A Trinuclear Ni(Ⅱ) Mixed-ligand Complex Containing Pentadentate N-butylsalicylhydrazide and Monodentate Imidazole:Synthesis, Characterization and Crystal Structure

A novel trinuclear nickel(Ⅱ) complex [Ni3(bushz)2(Himdz)2(H2O)2]?2DMF (1, bushz=N-butylsalicylhydrazide, Himdz=imidazole, DMF=N,N-dimethyl-formamide) has been synthesized and characterized by X-ray single-crystal diffraction characterization. Complex 1 crystallizes in the monoclinic system, space group P21/c with a=7.706(7), b=14.882(6), c=18.639(6) , β=108.08(2)o, V=2032(1) 3, Dc=1.525 g/cm3, Mr=932.95, Z=2, F(000)=972, μ=1.442 mm-1, the final R=0.0359 and wR=0.0771. The three nickel(Ⅱ) atoms in 1 are arranged in a strictly linear structure and exhibit alternating square-planar and octahedral geometries. The complex is connected to form a supramolecule with an infinite three-dimensional network through intermolecular hydrogen bonds. The electrochemical studies reveal that redox of Ni3+/Ni2+ in the complex is a quasi-reversible process. The thermal stability of the title complex was also studied.     

Simultaneous determination of cyromazine,melamine and their biodegradation products by ion-pair high-performance liquid chromatography

An ion-pair high-performance liquid chromatography with ultraviolet detection method for the determination of cyromazine, melamine and its biodegradation products (ammeline, ammelide, cyanuric acid and biuret) was developed. C18 column was utilised to separate the six analytes with a mobile phase consisting of perchloric acid-ammonia solution and acetonitrile, under gradient elution and variable flow rate. The detection wavelengths were 205 nm for cyanuric acid and biuret and 222 nm for cyromazine, melamine, ammeline and ammelide. For analysis of sediment samples, the extraction solution containing acetonitrile, ammonia and water (80:10:10 by volume) was used to extract the analytes from sediment matrix. Using the extraction method for the spiked sediment sample, high linearity of matrix-matched standard curve could be obtained for the six analytes. The method detection limit was 0.1 μg g^?1 for melamine and cyromazine, 0.2 μg g^?1 for ammeline and ammelide, 1.2 μg g^?1 for cyanuric acid and 1.0 μg g^?1 for biuret in sediment matrix. The recoveries of these compounds were 70.1–98.3% and the relative standard deviations were 0.5–4.4%. Finally, the proposed method was successfully applied to the analysis of the sediment sample near the wastewater outlet of a melamine-producing factory.     

一种新型黄色荧光类水滑石材料的制备及表征

用适量的Zn(Ⅱ)取代镁铝水滑石中的Mg(Ⅱ),同时将一定量的2-对联苯基-8-羟基喹啉分散到类水滑石层间的亲油性阴离子中,使其与层板表面上的Zn(Ⅱ)配位,用一步法合成、组装得到一类新型黄色荧光类水滑石复合物(Zn-(HQ-4-biPh)-HTlc)。采用荧光光谱、红外光谱、X射线衍射、扫描电子显微镜和热分析等对其进行了表征。研究结果表明,Zn-(HQ-4-biPh)-HTlc在蓝光(481 nm)激发下可发出黄色荧光(554 nm),与其相应的含锌配合物(Zn[2-(p-biph)-8-Q-O]2)相比,不仅可节省配体用量,而且具有更高的发光强度和更好的热稳定性,有望在白光LED等光电领域得到应用。     

2-氨基对苯二甲酸根及2-咪唑烷酮构筑的镉(Ⅱ)配位聚合物的合成、晶体结构及荧光性质

以一种尿素的衍生物2-咪唑烷酮为溶剂,采用脲热法合成了一个新的配位聚合物[Cd(NH₂bdc)(e-urea)]_n(1)(H₂NH₂bdc为2-氨基对苯二甲酸,e-urea为2-咪唑烷酮),并对其结构和荧光性质进行了研究。单晶结构分析结果表明,标题化合物的中心镉(Ⅱ)离子分别与2-氨基对苯二甲酸根配体的羧基氧原子和溶剂氧原子配位形成七配位的变形五角双锥结构。相邻的中心镉(Ⅱ)离子通过溶剂氧原子和配体羧基基团的连接,形成无限的一维链。这些一维的链进一步通过2-氨基对苯二甲酸根配体的连接最终形成了具有一维孔道的三维框架结构。研究表明,该化合物在室温下能发出较强的蓝色荧光。     

基于烟酰腙Schiff碱的Cu(Ⅱ)和Ni(Ⅱ)配合物的合成、晶体结构和性质

采用缓慢挥发法合成了2个烟酰腙类Schiff碱配合物[Cu(Py)(HL¹)]₂ (1)和[Ni(L²)₂] (2), 其中, H₃L¹=2, 4-二羟基苯甲醛缩烟酰腙, HL²=2-乙酰基吡啶缩烟酰腙。采用元素分析、红外光谱、紫外光谱、荧光光谱和热重分析以及X-射线单晶衍射分析进行 了表征。结果表明, 1和2的晶体均属单斜晶系, P2₁/c空间群;1的晶胞参数a=0.739 86(12) nm, b=1.903 7(3) nm, c=1.154 86(19) nm, β=105.090(3)°, V=1.570 5(4) nm³;该化合物是中心对称的双核配合物, 每个Cu(Ⅱ)离子都处于畸变四方锥配位环境;结构基 元通过π-π相互作用和O-H…N氢键形成三维超分子。2的晶胞参数a=2.034 0(5) nm, b=1.183 2(3) nm, c=1.020 7(3) nm, V=2.456 1(11) nm³;中心离子Ni(Ⅱ)的配位数为6, 它处于畸变八面体配位环境。配合物有很高的热稳定性, 分解温度分别为315 ℃ (1)和358 ℃ (2)。     

一类Hermitian鞍点矩阵的特征值估计

本文研究了一类大型稀疏Hermitian鞍点线性系统Az=(B E E* 0)(x y)=(f g)=b系数矩阵的特征值,其中B∈C~(p×p)是Hermitian正定阵矩阵,E∈C~(p×q)是列降秩.本文分别给出了该系数矩阵正特征值与负特征值界的一个估计式,同时通过数值算例验证本文所给出的特征值界的估计是合理且有效的.     

Numerical discretization-based kernel type estimation methods for ordinary differential equation models

We consider the problem of parameter estimation in both linear and nonlinear ordinary differential equation(ODE) models. Nonlinear ODE models are widely used in applications. But their analytic solutions are usually not available. Thus regular methods usually depend on repetitive use of numerical solutions which bring huge computational cost. We proposed a new two-stage approach which includes a smoothing method(kernel smoothing or local polynomial fitting) in the first stage, and a numerical discretization method(Eulers discretization method, the trapezoidal discretization method,or the Runge–Kutta discretization method) in the second stage. Through numerical simulations, we find the proposed method gains a proper balance between estimation accuracy and computational cost.Asymptotic properties are also presented, which show the consistency and asymptotic normality of estimators under some mild conditions. The proposed method is compared to existing methods in term of accuracy and computational cost. The simulation results show that the estimators with local linear smoothing in the first stage and trapezoidal discretization in the second stage have the lowest average relative errors. We apply the proposed method to HIV dynamics data to illustrate the practicability of the estimator.     

Nano-crystalline FeOOH mixed with SWNT matrix as a superior anode material for lithium batteries

Nano-crystalline FeOOH particles(5～10 nm) have been uniformly mixed with electric matrix of single-walled carbon nanotubes(SWNTs)for forming FeOOH/SWNT composite via a facile ultrasonication method. Directly using the FeOOH/SWNT composite(containing 15 wt%SWNTs) as anode material for lithium battery enhances kinetics of the Li+insertion/extraction processes, thereby effectively improving reversible capacity and cycle performance, which delivers a high reversible capacity of 758 mAh g-1under a current density of 400 mA g-1even after 180 cycles, being comparable with previous reports in terms of electrochemical performance for FeOOH anode. The good electrochemical performance should be ascribed to the small particle size and nano-crystalline of FeOOH, as well as the good electronic conductivity of SWNT matrix.     

Dearomative spirocyclization via visible-light-induced reductive hydroarylation of non-activated arenes

A visible-light-induced spirocyclizative hydroarylation via reductive dearomatization of a series of non activated arenes including 2-phenyl indoles and naphthalene derivatives under mild conditions is de scribed. An intriguing chemoselective dearomative hydroarylation of 2-phenyl indoles is presented. Th dearomative hydroarylation protocol rapidly delivers valuable spirocycles with carbon-carbon doub bonds from readily accessible aromatic precursors in a single step.     

利用游戏化教学促进“微粒观”建构*——以“原子的结构”第一课时为例

分析了初中化学微粒观的教学内容和“原子的结构”的相关教学设计,针对学生“微粒观”建构存在的难题,提出利用反馈机制,采用“寓教于乐”的游戏化教学设计,并进行实践效果访谈。不仅完成了本课时的教学目标,也让学生对化学的兴趣更加浓厚。