube for working electrode was designed and integrated on a home-made glass microchip. The guide tube was directly patterned and fabricated at the end of the detection reservoir, which made the fixation and alignment of working electrode relatively easy. The fabrication was carried out in a two-step etching process. A 30 μm carbon fiber microdisk electrode and Pt cathode were also integrated onto the amperometric detector. The baseline separation of dopamine (DA), catechol (CA) and epinephrine (EP) was achieved within 80 s. Relative standard deviations of not more than 5.2% were obtained for both peak currents and migration times of DA and CA (n=5). Using standard adding method, DA in tLrine and plasma samples was detected. The recoveries were in the range of 83%—103%.     

Preparation of a Carbon-Coated SPME Fiber and Application to the Analysis of BTEX and Halocarbons in Water

A carbon-coated fiber for solid-phase microextraction (SPME) has been prepared from powdered activated carbon (PAC) and a fused-silica fiber. Scanning electron microscopy of the coating revealed the carbon particles were uniformly distributed on the surface of the fiber substrate. Efficient extraction of BTEX (benzene, toluene, ethylbenzene, p-xylene, and o-xylene) and halocarbons (chloroform, trichloroethylene, and carbon tetrachloride), with short extraction and desorption times, was achieved by use of the coated fiber. The maximum working temperature of the coated fiber was 300 °C and the lifetime was over 140 desorption operations at 260 °C. Limits of quantification (LOQ) of the SPME method for the eight analytes ranged from 0.01 to 0.94 μg L⁻¹, and relative standard deviations (RSD) were below 7.2% (n=6). Recoveries were 87.9–113.4% when the method was applied to the analysis of BTEX and the halocarbons in real aqueous samples. An erratum to this article is available at .