Synthesis and Structures of Four Metal-Organic Coordination Compounds with Isomeric Tripodal Ligands

Four new metal-organic coordination compounds [Ni(L4)₂](ClO₄)₂ · 2H₂O ( 1 ), [Cu₂(L4)₂(H₂O)₂(Cl)](Cl)₃ · 5H₂O ( 2 ), [Cu₂(L3)₂(H₂O)(Cl)](Cl)₂ · (NO₃) · 6H₂O ( 3 ), and [Cu(L3)(H₂O)(NO₃)](NO₃) · H₂O ( 4 ), were synthesized and characterized by X-ray crystallography with two isomeric tripodal ligands N¹-(2-amino-ethyl)-N¹-pyridin-3-ylmethyl-ethane-1,2-diamine (L3) and N¹-(2-amino-ethyl)-N¹-pyridin-4-ylmethyl-ethane-1,2-diamine (L4), respectively. It was found that coordination compound 1 exhibits mononuclear structure, and coordination compound 2 displays a one dimensional (1D) zigzag chain structure. Coordination compound 3 shows interesting cyclic hexanuclear structure, whereas coordination compound 4 is a 1D zigzag chain structure. The results indicate that metal ions, organic ligands, and anions have remarkable influence on the formation and structures of the coordination compounds.     

Delay induced subcritical Hopf bifurcation in a diffusive predator-prey model with herd behavior and hyperbolic mortality

In this paper, we consider the dynamics of a delayed diffusive predator-prey model with herd behavior and hyperbolic mortality under Neumann boundary conditions. Firstly, by analyzing the characteristic equations in detail and taking the delay as a bifurcation parameter, the stability of the positive equilibria and the existence of Hopf bifurcations induced by delay are investigated. Then, applying the normal form theory and the center manifold argument for partial functional differential equations, the formula determining the properties of the Hopf bifurcation are obtained. Finally, some numerical simulations are also carried out and we obtain the unstable spatial periodic solutions, which are induced by the subcritical Hopf bifurcation.     

Synthesis and Crystal Structure of [{Mn(IBG)(2,2'-bipy)(H_2O)}·4H_2O]_n

A novel MnⅡ complex [{Mn(IBG)(2,2'-bipy)(H2O)}·4H2O]n 1(H2IBG=isophtha-loylbisglycine and 2,2'-bipy = 2,2'-bipyridine) has been synthesized and characterized by singlecrystal X-ray diffraction,elemental analysis,IR spectra and thermogravimetric analysis.It crystallizes in monoclinic,space group P21/n,with a=13.667(2),b=14.045(2),c=14.195(2),β=101.483(3)°,V=2670.1(7)3,Z=4,C22H26N4O11Mn,Mr=577.41,Dc=1.436 g/cm3,F(000)=1196.0,μ(MoKα)=0.558 mm-1,the final R=0.0578 and wR=0.1460 for 2974 observed reflections with I2σ(I).In the structure,the MnⅡ atom is coordinated in a distorted octahedral environment arranged by one water molecule,one 2,2'-bipy ligand and two IBG ligands.     

Impact of fullerenes on the thermal stability of melt processed polystyrene and poly(methyl methacrylate) composites

The impact of the two fullerenes C₆₀ and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) on the thermal and thermo-oxidative stability of the corresponding melt processed composites with the two polymers polystyrene (PS) and poly(methyl methacrylate) (PMMA), was studied using both dynamic and isothermal thermogravimetric analysis (TGA). For each polymer, three different composites with C₆₀ loadings of 1.0 wt% and 3.0 wt% and PCBM loadings of 1.0 wt% were considered. The aim of this work was to compare the stabilization effect of both fullerenes on PS and PMMA. The results obtained show unequivocally that, although PCBM has lower thermal and thermo-oxidative stability than C₆₀, the PS-PCBM and PMMA-PCBM composites have higher thermal and thermo-oxidative stability than the corresponding PS-C₆₀ and PMMA-C₆₀ composites. These results corroborate our previous reports, on showing that PCBM is better than C₆₀ at improving the thermal and thermo-oxidative stability of polymers which degrade through radical degradation mechanisms.     

两个d10金属配位聚合物的合成、结构及对2,4,6-三硝基苯酚的选择性检测

以4,4''-二（1-咪唑基）苯硫醚（BIDPT）,4,4''-羧基二苯胺（H₂aba）,5-氧乙酸间苯二酸（H₃OABDC）,Zn（NO₃）₂·6H₂O和Cd（NO₃）₂·6H₂O为原料,用溶剂热法合成了2个配位聚合物[Zn（BIDPT）（aba）]_n（1）和[Cd（BIDPT）（HOABDC）]_n（2）。利用X射线单晶衍射、红外、元素分析、热重分析和X射线粉末衍射对其进行了表征。单晶X射线衍射研究发现配合物1为具有二重穿插的三维dia拓扑网络结构;配合物2为3-连接六边形的hcb二维拓扑结构,再通过氢键堆积作用形成三维超分子结构。1和2具有很好的荧光性质,硝基苯化合物对配合物1和2的荧光性质有不同程度的淬灭作用。它们都对2,4,6-三硝基苯酚的检测具有很好的灵敏性。对其淬灭机理进行了深入的研究。     

示波器实验的教学改革

示波器的原理和使用是大学物理实验教学的一个基础实验项目.传统的教学仅限于向学生介绍示波器显示波形的原理,测量信号电压、频率和周期等参数,以及采用利萨如图形测量待测信号频率等内容.随着科技的进步,传统的模拟示波器已经逐步被数字示波器所替代,一些高校实验项目也做了相应的调整.本课题探讨数字示波器的实验拓展,即结合压电传感器...     

基于冷原子重力仪的绝对重力动态移动测量实验

动态重力测量可以提高重力场的勘测效率,对基础地质调查、资源勘探、地球物理研究等具有十分重要意义.本文基于冷原子重力仪、惯性稳定平台和牵引动力装置搭建了一套绝对重力动态移动测量系统,并开展了绝对重力动态测量实验.首先测量了不同牵引速度下的垂向振动噪声功率谱,理论分析了其对动态重力测量的影响;其次评估了不同牵引速度对原子干...     

茶树叶与根表面的XPS表征

利用X射线光电子能谱(XPS)研究了茶树叶与根的表面化学组成与结构。结果表明,茶树表面主要由C, O, N和Al等四种元素组成,在茶树叶远轴面还有少量的P和F。通过查阅标准图谱数据库、参照木材表面XPS分析结果,对茶树表面测得的C1s结合能采用曲线拟合与分峰,得到三种形态：结合能为285 eV的是C1,来自C—C或C—H,代表角质、蜡质等脂类化合物;C2的结合能在286.35 eV（近轴面）和286.61 eV（远轴面）,是能够与氧形成单键的C—O,主要源于表面的纤维素;C3的结合能为288.04 eV（近轴面）和288.09 eV（远轴面）,为CO基团标志,综合N（1s）的结合能（399～401 eV）和O（1s）的分峰情况,为蛋白质的酰基标志。茶树根表面除含有与叶表面相同的C1(结合能285 eV)、C2（结合能286.49 eV）和C3（结合能288.78 eV）所代表的角质、蜡质、纤维素和蛋白质之外,还出现了结合能为283.32 eV的C5。由于其结合能低于C1,推测为茶树根表面的有机金属形态。茶树叶和根表面没有木材表面具有的羧基C4,说明根系分泌的有机酸游离存在于根表面。对茶树表面O（1s）图谱的拟合结果与C（1s）结果相吻合。计算不同C和O形态所占的比例得知,茶树叶面远轴面含氧基团多于近轴面,呈较高的氧化状态,因此远轴面化学性质较活泼;与叶相比,茶树根的角质和蜡质含量显著降低,含氧基团相对增多,因此化学性质较活泼,适于水分子和其他溶质分子通过。由于蛋白质含量为根表面＞远轴面＞近轴面,表明根表面的湿润度高于叶表面,而远轴面湿润度高于近轴面。存在于茶树表面Al的结合能均大于单质铝72.7 eV,在73.50 eV以上,为Al₂O₃形态,这将增大茶树表面的吸附作用。由于根表面Al₂O₃含量高于叶面,显示根具有更强的吸附能力。     

Entanglement Dynamics of Multipartite Systems Under Decoherence from a Spin Environment

The entanglement evolution of multipartite quantum states under a spin environment is analyzed. Due to interaction, the extent to which the entanglement vanishes depends not only on the size of system and the structure of quantum states, but also on the exchange couplings with environment. The decoherence-free subspaces have been identified by using the linear entropy.     

New cyclometalated palladium(II) complexes with iminophosphines: Crystal structures of [Pd(C^N)(o-Ph2PC6H4–CH=NR)][PF6] (C^N=azobenzene,R=Et; C^N=2-phenylpyridine,R=Me)

The synthesis of new cyclometalated compounds of palladium(II) with the mixed-donor bidentate ligands o-Ph₂PC₆H₄–CH=NR is described. Two series of complexes [Pd(C^N)(o-Ph₂PC₆H₄–CH=NR)][PF₆] have been prepared using either azobenzene or 2-phenylpyridine as cyclometalated ligands [C^N=azobenzene (azb); R=Me (1a), Et (2a), ⁿPr (3a), ⁱPr (4a), ^tBu (5a), Ph (6a), NH–Me (7a); C^N=2-phenylpyridine (phpy); R=Me (1b), Et (2b), ⁿPr (3b), ⁱPr (4b), ^tBu (5b), Ph (6b), NH–Me (7b)]. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, FAB, ¹H and ³¹P NMR). The molecular structures of compounds 2a (monoclinic, P 2₁/n) and 1b (monoclinic, C 2/c) have been determined by a single-crystal diffraction study. In both cases this technique revealed the relative trans configuration between the phosphorus atom and the nitrogen atom of the ortho-metalated ligand.