Self‐assembly of metal–organic framework thin films containing metalloporphyrin and their photocatalytic activity under visible light

With [5,10,15,20‐tetra(4‐carboxyphenyl)porphyrin]Mn(III) and sterically controlled 2,2¢‐dimethyl‐4,4¢‐pyridine as the main raw materials, metal–organic framework thin films containing metalloporphyrin (MnPor‐MOF) with catalytically active sites were built up on functionalized quartz glass surfaces using a layer‐by‐layer self‐assembly method. Retaining active catalytic sites and having a porous reticular structure, the MnPor‐MOF films possessed remarkable photocatalytic activity for oxidative degradation of methylene blue in the presence of hydrogen peroxide under visible‐light irradiation. Most meaningfully, the MnPor‐MOF films were highly stable and simply and conveniently reusable, and are thus a potentially new organic material for photocatalytic wastewater treatment. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparison of sample preparation methods combined with gas chromatography with electron‐capture detection for the analysis of multipesticide residues in lotus seeds

Sample preparation is always the major bottleneck in analytical chemistry for the determination of pesticide residues. Different sample preparation methods have been proposed due to the wide variety of pesticides used and the inherent complexity of the matrices. In this study, different sample preparation methods including SPE, matrix solid‐phase dispersion, the quick, easy, cheap, efficient, rugged, and safe method, and a one‐step completion method were compared and evaluated for extracting pesticides from lotus seeds. Analysis was carried out using GC with electron‐capture detection. The results showed that good recoveries for tested pesticides were obtained by using Florisil in the four methods, and the extraction efficiency of the one‐step completion method was superior to the other three methods. The one‐step completion method was confirmed to have good linearity, reproducibility, stability, and recovery for the detection of 36 pesticides in lotus seed samples. The data collected from this study are expected to prove useful in regulating the concentration of the residues in lotus seeds, as well as in protecting human health from the hazards posed by these residues.     

Comparative study on structure and properties of titanium/silicon mono‐ and co‐doped amorphous carbon films deposited by mid‐frequency magnetron sputtering

The titanium/silicon mono‐ and co‐doped amorphous carbon films were deposited by mid‐frequency magnetron sputtering Ti target, Si target, and Ti80S20 alloy target, respectively. The effects of doped elements on the composition, surface morphology, microstructure, and mechanical and tribological properties of the films were investigated. The results reveal that the ratio of sp³ and sp² carbon bonds of the films is regulated between 0.28 and 0.62 by a combination of Ti and Si dopant. The addition of small amounts of silicon leads to an increase in sp³ bonds and disorder degree of the sp² carbon. The co‐doped film exhibits significantly superior friction performance than the mono‐doped films. The ultra‐low friction (μ < 0.01) was achieved under a load of 2 N in ambient air with 40% RH. By comparing to the mono‐and co‐doped films, it is thought that the sp³/sp² ratio of the films may play a key role for the superlow friction. Copyright © 2013 John Wiley & Sons, Ltd.     

气相中HRnCCH和X(X=H_2O,NH_3)反应机理的理论研究

在CCSD(T)//MP2/aug-cc-pVTZ-pp理论水平上,研究了HRnCCH与大气中H2O及NH3分子反应的机理,反应主要包括HRnCCH与HRnOH及HRnNH2之间的转化、H2O和NH3在HRnCCH中的碳碳三键上的加成反应以及HRnCCH与双分子水反应等.结果表明,HRnCCH与H2O反应生成HCCH和HRnOH及HRnCCH与NH3反应生成HCCH和HRnNH2的能垒分别为54.1和75.2 kJ/mol,而生成HRnCHC(OH)H,HRnC(OH)CH2,HRnCHC(NH2)H和HRnC(NH2)CH2的活化能分别为219.6,220.5,174.4和182.4kJ/mol,此结果表明HRnCCH反应性较弱且是稳态存在的.此外,在HRnCCH与H2O反应中加入单个水分子,仍然生成HRnCHC(OH)H,但反应活化能却降低了96.4 kJ/mol,说明水分子对该反应有明显的催化作用.     

整体柱在线净化-液相色谱-高分辨质谱法快速测定牛奶中15种糖皮质激素

将自制的在线固相萃取柱与液相色谱串联四极杆静电轨道离子阱质谱技术相结合,建立了快速测定牛奶中15种糖皮质激素类药物的新方法.样品采用乙腈均质提取2 min,经自制在线固相萃取小柱富集净化,在Waters CORTECS T3(150 mm ×2.1 mm,5μm)分析柱上实现良好分离,外标法定量.15种目标物质量浓度在0.10～100 ng/mL范围内线性关系良好,相关系数均大于0.99;在0.20,0.40,2.0μg/kg3个添加水平下,15种糖皮质激素的回收率在87.1％ ～ 116.0％之间,相对标准偏差(RSD)在3.2％～8.7％(n=6)之间;方法的检出限(LOD,S/N≥3)和定量限(LOQ,S/N≥1O)分别为0.10和0.20μg/kg.该法适用于大批量牛奶中糖皮质激素类药物的快速定性筛查和定量分析.     

尼龙6纳米纤维膜的制备及其对己烷雌酚的吸附性能研究

采用静电纺丝设备制备尼龙6纳米纤维膜。用静、动态吸附方法,研究了尼龙6纳米纤维膜对己烷雌酚的吸附性能,考察了吸附时间、初始浓度及介质p H值对尼龙6纳米纤维膜吸附己烷雌酚的影响。结果表明,初始浓度为2mg/L时,尼龙6纳米纤维膜吸附己烷雌酚的过程符合准一级动力学模型;当初始浓度在5~20mg/L范围内,吸附过程符合准二级动力学模型。尼龙6纳米纤维膜吸附己烷雌酚的过程符合Freundlich等温吸附模型。     

Modulating the Acidic and Basic Site Concentration of Metal-Organic Framework Derivatives to Promote the Carbon Dioxide Epoxidation Reaction

Metal-organic framework (MOF) is an ideal precursor/template for porous carbon, and its active components are uniformly doped, which can be used in energy storage and catalytic conversion fields. Metal-organic framework PCN-224 with carboxylporphyrin as the ligand was synthesized, and then Zn²⁺ and Co²⁺ ions were coordinated in the center of the porphyrin ring by post-modification. Here, PCN-224−ZnCo with different ratios of bimetallic Zn²⁺/Co²⁺ ions were used as the precursor, and the metal-nitrogen-carbon(M−N−C) material of PCN-224−ZnCo-950 was obtained by pyrolyzing the precursor at 950 °C in Ar. Because Zn is easy to volatilize at 950 °C, the formed M−N−C materials can reflect different Co contents and different basic site concentrations. The formed material still maintains the original basic framework. With the increase of Zn²⁺/Co²⁺ ratio in precursor, the concentration of N-containing alkaline sites in pyrolysis products gradually increase. Compared with the precursor, PCN-224−ZnCo₁-950 with Zn²⁺/Co²⁺=1 : 1 has greatly improved basicity and suitable acidic/ alkaline site concentration. It can be efficiently used to carbon dioxide absorption and catalyze the cycloaddition of CO₂ with epoxide. More importantly, the current method of adjusting the acidic/basic sites in M−N−C materials through volatilization of volatile metals can provide an effective strategy for adjusting the catalysis of MOF derivatives with porphyrin structure.     

Investigation of trace laser mass p-dichlorobenzene using spectrometry

The time-of-flight mass spectrum （TOFMS） relative to the resonant two-photon ionization of gas phase p- dichlorobenzene was obtained in the wavelength range of 240 - 250 nm by a home-made system. A special design was made to reduce the effect of memory on the inner wall of the sample inlet system suitable for the investigation of semi-volatile organic compound. In this wavelength range, p-dichlorobenzene molecules firstly absorbed one photon to be excited from the ground state ^1Ag（So） to the first excited state ^1B2u （S1）, then absorbed another photon to be ionized. The relationship between the signal intensity of p-dichlorobenzene molecular ion C6H4^35Cl2^＋ at 248-nm wavelength and the laser power was given. The 1.52 power index of C6H4^35Cl2^＋ was a typical identification of the 3/2 power law. The relationship between the ion signal intensity of C6H4^35Cl2^＋ and the sample concentration was close to a linear one in the ppm（V/V） range, which led to a detection limit of 125 ppb（V/V） for p-dichlorobenzene.     

高橡胶含量透明MBS合成及其对PVC的改性

高橡胶含量透明ＭＢＳ合成及其对ＰＶＣ的改性高南，肖贵斌，胡伟军（上海大学化学系上海嘉定２０１８００）关键词　ＭＢＳ树脂，ＰＶＣ树脂，乳液聚合，塑料增韧，透射电镜ＭＢＳ（甲基丙烯酸甲酚－丁二烯－苯乙烯）树脂具有复杂的多相结构，可用作硬质聚氯乙烯（ＰＶＣ...