Synthesis, structure, and fluorescence of the novel cadmium(II)-trimesate coordination polymers with different coordination architectures

Three novel complexes, Cd3tma2*13H2O (1), Cd3tma2*dabco*2H2O (2), and Cd3Htma3*8H2O (3) (tma = trimesate), of cadmium(II)-trimesate coordination polymers are obtained from hydrothermal reaction. 1 (C18H32O25Cd3) crystallizes in the monoclinic C2/c space group [a = 18.985(2) A, b = 7.3872(6) A, c = 20.432(2) A, = 97.1660(10), and Z = 4]. 2 (C24H22N2O14Cd3) crystallizes in the monoclinic P2(1)/c space group [a = 10.1323(2) A, b = 19.5669(5) A, c = 13.15880(10) A, = 108.9810(10), and Z = 4]. 3 (C27H28O26Cd3) belongs to the trigonal P31c space group [a = 15.7547(3) A, b = 15.7547(3) A, c = 7.93160(10) A, and Z = 2]. The Cd(II) centers in the three complexes are bridged by tma ligands in the coordination fashion of unidentate, bridging unidentate, bidentate, chelating bis-bidentate, chelating/bridging bis-bidentate, or chelating/bridging bidentate to form the T-shaped molecular bilayer motif for 1, chicken-wire-like motif for 2, and honeycomb-like porous structure for 3, respectively, in which the T-shaped molecular bilayer motif and chicken-wire-like motif are further interlinked in interdigitating or alternating fashion to construct the different coordination architectures. These three complexes exhibit strong fluorescent emission bands at 355 nm (lambda(ex) = 220 nm) for 1, 437 nm (lambda(ex) = 365 nm) for 2, and 353 nm (lambda(ex) = 218 nm) for 3 in the solid state at room temperature.     

非晶态Co-B的局域电子结构的Xα原子簇计算

In the research on metallic glass, there are arguments against the "rigid band charge transfer", model which assumes a charge transfer from metalloid atoms to transition metal atoms to explain the experimental evidence of linear reduction of average atomic magnetic moment with the increasing concentration of metalloid atoms, but they could not explain the experimental relation of the reduction. In the present work, spin-polarized SCC-DV-X_a calculation for atomic clusters for metallic glass Co-B has been empoloyed to investigate the local electronic structure and magnetic property of the metallic glass. As opposed to the "rigid band charge transfer" model, calculation in the present work indicates that charge transfers from Co4s to both B and Co3d. It is found that there is Co3d4s-B2p hybird bonding in Co-B, which leads to the linear reduction of average atomic magnetic moment. Thus the explanation removes the above controversy.     

New solid-gas metathetical synthesis of binary metal polysulfides and sulfides at intermediate temperatures: utilization of boron sulfides

A new simple synthetic method for binary metal polysulfides and sulfides was developed by utilizing an in situ formation of boron sulfides and their subsequent reactions with metal-source oxides in a closed container at intermediate temperatures above 350 degrees C at which the boron sulfides react in a gaseous form. The versatility of the new method is demonstrated with oxides of various transition metals (Ti, V, Mn, Fe, Ni, Nb, Mo, Ru, and W) and rare-earth metals (Y, Ce, Nd, Sm, Eu, Tb, and Er) as starting materials that exhibit different chemical characteristics. Regardless of the oxidation states of metals in the starting materials, the sulfidation reactions occurred quantitatively with stoichiometric mixtures of boron and sulfur, and within 24 h the reactions yielded pure products of TiS(2), TiS(3), VS(4), FeS(2), NiS(2), NbS(3), MoS(2), RuS(2), WS(2), Y(2)S(3), and RS(2) (R = Ce, Nd, Sm, Eu, Tb, and Er) which were the thermodynamically stable phases under the reaction conditions. The scope and implications of the new sulfidation method are also discussed.     

超微粒γ-FeOOH的制备工艺研究

以ＦｅＣｌ２为原料，研究了γ－ＦｅＯＯＨ晶种制备和晶粒生长的反应温度、反应物浓度及配比、碱液滴加等工艺条件，得到了比较理想的合成工艺途径．结果表明，在晶种制备过程中温度及配比是影响晶种粒子形态和产物晶型的重要因素；在晶种的生长过程中，滴入体相的碱液的分散状态是宏观混合与微观混合共同作用的结果，而促进微观混合是选择优化生长工艺的判据．     

Titanium complexes bearing aromatic-substituted β-enaminoketonato ligands: Syntheses, structure and olefin polymerization behavior

A series of titanium complexes [(Ar)NC(CF₃)CHC(R)O]₂TiCl₂ (4b: Ar = -C₆H₄OMe(p), R = Ph; 4c: Ar = -C₆H₄Me(p), R = Ph; 4d: Ar = -C₆H₄Me(o), R = Ph; 4e: Ar = α-Naphthyl, R = Ph; 4f: Ar = -C₆H₅, R = t-Bu; 4g: Ar = -C₆H₄OMe(p); R = t-Bu; 4h: Ar = -C₆H₄Me(p); R = t-Bu; 4i: Ar = -C₆H₄Me(o); R = t-Bu) has been synthesized and characterized. X-ray crystal structures reveal that complexes 4b, 4c and 4h adopt distorted octahedral geometry around the titanium center. With modified methylaluminoxane (MMAO) as a cocatalyst, complexes 4b-c and 4f-i are active catalysts for ethylene polymerization and ethylene/norbornene copolymerization, and produce high molecular weight polyethylenes and ethylene/norbornene alternating copolymers. In addition, the complex 4c/MMAO catalyst system exhibits the characteristics of a quasi-living copolymerization of ethylene and norbornene with narrow molecular weight distribution.     

Impacts of air pressure on the evolution of nanosecond pulse discharge products

Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge (NPD) plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, O3 molecules, N2(A3) molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2(B3) and N2(C3) molecules in excited states are only slightly affected by the air pressure.     

Nukiangendines A and B,two novel 13,14-seco-abietanes from Abies nukiangensis

From Abies nukiangensis, two novel 13,14-seco-abietane diterpenes, nukiangendines A (1) and B (2) were isolated. Their relative structures were determined by extensive NMR and HRMS spectroscopic analysis. The absolute configuration of 1 was established by ECD calculations. Compound 1 showed significant anti-hepatitis C virus (HCV) effects.     

Thermosetting resins from a tetra-functional vinylbenzene compound possessing cyclic siloxane cores

Cyclic siloxane is an attractive building block for incorporation of silicon-containing units as well as their distinguished properties to polymer materials. This work reports the synthesis and characterization of a tetra-functional vinylbenzene compound possessing cyclic siloxane cores (cD₄-4VB). Synthesis of cD₄-4VB is carried out using cD₄-4SiH as the reactive precursor and multiple-step reactions, including hydrosilylation, deacetylation, and S_N2 substitution. cD₄-4VB is an effective monomer for preparation of the corresponding cyclic silicon-based thermosetting resins (CR-cD₄-4VB). CR-cD₄-4VB shows attractive film formability and good thermo-mechanical properties, including a storage modulus of 2.0 GPa, a glass transition temperature of 282°C, a thermal stability above 400°C, a high char yield (at 800°C in nitrogen) of 55 wt%, and a dielectric constant of 3.12 at 10 GHz. This kind of resins have potential of application for halogen-free flame retardants and high-performance polymer films.     

TMEDA-CATALYZED SYNTHESIS OF N-ARYL-N′-ETHOXYCARBONYL THIOUREA AND ARENE (OR POLYMETHYLENE)-BIS-ETHOXYCARBONYLTHIOUREA DERIVATIVES

A novel and efficient method for synthesis ethoxycarbonyl isothiocyanate and ethoxycarbonyl thioureas catalyzed by TMEDA is reported. A series of N-aryl-N′-ethoxycarbonyl thioureas and arene (or polymethylene)-bis-ethoxycarbonyl thiourea derivatives have been synthesized in good-to-excellent yields via this method at room temperature.     

ZnFe2O4/Ag/TiO2复合材料的制备及其光催化性能

以硝酸银、钛酸四丁酯、无水氯化锌、六水氯化铁为原料,采用溶胶-凝胶法与溶剂热相结合的方法制备了ZnFe₂O₄/Ag/TiO₂复合材料,通过扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、X射线光电子能谱仪、振动样品磁强计、紫外可见分光光度计对样品进行表征及测试。结果表明： ZnFe₂O₄/Ag/TiO₂-10具有最佳的光催化效果,在紫外和可见光下对染料的降解率都能达到90%以上,具有优异的紫外可见光光催化活性。ZnFe₂O₄/Ag/TiO₂具有独特的磁性,能在外部磁场作用下进行回收利用,这使其在实际应用中成为可能。通过磁分离技术重复回收利用5次后仍然保持优良的光催化性能,说明ZnFe₂O₄/Ag/TiO₂-10具有优异的磁性及较高的光催化循环稳定性。