Propagation of singularities in Cauchy problems for quasilinear thermoelastic systems in three space variables

By using microlocal analysis, the propagation of weak singularities in Cauchy problems for quasilinear thermoelastic systems in three space variables are investigated. First, paradifferential operators are employed to decouple the quasilinear thermoelastic systems. Second, by investigating the decoupled hyperbolic-parabolic systems and using the classical bootstrap argument, the property of finite propagation speeds of singularities in Cauchy problems for the quasilinear thermoelastic systems is obtained. Finally, it is shown that the microlocal weak singularities for Cauchy problems of the thermoelastic systems are propagated along the null bicharacteristics of the hyperbolic operators.     

Synthesis and Crystal Structure of a Ternary Complex: [Ni(phen)2(pmal)]·8H2O

A new ternary complex [Ni(phen)(pmal)]·8H2O (phen = 1,10-phenanthroline,pmal2- = phenethyl malonic acid) has been synthesized by the reaction of nickel acetate, phen and phenethyl malonic acid. Elemental analysis, IR spectra and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure. Crystal data for this complex: triclinic system, space group P1, a = 10.387(5), b = 13.112(6), c = 14.229(6) (A), α = 76.176(7), β =83.778(8), y = 71.770(6)°, C35H42N4O12Ni, Mr= 769.44, Z = 2, F(000) = 808, V = 1786.1 (A)3, Dc =1.431 g/cm3, μ = 0.612 mm-1, the final R = 0.0653 and wR = 0.1033 for 9379 (Rint = 0.0244)independent reflections and 4730 observed reflections (I ＞ 2σ(I)). Structural analysis shows that the coordination geometry of Ni(Ⅱ) is a distorted octahedron. A novel two-dimensional structure is constructed from (H2O)4 and (H2O)12 water clusters, and the complex forms a 3-D network supramolecular structure by hydrogen bonds and π-π stacking of neighboring phens.     

Synthesis and Crystal Structure of Complex [Pb(qina)2(DMSO)]·H2O

A novel complex [Pb(qina)2(DMSO)]·H2O was synthesized, of which qina- is the quinaldic acid radical and DMSO the dimethyl sulfoxide. Elemental analysis, IR spectra, and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure. This complex belongs to monoclinic system, space group P121/n1, with a = 7.1553(17), b = 17.543(2), c = 17.306(2)(A),β = 91.671(4)°, C22H20N2O6PbS, Mr = 647.65, Z = 4, V= 2171.5(6)(A)3, Dc= 1.981g/cm3,μ = 7.908 mm-1, F(000) = 1248, -9≤h≤6, -23≤k≤ 19, -22≤l≤22, R= 0.0221 and wR =0.0488. Weak coordinate bond is formed between oxygen atom in DMSO and Pb(Ⅱ ). There are also weak interactions, such as π-π interaction, hydrogen bonds and so on, among the complex molecules.     

基于知识体系整合的元素无机化学教学改革

元素无机化学是大学化学及相关专业无机化学课程的核心内容。如何教好、学好元素无机化学的知识一直是教学工作者研究的课题。为改变教学现状，提高教学效果，培养学生的逻辑思维和科学创新能力，提出一种整合元素无机化学知识的思路，即：以化合物类型为主线对元素无机化学知识进行系统化整合，并以氧化物部分为例加以说明。     

A Novel Uranyl Complex with Dimeric Lacunary Polyoxoanion: [(A-α-SiW<Subscript>9</Subscript>O<Subscript>33</Subscript>)<Subscript>2</Subscript>K{UO<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)}<Subscript>2</Subscript>]<Superscript>11−</Superscript>

A novel uranyl complex with dimeric lacunary polyoxoanion like open-mouthed clam, Na₅[(A-α-SiW₉O₃₃H₃)₂K{UO₂(H₂O)}₂], was prepared and characterized by elemental analysis, infrared and ultraviolet–visible spectroscopy and single crystal X-ray diffraction. In the anion, two A-α-SiW₉O₃₄¹⁰⁻ groups share two terminal oxygen atoms O_d′ derived from removal of three corner-shared W atoms from saturated α-Keggin anion, forming a dimeric anion with an open mouth in which potassium ion and uranyl ions are coordinated. Uranium atom adopts a pentagonal bipyramidal geometry. The coordinating anions are linked by sodium ions via coordination of terminal or bridging oxygen atoms, forming two-dimensional layer arrangement. Between the layers are the hydrogen bonds from which a supramolecular architecture is created. UV–VIS spectrum gives W–O and U–O charge transfer transitions at 230–265 and 432 nm, showing the change of geometry of the polyanion and weakening of the U–O bonds of the uranyl cation. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users.     

Synthesis and Crystal Structure of the Coordination Polymer of Ni-Mo8-Pyrazinecarboxylic Acid

An inorganic–organic hybrid compound [Ni₄(pzac)₄(H₂O)₈(β-Mo₈O₂₆)]·2H₂O (1), pzac = 2- pyrazinecarboxylic acid, was synthesized hydrothermally and characterized by IR spectrum, TGA, X-ray single-crystal diffraction. Photoluminescence property has been investigated. In 1 pzac coordinates to Ni1 with a chelating mode and bridges Ni2 forming a one-dimensional undulate chain structure. Ni atom accepts a terminal oxygen atom of [β-Mo₈O₂₆]^4? anion with a little longer Ni–O distances of 2.685 Å and 2.767 Å. [β-Mo₈O₂₆]^4? anion links four Ni atoms of four chains, forming a three-dimensional covalent framework. Lattice water molecules fill the vacancies of the framework.     

含联苯三羧酸及二咪唑基吡啶配体的两个锌配位聚合物的合成、结构及荧光性质

以3,3′,5-联苯三羧酸(biphenyl-3,3′,5-tricarboxylic acid,H3bpta)、2,6-二(1-咪唑基)吡啶(2,6-bis(imidazole-1-yl)pyridine,bip)、Zn(NO3)2·6H2O和ZnCl2为原料,在水热条件下合成了配位聚合物{[Zn3(H2O)7(bpta)2]·5H2O}n(1)和{[Zn2Cl(bpta)(bip)2]·2H2O}n(2)。并利用红外、元素分析和X-射线单晶衍射等对其结构进行表征。X-射线单晶衍射分析表明:化合物1属于单斜晶系,C2/c空间群,a=3.317 1(11)nm,b=1.495 7(5)nm,c=0.695 1(2)nm,β=91.50°,Z=4;化合物2属于单斜晶系,P2/c空间群,a=1.960 4(4)nm,b=1.035 7(2)nm,c=1.998 7(4)nm,β=101.97(3)°,Z=4。化合物1通过bpta桥联Zn髤形成1D链,通过配位水与羧基氧之间的氢键作用构筑成3D结构。化合物2中bip桥联Zn髤构成1D螺旋链状结构,进一步通过bpta桥连形成2D网状结构。此外,对化合物1和2进行了热稳定性分析和荧光性质研究。     

A flexible chelate ligand in dodecatungstoborate-based supramolecular compounds

Two new dodecatungstoborate-based supramolecular compounds, [Cu₄(H₂EGTA)₂(H₂O)₄(HBW₁₂O₄₀)]·18H₂O (1) and [Na₃(H₂O)₆Ca₃(H₂O)₆(HEGTA)₂] [H₂BW₁₂O₄₀]·21H₂O (2) (EGTA = ethyleneglycol-bis-(2-aminoethylether)-tetra acetate anion), were synthesized in aqua solution and characterized by element analysis, infrared spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction technique. The results show that in 1 two H₂EGTA^2? anions bond to four Cu²⁺ ions forming a four-nuclear cyclic cation, Cu₄(H₂EGTA)₂(H₂O) ₄ ⁴⁺ ; and dodecatungstoborate anion HBW₁₂O₄₀ ^4? acting as a bidentate ligand links two four-nuclear cations, leading to one-dimensional chain extending along [101] direction, [Cu₄(H₂EGTA)₂(H₂O)₄(HBW₁₂O₄₀)] _n (Cu–EGTA–BW₁₂). In 2 two HEGTA^3? anions coordinate to four Ca²⁺ ions in different modes, forming a Ca-EGTA polymeric chain. The building blocks (Cu–EGTA–BW₁₂ chains in 1, Ca–HEGTA chains and BW₁₂ anions in 2) are fused into three-dimensional architectures by hydrogen bonds. Variable temperature magnetic susceptibilities of 1 were determined and the results show that in 1 there is a weak ferromagnetic interaction.