Evidence of a Photo‐Radical Pathway Responsible of the Rearrangement of a Manganese(III)‐Schiff Base Complex in Solution

A new Mn^III‐Schiff base complex, [MnL(OH₂)](ClO₄) ( 1 ) (H₂L = N, N′‐bis‐(3‐Br‐5‐Cl‐salicylidene)‐1, 2‐diimino‐2‐methylethane), an inorganic model of the catalytic center (OEC, Oxygen Evolving Complex) in photosystem II (PSII), has been synthesized and characterized by elemental analysis, IR and EPR spectroscopy, mass spectrometry, magnetic susceptibility measurement and the study of its redox properties by cyclic and normal pulse voltammetry. This complex mimics reactivity (showing a relevant photolytic activity), and also some structural characteristics (parallel‐mode Mn^III EPR signal from partially assembled OEC cluster) of the natural OEC. The complex 1 was found to rearrange in solution into a crystallographically solved square‐pyramidal complex, [MnLL′] ( 2 ) (HL′ = 6‐bromo‐4‐chloro‐2‐cyanophenol), through a process, which probably liberates radical species (detected by EPR), and provokes a C—N bond cleavage in the ligand. A photo‐radical mechanism is discussed to explain this rearrangement.     

Cu/TiO2-NiO上光促表面催化CO2和H2O合成CH3OH反应规律

采用溶胶-凝胶法制备了n(电子型)-p(空穴型) 复合半导体材料0.5％Cu/TiO2-2.0％NiO (w),利用X射线衍射(XRD)、透射电镜(TEM)、红外光谱(IR)、紫外-可见光漫反射(UV-Vis)、程序升温脱附(TPD)技术对材料结构、吸光性能、化学吸附性能进行了表征,研究了该材料对CO2和H2O合成CH3OH的光促表面催化反应(PSSR)规律.结果表明,所制备材料能够明显促进目的反应,室温条件下即有CH3OH生成.在200 ℃下,由于光-表面-热的协同效应,CO2转化率得以提高,且CH3OH的选择性达到87.5％ .根据实验结果,得出CO2在材料表面的卧式吸附态为CH3OH的前驱物,并对PSSR机理进行了讨论.     

液晶光定向层材料

本文综述了近10年来液晶显示用光定向层材料领域的研究现状和进展情况，主要概述了光降解型、光致异构型、光交联型以及自组装等材料，并对目前报道的液晶光定向机理进行了总结和归纳。     

一代树状碳硅烷液晶的光化学研究－－端基含12个4－丁氧基氮苯介晶基元

研究了新的含12个丁氧基偶氮苯介晶基元的五代树状碳硅烷液晶D1及偶氮苯介 晶基元化合物M5在氯仿、四氢呋喃、N，N－二甲基甲酰胺、乙醇和苯等溶剂中的量 子产率、反－顺光异构化、光回复异构、反／顺异构组分比、热回复异构及活化能 。D1和M5的光致变色速率常数为10~(-1)s~(-1)，而含同一偶氮基元的光致变色液 晶聚硅氧烷的光致变色速率常数为10~(-8)s~(-1)，因此，液晶树状物D1的光响应 速度比后者快10~7倍。     

PHOTO-INDUCED DOPED POLYANILINE BY THE VINYLIDENE CHLORIDE AND METHYL ACRYLATE COPOLYMER AS PHOTO ACID GENERATOR

The emeraldine base form of polyaniline (PANI) can be doped by a photo-induceddoping method. In this method a copolymer of vinylidene chloride and methyl acrylate(VCMAC) was used as photo acid generator which can release proton when it is exposedto ultraviolet light (λ= 254 nm). The structure of PANI-VCMAC system before and afterirradiation was characterized by elemental analysis, IR, XPS, and SEM images. Resultsobtained indicate that the photo-induced doping characteristics, such as doping positionand type of charge carriers, are similar to that of PANI doped with HCl. The poor room-temperature conductivity (～10~(-5)S/cm) of PANI-VCMAC system after irradiation maybe due to low doping degree (～pH= 3) and the difference in morphology as compared withPANI-HCl film.     

Spectral,Optical and Mechanical studies on pure and thiourea doped ammonium di-hydrogen phosphate NLO single crystals

Pure and thiourea substituted single crystals of ammonium di-hydrogen phosphate have been grown from aqueous solution by isothermal solvent evaporation technique. Doped crystal exhibits prominent changes in physical and chemical properties. Single crystal XRD analyses of the samples are carried out and the results are compared. FTIR and UV–vis–NIR spectral analyses have been employed to identify the presence of various functional groups and the UV cut-off range in the grown crystals. Density measurements have been made and Photoconductivity studies revealed the negative photo conducting nature. Hardness measurement shows that the mechanical strength of the doped crystal is high when compared to pure ammonium di-hydrogen phosphate. The dielectric response of the samples has been studied in the frequency range 100 Hz–5 MHz at room temperature and the results are discussed.     

Synthesis and Polymerization of Spiro Oxyphosphoranes

Novel methods of synthesis of spiro acyloxyphosphoranes are described emphasizing the significance of the first isolated instance of these new species. Then, the no-catalyst alternating copolymerizations of the combinations of cyclic phosphorus(III) compounds (serving as nucleophilic monomer, M_N) with acrylic acid derivatives and with α-keto acids (electrophilic monomer, M_E) are mentioned. These copolymerizations proceed without added initiator. Spiro oxyphosphoranes play an important role in the copolymerization scheme in the equilibrium with the ⁺M_N - M_E ^? zwitterion, the key intermediate of the copolymerization. Finally, new reactions of spiro acyloxyphosphoranes with nucleophiles, alcoholysis and aminolysis polymerizations are presented.     

红外光谱法研究重氮树脂自组装膜的光化学反应

将具有导电功能的聚(4-羧酸钠苯基)乙炔阴离子(PCPA)与具有生物活性的DNA聚阴离子交替与重氮树脂聚阳离子(DR)进行自组装,可以得到层重复单元为DR／DNA／DR／PCPA的三夹层聚电解质自组装膜。重氮树脂聚阳离子在紫外光照射下可与聚阴离子发生光化学反应,使层与层之间的离子键连接转化为共价键连接,从而制备稳定的纳米级超薄膜。本文用红外光谱法对此类聚电解质自组装膜的光化学反应过程进行了研究。     

偶氮型光致变色液晶树状大分子的量子产率、异构转化率和活化能研究

研究了化合物端基含36个己氧基偶氮苯介晶基元的二代(G2)光致变色液晶树状大分子在氯仿及四氢呋喃溶液中的量子产率、吸收光强Ia、活化能E、异构转化率A/A0、热回复异构化速率常数kH及其反/顺异构体组分比A′/A′0,并与一代光致变色液晶碳硅烷树状大分子(G1)及介晶基元化合物(M3)的光化学行为进行了比较.在氯仿及四氢呋喃溶液中的量子产率的顺序均为M3>G1>G2,吸收光强Ia在氯仿及四氢呋喃溶液中的顺序分别为G2>G1>M3(氯仿)和M3>G1>G2(四氢呋喃),在氯仿及四氢呋喃溶液中活化能的顺序均为M3>G2>G1,在氯仿及四氢呋喃溶液中热回复异构化速率常数kH的顺序均为G1>G2>M3,在热回复异构化反应中的反/顺异构体组分比A′/A0′在氯仿及四氢呋喃溶液中的顺序均为G2>G1>M3.     

含偶氮苯类星型液晶化合物的光致变色

研究了一种以Si为中心外围含4个丁氧基偶氮苯液晶基元的星型液晶化合物Si(AZO)4的光致变色规律,利用紫外-可见吸收光谱研究了在氯仿和四氢呋喃溶液中的量子产率、光致变色和光回复反应.实验结果表明样品在各溶液的光致变色和光回复反应均为一级动力学反应,并求算了光致变色反应的正、逆反应速率常数均为10-1s-1数量级,是偶氮类侧链液晶高分子的速率常数的107倍,表明Si(AZO)4的星型结构对末端偶氮基团的吸收光谱没有明显影响,产物具有类似小分子的光致变色性,并且Si(AZO)4的正、逆反应速率常数比值小于液晶基元的比值,表明具有更好的光可逆性,有望作为光控开关和新型信息功能材料.