卟啉试剂与贵金属高灵敏显色反应的研究 Ⅴ.Ru(Ⅲ)-T(4-AOP)P-TritonX-100体系

本文研究了在Ｃｄ（Ⅱ）和ＴｒｉｔｏｎＸ－１００存在下，ｍｅｓｏ－四（４－乙酰氧基苯）卟啉［Ｔ（４－ＡＯＰ）Ｐ］与钌（Ⅲ）的显色反应。结果表明，在ｐＨ９．７～１０．３介质中，Ｒｕ（Ⅲ）与Ｔ（４－ＡＯＰ）Ｐ形成了灵敏度很高的稳定络合物，其表观摩尔吸光系数为７．０４×１０５Ｌ·ｍｏｌ－１·ｃｍ－１。钌浓度在０～１．２μｇ／１０ｍＬ范围内服从比尔定律。络合物的摩尔比为Ｒｕ（Ⅲ）∶Ｔ（４－ＡＯＰ）Ｐ＝１∶１。在掩蔽剂存在下，方法有一定的选择性，应用于合成试样中钌的测定，结果满意。     

α,β,γ,δ-四-(羟基苯)卟吩与锌离子络合物光度特性的研究

为探讨羟基苯卟吩与锌离子络合物的光度特性,对三种新合成的卟啉化合物与锌离子的显色反应分别作了研究和比较。实验表明T-(3-HP)P所生成的络合物的灵敏度最高,其表观摩尔吸光系数达4.76×10~5L·mol~(-1)·cm~(-1)。本文还就试剂的分子结构与显色反应的某些规律作了初步的讨论。     

特种合金钢系列标准物质研制

介绍了特种合金钢系列标准物质的研制过程。采用合理的冶炼锻轧工艺,选取不同部位的样品进行均匀性检验,确定了15种元素的认定值及扩展不确定度,并进行了线性、一致性考察以及与国内外同类标准物质的比对。结果表明,本套特种合金钢系列标准物质的均匀性良好,定值准确且有良好的梯度分布。     

Three‐Dimensional Architectures Incorporating Stereoregular Donor–Acceptor Stacks

We report the synthesis of two [2]catenane‐containing struts that are composed of a tetracationic cyclophane (TC⁴⁺) encircling a 1,5‐dioxynaphthalene (DNP)‐based crown ether, which bears two terphenylene arms. The TC⁴⁺ rings comprise either 1) two bipyridinium (BIPY²⁺) units or 2) a BIPY²⁺ and a diazapyrenium (DAP²⁺) unit. These degenerate and nondegenerate catenanes were reacted in the presence of Cu(NO₃)₂?2.5 H₂O to yield Cu‐paddlewheel‐based MOF‐1050 and MOF‐1051. The solid‐state structures of these MOFs reveal that the metal clusters serve to join the heptaphenylene struts into grid‐like 2D networks. These 2D sheets are then held together by infinite donor–acceptor stacks involving the [2]catenanes to produce interpenetrated 3D architectures. As a consequence of the planar chirality associated with both the DNP and hydroquinone (HQ) units present in the crown ether, each catenane can exist as four stereoisomers. In the case of the nondegenerate (bistable) catenane, the situation is further complicated by the presence of translational isomers. Upon crystallization, however, only two of the four possible stereoisomers—namely, the enantiomeric RR and SS forms—are observed in the crystals. An additional element of co‐conformational selectivity is present in MOF‐1051 as a consequence of the substitution of one of the BIPY²⁺ units by a DAP²⁺ unit: only the translational isomer in which the DAP²⁺ unit is encircled by the crown ether is observed. The overall topologies of MOF‐1050 and MOF‐1051, and the selective formation of stereoisomers and translational isomers during the kinetically driven crystallization, provide evidence that weak noncovalent bonding interactions play a significant role in the assembly of these extended (super)structures.     

α‐FeOOH−MoO3 Nanorod for Effective Photo‐Fenton Degradation of Dyes and Antibiotics at a Wide Range of pH

It's highly significant to develop a novel catalyst, which can be active at a wide range of pH, for an effective photo‐Fenton reaction. In this work, α‐FeOOH?MoO₃ nanorod was prepared by a one‐step hydrothermal method and applied in photo‐Fenton degradation of organic pollutants. Benefit from the electron migration mechanism of Z‐scheme and excellent photoelectric performance, the catalyst exhibited superior photo‐Fenton activity in degradation of organic pollutants. In addition, the catalyst holds good stability after 5 recycles. These results demonstrated that this catalyst has wide application prospect in organic wastewater treatment.     

Mesoporous graphitic carbon nitride materials: synthesis and modifications

Graphitic carbon nitride (g-C₃N₄), as a kind of polymeric semiconductor that has unique electronic structure and excellent chemical stability, has attracted increasing attention of researchers. Moreover, the raw materials for the preparation of g-C₃N₄ are various and easily accessible. All of these have provided favorable advantages for the fast development of g-C₃N₄. Compared to bulk g-C₃N₄, mesoporous g-C₃N₄ has more prominent natures, such as high specific surface area, large pore volume, and the increased amount of surface active sites. Therefore, great efforts have been devoted to develop mesoporous g-C₃N₄ (MCN). Up to now, many methods have been explored for the synthesis of MCN, such as hard-template method, soft-template method, template-free method, sol–gel method, and so on. Among these methods, the hard template method is used most widely. In this paper, the recent research on the synthesis of MCN was reviewed. In addition, the modifications to the obtained MCN, which lead to performance enhancement of the MCN for better applications, were also summarized.     

基于营养元素含量的名茶产地识别——以我国东部地区几种名茶为例

名茶营养元素含量在相当程度上反映了原产地的自然地理环境如母岩、土壤、气候等因素的印迹。基于茶叶的P、K、Ca、Mg、Fe、Cu、Zn、Mn、Se等矿质元素含量,综合应用系统聚类和主成分分析法,探讨了我国东部地区的安溪铁观音、武夷岩茶、庐山云雾茶、西湖龙井、黄山毛峰、太平猴魁、崂山绿茶等几种闻名遐迩的地理标志产品的产地识别问题。结果表明,矿质元素含量可以做为茶叶产地的判别指标之一,用于茶叶流通、销售过程的质量控制依据。     

Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions

Two redox-active bistable [2]catenanes composed of macrocyclic polyethers of different sizes incorporating both electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4'-bipyridinium (BIPY(2+)) units, interlocked mechanically with the tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT(4+)), were obtained by donor-acceptor template-directed syntheses in a threading-followed-by-cyclization protocol employing Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloadditions in the final mechanical-bond forming steps. These bistable [2]catenanes exemplify a design strategy for achieving redox-active switching between two translational isomers, which are driven (i) by donor-acceptor interactions between the CBPQT(4+) ring and DNP, or (ii) radical-radical interactions between CBPQT(2(?+)) and BIPY(?+), respectively. The switching processes, as well as the nature of the donor-acceptor interactions in the ground states and the radical-radical interactions in the reduced states, were investigated by single-crystal X-ray crystallography, dynamic (1)H NMR spectroscopy, cyclic voltammetry, UV/vis spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy. The crystal structure of one of the [2]catenanes in its trisradical tricationic redox state provides direct evidence for the radical-radical interactions which drive the switching processes for these types of mechanically interlocked molecules (MIMs). Variable-temperature (1)H NMR spectroscopy reveals a degenerate rotational motion of the BIPY(2+) units in the CBPQT(4+) ring for both of the two [2]catenanes, that is governed by a free energy barrier of 14.4 kcal mol(-1) for the larger catenane and 17.0 kcal mol(-1) for the smaller one. Cyclic voltammetry provides evidence for the reversibility of the switching processes which occurs following a three-electron reduction of the three BIPY(2+) units to their radical cationic forms. UV/vis spectroscopy confirms that the processes driving the switching are (i) of the donor-acceptor type, by the observation of a 530 nm charge-transfer band in the ground state, and (ii) of the radical-radical ilk in the switched state as indicated by an intense visible absorption (ca. 530 nm) and near-infrared (ca. 1100 nm) bands. EPR spectroscopic data reveal that, in the switched state, the interacting BIPY(?+) radical cations are in a fast exchange regime. In general, the findings lay the foundations for future investigations where this radical-radical recognition motif is harnessed in bistable redox-active MIMs in order to achieve close to homogeneous populations of co-conformations in both the ground and switched states.     

含钼碱性电解液中乙醇在铂黑电极上氧化循环伏安曲线的2,3,5周期及非周期振荡

中图分类号Ｏ６５７·１４文献标识码Ａ通常乙醇在铂黑电极上氧化的循环伏安曲线在经过开始的一段过渡期后会变得稳定，但在特定的条件下也会出现不稳定的振荡现象〔１～５〕．由于钼的存在可以促进有机小分子氧化过程中强吸附物种的氧化，降低过电位〔６〕，因此我们设想...     

Green,ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal through incorporation of chitosan by various electrospinning ways

Rapid global industrialization has worsened the heavy metal contamination of aquatic ecosystems globally. In this study, green, ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal were obtained by incorporating chitosan (CS) and using conventional and core–shell electrospinning ways. The relationship between the parameters of the electrospinning solution, the micro-morphology and porosity, the chemically active sites, the thermal stability, and the adsorption performance of the biocomposite nanofibrous membranes were analyzed. The adsorption effects of the copper ions, including the initial concentration, solution pH, and interaction time, were investigated. The results show that the average diameters of the conventional and core–shell ultrafine nanofibers with 50% and 30% CS loading are 56.22 nm and 37.28 nm, respectively. The core–shell cellulose acetate (CA)/CS biocomposite nanofibrous membranes showed the weaker thermal stability with a 48.2 °C lower maximum thermal decomposition temperature and induced the surface aggregation of more copper ions compared to the conventional one. A more uniform distribution of the chemical adsorption sites is obtained by conventional single-nozzle electrospinning than by core–shell electrospinning, which effectively promotes the adsorption performance of copper ions and decreases the surface shrinkage of the nanofibrous membranes during adsorption. The 30% CS conventional nanofibrous membranes at an aqueous solution pH of 5 showed the optimum adsorption capacity of copper ions (86.4 mg/g). The smart combination of renewable biomass with effective chemical adsorption sites, electrospinning technology that produces an interwoven porous structure, and an adsorption method with low cost and facile operation shows a promising prospect for water treatment.