Characterization of anti‐Coxsackie virus B3 constituents of Radix Astragali by high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

To profile the anti‐Coxsackie virus B3 constituents of Radix Astragali, an HPLC‐DAD‐MSⁿ analytical method, combined with an in vivo test, has been developed to identify the constituents of the active part, which has been demonstrated to have potency to inhibit the proliferation of virus in cardiac muscle, alleviate infraction in heart and elevate the survival rate of the animal. By comparing their retention time and MS data with those obtained from the authentic compounds and the published data, a total of 19 compounds, including 11 isoflavonoids and eight saponins, were identified, among which one pterocarpane glucoside was reported for the first time. The present study provides an approach to rapidly screening bioactive constituents in traditional Chinese medicines. Copyright © 2010 John Wiley & Sons, Ltd.     

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape‐controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution‐phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape‐controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.     

RAFT分散聚合方法制备支化聚甲基丙烯酸甲酯

以甲基丙烯酸甲酯(MMA)与三缩丙二醇双丙烯酸酯(TPGDA)为单体,S-1-十二烷基-S′-(α,α′-二甲基-α″-乙酸)三硫代碳酸酯作为RAFT试剂防止反应体系交联,进行RAFT分散共聚合.通过在成核以后加入RAFT试剂和多官能度单体(TPGDA)的两步法分散聚合反应得到了粒径接近单分散的球形聚合物粒子,其粒径大小在1.9～2.7μm范围,粒径分布为1.12～1.24.采用凝胶色谱法(GPC)、核磁共振(1H-NMR)对所得共聚物的分子量、分子量分布(MWD)、共聚物组成、共聚物结构进行了表征.GPC结果表明所得聚合物的分子量分布曲线呈双峰分布,说明在成核期形成了线形的MMA均聚物,而在成核后由MMA与TPGDA共聚生成了支化的共聚物.1H-NMR结果显示所得共聚物具有支化的结构,共聚物中TPGDA的比例低于其在初始原料中的比例.此外,所得共聚物的特性黏度随转化率升高而降低,形状因子α从0.643降低到0.548,进一步证明了聚合物具有支化结构.     

2-[2-(7H-二苯并[a,g]咔唑)-乙氧基]-乙基氯甲酸酯对脂肪胺类化合物的荧光标记及质谱鉴定

利用新型荧光标记试剂2-[2-(7H-二苯并[a,g]咔唑-乙氧基)-乙基氯甲酸酯作为柱前衍生化试剂, 在Eclipse XDB-C8反相色谱柱上,采用梯度洗脱,实现了12种脂肪胺类化合物完全基线分离.检测最佳激发和发射波长分别为300和400 nm.通过荧光检测及离子阱大气压化学电离源(APCI Source)正离子模式实现了在线的柱后质谱鉴定.对土壤中脂肪胺类化合物的测定快速、准确,具有良好的重现性.荧光定量检测的回归系数大于0.9991; 检出限为10.1～0.3 fmol.     

Effect of unsaturated hydroxyl-fatty acid modified nano-CaCO3 on the morphological and rheological behavior of PP

A modified nano-calcium carbonate (R-CCR) was prepared by coating a layer of unsaturated hydroxylfatty acid on the surface of CCR powders using a solid state method; the latter were commercial nano-CaCO₃ modified with stearic acid. FTIR studies indicate that the modifier is combined on the surface of CaCO₃. PP/EPDM/nano-CaCO₃ ternary composites were prepared by a melt-mixing method. SEM and TEM were utilized to examine the morphology of the composites. The tensile fractured surface of PP/EPDM/R-CCR showed a fibroid morphology and large-scale yield deformation. The impact fractured surface showed that the amount of cavities in the PP/EPDM/R-CCR system was increased, however their size diminished obviously. R-CCR particles were dispersed uniformly in the PP matrix, and their compatibility was distinctly improved as compared to CCR when the amount of R-CCR was 15 h⁻¹. The tensile strength remained nearly constant (reduced from 27.6 MPa to 27.5 MPa), while the impact strength increased from 9.6 kJ/m² to 15.4 kJ/m² as CCR was replaced by R-CCR. Meanwhile, the bending strength and bending modulus also increased correspondingly. Furthermore, the impact strength of PP/EPDM/R-CCR was maintained at a high level (15.4 kJ/m²), which was more than the sum of that of PP/EPDM and PP/R-CCR (6.6 kJ/m² and 6.1 kJ/m² respectively). This indicates that the R-CCR and EPDM have a significant synergistic toughening effect on PP while maintaining the strength and modulus of virgin PP. Both the storage modulus G′ and loss modulus G″ of PP/EPDM and PP/EPDM/R-CCR composites increase with increasing frequency, but the values of G′ and G″ of the tertiary composite are relatively higher than those of the binary system. The loss factor and viscosity decrease with increasing frequency, but there is little difference between tertiary and binary composites. The apparent viscosity η of the tertiary system containing R-CCR is lower than that of the tertiary system containing CCR and virgin PP. The viscosity of the composites sig-nificantly decreases with increasing shear rate. The mea-sured mechanical properties of the composites indicate that replacing CCR with R-CCR for binary composites could simultaneously enhance the toughness and strength of PP. __________ Translated from Acta Polymerica Sinica, 2008, 4 (in Chinese)     

Structure–composition sensitivity in “Metallic” Zintl phases: A study of Eu(Ga1−xTtx)2 (Tt=Si, Ge, 0≤x≤1)

Two isoelectronic series, Eu(Ga_1−xTt_x)₂ (Tt=Si, Ge, 0≤x≤1), have been synthesized and characterized by powder and single-crystal X-ray diffraction, physical property measurements, and electronic structure calculations. In Eu(Ga_1−xSi_x)₂, crystal structures vary from the KHg₂-type to the AlB₂-type, and, finally, the ThSi₂-type structure as x increases. The hexagonal AlB₂-type structure is identified for compositions 0.18(2)≤x<0.70(2) with Ga and Si atoms statistically distributed in the polyanionic 6³ nets. As smaller Si atoms replace Ga atoms while the number of valence electrons increases, the lattice parameters, unit cell volumes, and Ga–Si distances in this phase region decrease significantly. Although aspects of X-ray diffraction results suggest puckering of the 6³ nets for the Si-richest example of the AlB₂-type Eu(Ga_1−xSi_x)₂, the complete experimental evidence remains inconclusive. On the other hand, in Eu(Ga_1−xGe_x)₂, six different structural types were observed as x varies. In addition to EuGa₂ (KHg₂-type; space group Imma) and EuGe₂ (own structure type, space group P3¯m1), the ternary phases studied show four different structures: the AlB₂-type for Ga-rich compositions; the YPtAs-type structure for EuGaGe; and two new structures, which are intergrowths of the YPtAs-type EuGaGe and EuGe₂, for Ge-rich compositions. These two Ge-rich phases include: (1) Eu(Ga_0.45(2)Ge_0.55(2))₂ containing two YPtAs-type motifs of EuGaGe plus one EuGe₂ motif; and (2) Eu(Ga_0.40(2)Ge_0.60(2))₂ containing one YPtAs-type motif alternating with a split site at and z=0.4798(2) with ca. 50% site occupancy by Ga and Ge along the c-axis. Magnetic susceptibilities of three Eu(Ga_1−xGe_x)₂ compounds display Curie–Weiss behavior above ca. 100 K, and show effective magnetic moments indicative of divalent Eu with a 4f⁷ electronic configuration, consistent with. X-ray absorption spectra (XAS). Density of states (DOS) and crystal orbital Hamilton population (COHP) analyses, based on first principles electronic structure calculations, rationalize the observed homogeneity ranges of the AlB₂-type phases in both systems and the structural variations as a function of Tt content.     

A Tetranuclear Complex Assembled from N,N＇-Bis（4-（3＇-formyl-5＇-methylsalicyclidene）-iminoethyl）-4-methyl-2,6-bimethyliminophenol

The reaction of 2,6-diformyl-4-methylphenol, ethylenediamine and Cu（Ⅱ） in the proportion of 3：2：2 yields a new tetranuclear copper（Ⅱ） complex, [Cu2L]2（ClO4）2.2H2O（H3L= N,N＇-bis（4-（3＇-formyl-5＇-methylsalicyclidene）iminoethyl）-4-methyl-2,6-bimethyliminophenol）. The complex has been characterized by ES-MS, IR and X-ray diffraction analysis, and its crystal crystallizes in the triclinic system, space group P1 with a = 10.8673（11）, b = 12.0829（12）, c = 14.4834（15） А, α= 111.946（2）, β= 105.828（2）, γ = 99.583（2）°,V= 1618.5（3） А^3, Dc = 1.605 g/cm^3, Z = 2, Mr = 1564.26, F（000） = 800.0,μ（MoKa） = 1.460/mm, S = 1.063, R = 0.0612 and wR = 0.1163 for 6245 observed reflections （I 〉 2σ（I））. The complex is a dimer of dinuclear copper（Ⅱ） acylic enantiomorph subunit [Cu2L]ClO4.H_2O, held together by π…π weak coordination and hydrogen bonding interactions. In addition, the π…π interactions related to phenyl moieties as well as CH=N…π interactions were also found to stabilize the supramolecular architectures in the solid state.     

Preparation of ferrocenyl imidazolines using bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate

An efficient synthesis of ferrocenyl imidazolines starting from ferrocenyl carboxylic acids has been developed. Bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate was used to convert smoothly ferrocenyl carboxylic amides bearing an amine side chain, derived from ferrocenyl carboxylic acids and 1,2-diamines, to their corresponding ferrocenyl imidazolines.     

Bis(<Emphasis Type="Italic">β</Emphasis>-cyclodextrin)s Linked with an Aromatic Diamine as Fluorescent Sensor for the Molecular Recognition of Bile Salts

The binding behavior of three aromatic diamino-bridged bis(β-cyclodextrin)s (2–4) with four bile salts {cholate (CA), deoxycholate (DCA), glycocholate (GCA) and taurocholate (TCA)} has been investigated at 25 °C in a phosphate buffer (pH=7.20) by fluorescence and 2D NMR spectroscopy. The results indicate that these bis(β-cyclodextrin)s act as fluorescent sensors. From the ROESY spectra, it is deduced that the phenyl moieties of bis(β-cyclodextrin)s 2–4 are partially self included in the cyclodextrin cavity, and are not expelled from the cavity upon complexation with bile guests. Owing to the cooperative host-tether-guest binding mode in which the linker and guest are co-included in the two cyclodextrin cavities, these bis(β-cyclodextrin)s significantly enhance the binding ability and selectivity as compared with the native β-cyclodextrin 1. Possessing suitable tether length, bis(β-cyclodextrin) 3 gives the highest K _S values, ranging up to 39,900 mol⋅L⁻¹, for complexation with CA. The complex stability constants are discussed from the viewpoint of multiple recognitions between host and guest.