Construction of robust open metal-organic frameworks with chiral channels and permanent porosity

Four new metal-organic frameworks (MOFs) containing chiral channels have been synthesized using an achiral, triazine-based trigonal-planar ligand, 4,4',4' '-s-triazine-2,4,6-triyltribenzoate (TATB), and an hourglass secondary building unit (SBU): Zn3(TATB)2(H2O)2.4DMF.6H2O (1); Cd3(TATB)2(H2O)2.7DMA.10H2O (2); [H2N(CH3)2][Zn3(TATB)2(HCOO)].HN(CH3)2.3DMF.3H2O (3); [H2N(CH3)2][Cd3(TATB)2(CH3COO)].HN(CH3)2.3DMA.4H2O (4). MOFs 1 and 2 are isostructural and possess (10,3)-a nets containing large chiral channels of 20.93 and 21.23 A, respectively, but are thermally unstable due to the easy removal of coordinated water molecules on the SBU. Replacement of these water molecules by formate or acetate generated in situ leads to 3 and 4, respectively. Formate or acetate links SBUs to form infinite helical chains bridged by TATB to create three-dimensional anionic networks, in which one of the two oxygen atoms of the formate or acetate is uncoordinated and points into the void of the channels. This novel SBU-stabilization and channel-functionalization strategy may have general implications in the preparation of new MOFs. Thermogravimetric analysis (TGA) shows that solvent-free 3' is thermally stable to 410 degrees C, while TGA studies on samples vapor-diffused with water, methanol, and chloroform show reversible adsorption. MOF 3 also has permanent porosity with a large Langmuir surface area of 1558 m2/g. All complexes exhibit similar strong luminescence with a lambdamax of approximately 423 nm upon excitation at 268.5 nm.     

Improvement of chiral stationary phases based on cinchona alkaloids bonded to crown ethers by chiral modification

To improve the chiral recognition capability of a cinchona alkaloid crown ether chiral stationary phase, the crown ether moiety was modified by the chiral group of (1S, 2S)‐2‐aminocyclohexyl phenylcarbamate. Both quinine and quinidine‐based stationary phases were evaluated by chiral acids, chiral primary amines and amino acids. The quinine/quinidine and crown ether provided ion‐exchange sites and complex interaction site for carboxyl group and primary amine group in amino acids, respectively, which were necessary for the chiral discrimination of amino acid enantiomers. The introduction of the chiral group greatly improved the chiral recognition for chiral primary amines. The structure of crown ether moiety was proved to play a dominant role in the chiral recognitions for chiral primary amines and amino acids.     

岭回归分光光度法测定扑热息痛合成过程中多组分样品的研究

将岭回归分光光度法应用于扑热息痛合成过程中对乙酰氨基酚、对硝基酚、对氨基酚和醋酸４组分含量的分析研究。详细介绍了该法的基本原理和具体的分析步骤。实验结果表明,该法对样品中各组分的平均回收率在１００．１％～１０６．７％之间,相对标准偏差在２．０３％～５．２１％之间,结果较满意。与高效液相色谱法相比,两者测得结果的相对误差＜１５％。该法还具有简便、快速、适宜于计算机联机分析等特点。     

接枝亲水型高分子的丝瓜络对水中重金属离子的吸附行为

采用接枝聚合的方法将亲水性聚丙烯酰胺接枝到丝瓜络上,部分水解的聚丙烯酰胺的接枝率可高达161.3%.选择典型的Cu~(2+)和Pb~(2+)体系,研究亲水型丝瓜络对水中重金属离子的吸附行为.结果表明,在单离子体系中,准二级动力学方程适于描述亲水型丝瓜络吸附动力学过程,饱和吸附量随着接枝率和pH值增加而增大,对Cu~(2+)和Pb~(2+)的最大饱和吸附量分别为647和887 mg/g.Langmuir和Freundlich等温吸附模型都适合描述等温吸附过程.8次吸附-解吸附循环实验表明,饱和吸附量基本保持恒定,同时对吸附机理进行了讨论.     

Morphology-Dependent Peroxidase Mimicking Enzyme Activity of Copper Metal-Organic Polyhedra Assemblies

The morphology of nanomaterials (geometric shape and dimension) play a significant role in its various physical and chemical properties. Thus, it is essential to link morphology with performance in specific applications. For this purpose, the morphology of copper metal–organic polyhedra (Cu-MOP) can be modulated through distinct assembly process, which facilitates the exploration of the relationship between morphology and catalytic performance. In this work, the assemblies of Cu-MOP with three different morphologies (nanorods, nanofibers and nanosheets) were facilely prepared by the variation of solvent mixture of N, N-dimethylformamide (DMF) and methanol, revealed the important role of the interaction between the surface group and the solvent on the morphology of these assemblies. Cu-MOP nanofibers exhibited the highest mimetic peroxidase enzyme activity over the Cu-MOP nanosheets and nanorods, which have been utilized in the detection of glucose. Cu-MOPs assemblies with tunable morphology accompanied with adjustable mimic peroxidase activity, had great potential applications in the field of bioanalytical chemistry and biomedicals.     

The Crystal Structure of [La(NO3)6{Cu(2,2′-bipy)2}2][La(NO3)6Cu(2,2′-bipy)2]CH3CN with the Most Profuse Modes of Nitrate Coordination

The title compound [La(NO₃)₆{Cu(2,2′-bipy)₂}₂][La(NO₃)₆Cu(2,2′-bipy)₂] CH₃CN was synthesized, the crystal and molecular structures were determined at room temperature. The complex formed monoclinic crystals, space group P21/n (No.14), a = 10.354 (3) A, b = 23.440 (9) A, c = 32.817 (9) A, b = 90.39 (2)°, Z = 4. The crystal structure consisted of a discrete [La(NO₃)₆{Cu(2,2′-bipy)₂}₂]⁺ cation and [La(NO₃)₆Cu(2,2′-bipy)₂]^- anion and a non-coordinated CH₃CN molecule. Each La(III) ion was 12-coordinate with twelve oxygen atoms from six chelating nitrate ligands. There were four modes of nitrate coordination and the coordination geometry of all three copper ions was different in the crystal structure.     

A Novel Coordination Structure of Dichromates Bonding to Copper (II): [Cu(bipy)2(Cr2O7)] · 2 H2O

Dark-green multimetal compound crystal [Cu(bipy)₂(Cr₂O₇)]· 2 H₂O was obtained from aqueous solution of Cu(NO₃)₂, K₂Cr₂O₇ and bipyridine. The crystal structure was determined by X-ray crystallography: triclinic P1 , a = 7.716(3) Å, b = 9.656(3) Å, c = 15.517(5)Å, α = 77.41(3)°, β = 81.04(3)°, γ = 82.33(3)°, Z = 2. In this compound, two chromium atoms and a copper atom are linked by two oxo bridges (Cu(II) O Cr(VI) O Cr(VI)). The copper coordination polyhedron corresponds to a five-coordinated distorted trigonal bipyramid.     

Synthesis and structure of 2D‐ and 3D‐ inorganic‐organic coordination polymers: based on Ag‐hmt subunit

Two new inorganic‐organic complexes, namely, [Ag₂(hmt)₂]Cr₂O₇·H₂O ( 1 ) and [Ag(hmt)(tar)_0.5]·H₂O ( 2 ), (hmt = hexamethylenetetramine, Tar = tartarate,), have been synthesized in H₂O/CH₃CN solvent at room temperature. Both molecules have the common [Ag₃hmt₃]³⁺ layers. Compound 1 is a two‐dimensional structure, and Complex 2 shows three‐dimensional topology. In complex 2 , the tartarate molecules are connected with adjacent layers to form parallelogram pores of 18.55×7.44 Å, which are occupied by two water molecules. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

光学窗口材料激光辐照热-力效应的解析计算研究

建立了高功率连续激光辐照透明光学材料的热力学模型,通过积分变换方法求解三维热传导方程,得出了激光辐照引起的瞬态温度场分布的精确解析解,并在此基础上进一步求得热应力场的瞬态分布。以1.315μm的高能氧碘激光辐照熔石英玻璃为例,计算了熔石英在激光辐照下的温度场与热应力场分布,分析了其激光损伤机理。研究结果表明由于熔石英具有优良的热稳定性,温度不均匀分布所产生的热应力相对较小,激光损伤主要是受辐照区域温度值超过材料熔点发生熔融破坏。理论分析结果与相关的实验结论一致,说明所建立激光辐照效应模型的合理性。     

L-脯氨酸衍生物为手性侧链的新型C_2对称型手性固定相

绕轴旋转180°能与自身重合的C_2对称型手性化合物在手性催化和手性分离领域有重要应用。以L-脯氨酸苯基酰胺衍生物为手性源,合成了一类新型的C_2对称型手性固定相,并进行了手性色谱拆分评价。与单侧链取代的刷型固定相进行对比,C_2对称型手性固定相对所评价的31种酸性、中性和碱性分析物表现出更好的手性选择性。考察了固定相末端苯环上的取代基团对手性拆分的影响,综合来看,苯环上无取代基的C_2对称型手性固定相的分离性能最优。对某些手性对映体,C_2对称型手性固定相的分离因子随温度的增高而呈现异常增大的现象,表明了其有别于单侧链取代的固定相的分离机理。该类新型手性固定相的提出对进一步丰富刷型手性固定相的种类和拓展其应用具有重要意义。