Homogeneous rare earth coordination catalysts for copolymerization of styrene with acrylonitrile

The study on homogeneous rare earth coordination catalysts, LnL₃-Al(i-Bu)₃-CCl₄, for the copolymerization of styrene with acrylonitrile has been successfully carried out for the first time. Some features and kinetic behavior of copolymerization of styrene with acrylonitrile by Nd(P₂₀₄)₃-Al(i-Bu)₃-CCl₄ system are described. The catalyst sites appear to possess both coordinate anionic and free radical characteristics. The catalytic activity of various rare earth elements in Ln(P₂₀₄)₃ and ligands in NdL₃ for the copolymerization have the following order, respectively: Yb > Er > Tb ～ Tm > Ho > Ce > Lu ～ Sm ～ La > Pr > Nd, and Nd(naph)₃ > Nd(P₂₀₄)₃ ～ Nd(P₅₀₇)₃ > Nd(acac)₃·3H₂O. An alternating-rich copolymer of styrene-acrylonitrile with a high softening point (195–230°C) was obtained by the LnL₃-Al(i-Bu)₃-CCl₄ systems in toluene at 80°C.     

Improving MCM‐41 as a Nitrosamines Trap through a One‐Pot Synthesis

Copper oxide was incorporated into MCM‐41 by a one‐pot synthesis under acidic conditions to prepare a new mesoporous nitrosamines trap for protection of the environment. The resulting composites were characterized by XRD, N₂ adsorption–desorption, and H₂ temperature‐programmed reduction techniques, and their adsorption capabilities were assessed in the gaseous adsorption of N‐nitrosopyrrolidine (NPYR). The adsorption isotherms were consistent with the Freundlich equation. The copper salt was deposited onto MCM‐41 during the evaporation stage and was fixed on the host in the calcination process that followed. MCM‐41 was able to capture NPYR in air below 373 K but not at 453 K. Loading of copper oxide on MCM‐41 greatly improved its adsorption capability at elevated temperatures. The influence of the incorporation of copper into MCM‐41 samples and the adsorption behavior of these samples are discussed in detail.     

固定波长同步荧光光谱参数的理论计算

基于荧光激发光谱和发射光谱对波长呈高斯分布的设定,本文推导出固定波长同步荧光光谱峰峰值位置、相对强度和半峰宽度等3个主要光谱参数的理论计算式。所提出的计算式应用于若干荧光物质光谱参数的计算,并和实测值、文献计算值作了对照。结果表明,和文献计算方法相比,本法与所研究物质的实际光谱参数较为接近,可为固定波长同步荧光光谱参数的理论计算提供一有效方法。     

希土元素与三甲胺氧化物配合物的制备及光谱性质

尽管文献报道了三甲胺氧化物与Mn、Co、Ni、Zn、Cd、Cu等多种离子在有机溶剂中形成较稳定的配合物。但对其金属配合物的研究远不如芳香族杂环化合物那样引起人们广泛的注意。本文研究了它与希土元素形成配合物的合成和光谱性质。     

γ-irradiation of polypropylene in vacuum and in air

Polypropylene films were irradiated with ⁶⁰Co γ-rays in vacuum or in air and stored in air. Just after irradiation, the concentration of carbonyl group of the sample irradiated in air only increased with dose. The concentrations of both samples increased with storage time. The more the absorbed doses, the higher the increasing rates. The increasing rate of the concentration of carbonyl group during irradiation in air was higher than those during storage in air. Just after irradiation, the tensile strengths and the elongations of the both samples somewhat increased with dose at the doses less than 5 Mrad, but decreased at doses more than 13 Mrad. The tensile strength and the elongation of the sample irradiated in air decreased with storage time. Those of the sample irradiated in vacuum also decreased with storage time but the decreasing rates were much smaller than those in the sample irradiated in air. The gel fractions of the samples irradiated in vacuum and annealed in vacuum were somewhat higher than those irradiated in vacuum and not annealed. To elucidate high oxidation rate in the sample irradiated in air during and after irradiation, reaction mechanisms were discussed. To clarify the difference of mechanical properties between the samples irradiated in vacuum and in air, the effect of crosslink was considered, together with the oxidation.     

Linear scaling computation of the Fock matrix. VII. Parallel computation of the Coulomb matrix

We present parallelization of a quantum-chemical tree-code for linear scaling computation of the Coulomb matrix. Equal time partition is used to load balance computation of the Coulomb matrix. Equal time partition is a measurement based algorithm for domain decomposition that exploits small variation of the density between self-consistent-field cycles to achieve load balance. Efficiency of the equal time partition is illustrated by several tests involving both finite and periodic systems. It is found that equal time partition is able to deliver 91%-98% efficiency with 128 processors in the most time consuming part of the Coulomb matrix calculation. The current parallel quantum chemical tree code is able to deliver 63%-81% overall efficiency on 128 processors with fine grained parallelism (less than two heavy atoms per processor).     

Investigation on the chain-to-chain and chain-to-open-framework transformations of two one-dimensional aluminophosphate chains

Using ethylenediamine as a template, two one-dimensional (1-D) aluminophosphate compounds [AlP(2)O(8)H][NH(3)CH(2)CH(2)NH(3)] (1) and [AlP(2)O(8)][NH(3)CH(2)CH(2)NH(3)][NH(4)] (2) have been prepared from a gel system: 1.0:x:y:44 Al(i-PrO)(3)-H(3)PO(4)-en-EG (x = 3.0-9.0, y = 1.0-11.0). Compound 1 consists of edge-sharing four-membered ring (MR) chains, denoted as AlPO-ESC, and compound 2 consists of corner-sharing 4-MR chains, denoted as AlPO-CSC. The molar ratio of en:H(3)PO(4) in the starting gel has an important influence on the final product. If en:H(3)PO(4) > or = 1, AlPO-CSC is obtained, while if en:H(3)PO(4) < 1, AlPO-ESC is formed. These two chains can transform to each other upon addition of some extra amount of en or H(3)PO(4) to the reaction mixture in which AlPO-ESC or AlPO-CSC is crystallized. On the basis of XRD and (27)Al and (31)P MAS NMR analyses, a possible chain-to-chain transformation mechanism is proposed. The corner-sharing 4-MR chains of AlPO-CSC, as well as the edge-sharing 4-MR chains of AlPO-ESC can be assembled to 3-D open-framework compound NiAlP(2)O(8).C(2)N(2)H(9) through Ni(2+) cations. It is noted that AlPO-CSC remains in the structure of NiAlP(2)O(8).C(2)N(2)H(9). It is believed that AlPO-ESC might be first transformed to AlPO-CSC followed by the assembly to 3-D open-framework of NiAlP(2)O(8).C(2)N(2)H(9) through Ni(2+) cations.     

Synthesis and Characterization of a New Layered Aluminophosphate [Al3P4O16][(CH3)2NHCH2CH2NH(CH3)2][H3O]

A new layered aluminophosphate, denoted AlPO-CJ12, has been synthesized in the system Al(OPrⁱ)₃-H₃PO₄-tetramethylethylenediamine-triethyleneglycol and its structure solved by single-crystal X-ray diffraction analysis. It is further characterized by X-ray powder diffraction, ICP, TG, DTA, and elemental analyses. The compound has an empirical formula of [Al₃P₄O₁₆][(CH₃)₂NHCH₂CH₂NH(CH₃)₂][H₃O], and crystallizes in the triclinic space group P-1 (No. 2) with a=8.9907(6) Å b=9.8359(6) Å, c=14.5566(8) Å, α=75.872(3)°, β=88.616(3)°, γ=63.404(3)°, Z=2, R₁=0.0451, and wR₂=0.1094. The alternation of tetrahedral AlO₄ and PO₃ (=O) units forms a sheet structure with a 4×6×8 network. The inorganic layers stacked in an AAAA sequence are held together by the protonated organic amine and water molecules. The co-templating role of the water molecules is studied by the calculation of the nonbonding host-guest interaction energies through a computational simulation.     

二安替比林基-(对二甲氨基)苯基甲烷与铬(Ⅵ)显色反应

合成了二安替比林基-(对二甲氨基)苯基甲烷(DADM).在Mn(Ⅱ)和吐温-60存在下,Cr(Ⅵ)与DADM反应生成生色化合物,λ_(max)为550nm,ε为1.03×~5L·mol~(-1).cm~(-1)。Cr(Ⅵ)量在0～10μg/25ml间符合比尔定律。用于天然水和电镀废液中微量铬(Ⅵ)的测定,结果满意。