带有给定切线多边形的有理二次贝齐尔样条曲线

本讨论与给定切线多边形相切的分段有理二次贝齐尔曲线，所构造的曲线在一定的条件下可达到C^1连续，且对切线多边形是保形的；所有有理二次贝齐尔曲线段的控制点由切线多边形的顶点直接计算产生．最后以实例表明，本的方法是有效的．     

Synthesis of bis(amidoxime)s and evaluation of their properties as uranyl-complexing agents

Uranium pollution involves high toxicity and radioactivity and, therefore, constitutes a grave threat to human health and the environment. Chelation is an effective method for sequestering uranium. It is well known that chelators based on oxime groups are able to complex uranyl cations efficiently. To this end, various bis(amidoxime)s were synthesized by reaction of hydroxylamine with the corresponding dinitriles. In these compounds the amidoximes are separated by chains of various lengths, some including a heterocycle (pyridine or 1,3,5-triazine). The abilities of these bis(amidoxime)s to complex uranyl cation in water were evaluated by determining their affinity constants and thermodynamic parameters by means of Isothermal Titration Calorimetry (ITC). DFT calculations were also performed, to determine the optimum structures of the complexes formed between uranyl cations and the oximate groups. A tetrakis(amidoxime), also synthesized in this work, shows good affinity for uranium, and a single molecule is able chelate several uranyl cations. These results are of importance for the remediation of uranium-polluted wastewaters, and open up several perspectives for the design and synthesis of new amidoxime compounds.     

利用AgVO3改性MoS2增强活性氧产生及其光催化性能的提高

随着全球工业化进程的发展,环境污染问题日益严重,已经成为21世纪影响人类生存与发展的重要问题.光催化氧化技术被认为是解决环境问题最有应用前景的技术之一,已经成为环境领域的研究热点.众所周知,二硫化钼(MoS2)可以被可见光激发产生电子-空穴对,但是由于其氧化还原电势并不高,抑制了氧分子活化的量子效率,且激发后的光生载流子容易复合,导致光催化效率不高.因此,迫切需要对MoS2光催化材料进行修饰与改性,采用提高光催化过程中活性氧(ROSs)的量来提高其光催化活性.银钒氧化物(AgVO3,Ag2V4O11,Ag3VO4和Ag4V2O7等)因其在锂电池、传感器和光催化剂领域的应用而引起了人们的关注.其中,AgVO3具有较窄的带隙和高度分散的价带,具有潜在的应用价值.本文采用水热法成功制备了AgVO3/MoS2复合光催化剂,并采用X射线粉末衍射、扫描电子显微、透射电子显微镜和紫外-可见漫反射光谱等表征技术研究了所制光催化剂的物相结构、样品形貌和光学性能.以四环素为研究对象,将其应用于AgVO3/MoS2复合光催化剂的降解实验.结果表明,随着AgVO3质量比从1.0 wt%增加到3.0 wt%,所得催化剂的光催化活性不断提高;当进一步增加AgVO3的质量时,复合催化剂的活性逐渐降低.这是由于过多的AgVO3的引入导致在光催化剂表面形成电子-空穴对复合中心,增加了载流子复合几率.因此,AgVO3/MoS2复合光催化剂中AgVO3的最佳质量比为3.0 wt%,其降解速率常数为0.0087 min–1,分别是MoS2(0.00509 min–1)和AgVO3(0.00495 min–1)的1.71和1.76倍.由于AgVO3改性后的MoS2具有优异的光催化性能,能促进O2的吸附/活化,加速MoS2表面生成H2O2的双电子氧还原反应,从而产生更多的ROSs.利用电子自旋共振光谱、POPHA荧光检测和自由基捕获实验相结合的方法来阐明ROSs的形成机理.同时,ROSs的产生会加速消耗AgOV3导带上的电子,为降解污染物留下更多的空穴.本文为表面催化工程促进ROSs生成的合理设计提供了新的思路,有望在环境治理中得到实际应用.     

Facile synthesis of TEG-substituted 4-(N-methyl-N-Boc-amino)styrylpyridine and PET imaging agent [F]florbetapir ([F]AV-45)

Triethylene glycol-substituted 4-(N-methyl-N-Boc-amino)styrylpyridine which can serve as key precursor for many monodentate and multidentate imaging agents for Aβ plaques in human brain has been readily synthesized with cost-effective starting materials. The important non-radioactive monodentate positron emission tomography agent [F]florbetapir ([F]AV-45) has also been prepared by our new method.     

Cover Picture: Benzene Triimides: Facile Synthesis and Self‐Assembly Study (Chin. J. Chem. 7/2019)

The cover picture shows an efficient one‐pot condensation of maleimide derivatives in the presence of acetic acid and water to afford a series of benzene triimides (BTIs). The structure, physicochemical properties and electrochemistry behavior of BTIs were systematically investigated. Owing to the planar structure and unique electron‐deficient nature, BTIs can self‐assemble into different motifs. More details are discussed by Wang et al. on page 684–688.

     

新型支化侧链偶氮聚电解质的合成与性能研究

通过后重氮偶合的方法合成了一种含支化侧链偶氮苯生色团的聚电解质 (PBANT AC) .用IR、NMR、DSC、UV和元素分析等手段对聚合物的结构和性能进行了表征 .研究发现 ,在不同比例的水和四氢呋喃混合溶剂中PBANT AC的紫外 可见光光谱有很大的差别 .这种差别反映了PBANT AC分子中的偶氮苯生色团的不同聚集状态 .通过静电吸附逐层自组装的方法将PBANT AC分子组装成多层膜 .在 488nm的偏振Ar+ 激光的照射下 ,聚合物薄膜中的偶氮苯生色团可发生光致取向 ,取向有序度约 0 0 5 .偶氮苯生色团的顺反异构化反应使H 聚集体在光照后发生解聚集     

合成食用色素柠檬黄选择性电极的研制和应用

本文研究了以十二烷基三庚基碘化铵-柠檬黄缔合物为活性材料的PVC膜电极和涂丝电极,两电极对柠檬黄浓度在1.0×10~(-6)～1.0×10~(-3)mol/L间的响应符合Nernst关系式,斜率为20.0±1.0mV/PC(22℃),pH范围为4.0～9.4,电极的选择性、重现性和稳定性良好。对样品的测定结果与分光光度法测定结果基本一致。该方法简便、准确、可靠。     

聚苯乙烯基N-甲基-N-酰基磺酰胺树脂的制备及其作为酰基转移试剂在酰胺合成中的应用

聚苯乙烯基磺酰氯树脂(树脂1)与甲胺水溶液在吡啶的催化作用下反应，制备了N—甲基磺酰胺树脂(树脂2)．用酰氯在吡啶中与树脂2反应，得到N—酰基—N—甲基磺酰胺树脂(树脂3)．树脂3作为胺底物的酰基转移试剂，用来制备N—取代的酰胺，收率14～81％．树脂3可以有选择性地酰化乙醇胺中的氨基而不会使羟基酰化。     

聚苯乙烯磺酸树脂与三氯化铝复合树脂的合成及其对酯化反应的催化性能

聚苯乙烯磺酸树脂D72与三氯化铝在二硫化碳的回流温度下，通过不同的洗涤处理分别制备了复合树脂1—4。复合树脂2，4在二硫化碳中分别与无水HCl作用得到复合树脂2’、4’，这些复合树脂在60℃下催化乙酸和正丁醇（摩尔比为1／13）的酯化反应，其催化活性与复合树脂中Cl、Al含量和Cl／Al摩尔比值的增加而增大。这些复合树脂对水比较敏感，与水会发生水解脱氯作用，使催化活性降低。但在非水体系如：仲丁醇与乙酸酐的酯化反应中这些复合树脂具有较高的催化活性和较好的重复使用性能。     

Recyclable and reusable NiCl2(PPh3)2/CuI/PEG‐400/H2O system for the sonogashira coupling reaction of aryl iodides with alkynes

A stable and highly efficient NiCl2(PPh₃)₂/CuI/PEG‐400/H₂O catalytic system for the Sonogashira reaction has been developed. In the presence of NiCl₂(PPh₃)₂ and CuI, the coupling reaction of aryl iodides with terminal alkynes was carried out smoothly in a mixture of poly(ethylene glycol) (PEG‐400) and water at 100°C with K₂CO₃ as base to afford a variety of arylacetylenes in good to excellent yields. The isolation of the products was readily performed by extraction with petroleum ether, and the NiCl₂(PPh₃)₂/CuI/PEG‐400/H₂O system could be easily recycled and reused six times without significant loss of catalytic activity. Our system not only avoids the use of easily volatile organic solvents but also solves the basic problem of catalyst reuse. Copyright © 2015 John Wiley & Sons, Ltd.