Highly visible-light luminescence properties of the carboxyl-functionalized short and ultrashort MWNTs

Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 μm polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure.     

［Mo_3（μ_3－O）（μ－Cl）_3（μ－O_2CR）_3Cl_3］~－系列三核钼的电化学及热化学性质的研究

用循环伏安法研究了［Ｍｏ_３ＯＣｌ_６（Ｏ_２ＣＲ）_３］－（其中Ｒ＝ＣＨ_３，Ｈ，ＣＨ_２Ｃｌ）系列三核钼簇合物在ＣＨ_３ＣＮ和ＤＭＦ溶剂中的电化学行为，并用差热－热重手段研究了它们的热稳定性和热分解过程的可能机理。结果表明在不同溶剂中它们有相似的二对氧化还原峰，而且在同一溶剂中随着Ｒ基团吸电子能力的增强，相应的第一氧化还原电位值向正向移动。当Ｒ＝ＣＨ_３，Ｈ时，它们的起始分解温度分别为２６５℃和２１０℃，即同样随着Ｒ基团吸电子能力的增强，起始分解温度降低。     

联二炔囊泡的光致聚合、热致变色及应用

物理化学实验为各大高校本科化学教学的主干实验课程之一。虽然各高校的物理化学实验内容已十分丰富,但仍然缺乏将不同章节知识点融会贯通以及与学科前沿密切联系的综合型实验内容。我们根据南开大学郭东升教授课题组发表的一篇有关联二炔程序性响应检测胆碱酯酶的工作设计了“联二炔囊泡的光致聚合、热致变色及应用”的物理化学实验,涉及到联二炔缔合胶体的制备、联二炔的紫外光致聚合反应和聚联二炔的热致变色,进而显示其在防伪领域的潜在应用价值。希望通过此实验,使学生对物理化学中的缔合胶体、光化学、热力学、动力学等章节有更深一步的贯通性掌握,并了解自组装、光聚合、变色材料和防伪等相关研究领域的前沿动态。     

Aerobic oxidation assisted by ligand-free palladium catalysts

Aerobic oxidation of electron-rich benzylic and phenyl allylic alcohols was achieved with high yields with only 0.1 mol.% of Pd(OAc)2 catalyst in the absence of any ligand. This procedure was expected to be valuable for realistic industrial-scale applications from both economic as well as environmental points of view.     

稀土在鼠肝中的物种分布

采用 ICP-MS、微量蛋白层析分离技术 ,研究了长时间、低剂量混合稀土及短时间、高剂量硝酸镧分别对大鼠及小鼠作用后 ,稀土在鼠肝中的代谢累积及其物种分布 .结果表明 ,鼠肝中各稀土含量随给药剂量的增加而增大 ,其累积速度大小顺序为 La>Ce>Nd>Pr;经柱层析分离未得到与稀土特异结合的鼠肝蛋白 ;稀土可与多种鼠肝蛋白 (包括多种重要的酶 )结合 ,在一定条件下 ,稀土与其结合蛋白可发生解离     

可剥离膜去除不锈钢表面铀污染的研究

退役的核设施中不锈钢制件表面附着的放射性污染物 ,必须经去污处理后才能回收利用。铀是核工业中最常见的污染放射性元素 ,而不锈钢是核设施中最常用的耐腐蚀金属材料 ,由于以ＵＯ2 +2 状态存在的铀 (Ⅵ ) ,在空气和自身的辐射作用下 ,将逐渐转变为不同的氧化物。采用酸性去污液对不锈钢表面铀污染进行浸泡和擦试去污的方法 ,可以有效的除去不锈钢表面铀污染[1] 。但因浸泡需大量的去污液 ,随之产生大量的带有放射性的废液 ,对这些废液还必须经进一步的浓缩———固化处理。擦试法虽产生固体废物 ,但去污操作麻烦 ,难以对大批量、形状复杂…     

碱解增敏荧光法测定残留甲萘威

甲萘威在0.01mo1/L KOH溶液中可降解为强荧光产物。十六烷基三甲基溴化铵对其增敏后,荧光强度达到其自身荧光强度的6倍。基于此,建立了对残留甲萘威进行荧光测定的新方法。线性动态范围为2.00~1.70×103μg/L;检出限为0.95μg/L;样品的加标回收率在90.2%~99.9%。本法成功地用于叶菜中残留甲萘威的测定。     

Alkylation of benzene with 1-hexene in acidic ionic liquid systems: Et3NHCl-FeCl3and Et3NHCl-AlCl3ionic liquids

Summary The alkylation of benzene with 1-hexene has been investigated in different triethylamine hydrochloride-ferric chloride (Et₃NHCl-FeCl₃) and triethylamine hydrochloride-aluminium chloride (Et₃NHCl-AlCl₃) ionic liquids. Both high catalyst activity and monoalkylation selectivity were observed for these two type of ionic liquids. Systems prepared by modification with HCl in Et₃NHCl-FeCl₃ionic liquids prove to be very suitable solvents and catalysts for the reaction. When employing Et₃NHCl-AlCl₃ionic liquids as catalysts, the reaction takes place in biphasic mode with facile catalyst separation and catalyst recycling.     

2-乙酰氨基-3-苯基-N-苯基-丙烯酰胺衍生物的电子轰击质谱研究

本文报道了6种新的丙烯酰胺衍生物的EI谱。在精确质量测量和B/E,B~2/E联动扫描亚稳离子测定的基础上,着重讨论了该类化合物的共同质谱特征:如分子离子失去H_2O的成环反应;产物离子的开环反应;分子内的氢重排反应等。同时,利用Hammett方程讨论了化合物中N-苯基端苯环上不同取代基对特定碎片离子强度的影响