偶氮材料——乙基橙的光致双折射特性

将偶氮化合物乙基橙样品置于一对正交的偏振片之间，用一束激发光照射该样品，分别测量 在激发光的不同强度和不同偏振方向下探测光的透射功率，研究样品的双折射特性.实验表 明，透射光的饱和值和稳定值与激发光强成正比，且与激发光偏振方向有关，探测光与激发 光振动方向的夹角(θ)为45°时，其值最大；若θ不太小（>10°），sin²2θ 与透射光的饱和值、稳定值成线性关系.同时，利用巴俾涅补偿器对样品的双折射率差进 行了测量，分别得到了绿光激发前后的准确数值为1.11×10^-3和3.57×10 ^-3. 关键词： 偶氮 双折射 测量     

光响应离子液体的结构与性能调控

光响应离子液体是一类兼具光刺激响应和离子液体双重特性的功能材料。在紫外/可见光照下,这类“智能型”离子液体的结构会发生变化,从而引起物理化学性质和相关体系性能的显著变化,以满足某些特定过程的需要。光刺激具有信号稳定、刺激部位精准、可快速切换、刺激过程不引入其他物质等优点,在刺激响应离子液体的结构与性质调控中具有独特的优势。本文以光响应离子液体的结构-性质-性能关系为主线,对光响应离子液体的光致异构化、物理化学性质调制、簇集行为调控、光致相转移及离子液体参与构筑的光响应乳液相行为调控等方面的研究进展进行了评述,分析了该领域研究中存在的主要问题,并对其发展前景进行了展望。     

Ionic Liquid Crystalline Calixarene with Photo-Switchable Proton Conduction

We have developed a new strategy for the preparation of a light-responsive ionic liquid crystal (LC) that shows photo-switchable proton conduction. The ionic LC consists of a bowl-shaped calix[4]arene core ionically functionalized with azobenzene moieties. The non-covalent architectures were obtained by the formation of ionic salts between the carboxylic acid group of an azo-derivative and the terminal amine groups of a calixarene core. The presence of ionic salts results in a hierarchical self-assembly process that extends to the formation of a nanostructured lamellar LC arrangement (smectic A phase). In this LC phase, the ionic LC calixarene is able to display proton conductive properties, since the ionic nanosegregated areas (formed by the ionic pairs) generate the continuous channels that favor proton transport. The optical and photo-responsive properties were studied by UV-Vis spectroscopy, demonstrating that the azobenzene moieties of the ionic LC undergo reversible (E)-to-(Z) isomerization by irradiation with UV light. Interestingly, this (E)-to-(Z) photoisomerization results in a decrease of the proton conductivity values since the bent-shaped (Z)-isomer disrupts the lamellar LC phase. This isomerization process is totally reversible and leads to an ionic LC material with unique photo-switchable proton conductive properties.     

高效液相色谱法研究白藜芦醇光致异构化动力学与平衡常数

反式白藜芦醇有多种生理活性,自然资源丰富,但存在光不稳定现象。以光致异构平衡对照品溶液,采用高效液相色谱建立了同时测定顺、反异构体浓度的方法。方法学考察显示符合含量测定要求,反式异构体在1.5~60 μ mol/L、顺式异构体在1.5~55 μ mol/L范围内线性关系良好,R²均达0.999。将该方法应用于研究光致异构化动力学及平衡常数,结果显示反式白藜芦醇在室温避光条件下中性、偏酸性及乙醇介质中稳定;25 ℃时在50%（v/v）乙醇介质中的光异构平衡常数为11.7±0.3。以光致异构平衡液制作标准曲线的策略简单方便,具有可操作性;反式白藜芦醇的稳定性与介质有关,在pH < 7的溶液中光致异构化为一级反应。     

Thermal and photo-actuation in nematic elastomers

Mono domain nematic elastomers change shape by as much as 400% on being heated from the nematic to isotropic state. The reason is that nematic order, Q, elongates the distribution of chains and thus the network that they form. Experimental evidence for this, and simple theory is presented. A novel method to change Q, and hence obtain an analogous elastic strain, is to bend the nematic's rods by photoisomerization. On absorbing a photon, photochromes such as azo rods leave the (straight) trans state and adopt the cis (bent) form. We show data and give simple theory to explain this remarkable, reversible elastic phenomenon.     

三代碳硅烷光致变色液晶树状物的光化学研究——端基含108个4-丁氧基偶氮苯介晶基元

报道了新化合物含108个丁氧基偶氮基元端基的三代(D3)碳硅烷光致变色液晶树状物在各溶液中的反-顺光异构化(光致变色)反应速率常数k_p, 光化学回复异构化正/逆反应速率常数k_t和k_c, 热回复异构化反应速率常数k_H, 光化学回复异构化反应平衡常数k_t/k_c, 活化能E, 异构化转换率及热回复异构化反应中的反-顺异构体组分比. D3的光致变色反应速率常数为10^－1 s^－1, 而含偶氮基元的光致变色液晶聚硅氧烷的光致变色反应速率常数为10^－8 s^－1, 因此, D3的光响应速度比后者快10⁷倍.     

Monoolein cubic phase containing azobenzene and its UV/visible light irradiation-dependent release property

Monoolein (MO) cubic phase, whose MO/azobenzene mass ratios were 1:0, 1:0.0025, 1:0.005, and 1:0.025, was prepared by a melt-hydration method. According to the polarized optical micrographs and the differential thermograms, the phase transition temperature of the cubic phase was lower as the content of azobenzene was higher, and it decreased upon the subsequent irradiation of UV light for 1 hour and visible light for 1 hour. The photoirradiation significantly promoted the release of methylene blue (a water-soluble dye) loaded in the cubic phase only when the MO/azobenzene mass ratio was 1:0.025. The photoirradiation could promote the release of Nile red (an oil-soluble dye) even when the MO/azobenzene mass ratio was less than 1:0.025. The higher photo-susceptibility of Nile red release was possibly because the dye would be intercalated in the MO lipid matrix and the photoirradiation could affect the lipid matrix property.     

LDS751激发态电荷转移和光致异构化的量子化学研究

利用密度泛函方法对激光染料分子LDS751的电子结构和激发态性质进行了一系列的量子化学计算, 在理论上对其激发态下可能的构型变化和动力学过程进行了预测. 从计算结果得出LDS751分子可能存在两个分别通过C—C桥键和端基C—N键旋转而实现的影响其光谱性质的光致异构化通道. 利用分子内官能团在激发过程中的电荷布居变化定量地分析了分子内电荷转移过程. 所得结论可以预测不同时间尺度下的光谱特征谱线和解释相关的光谱实验.     

反式白藜芦醇热稳定性与光致异构化的高效液相色谱和液相色谱-电喷雾离子化质谱研究

应用高效液相色谱(HPLC)及液相色谱-电喷雾离子化质谱(LC-ESI-MS)方法对反式白藜芦醇的长期热稳定性及光致顺反异构化反应进行了研究。色谱条件为:采用Hypersil-ODS色谱柱分离,流动相为甲醇-0.05%三氟乙酸水溶液(体积比为60∶40)(用于HPLC分析)及甲醇-5 mmol/L甲酸铵水溶液(含0.1%甲酸)（体积比为60∶40)(用于LC-ESI-MS分析),检测波长300 nm,进样量20　μL(HPLC)或10 μL(LC-ESI-MS);质谱检测中设定为负离子模式。在4~40