链状双苯基恶二唑基乙烯光化学性质的研究

本文合成了1,n-双[4-[2-(5-苯基－1,3,4－恶二唑基）]乙烯基]苯氧基 ]烷烃（n分别为3,4,6）和2,2‘－双[4-2-[2-(5-苯基－1,3,4－恶二唑基）]乙烯基]乙醚4个未见文献报导的甸 双杂芳基乙烯化合物及其参比物4-[2-2[(5－苯基－1,3,4－恶二唑基）]乙烯基]苯甲醚。用元素分析、紫外、红外、核磁和质谱表征了化合物的结构并用紫外吸收光谱跟踪研究了其在稀溶液中的光化学性质。结果发现：上述化合物在高压汞灯照射下可同时发生反顺异构化和[2 2]分子内光二聚两种反应,前者迅速可逆,后者缓慢且不可逆。其分子内光二聚体在短波长紫外光照射下极易进行逆[2 2]光解开环反应而得到原来的化合物。另外,上述化合物的分子内光二聚反应和光解开环反应可反复进行多次,再现性较好,此类化合物在光信息储存方面具有潜在应用前景。     

反-1,2-双[2-(5-取代苯基噁唑基)]乙烯的结构与光性能及光二聚反应机理的研究

测试了反１，２双［２（５苯基唑基）］乙烯（ＰＯＥＯＰ）类化合物在１，４二氧六环中的荧光寿命及其在不同溶剂中的光二聚量子产率，计算了其荧光辐射速率常数和非辐射速率常数，研究了取代基效应及溶剂性质对该类化合物光二聚反应的影响．结果发现，溶剂的极性增加有利于光二聚反应，但重原子溶剂对光二聚反应不利，表明该类化合物经单重态历程进行光二聚     

反—1,2—双[2—（5—取代苯基恶唑基）]乙烯的结构与光性能及光二…

测试了反－１，２－双「（２－（５－苯基恶唑基）」乙烯类化合物在１，４－二氧六环中的荧光寿命及其在不同溶剂中的光二聚量子产率，计算了其荧光辐射速率常数和非辐射速率常数，研究了取代基效应及溶剂性质对该类化合物光二聚反应的影响。     

二芳基乙烯的发展与应用

光致变色是指化合物在一定波长和强度的光作用下分子结构发生可逆变化。二芳基乙烯相比于传统的光致变色分子具有良好的热稳定性和抗疲劳性,是目前最有应用前景的一类光致变色材料。本文归纳了二芳基乙烯具有的热稳定性和抗疲劳性的机理,并简述了其基于这些特性在光存储、分子开关、超分辨荧光成像以及分子机器领域的应用,同时对未来二芳基乙烯的发展方向作出展望。     

双苯并噁唑二苯乙烯的合成

研究了由对甲苯甲腈经氯化、环化和缩合等过程制备双苯并唑二苯乙烯的合成工艺 ,产品总收率达 50 %以上 ,纯度大于 99% (HPLC测定 )。通过对化合物进行元素分析、红外光谱以及在 DMF中紫外吸收光谱的测定 ,确定了目标化合物的结构。     

双苯并噁唑二苯乙烯的合成

研究了由对甲苯甲腈经氯化、环化和缩合等过程制备双苯并唑二苯乙烯的合成工艺 ,得出了各步反应的最佳工艺条件。实验表明 :对甲苯甲腈经氯化、环化后所得中间体 ,以二甲基甲酰胺作溶剂 ,原料配比 (环化产物与氢氧化钾摩尔比 )为 1∶3 ,N2 保护下于室温反应 2 0h即得产品。三步反应总收率达 5 0 %以上 ,产品经HPLC测定 ,纯度大于 99%。通过对化合物进行元素分析、红外光谱以及在二甲基甲酰胺中紫外吸收光谱的测定 ,确定了目标分子     

一种席夫碱类二芳基乙烯荧光探针的合成与性质研究

设计合成了由2,2'-联噻吩-5-甲醛修饰的二芳烯化合物1O,并对其光学性能进行表征。紫外光谱和荧光光谱表明1O可高效、灵敏地检测Fe3+和F-。除此之外,二芳基乙烯是光致变色材料之一,探针1O除了具有识别性能之外也具有光致变色性能,因此在紫外光和白光的交替照射下也能发生可逆现象。     

二芳基乙烯类光致变色化合物的合成及其光电性质研究

在氮气及-78℃条件下,合成了两种二芳基乙烯类光致变色化合物1,2-双(2-甲基-5-(4-N,N-二甲氨基苯基)噻吩-3-基)全氟环戊烯(Ⅰa)和1,2-双(2-甲基-5-萘基噻吩-3-基)全氟环戊烯(Ⅱa),通过紫外-可见吸收光谱、荧光光谱、循环伏安法对其光谱特性和电化学性质进行了初步研究。在254nm紫外光照射下,Ⅰa和Ⅱa的氯仿溶液均由无色变为蓝色,最大吸收峰分别为620和570nm,在适当波长可见光照射下,均从有色态返回到无色态。通过UV-Vis光谱考察了这两种二芳基乙烯类化合物在溶液中的光致变色反应的动力学特征,实验结果表明,二芳基乙烯类光致变色化合物的闭环反应属于零级反应,开环反应为一级。电化学研究表明,在溶液中,Ⅰa和Ⅱa可发生不可逆的阳极氧化反应。     

基于二芳基乙烯新型门控光致变色材料的制备与应用

一种基于二芳基乙烯的门控光致变色衍生物DTEC在溶液中对光具有反应惰性,即用任何波长的光辐照下,DTEC都不会发生环化反应,溶液始终为无色。但当加入银离子,DTEC的光致变色反应活性被激活,用紫外光辐照,溶液从无色变为黄色,这表明DTEC由开环体向闭环体转变。因此,对于光惰性的DTEC,可通过加入银离子来调节其光反应活性,即通过银离子来门控DTEC的光致变色性能。进而,在单分子平台的基础上,可构建一个具有三个输入信号(银离子、紫外光和DTEC)和一个输出信号(410 nm处的吸光度)的分子逻辑电路,这对于多刺激响应光开关的开发具有重要价值。     

双噁唑啉化合物偶联聚酯的研究─—聚对苯二甲酸丁二酯的偶联反应

报告双唑啉化合物（ＢＯＺ）对聚对苯二甲酸丁二酯（ＰＢＴ）的偶联扩链的研究结果，表明与偶联聚对苯二甲酸乙二酯（ＰＥＴ）一样，特性粘数（［η］）在３～６ｍｉｎ迅速达到极大值，随后缓慢下降，ＰＢＴ熔点较低，故此反应可在较低温度下进行，偶联效率与ＰＥＴ的结果相近，以丁二酸为模型化合物考察表明偶联作用是在羧基进行，同时反应的最低温度可至１６４℃左右。     

Poly(1,4‐cyclohexylenedimethylene‐1, 4‐cyclohexanedicarboxylate): analysis of parameters affecting polymerization and cis–trans isomerization

Weatherable semicrystalline polyesters based on 1,4‐cyclohexanedimethanol, 1,4‐cyclohexanedicarboxylic acid (CHDA) or dimethyl 1,4‐cyclohexane dicarboxylate (DMCD) can be prepared under normal melt‐phase conditions, using titanium tetrabutoxide as catalyst. The effect of monomer ratio, reaction temperature and catalyst loading on the final polymer properties was studied. Under the proper polymerization conditions, poly(1,4‐cyclohexylenedimethylene‐1,4‐cyclohexanedicarboxylate) polymers with high molecular weight can be obtained. During polymerization, isomerization can occur towards the thermodynamically stable cis‐trans ratio of 34–66 mol%. Carboxylic acid end groups can catalyze the isomerization and therefore the polymerization is more critical starting from CHDA rather than DMCD. Moreover, temperature control becomes a key factor to avoid or to limit isomerization. The study of the isomerization of the different monomers permitted a better understanding of the isomerization and therefore of the polymerization process. Copyright © 2011 Society of Chemical Industry     

Acceleration of the Rate‐Limiting Step of Thioredoxin Folding by Replacement of its Conserved cis‐Proline with (4 S)‐Fluoroproline

The incorporation of the non‐natural amino acids (4R)‐ and (4S)‐fluoroproline (Flp) has been successfully used to improve protein stability, but little is known about their effect on protein folding kinetics. Here we analyzed the influence of (4R)‐ and (4S)‐Flp on the rate‐limiting trans‐to‐cis isomerization of the Ile75–Pro76 peptide bond in the folding of Escherichia coli thioredoxin (Trx). While (4R)‐Flp at position 76 had essentially no effect on the isomerization rate in the context of the intact tertiary structure, (4S)‐Flp accelerated the folding reaction ninefold. Similarly, tenfold faster trans‐to‐cis isomerization of Ile75–(4S)‐Flp76 relative to Ile75–Pro76 was observed in the unfolded state of Trx. Our results show that the replacement of cis prolines by non‐natural proline analogues can be used for modulating the folding rates of proteins with cis prolyl‐peptide bonds in the native state.     

氧化蒽基二吲哚基甲烷显色现象的研究

通过两步反应合成了两个具有显色特性的化合物:氧化2-蒽基二吲哚基甲烷(2-AnBIM)和氧化9-蒽基二吲哚基甲烷(9-AnBIM).比较了它们在不同非质子溶剂、不同阴离子和酸性环境中的光谱行为.在非质子溶剂中,发现这两种化合物仅在CCl4中有很大的红移,该红移现象的本质尚不清楚.浓度效应与NMR证据均表明在CCl4中化合物存在基于氢键的分子间相互作用.在含有不同阴离子的乙腈中,2-AnBIM对F-离子有选择性响应,而9-AnBIM则对F-、Cl-和Ac-等阴离子均有响应;在质子性溶剂中二者均只对HSO4-有选择性响应.2-AnBIM与9-AnBIM在77 K下有荧光发射,而平面性较好的2-AnBIM具有较低的发射能级与较强的发光效率.室温下二者均无明显的荧光发射,这可能与激发态下快速的质子转移导致分子共轭、共平面程度降低有关.     

Density‐Dependent Formation of the Pure trans‐Isomer of the Unsaturated Alcohol by Selective Hydrogenation of Citral in Supercritical Carbon Dioxide

Selective hydrogenation of citral to unsaturated alcohol [geraniol (trans) + nerol (cis)] was carried out in supercritical carbon dioxide (scCO₂) using an MCM‐41 supported plantinum catalyst (∼1 wt% Pt). A remarkable rate of isomerization of the unsaturated alcohol [nerol (cis) to geraniol (trans)] during the hydrogenation of citral was achieved simply by tuning the density of CO₂. Optimum reaction conditions were developed to obtain only geraniol (trans) with a selectivity of 98.8% and citral conversion of 99.8%. A significant change in the cis:trans ratio of the product (1:82.3) from the substrate (1:1.3) was observed depending on the various reaction parameters like carbon dioxide and hydrogen pressure, reactant concentration, reaction time and, particularly, the total selectivity for unsaturated alcohol [geraniol (trans) +nerol (cis)]. It has been observed that the presence of hydrogen is necessary for isomerization. Our results were explained in terms of a density‐dependent, two‐step model. The kinetic behaviour shows that the rate of isomerization was higher in scCO₂ compared to other organic solvents and the pure form of geraniol (trans) was obtained exclusively. A probable reaction pathway was proposed in order to explain the isomerization during hydrogenation of citral in scCO₂ medium.     

双（萘-类硫脲盐）化合物的光化学反应

合成了一种带芳基的硫脲镐盐类化合物，对其在光照下的光化学和光物理行为进行了较详细的研究．发现该化合物在光照下，能通过光诱导的分子内电子转移，产生离子自由基和自由基，继而有可能经自由基的重合反应形成环状化合物，并引起所含芳基基团处于合适的易于出现很强激基缔合物的位置．为进一步搞清上述反应机制，工作中设计了相应的实验，包括：ESR的测定、加入稳定的氮氧自由基化合物以及加入β-CD来阻抑重合反应的进行等，以证明上述的看法、     

Geometrical and positional isomerization of alkenyl acetates produced by hydrogenation of alkynyl acetates over palladium metal catalysts

Alkenyl acetates containing both geometrical isomers can be produced by a single controlled catalytic hydrogenation of the corresponding alkynyl acetate. The hydrogenation is capable of yielding formulations containing up to 60% trans isomer; the reduction is attended by positional isomerization in both geometrical isomers.NRCC No. 16834.     

Effect of 1,4‐cyclohexylene units on thermal properties of poly(1,4‐cyclohexylenedimethylene adipate) and similar aliphatic polyesters

In the field of aliphatic polyesters there is a great interest in building novel macromolecular structures that may effectively feature the required properties for specific applications. For this reason, it is extremely important to understand the correlations between chemical structure and final performance. Monomers based on the 1,4‐cyclohexylene unit are interesting as they are potentially bio‐based and rigid enough to improve glass transition and melting temperatures. The present paper describes the preparation of samples of poly(1,4‐cyclohexylenedimethylene adipate), characterized by different cis/trans isomeric ratio of the cyclic units, the analysis of their thermal properties and the comparison with the properties of similar polymers such as poly(butylene adipate), poly(butylene‐1,4‐cyclohexanedicarboxylate) and poly(1,4‐cyclohexylenedimethylene‐1,4‐cyclohexanedicarboxylate). The effect of the rigidity and of the stereochemistry of the 1,4‐cyclohexylene unit on the thermal properties was analysed. Such an effect reaches its maximum level when the cyclic‐containing monomers are the diacid or the diester and when the trans isomers predominate. Starting from such a result, the combination of specific cyclic building blocks with the correct cis/trans ratio makes it possible to build macromolecular structures with the required final properties.     

DBBDP阻燃聚碳酸酯性能研究

合成了一种新型无卤固态耐高温磷酸酯阻燃剂——4,4'-二羟基联苯双(二苯基磷酸酯)(DBBDP),利用FTIR、元素分析、1HNMR、31PNMR及TG对其结构及热分解行为进行了表征。研究了该阻燃剂对聚碳酸酯(PC)阻燃性能、力学性能、热分解行为及灼烧残炭的影响。结果表明:阻燃剂用量为4%即可使PC达UL94V—0级(3.2mm),氧指数(OI)接近30%。DBBDP还能改善PC的拉伸强度、拉伸模量、弯曲强度及弯曲模量等力学性能。DBBDP虽不能增加PC的成炭率,却可加速PC的交联成炭。此外,扫描电镜照片显示,DBBDP可使PC残炭的炭层加厚,但不能有效改善炭层的表面沟痕。     

双（N,N-二乙基）氨基甲基苯基硅烷的合成研究

以甲基苯基二氯硅烷和二乙胺为原料,低温下反应,合成了双(N,N-二乙基)氨基甲基苯基硅烷.通过正交试验方法考察了反应温度、反应介质、原料量之比以及反应时间等因素对目标产物产率的影响,利用红外光谱、核磁共振等手段对产物结构进行了表征和确认.利用方差分析确定的最佳反应条件为反应温度-15 ℃、溶剂为乙醚,二乙胺与甲基苯基二氯硅烷的量之比为5:1、反应时间为6 h.反应体系中加入三乙胺作为酸吸收剂、且用量为甲基苯基二氯硅烷的2倍时也可提高目标产物的产率;加入三乙胺后还可使铵盐副产物的后处理更易进行.