Hydro­gen bonds in the framework of bis{2-[bis(2-amino­ethyl)­amino]­ethanol}nickel(II) diperchlorate

The title molecule, [Ni(C₆H₁₇N₃O)₂](ClO₄)₂, possesses a crystallographic centre of symmetry at the Ni^II position. The coordination geometry around the Ni^II atom is distorted octahedral, consisting of six N atoms from two tripodal poly­amine ligands, while the ethanol O atoms of the ligands remain uncoordinated. The crystal packing shows two-dimensional layers and an infinite three-dimensional framework which is stabilized by a hydrogen-bonded network.     

层流与湍流等离子体冲击射流特性比较

本文采用数值模拟方法,对层流与湍流氩等离子体射流在空气环境中冲击平板时的流动与传热特性进行了对比研究.结果表明,在平板和射流进口间的距离较大时,平板的存在只对其附近的射流参数分布有较大影响,层流等离子体冲击射流的温度与轴向速度的轴向梯度明显小于湍流等离子体冲击射流情形;由于在平板表面形成的径向壁面射流对引射的附加贡献,层流和湍流等离子体冲击射流对环境空气的引射量明显增加.     

探针移动速度对等离子体射流热流密度测量结果的影响

采用自行研制的中心嵌有铜柱感应件的小尺寸杆状热流探针,在低扰动条件下,对射入大气环境的纯氩层流等热离子体射流传向铜探头表面的热流密度进行了动态测量.结果表明,在射流最高温度16500 K、最大轴向速度850 m/s、探针垂直于射流流动方向的移动速度130～260 mm/s的实验参数范围内,随着探针移动速度的提高,测得的热流密度值减小;射流温度和速度越高,探针移动速度对热流密度测量值的影响越大.     

Development of N-benzamidothioureas as a new generation of thiourea-based receptors for anion recognition and sensing

A series of neutral N-(substituted-benzamido)-N'-phenylthioureas (substituent = p-OC(2)H(5), p-CH(3), m-CH(3), H, p-Cl, p-Br, m-Cl, and p-NO(2)) were designed as anion receptors, in which the thiourea binding site was attached to the benzamido moiety via an N-N bond. The absorption spectra of these N-benzamidothioureas in acetonitrile peaked at ca. 270 nm were found to show unprecedented red shifts by 7 373 to 14 325 cm(-1) in the presence of anions such as AcO(-), F(-), and H(2)PO(4)(-). Under the same conditions, the classic neutral thiourea receptors, N-(substituted-phenyl)-N'-phenylthioureas, showed absorption spectral shifts in most cases of less than 800 cm(-1) with one exception of 6501 cm(-1). Control experiments, effects of protic solvent, and (1)H NMR titration confirmed the formation of hydrogen-bonding complexes between the new N-benzamidothiourea receptors and anions. The binding constants with AcO(-), for example, are at 10(5)-10(7) mol(-1) L order of magnitude, which are 13 to 590 times those of the corresponding classic N-phenylthioureas in the same solvent. It was found that, whereas the absorption of the N-benzamidothiourea receptors showed essentially no dependence on the substituent, the substantially red-shifted new absorption band of the N-benzamidothiourea-anion binding complex was sensitively subject to the substituent. A linear relationship was found between the absorption energies of the N-benzamidothiourea-acetate binding complexes and the Hammett constants of the substituents with a negative slope of -0.34 eV. This led to the assignment that the substantially red-shifted absorption band was the ground-state intramolecular charge-transfer absorption with the substituent locating in the electron acceptor moiety. It was concluded that anion binding to the thiourea moiety of the N-benzamidothiourea receptors switched on their ground-state charge transfer. An anion-binding induced structural change was suggested to occur around the N-N bond in N-benzamidothioureas, which resulted in a substantially increased electron donating ability of the electron donor in the receptor molecules. As a consequence, the ground-state charge transfer takes place in the N-benzamidothiourea-anion binding complexes, leading to unprecedented red shifts in the absorption spectra and substantially enhanced anion binding affinities than those of the corresponding N-phenylthiourea receptors. N-Benzamido-N'-phenylthioureas represent a new generation of neutral thiourea-based anion receptors that show substantially improved anion binding performance important for anion sensing and recognition.     

1,2,4-苯三甲酸铜二维网状配合物的合成及结构表征(英)

在室温下,MnSO₄·H₂O和1,2,4-苯三甲酸(H₃BTC)反应得到化合物[Mn(H₂BTC)₂(H₂O)₄]·2H₂O (1),化合物1和CuSO₄·5H₂O反应得到化合物[Cu(HBTC)(H₂O)_1.5]·H₂O (2)。化合物1是一个单核分子化合物。在化合物1中,每个锰离子和两个H₂BTC^－离子及四个水分子配位。化合物2中,每个铜离子和三个HBTC^2－及两个水分子配位,其中的一个水分子起桥联作用从而形成二维网状结构。     

Solubilities, Densities and Refractive Indices of Rubidium Chloride or Cesium Chloride in Ethanol Aqueous Solutions at Different Temperatures

The data of solubilities, densities and refractive indices of rubidium chloride or cesium chloride in the system CEHsOH-H2O were measured by using a simple accurate analytical method at different temperatures, with mass fractions of ethanol in the range of 0 to 1.0. In all cases, the presence of ethanol significantly reduced the solubility of rubidium chloride and cesium chloride in aqueous solution. The solubilities of the saturated solutions were fitted via polynomial equations as a function of the mass fraction of ethanol. The CsC1-C2H5OH-H2O ternary system appeared in two liquid phases： alcoholic phase and water phase, when the mass fractions of ethanol were in the range of 10.37% to 49.59% at 35 ℃. Density and refractive index were also determined for the same ternary systems with varied unsaturated salt concentrations. Values for both experiment and theory were correlated with the salt concentrations and proportions of alcohol in the solutions. The equations proposed could also account for the saturated solutions.     

Synthesis,structure and properties of an imidazolate bridged copper,zinc binuclear complex

A new imidazolate bridged Cu~(2+),Zn~(2+)binuclear complex[(dtma) CulmZn (dtma)]ClO_4·2.5H_2O taken as active site model for Cu,Zn-SOD has been synthesized and its crystal structuredetermined.All the bond lengths, bond angles and the distance between Cu and Zn atoms in Cu-Im-Zn core of the model complex are close to those in Cu,Zn-SOD.ESR parameters of the modelcomplex as a function of pH show that the imidazolate bridge is stable in pH range 10—12,and isbroken on Zn side at pH～9.With decreasing pH,the imidazole is released at pH～4 and the dtmaligand dissociates from the Cu containing fragment at pH～2.4.     

A 2-D bimetallic assembly with bridging cyanide ions

A novel cyanide-bridged bimetallic assembly, [Cu(1,3-Pn)₂]₂[Fe^III(CN)₆]ClO₄ · 2H₂O (1,3-Pn = 1,3-diaminopropane), derived from [Fe(CN)₆]^3– building blocks and four-coordinated bisdiamine metal(II) ions [Cu(1,3-Pn)₂]²⁺ is described and characterized by X-ray crystal analysis. The compound contains a two-dimensional network structure extended through Fe^III—CN—Cu linkages. Mössbauer experimental results indicate that the iron is ferric (Fe³⁺) in the complex. Cryomagnetic measurements reveal an antiferromagnetic exchange interaction between the nearest paramagnetic metal ions in the compound. The exchange mechanism was also discussed.     

新型二维网状双席夫碱银配合物的合成与结构

席夫碱配体由于在合成上具有极大的灵活性和良好的配位能力 ,因而席夫碱 -金属配合物的研究一直受到广泛重视 .多年来 ,席夫碱配体由简单的单齿发展到多齿和大环配体 .此外 ,过渡金属的席夫碱配合物具有独特的结构、性能和广泛的应用 ,如氧化还原 [1] 、催化 [2 ] 以及生物体系的化学模拟 [3 ] ;另一方面 ,由于银原子配位方式的多样性 (二、三、四和五配位 ) ,便于人们对超分子化合物的组装规律进行系统研究 ,因而银配合物的研究正日益引起人们极大的兴趣 [4～ 7] .鉴于此 ,我们设计合成了一个新的四齿席夫碱配体 L ,研究了其与 CF3 SO3 …     

低功率电弧加热发动机喷管扩张段内壁面温度测量

采用滤光成像,摒弃电弧及羽流干扰,实验获得了采用纯氮、纯氢以及氢-氮混合气为推进剂时,低功率电弧加热发动机喷管内壁面的热辐射强度分布。通过辐射强度-温度标定以及图像分析,导出了相应的温度分布。实验结果表明,喷管扩张段内壁面温度最高处位于喉道出口附近。采用不同推进剂时,喷管内壁面温度分布情况有显著区别。