Hydrothermal Synthesis and Optical Properties of ZnO Nanostructured Films Directly Grown from/on Zinc Substrates

Uniform ZnO nanorods arrays are grown directly from and on Zn foils in pure water under hydrothermal conditions at a relatively low temperature. The nanorods are 80–200 nm in diameter and ∼ 1 μm in length, which grow on the Zn foil along the [001] direction. By changing the pure water to a urea solution, a Zn compound ([Zn₅(OH)₆(CO₃)₂], a precursor of ZnO nanoflowers film, is created by self-assembly. The ZnO nanoflowers film can be easily obtained by heating the [Zn₅(OH)₆(CO₃)₂] compound in N₂ at 350∘C for 5–6 hours. Possible growth processes of the ZnO nanorods arrays and the [Zn₅(OH)₆(CO₃)₂] nanoflowers are discussed. Photoluminescence properties of the as-prepared ZnO nanostructures have been measured. The ZnO nanorods array synthesized using our method has minimal defects so that only band-gap emission is observed. However, the ZnO nanoflowers film, obtained by heating the [Zn₅(OH)₆(CO₃)₂] nanoflower precursor in N₂, is polycrystalline and displays strong defect-related emission.     

Synthesis, crystal structures and magnetic properties of Cu(II) compounds bridged by the terephthalate ligand and hydrogen bonds

A 3D network [Cu(tmen)(tp)(H₂O)₂]_n (1) (tmen = N,N,N′,N′-tetramethylethylenediamine; tp = terephthalate) and a 2D sheet [Cu(pyrazole)₂(tp)]_n (2), featuring 1D chains interwoven by hydrogen bonds, have been prepared and characterized by means of X-ray analyses and magnetic measurements. For 1, coordinative zigzag chains contain Cu(II) centers capped by the chelate ligand tmen, in which the tetragonal structure is elongated due to Jahn–Teller distortion. Coordinated water molecules are hydrogen-bonded to two free carboxylate oxygens of tp bridges, leading to the observed 3D structure. The use of the non-chelating capping ligand pyrazole produced the covalent-bonded 1D linear compound 2 with hydrogen bonds. A severe octahedral distortion of the Cu(II) center arises from a small bite angle (52.3(1)°) of two carboxylate oxygen atoms of tp, which are in turn hydrogen-bonded to the N–H groups of pyrazole ligands coordinated to Cu(II) atoms in neighboring chains. Magnetic data were fitted with the high-temperature series expansion for the Heisenberg chain spin Hamiltonian H = −J∑_iS_i · S_i + 1 together with consideration of the molecular field approximation (zJ′). Both compounds interestingly exhibit ferromagnetic interactions with g = 2.17, J = 4.08 cm⁻¹, zJ′ = −0.28 cm⁻¹ for 1 and g = 2.09, J = 1.47 cm⁻¹, zJ′ = −0.04 cm⁻¹ for 2. By taking into account structural parameters of distances between Cu atoms, it is reasonably assigned that the ferromagnetic couplings (J > 0) in these systems originate from the hydrogen bonds. The spin density of the d_x²-y² orbital on a Cu(II) atom in a chain is propagated and induced over the d_z² orbital of another Cu(II) atom in an adjacent chain. This orbital orthogonality gives rise to such interactions. The negative zJ′ term suggests that the tp bridges communicate only tiny antiferromagnetic interactions.     

Novel composite polymer electrolytes based on poly(ether-urethane) network polymer and fumed silicas

Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) network polymer (PUN), fumed silicas and LiClO₄. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition of fumed silicas and can be above 1×10⁻⁵ S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO₂ with hydrophilic groups at the surface and mSiO₂ with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO₄–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10⁻³ S/cm at room temperature and above 3×10⁻⁴ S/cm at low temperature −40 °C.     

Rhodium(II,II) dimer as an efficient catalyst for aziridination of sulfonamides and amidation of steroids

[reaction: see text] Unsaturated sulfonamides underwent direct intramolecular aziridination catalyzed by Rh(2)(OAc)(4) with PhI(OAc)(2) and Al(2)O(3) to give the corresponding aziridine products in excellent yields (up to 98%) and with good to excellent conversions. High turnovers (up to 1375) were achieved. The intermolecular rhodium-catalyzed amidation of cholesteryl acetate with PhI=NTs or PhI(OAc)(2)/NH(2)R as the nitrogen source exhibited both excellent regio- and alpha-selectivity (alpha/beta ratio up to 9:1).     

1—酰基—4—氯环己烷与取代芳烃的区域与立体选择性反应

从环己烯合成了１－酰基－４－氯环己烷，发现在其在ＡｌＣｌ３催化与苯，氯苯，溴苯等优先生成反式１－芳基－４－酰基环己烷，与联苯反应时选择性较差。     

MINDO/3研究胞嘧啶异构体间异构化反应——Ⅰ. N1-氢-4-氨基-2-羰基胞嘧啶与4-亚氨基-2-羰基胞嘧啶异构反应

本文报导用半经验方法研究N_1-氢-4-氨基-2-羰基胞嘧啶与4-亚氨基-2-羰基胞嘧啶异构化反应。用MINDO/3能量梯度法优化了孤立体系的全部自由度, 计算结果表明氨型比亚氨型稳定, △E=33.85 kJ mol~(-1); 限定分子体系在同一平面, 用Powell法优化过渡态几何构型, 计算所得正反应活化势垒为168.87 kJ mol~(-1), 逆反应活化势垒为135.02 kJ mol~(-1)。从IRC途径分析了该异构化反应的物理实质。     

α－甲基丙烯酸烯丙酯的合成及其自由基、阴离子聚合的研究

合成了α－甲基丙烯酸烯丙酯（ＡＭＡ），并对其自由基、阴离子聚合进行了探讨。结果发现，该单体难以进行选择性自由基聚合，但可用作多种单体自由基聚合的交联剂。用１，１′－二苯基己基锂在ＴＨＦ中引发ＡＭＡ，可顺利地进行α位双键的选择性阴离子聚合，分子量实测值与计算值基本一致。在较低温度下（≤－６０℃），可得窄分布ＰＡＭＡ（Ｍｗ／Ｍｎ＝１．１２～１．１５）。随聚合温度升高，间同和无规聚合物含量分别呈下降和上升趋势。ＧＰＣ、１ＨＮＭＲ及ＦＴＩＲ鉴定表明，用阴离子聚合法可得到溶于多种溶剂、每个重复单元上均定量带有烯丙基双键的窄分布官能性ＰＡＭＡ。     

Application of the slotted quartz tube in flow-injection flame atomic-absorption spectrometry

The slotted quartz has been applied to flow-injection flame atomic-absorption spectrometry (FI-FAAS) showing several important advantages. The tube life was improved by a factor of 5-6 compared to conventional continuous aspiration. Flow impact systems were found not to be necessary in the applications so that larger enhancement factors may be achieved without sacrifice in precision. For 1.0 mg/l. copper, 1.0 mg/l. lead, 0.1 mg/l. cadmium and 1.0 mg/l. gold sensitivity enhancement factors of 3.1, 5.5, 5.3 and 4.0 were obtained with precisions of 1.3%, 1.1%, 1.6% and 1.7% RSD (n = 11) respectively. Application of the slotted quartz tube FI-FAAS method to the determination of heavy metals in urine has shown improved tolerance to interfering matrices. Recoveries obtained by spiking undiluted urine samples with 0.1 mg/l. copper and lead, and 0.01 mg/l. cadmium were in the range 100-102%.     

有机官能化MSU-x孔分子筛的界面特征

MSU- x是自 M41S系列介孔分子筛问世以来所合成的另一类新型介孔分子筛材料 ,它具有三维立体交叉排列的 " worm- like"孔道结构特征及采用中性模板剂、廉价无毒等诸多合成优点 [1～ 4],有着潜在的应用价值 .为了改善纯硅的介孔材料的表面和孔道性质 ,扩大其应用领域 ,除了在骨架引入金属离子或在其孔道中负载催化活性物质外 ,对介孔材料进行有机官能化制备无机-有机杂化材料改善其骨架和孔道性质是当前研究的热点之一 [5].正是由于活性有机基团的存在 ,使得这些材料可直接用于催化反应 ,或作为中间介质成为其它络合离子的主体 .由于有机基…     

A cytotoxic compound from the leaves of Juglans mandshurica

From Juglans mandshurica leaves, a new quinone compound was isolated through bioassay-guided fractionation. The structure elucidation of the compound was established based on spectroscopic studies, notably of the 2D NMR spectra. The compound exhibited moderate cytotoxic activities against Hela, MCF-7, BGC823 and 3T3-Llcell lines with IC50 ranges from 7.5 to 26.8 μmol/L.