基于侧链不对称喹喔啉聚合物的高效非富勒烯太阳电池

喹喔啉衍生物由于合成简单,易功能化,成本较低等特点在众多领域都有广泛应用。其自身具有平面刚性结构,也是构建光电聚合物的重要单体。基于喹喔啉单元的有机分子化学结构和电子结构可修饰性强,通过骨架、侧链和取代基等修饰,易于调控分子的能级和吸光光谱,因此,当使用喹喔啉体系的共轭给体与球形富勒烯受体(如PCBM)及弱结晶性非富勒烯受体(如ITIC)均可表现出优异的光伏性能。在本工作中,基于结晶性较强的非富勒烯受体(o-IDTBR),我们首次制备出侧链不对称喹喔啉(简称：不对称喹喔啉)基聚合物(TPQ-1)与之匹配。相比于侧链对称性喹喔啉(简称：对称喹喔啉)(HFQx-T)与o-IDTBR组合,“弱结晶给体-强结晶受体”组合能表现出更佳均匀的相分离尺度,从而获得更高的短路电流及能量转换效率。TPQ-1与o-IDTBR共混后器件效率为8.6%,加入15%的TB7-Th后,器件效率达到9.6%。     

高三尖杉酯碱和三尖杉酯碱的合成研究

天然药物高三尖杉酯碱和三尖杉酯碱是从三尖杉植物的叶和茎中分离得到的微量生物碱,是手性化合物。结构上,二者不仅含有一个共同的母核三尖杉碱,酯基侧链的α位也均为手性叔醇。因母核三尖杉碱和酯基侧链较大的空间位阻,两个结构片段的酯化偶联具有较大的挑战性。设计合成位阻较小的侧链中间体是酯化反应发生的关键。因此,化学家们相继合成了结构多样的α-羰基羧酸侧链以及含有杂环的侧链中间体,如四元内酯杂环侧链、四氢呋喃杂环侧链、六氢吡喃杂环侧链、七元内酯杂环侧链,并成功地完成了高三尖杉酯碱、三尖杉酯碱和同属其他活性生物碱的合成。本文基于本课题组的相关研究,根据侧链片段的构建策略和方法,综述了天然药物高三尖杉酯碱、三尖杉酯碱以及其他天然产物的合成研究。不仅总结了近几年来的新进展,还对我国老一辈的科学家们在此方面作出的贡献进行了回顾。     

主链含N-烷基咔唑环结构聚芳醚酮的性能表征

对含N-烷基咔唑环结构的聚芳醚酮(PPCzE、PPCzB和PPCzH)进行基本物理性能方面的表征,并与商业化酚酞基聚芳醚酮(PEK-C)进行比较。 咔唑环结构的引入使聚合物在345 nm附近有强紫外光吸收并表现出发蓝光能力。 由于疏水性烷基侧链的存在,聚合物薄膜的水接触角(87°~103°)大于PEK-C(76°),但同时烷基侧链所引起的聚合物链间距的增大导致聚合物的吸水率(0.65%~0.86%)高于PEK-C(0.56%)。 此外,聚合物表现出较好的尺寸稳定性(平均线膨胀系数6.4×10^-5 ℃^-1)和电绝缘性能(体积电阻率10¹⁶ Ω·cm)。 聚合物的拉伸模量在1.9~2.0 GPa之间,拉伸强度在72.5~75.0 MPa之间以及断裂伸长率在6.5%~7.2%之间。 高温条件下(≤225 ℃),PPCzE仍具有良好的拉伸性能。     

巧用具支试管改进化学实验

巧用具支试管改进了“钠与硫酸铜溶液的反应”“氢氧化亚铁的制备”“铜与浓硫酸反应”等实验,不仅节约药品、操作简便、快捷,而且现象明显,既适合教师演示实验,更利于学生开展探究实验。     

A novel method for enzyme design

Rational design of enzymes is a stringent test of our understanding of protein structure and function relationship, which also has numerous potential applications. We present a novel method for enzyme design that can find good candidate protein scaffolds in a protein-ligand database based on vector matching of key residues. Residues in the vicinity of the active site were also compared according to a similarity score between the scaffold protein and the target enzyme. Suitable scaffold proteins were selected, and the side chains of residues around the active sites were rebuilt using a previously developed side-chain packing program. Triose phosphate isomerase (TIM) was used as a validation test for enzyme design. Selected scaffold proteins were found to accommodate the enzyme active sites and successfully form a good transition state complex. This method overcomes the limitations of the current enzyme design methods that use limited number of protein scaffold and based on the position of ligands. As there are a large number of protein scaffolds available in the Protein Data Band, this method should be widely applicable for various types of enzyme design.     

新型苯并噁唑侧基聚酰亚胺的合成、结构与性能研究

为了改善聚酰亚胺的不溶不熔性, 一类可溶性苯并噁唑侧基聚酰亚胺树脂被成功制备. 从合成的新型二元胺单体出发, 制备了侧链为邻羟基苯胺酰胺结构的聚酰亚胺体系, 进一步催化环化邻羟基苯胺酰胺为苯并噁唑结构, 并对这两类不同结构的聚合物树脂进行了红外光谱的结构表征, 以及最终成膜的力学性能和耐热性能测试. 研究结果表明: 苯并噁唑侧基聚酰亚胺的力学性能优于相应的主链型聚酰亚胺, 且TGA分析表明, 其初始分解温度高达597 ℃, 有望用于航空航天方面高强、高模、耐高温的结构材料.     

Kinetic study of the complex reaction between copper(II) and 2-(2′-hydroxy-3′-methoxyphenyl)benzothiazole

2-(2′-Hydroxy-3′-methoxyphenyl)benzothiazole reacts with copper(II) in an ethanol/water mixture to form an O,S chelate which exhibits the remarkable property of changing the chelation site above a pH of ca. 5.0, to the O,N site. The detailed kinetics of this reaction in an ethanol/water mixture (3:1) at a temperature of 25 °C was investigated using a stopped-flow spectrophotometric technique employing a wavelength of 400 nm. The initial complex, Cu(O,S), is formed via a fast, reversible second-order complex formation step whereupon the formation of the Cu (O,N) follows first order kinetics. The Cu(O,N) complex is, however, unstable towards internal electron exchange and after the reaction is complete, a black polymeric material very slowly precipitates out of solution. Rate and equilibrium constants for the postulated reactions are presented and discussed.     

Weak solutions to a stationary heat equation with nonlocal radiation boundary condition and right‐hand side in Lp (p⩾1)

Accurate modelling of heat transfer in high‐temperature situations requires accounting for the effect of heat radiation. In complex industrial applications involving dissipative heating, we hardly can expect from the mathematical theory that the heat sources will be in a better space than L¹. In this paper, we focus on a stationary heat equation with nonlocal boundary conditions and L^p right‐hand side, with p?1 being arbitrary. Thanks to new coercivity results, we are able to produce energy estimates that involve only the L^p norm of the heat sources and to prove the existence of weak solutions. Copyright © 2008 John Wiley & Sons, Ltd.     

Flow of a generalized Maxwell fluid induced by a constantly accelerating plate between two side walls

The unsteady flow of a viscoelastic fluid with the fractional Maxwell model, induced by a constantly accelerating plate between two side walls perpendicular to the plate, is investigated by means of the integral transforms. Exact solutions for the velocity field are presented under integral and series forms in terms of the derivatives of generalized Mittag–Leffler functions. The corresponding solutions for Maxwell fluids are obtained as limiting cases for β → 1. In the absence of the side walls, all solutions that have been determined reduce to those corresponding to the motion over an infinite plate.