TX-100胶束中光解萘醌自由基的电子自旋极化研究

利用高时间分辨的电子自旋共振波谱仪(TRESR),研究了含有不同表面活性剂溶液中光解萘醌自由基CIDEP。在乙二醇溶剂中,在308nm的紫外激光照射下得到三重态机理极化的中性萘半醌自由基和以碳为中心的自由基R^.(OH)~2的信号,在表面活性剂TX-100的胶束中,得到萘醌阴离子自由基信号,并用萘醌分子与TX-100胶束间的电子转移进行解释。     

胶束微环境下光解苯半醌负离子基的CIDEP研究

用高时间分辨电子自旋共振(TRESR)波谱仪, 研究对苯醌(PBQ)在不同的介质中光解苯半醌自由基的化学诱导动态电子自旋极化(CIDEP)。实验结果指出, 在乙二醇溶液中得到苯半醌自由基(PBQH)和以碳为中心的自由基R(OH)2。在乙二醇/水溶液中, 得到以PBQH的六条峰为主的谱线图, 然后在该体系中随着加入表面活性剂TX-100, AOT的浓度增加, 苯半醌负离子基(PBQ^-)的谱线强度增加, 而PBQH的谱线减弱直至消失。本文从自由基所处微环境性质出发, 讨论其极化传递机理和有关物理化学性质。     

苯甲醛及对溴苯甲醛光解初级过程自由基的ESR研究

苯甲醛的光解与其在放置过程中的自氧化引发机理密切相关,因此确定光解过程的主要中间产物有重要意义。自氧化的全过程比较复杂,但单纯的光解本身显然相对简单一些。本文用自旋捕捉-ESR技术研究了苯甲醛及与其相类似的对溴苯甲醛在紫外和可见光作用下生成的活泼中间体,并讨论了在本文实验条件下的光解初级过程。     

吨染料与反胶束体系中CdS的光敏电子转移

用ＡＯＴ／异辛烷／水反胶束体系制备出了不同尺寸大小的纳米ＣｄＳ,并以曙红（ＥＯ）和孟加拉玫瑰红（ＲＢ）为探针分子,研究了它们与硫化镉微粒间的光致电荷转移相互作用,用光照实验和ＥＳＲ技术研究了这些染料向ＣｄＳ的导带注入电子的过程并讨论了作用机理     

激光光解苯醌自由基质子交换的TRESR研究

用时间分辨电子自旋共振（TRESR）波谱仪，研究了对苯醌/乙二醇/水体系中激光光解苯醌自由基的TRESR谱的线形与溶液pH值的关系.实验表明TRESR谱线均为发射极极化，极化过程以三重态机理（TM）为主.在中性溶液中谱线属中性苯半醌自由基BQH•,而在pH～2.02酸性溶液中谱线属阳离子基BQH＋.实验发现 BQH＋的TRESR谱强度的衰减具有超精细分量相关性，用质子交换理论对此进行了解释.     

光解苯半醌和2-羟基-2-丙基自由基的CIDEP谱

用高时间分辨ＥＳＲ波谱仪测量了光解苯半醌和２－羟基－２－丙基自由基的ＣＩＤＥＰ谱,苯半醌自由基的ＣＩＤＥＰ属ＴＭ机理,实验研究了微波功率,溶液浓度对苯半醌自由基的ＣＩＤＥＰ谱时间演化的影响,２－羟基－２－丙基自由基的ＣＩＤＥＰ属ＲＰＭ机理,实验研究了自旋极化的生成环境。     

阴离子表面活性剂SDBS胶束溶液的介电弛豫行为

用射频介电谱方法研究了0.1-80 mmol·L-1浓度的十二烷基苯磺酸钠(SDBS)水溶液体系的介质弛豫行为. 测量发现频率接近107 Hz时, 在临界胶束浓度(CMC)附近出现显著的介电弛豫现象. 采用Cole-Cole函数拟合SDBS体系介电数据, 其拟合参数具有明显变化规律: 介电增量(△ε)随SDBS摩尔浓度(cs)的增加而增大, 表现为两种线性关系, 并在cs=36 mmol·L-1附近出现拐点; 特征弛豫时间(τ0)却在cs=45 mmol·L-1出现极小值. 利用胶束电模型分析了介电弛豫机制, 认为束缚Na+对离子数量和胶束体积变化是引起介电增量和特征弛豫时间变化的两个重要原因.     

化学诱导动态核极化在光诱导自由基反应中的应用

介绍了化学诱导动态核极化(CIDNP)的原理以及在光诱导自由基反应机理研究方面的应用。     

硫酸水溶液中聚苯胺的两种极化子

应用自设计现场ESR电解池测量不同电势下的聚苯胺电导率,得到了高信/噪比的ESR谱图.谱线分解发现,在硫酸水溶液中聚苯胺生长的早期阶段存在两种极化子,根据这两种成分的ESR峰宽随电极电势的变化以及它和电导的关联分析,分别被指认为聚苯胺中有序区域和无序区域的极化子.随着掺杂程度的增大,两种极化子都是载流子,同样经历了由Curie自旋到Pauli自旋的转变.这一推论得到ESR饱和实验数据的支持.     

γ辐照 聚全氟乙丙烯(F46)的电子自旋共振研究 I.真空中俘获自由基的定量研究

A method for determining respectively the concentration of free radicials...CF2-CF2.(RI), ...CF2-CF-CF2...(RII)and...CF2- C(CF3)-CF2...(RIII) trapped in γ-irradiated F46 in vacuum at room temperature by analysing the ESR overlapping spectra is proposed. A quantitative relation between the concentration of free readicals and the total dose of γ-irradiation has been studied. The generating rate o free radicals caused by irradiation, i.e. G-value, has been calculated; it is 2.0 for RIII, 1.2 for RI, and 0.59 for RII. the magnitude of G value of free radicals is in the reverse order of their stability. Hence, we assume that the G value of free radicals in F46 mainly depends on the escaping rate of F2 and other fluorine-containing small molecules from surface of polymer into space. Therefore the looser the molecular chain, the larger becomes the G value of free radical. From that, we consider that both unstable free radicals RIII and RI with larger G-value mainly locate in the amorphous region, and the stable free radical RII with lower G-value is in the crystalline region. Recombinations between free radicals RII and RIII, or between RII and RI are forbidden at the temperature lower than 80C. An explanation for the saturation phenomenon of concentration of free radicals is given.     

A CIDEP study of photolysis of duroquinone/hydrogen-donor homogeneous and triton micelle solutions

The CIDEP spectra of transient radicals during photolysis of the duroquinone (DQ)/ethylene glycol (EG) system in acid, basic, and micellar environments were measured with a home-made highly time-resolved ESR spectrometer. In the DQ/EG homogeneous solution, the enhanced emissive CIDEP signal of the neutral durosemiquinone radical DQH^• was observed. When the DQ/EG solution at pH 9 or the DQ/EG/TX-100/H₂O micelle system was photolyzed, the CIDEP signal of the duroquinone anion radical (DQ^•−) was obtained. When the DQ/EG solution at pH 2.5 was irradiated, the CIDEP signal of DQH^• appeared. These experimental results indicate that the neutral radical DQH^• was formed by proton transfer from EG to ³DQ*, and that DQ^•− was formed by dissociation of DQH^• accompanying polarization transfer.     

A CIDEP study of photolysis benzophenone radicals in the microheterogeneous phase systems

The chemically induced dynamic electron polarization (CIDEP) of photolyzed benzophenone radicals in the microheterogeneous phase systems has been made by using the time-resolved electron spin resonance (TRESR) spectrometer. In the AEO_9/isoproanol/H_2O/C_8H_(18) liquid crystal system, the TRESR spectrum of Ph_2COH shows an unusual CIDEP of spin correlation radical pair (SCRP). The SCRP formation in these systems resulting from the character microenvironment and the related physical-chemistry property are discussed.     

苯甲醛不对称烯丙基化反应研究

对D-(－)-酒石酸异丙酯修饰的烯丙基硼试剂与苯甲醛的不对称烯丙基化反应机理进行了研究. 反应中间体和过渡态进行B3LYP/6-31G(d,p)全优化, 发现主要经六元环椅式过渡态生成手性烯丙基羟基化合物. 由相对反应速率理论,预测的主产物构型与实验的R-手性醇相吻合.     

A CIDEP and fluorescence study of the oxidation of vitamin E: The vitamin E radical cation

The photochemical and thermal oxidations of vitamin E in trifluoroacetic acid were investigated by the combination of electron spin resonance, chemically induced dynamic electron polarization, and fluorescence techniques. Two independent thermal pathways led to the formation of the vitamin E radical cation in which one of the paths involved the intermediate neutral semiquinone radical. Photo-oxidation, however, did not involve the neutral radicals. The fluorescence spectra of both the neutral and the charged forms of the vitamin E radicals are reported here for the first time. Some model charge transfer reactions involving the vitamin E radical cation were reported.     

反相胶束中辣根过氧化物酶的停流光谱研究

用停流光谱法研究了HRP在AOT、CTAB和SDS反相胶束中的吸收光谱和反应动力学，实验结果显示在AOT反相胶束中，HRP的吸收峰位置与水相中相同；而另外两种反相胶束对HRP的分子结构产生了较大影响，快速反应动力学研究显示在反相胶束中HRP形成化合物Ⅰ的速率常数远远高于化合物Ⅰ形成HRP—Ⅱ的反应速率常数，推测这是反相胶束的特殊性质造成的结果。     

大量制备4-苄氧基-2-羟基苯甲醛的新方法

以间苯二酚为原料,采用酚羟基的苄基保护、Vilsmeier反应及选择性去保护三步反应的新方法合成了4-苄氧基-2-羟基苯甲醛,总产率52%,其结构经1H NMR和13C NMR确认。     

Cylindrical and Branched Micelles at Low Temperature: A Rheological Study

We investigate the consequence of decreasing the temperature on the rheological behavior of the cylindrical and branched micelles of the ternary system of DDAB (dodecyldimethylammonium bromide)/STDC (sodium taurodeoxycholate)/water system. An isotropic cylindrical micelle-to-hexagonal liquid crystalline phase is optically (as a birefringence) and rheologically (gel like) detected on the STDC rich part at 6°C. On the other hand, branched micellar solution does not show any birefringence upon decreasing the temperature; however, it mainly exhibits disordered-ordered transition under shear. Such transition is more pronounced as the DDAB concentration increases as a consequence of the decrease in the curvature, and hence a sponge phase formation at low temperature.     

反相胶束对辣根过氧化物酶催化反应的影响

胶束体系是酶学研究比较理想的体系,因为它所具有的诸如热力学稳定、光学透明及能增溶亲水分子、亲油分子或两性分子等性质,使许多酶在胶束体系中的反应速率远远高于在水相中,即人们发现的所谓“超活性”［‘j．辣根过氧化物酶（HRP）是一种比较稳定的酶,且价廉易得,具备一般过氧化物酶的典型反应．在研究中人们发现,HRP在反相胶束体系中同样具有“超活性”,由于HRP能够催化大量底物进行反应,因此“超活性”对HRP的催化反应具有重要意义．已有研究者［’、’j对CTAB反相胶束体系中HRP的性质进行了探讨,但反相胶束对HRP的…