Noble gas-transition metal complexes: coordination of ScO+ by multiple Ar, Kr, and Xe atoms in noble gas matrixes

The combination of matrix isolation infrared spectroscopic and density functional calculation results provides strong evidence that the transition metal monoxide cation, ScO+, coordinates five noble gas atoms in forming the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe) complexes in noble gas matrixes.     

Spectroscopic studies of substrate interactions with clavaminate synthase 2, a multifunctional alpha-KG-dependent non-heme iron enzyme: correlation with mechanisms and reactivities

Using a single ferrous active site, clavaminate synthase 2 (CS2) activates O(2) and catalyzes the hydroxylation of deoxyguanidinoproclavaminic acid (DGPC), the oxidative ring closure of proclavaminic acid (PC), and the desaturation of dihydroclavaminic acid (and a substrate analogue, deoxyproclavaminic acid (DPC)), each coupled to the oxidative decarboxylation of cosubstrate, alpha-ketoglutarate (alpha-KG). CS2 can also catalyze an uncoupled decarboxylation of alpha-KG both in the absence and in the presence of substrate, which results in enzyme deactivation. Resting CS2/Fe(II) has a six-coordinate Fe(II) site, and alpha-KG binds to the iron in a bidentate mode. The active site becomes five-coordinate only when both substrate and alpha-KG are bound, the latter still in a bidentate mode. Absorption, CD, MCD, and VTVH MCD studies of the interaction of CS2 with DGPC, PC, and DPC provide significant molecular level insight into the structure/function correlations of this multifunctional enzyme. There are varying amounts of six-coordinate ferrous species in the substrate complexes, which correlate to the uncoupled reaction. Five-coordinate ferrous species with similar geometric and electronic structures are present for all three substrate/alpha-KG complexes. Coordinative unsaturation of the Fe(II) in the presence of both cosubstrate and substrate appears to be critical for the coupling of the oxidative decarboxylation of alpha-KG to the different substrate oxidation reactions. In addition to the substrate orientation relative to the open coordination position on the iron site, it is hypothesized that the enzyme can affect the nature of the reactivity by further regulating the binding energy of the water to the ferrous species in the enzyme/succinate/product complex.     

Stereoselective synthesis of substituted gamma-butyrolactones by the [3+2] annulation of allylic silanes with chlorosulfonyl isocyanate: enantioselective total synthesis of (+)-blastmycine

[structure: see text]. A stereoselective synthesis of gamma-butyrolactones by the [3 + 2] annulation of allylic silanes with N-chlorosulfonyl isocyanate (CSI) was developed. An enantioselective total synthesis of (+)-blastmycinone was accomplished using this annulation as the key step.     

利用“网包法”制备高效液相色谱大环抗生素类手性固定相

万古霉素和替考拉宁都属于糖肽类的大环抗生素，具有立体的环状结构和多个手性中心，是两种常见的手性识别材料，广泛应用于对映体的色谱手性分离分析。该文以万古霉素和替考拉宁为手性选择剂，哌嗪为单体，4，4'-二苯基甲烷二异氰酸酯（MDI）、1，6-己二异氰酸酯（HDI）和2，4-甲苯二异氰酸酯（TDI）为交联剂，通过界面聚合反应形成网状层包裹硅胶载体的方法制得6种高效液相色谱手性固定相，用于分离外消旋化合物，并与MDI直接交联万古霉素和替考拉宁在硅胶表面所得固定相进行了比较。结果表明，利用"网包法"和直接交联法制备的手性柱与商品万古霉素和替考拉宁柱之间具有互补性，均对不同的外消旋体有不同程度的拆分。     

水杨酸钴非等温热分解动力学研究

用热分析(TG/DTG)、X射线衍射(XRD)技术研究了固态物质水杨酸钴在空气中热分解的过程。热分析结果表明,水杨酸钴在空气中分两步分解,其失重率与理论计算失重率相吻合;XRD结果表明,水杨酸钴分解的终产物为Co3O4。用Friedman法和Flynn-Wall-Ozawa(FWO)法求取了分解过程的活化能E,并用多元线性回归和多元非线性回归法给出了可能的机理函数,由这些方法得到的动力学数据相互比较吻合。     

CHARACTERIZATION AND CATALYTIC PERFORMANCE OF PLATINUM SUPPORTED ON Sn-MgAl_2O_4

IntroductionSupportedPt-Sncatalystsareimpo~inthepdrileumandpthechendcalindustricsbecauseoftheirsuperiorcatalyticperformances.Forexample,Pt-Snsupportedonaneutralsupporthasbeenreportedtoexhibithighdehydrogenationselectivityanddebilitythansupportedplatinumca…     

酶联免疫吸附法直接测定血清雌二醇

本合成了３种不同载体蛋白的雌二醇抗原，研究了载体蛋白免疫原性对雌二醇抗体产生的影响。应用酶联免疫吸附分析法测定了血清中雌二醇，浓度范围为５－１６０ｎｇ／ｍｌ（１．８×１０＾－＾８－５．９×１０＾－＾７ｍｏｌ／Ｌ）．ＲＳＤ％小于１０．％，检测限为１．９７ｎｇ／ｍｌ，相当于９８．５ｐｇ／孔（按空白平均值的二倍标准偏差计算）。另外，本还建立了一种用考马斯亮蓝Ｇ－２５０测定半抗原与蛋白结合比的方法，提     

Direct Electrochemistry of Cytochrome c on EDTA-ZrO2 Organic-inorganic Hybrid Film Modified ElectrodesState Key Laborator3.＂ of Chemo／Biosensing and Chemometrics, Hunan Universit3; Changsha. Hunan 410082. China

A composite film of ethylenediamine tetraacetic acid (EDTA)‐ZrO₂ organic‐inorganic hybrid was prepared based on the chelation between Zr(IV) and EDTA. The direct electrochemical behavior of cytochrome c (cyt. c) at the hybrid film modified glassy carbon electrodes was investigated. The immobilized EDTA can promote the redox of heme in horse heart cyt. c which gives rise to a pair of reversible redox peaks with a formal potential of 40 mV (vs. SCE). The peak current increased linearly with the increase of cyt. c concentration in the range of 1.6 × 10^?6—8.0 × 10^?5 mol·L^?1 with the correlation coefficient of 0.996. Further investigation shows that metal ions can impede the electron transfer of cyt. c. The impediment capability of metal ions depends on their coordination capability with EDTA and their valence number.     

Formation of nanostructured polymer filaments in nanochannels

We describe the use of hard etching methods to create nanodimensional channels and their use as templates for the formation of polymer filament arrays with precise dimensional and orientational control in a single integrated step. The procedure is general as illustrated by the radical, coordination, and photochemical polymerizations that were performed in these nanochannels. The nanochannel templates (20 nm high, 20-200 nm wide, and 100 mum long) were fabricated by the combined use of electron-beam lithography and a sacrificial metal line etching technique. Radical polymerization of acrylates, metal-catalyzed polymerization of norbornene, and photochemical polymerization of 1,4-diiodothiophene were carried out in these nanochannels. The polymers grown follow the dimensions and orientation of the channels, and the polymer filaments can be released without breaking. The approach opens up the possibility of just-in-place manufacturing and processing of patterns and devices from nanostructured polymers using well-established polymer chemistry.