Itosides A – I,New Phenolic Glycosides from Itoa orientalis

Eight new benzoylated gentisyl alcohol (=2‐(hydroxymethyl)benzene‐1,4‐diol) glucosides, itosides A–H ( 1 – 8 ), together with the new pyrocatechol (=benzene‐1,2‐diol) glycoside itoside I ( 9 ) were isolated from the bark and twigs of Itoa orientalis (Flacourtiaceae). In itosides B–D ( 2 – 4 ), the gentisyl alcohol moiety was esterified by 1‐hydroxy‐6‐oxocyclohex‐2‐ene‐1‐carboxylic acid, while itosides E–H ( 5 – 8 ) contained instead an additional 2‐hydroxybenzoic acid moiety. The compounds were accompanied by the known derivatives 4‐hydroxytremulacin ( 10 ), poliothyrsoside ( 11 ), poliothyrsin ( 12 ), homaloside D ( 13 ), tremulacin, and pyrocatechol β‐D ‐glucopyranoside. The structures of the new compounds were elucidated by spectral and chemical methods.     

新型镍催化剂催化乙烯聚合的阳离子机理

含氮氧配位原子的镍催化剂是一类新型催化剂.文章以配体为[NH=CH－CH=CH－O]的镍催化剂为模型,用密度泛函方法（DFT）在B3LYP/LANL2MB水平上研究了该类乙烯聚合催化的反应机理.计算结果表明,催化的反应过程中,中心原子镍最先形成带空位的四边形阳离子配合物,乙烯以垂直于催化剂平面的方式占据空位,然后旋转到催化剂平面内以利于插入反应的进行；插入反应发生后,在催化剂中Ni和β-C之间形成一种氢桥键,协助新空位的形成,实现链的增长.     

微波辐射-酶耦合催化(MIECC)反应

将微波辐射用于非水相酶催化可以获得很多有别于常规加热下的反应结果.本文讨论了微波的非热效应在酶促反应中的表现,探讨了微波辐射对酶的结构、构象、活性及酶催化反应动力学的影响,以及微波辐射-酶耦合催化对反应的对映选择性、底物专一性、前手性选择性和区域选择性的影响.在大多数场合,适当的微波辐射不会损伤酶活而且可以提高反应速率,而对酶特异性的影响则不一而论.     

Voltammetric determination of uric acid by using gold nanotubule electrode

Gold nanotubule membranes were prepared by using electroless deposition of gold within the pores and surfaces of polycarbonate track-etched membranes.And the gold nanotubule membrane was used as an electrode for determination of uric acid in urine samples for the first time.In Britton-Robinson buffer of pH 4.56,uric acid exhibited well-defined differential pulse voltammograms.And the interference between coexistent ascorbic acid and uric acid was overcome owing to the attractive ability of the gold nanotubule electrode to yield a large anodic peak difference ca.0.404 V(vs.SCE).The proposed method was then applied to the determination of uric acid in urine without any pretreatment.     

Stabilities in field electron emissions from noble‐metal covered W nano‐tips: apex structure dependence

We observed field emission microscopy (FEM) patterns of noble‐metal (NM) covered W nano‐tips with three different apex structures fabricated by field evaporation. Each of the three tips was terminated with a single atom, three atoms or ten atoms. We investigated the temporal changes in the FEM of these tips to discuss the stabilities in the spatial distributions of the field emission (FE) beams. The single‐atom tip showed two characteristics that were superior to the others. First, the beams emitted from the single‐atom tip were the most collimated among the three tips (the semi‐cone angle of 1.0° , FWHM). Second, adsorption of residual gas had little influence on FE from the single‐atom tip, while the other tips were easily contaminated even at ultra high vacuum, resulting in the emission fluctuation. Copyright © 2006 John Wiley & Sons, Ltd.     

C207联醇催化剂的羰基硫中毒研究

以常压甲醇分解反应为基础实验测定了不同羰基硫含量和不同反应温度下甲醇合成铜基催化剂活性随时间的变化。结果表明，羰基硫含量增加时；失活速率增快；反应温度升高时，失活速率也加快。羰基硫中毒前后催化剂样品的ＸＲＤ谱图证实了起催化作用的活性组分为Ｃｕ＾＋／ＺｎＯ。应用改进的高斯－牛顿法对失活实验数据进行参数估值，获得了Ｃ２０７铜基催化剂羰基硫中毒的失活速率方程。     

16-脱氢孕烯醇酮醋酸酯的环境友好合成法

Instead of environmentally toxic chromium oxidant, singlet oxygen generated photcchemically was used as environmentally friendly and benign oxidizing agent to accomplish the transformation of pseudodiosgenin diacetate to diosone efficiently in a low toxic and less expensive solvent acetone. Accordingly 16-dehydropregnenolone acetate(16-DPA), an important intermediate for preparation of steroidal drugs, was prepared in good yield (75%) when photoreaction was run in acetone/acetic anhydride/pyridine system. The mild reaction condition as well as simple and environmentally friendly process made the method commercially viable and important for production of 16-DPA in industrial scale.     

Synthesis and Structure of the New Compound La2O(CN2)2 Possessing an Interchanged Anion Proportion Compared to the Parent La2O2(CN2). Synthese und Kristallstruktur der neuen Verbindung La2O(CN2)2 mit einem vertauschten Anionenverhältnis gegenüber der Bezugsverbindung La2O2(CN2)

La₂O(CN₂)₂ was synthesized from a 1:1:2 molar reaction mixture of LaCl₃, LaOCl, and Li₂(CN₂) at 650 °C. Well developed single crystals were grown from a LiCl‐KCl flux. The crystal structure was refined as monoclinic (space group C2/c, Z = 2, a = 13.530(2) Å, b = 6.250(1) Å, c = 6.1017(9) Å, β = 104.81(2)°) from single crystal X‐ray diffraction data. The La³⁺ and (CN₂)^2— ions in the crystal structure of La₂O(CN₂)₂ can be compared to Fe³⁺ and S₂^2— ions in the cubic pyrite structure, being arranged like in a distorted NaCl type structure with their centers of gravity. In addition, the O^2— ions in La₂O(CN₂)₂ are occupying 1/4 of the tetrahedral voids formed by the arrangement of metal ions.     

Intermolecular alkyne hydroaminations involving 1,1-disubstituted hydrazines

[reaction: see text] Two readily prepared catalysts have been developed for the hydroamination of alkynes by 1,1-disubstituted hydrazines. The catalyses are facile with terminal alkynes and some internal alkynes. If the hydrazine bears an aryl group, Fischer cyclization can occur in a one-pot procedure. In addition, reactions with acetylene to produce a plethora of hydrazones are described. Catalytic reactions involving acetylene and substituted hydrazines are complete in less than 2 h at room temperature and 1 atm of pressure.