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.     

Gaseous nitryl azide N4O2: A joint theoretical and experimental study

Gaseous nitryl azide N₄O₂ is generated by the heterogeneous reaction of gaseous ClNO₂ with freshly prepared AgN₃ at −50 °C. The geometric and electronic structure of the molecule in the gas phase has been characterized by in situ photoelectron spectroscopy (PES) and quantum chemical calculations. The experimental first vertical ionization energy of N₄O₂ is 11.39 eV, corresponding to the ionization of an electron on the highest occupied molecular orbital (HOMO) {4a″(π_{nb(N4–N5–N6)})}⁻¹. An apparent vibrational spacing of 1600 ± 60 cm⁻¹ (ν_asO1N2O3) on the second band at 12.52 eV (π_{nb(O1–N2–O3)}) further confirms the preference of energetically stable chain structure in the gas phase. To complement the experimental results, the potential-energy surface of this structurally novel transient molecule is discussed. Both calculations and spectroscopic results suggest that the molecule adopts a trans-planar chain structure, and a five-membered ring decomposition pathway is more favorable.     

Using three major criteria to evaluate aromaticity of five-member C-containing rings and their Si-, N-, and P-substituted aromatic heterocyclics

In this paper, we used bond-length equalization, aromatic stabilization energies (ASE) and nucleus-independent chemical shifts (NICS), calculated with (density functional theory) B3LYP levels at the 6-311+G^** basis set, to evaluate the aromaticity of a set of 38 five-member planar π-electron aromatic systems: sila-, aza- and phospha- derivatives and their parent systems. The result revealed statistically significant correlations among the above three criteria, and the order of aromaticity of the whole set was: Aza- derivatives rings > Phospha- derivatives rings > Sila- derivatives rings > Carbon-containing rings; NICS(0.6) and NICS(0.8) had the same results in evaluating the order of aromaticity in our case.     

Metal-free synthesis of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles via microwave-assisted synthesis pathway

Abstract

A simple, efficient, and metal-free methodology for the preparation of 2-mercaptobenzothiazole and derivatives in excellent yields via microwave-assisted pathway is reported. Our condition provides a convenient protocol for the synthesis of a diverse collection of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles with a very simple purification process. This report provides an alternative protocol for fast access to the wide range of compounds for sequence synthesis and biological studies.     

微孔中简单流体粘度的分子动力学模拟及关联模型

用分子动力学模拟计算了微孔介质中流体氩在不同温度、不同密度和不同孔径下的剪切粘度.并根据Chapman-Enskog关于硬球流体传递性质的理论以及Heyes的关于Lennard-Jones流体粘度的表达式,提出了两个描述微孔介质中流体粘度的模型,该模型可以计算微孔中流体氩在不同状态下的粘度值.通过与计算机模拟值的比较,证明这两个微孔流体粘度模型是可用的.     

Synthesis, crystal structure and magnetic property of the novel dinuclear nickel(II) complex with 4-(p-methoxyphenyl)-3,5-bis(pyridine-2-yl)-1,2,4-triazole

A novel dinuclear nickel(II) complex, [Ni₂(MOBPT)₂Cl₂(H₂O)₂]Cl₂ · 7H₂O (MOBPT = 4-(p-methoxyphenyl) −3,5-bis(pyridine-2-yl)-1,2,4-triazole), has been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction methods. The crystal structure determination shows that the dinuclear Ni₂N₈ unit is almost planer in which each Ni^II ion is coordinated by four nitrogen atoms from MOBPT equatorially and a water molecule and a chloride ion axially in a distorted octahedral geometry. Magnetic measurements reveal a relatively weak antiferromagnetic exchange in the complex.     

Streamlined construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation in solution and on DNA

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed. The method exhibits a broad substrate scope for thiols, aryl iodides and amino acid units. Peptide macrocycles of a wide range of size and composition can be readily assembled in high yield from various easily accessible building blocks. This method has been successfully employed to prepare an 8-million-membered tetrameric cyclic peptide DNA-encoded library (DEL). Preliminary screening of the DEL library against protein p300 identified compounds with single digit micromolar inhibition activity.

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed.     

三唑类硫醚及二硫醚化合物的合成

以2-苯基-1，2，3-三唑-4-甲酰肼为原料，合成了6个新的含连三唑和均三唑的硫醚类化合物，并经IR、^1HNMR、MS和元素分析进行了结构表征。     

用EXAFS研究NiO在γ-Al2O3表面上的分散

本文使用EXAFS方法研究NiO在γ-Al_2O_3的表面上的分散情况。文章讨论了Ni含量为7%、13%、18%、26%、35%的NiO/γ-Al_2O_3体系的径向结构函数图以及Ni含量为13%、26%的NiO/α-Al_2O_3样品的径向结构函数图,认为NiO能在γ-Al_2O_3表面上成单层分散。分散后的Ni-O距离接近NiO晶体的Ni-O距离,表明Ni离子和γ-Al_2O_3表面上的氧有很强的相互作用。     

Photocrosslinking of functionalized rubber. II. Photoinitiated cationic polymerization of epoxidized liquid natural rubber

Low molecular weight epoxidized natural rubber has been crosslinked within seconds by UV irradiation in the presence of a triarylsulfonium salt. The photoinitiated cationic ring-opening polymerization was studied quantitatively by infrared spectroscopy and shown to proceed with surprisingly long kinetic chains in such solid medium. The high conversion (60%) needed for complete insolubilization, together with the presence of tetrahydrofuran structures, argue in favor of an intramolecular polymerization process involving neighboring epoxy groups. The photoinitiator concentration has a strong influence on the rate and extent of the reaction, as well as on the depth of cure profile. Because of an efficient dark process, close to 100% conversion was reached upon storage of the irradiated elastomer at ambient, with a concomitant increase of the gel fraction and the polymer hardness. The grafting of pendent acrylate groups onto the polymer chain leads to a three-fold decrease of the initial rate of polymerization of the epoxide. The photocuring of natural rubber bearing both epoxy and acrylate groups generates a dual polymer network which combines the properties of the two moieties. © 1995 John Wiley & Sons, Inc.