超瑞利散射测定偶氮分子的一阶超极化率

用超瑞利散射技术测定了双羟乙氨基-硝基偶氮苯和偶氮-水杨醛的5个偶氮化合物的一阶超极化率。2个双羟乙氨基-硝基偶氮苯由于有效的给体-受体组合,使其β值达到177×10-30esu和211×10-30esu;而2个偶氮-水杨醛席夫碱同时存在二维分子内质子转移和分子内电荷转移,β值分别为87×10-30esu和94×10-30esu。这些偶氮生色分子显现出光学非线性-透明性-热稳定性三者之间综合平衡的良好性能。     

新型香豆素酮类不对称双光子染料的合成及其光物理性质

本文以二苯乙烯和香豆素为共轭桥,二乙氨基为电子给体,羰基为电子受体,合成了一个具有D-π1-A-π2-D结构的香豆素酮类双光子染料C3.用紫外-可见光谱、荧光光谱研究了该化合物的光物理性质.发现在光作用下C3很容易发生分子内电荷转移,进而转变为扭曲的分子内电荷转移,产生很大的偶极矩变化.以飞秒脉冲激光为激发光源,用上转换荧光法测定了其双光子吸收截面.在激发波长为850 nm时,新化合物的双光子吸收截面值达1292 GM,比同系列香豆素酮衍生物C1、C2的双光子吸收截面值高一到两个数量级.     

偶氮化合物的电晕极化薄膜及其非线性光学性能研究

在有机物中,给体受体取代的偶氮化合物,由于它们具有几乎最高的二阶非线性光学效应以及作为一类新的、有前景的电光材料而倍受重视。在这方面,材料分子的非中心对称的有序排列是首先重要的。把非线性光学活性分子如偶氮化合物溶于聚合物中,再用电场极化方法得到分子有序排列的聚合物薄膜,这是目前认为最有效的材料宏观形态工程。     

高性能有机非线性光学材料

近年来有机非线性光学及其材料的研究受到极大关注。其中具有代表性的是带有非线性基团的硝基苯胺衍生物,它们的分子不具有对称中心,含有TT共轭电子体系並具有分子内发生电荷转移的特性,从而具备了获取最大二次非线性光学特性的必要条件。此外,4-硝基-4-十八烷基氨基偶氮苯也是一类具有较大非线性光学效应的分子晶体,它具有偶氮基连接起来的共轭体系,其两端分别接有电子给体和受体,因此具有很大的微观二次超极化率β值。但此类化合物的晶体往往具有反演中心,使得宏观非线性二次超极化率x~(2)=0。若采用LB膜     

溶致变色法测定吡唑啉类化合物的分子二阶极化率

近年来一些具有π电子共轭的有机化合物引起了人们广泛的兴趣。这是因其中有的化合物具有较大的二阶分子极化率,因而有可能用作非线性光学材料,获得二次谐波(SHG)以及在电-光调制技术中得到应用。测定分子的二阶极化率一般的方法是通过所谓电场诱导二阶谐波测定,即EFISH法完成,但对一般的化学实验室要建该项设备并非易事,为此近年来对发展简易的测定方法受到重视。利用溶致变色法来测定上述数据是化学实验室易于完成的一种方法。其优点是理论基本健全、方法简单而且在测定中还     

含咔唑基团芘类荧光材料的合成与发光性质

以1-溴芘、1,6-二溴芘和9-对乙炔苯基咔唑为原料,通过Sonogashira偶联反应合成了1-[4-(9-咔唑)苯乙炔基]芘和1,6-二[4-(9-咔唑)苯乙炔基]芘两种荧光分子。经熔点、核磁共振氢谱以及元素分析等结构表征,对中间体和目标产物的紫外-可见吸收、荧光发射以及结构与性质之间的构效关系进行了研究。通过结构修饰,可有效调节此类分子的吸收及发射性质。当芘单元作为中心电子受体,以4-苯乙炔基为桥连基,引入咔唑基团作为电子给体时,其分子共轭程度、结构刚性和分子内电荷转移能力显著提高。相对于D-π-A结构的单取代化合物,双取代D-π-A-π-D结构分子的最大发射峰由422 nm红移至446 nm,荧光量子效率由0.64提升至1.08。该类化合物可作为高效的蓝光荧光材料,应用于有机光致/电致发光材料以及有机发光二极管等领域。     

含咔唑基团芘类荧光材料的合成与发光性质

以1-溴芘、1,6-二溴芘和9-对乙炔苯基咔唑为原料,通过Sonogashira偶联反应合成了1-（4-（9-咔唑）苯乙炔基）芘和1,6-二（4-（9-咔唑）苯乙炔基）芘两种荧光分子。经熔点、核磁共振氢谱以及元素分析等结构表征,对中间体和目标产物的紫外-可见吸收、荧光发射以及结构与性质之间的构效关系进行了研究。通过结构修饰,可有效调节此类分子的吸收及发射性质。当芘单元作为中心电子受体,以4-苯乙炔基为桥连基,引入咔唑基团作为电子给体时,其分子共轭程度、结构刚性和分子内电荷转移能力显著提高。相对于D-π-A结构的单取代化合物,双取代D-π-A-π-D结构分子的最大发射峰由422 nm红移至446 nm,荧光量子效率由0.64提升至1.08。该类化合物可作为高效的蓝光荧光材料,应用于有机光致/电致发光材料以及有机发光二极管等领域。     

非线性光学偶氮分子的合成和跃迁偶极矩的测定

以对硝基苯胺、苯胺、5 氨基嘧啶和N,N 二羟乙基苯胺为原料通过两步重氮化-偶合反应合成了两种给体-受体型非线性光学偶氮分子,用红外光谱、核磁共振、熔点、紫外光谱进行了表征,测定了分子的跃迁偶极矩,两个化合物的跃迁偶极矩分别为7 12D和8 76D,它们在不同极性溶剂中表现出明显的溶致变色效应,紫外吸收最大位移分别达到20nm和15nm。     

含偶氮侧链聚酰胺酸合成及其三阶非线性光学性能

选取苯代三聚氰胺(BGA)和均苯四酸二酐(PMDA)为单体进行微波辐射溶液聚合反应,所得聚酰胺酸(PAA)通过重氮偶合反应引入含偶氮键的侧链,并且通过二次偶合进一步增加偶氮侧链的长度,从而合成新的具有三阶非线性光学活性的侧链型聚合物。通过红外、紫外、元素分析、拉曼等测试方法对接枝聚合物的结构进行了表征。通过简并四波混频飞秒激光系统对各个接枝聚合物的三阶非线性极化率系数进行了测定,考察了含取代基的偶氮侧链的引入对聚合物主链三阶非线性的影响,并考察了侧链上偶氮键的共轭长度对主链三阶非线性的影响。结果表明,侧链上偶氮基团的引入及其长度对提高聚合物主链三阶非线性都具有一定的影响。     

偶氮香豆素化合物的二阶非线性极化率

测定了一系列偶氮香豆素化合物的紫外吸收波长(λa)、摩尔吸光系数(ε)和最大荧光发射波长(λe)的数据,并用溶致变色法测算了它们的二阶非线性极化率(βxxx).结果表明,所测定的化合物在溶液状态下表现出较强的二阶非线性极化特性.     

Nonlinear optical polymers with novel benzoxazole chromophores II. Synthesis of polyurethanes with good thermal stability

Novel diol monomer having a π-conjugated benzoxazole ring, 2-(4-nitrophenyl)-6-[N,N-bis(2-hydroxyethyl)amino]benzoxazole was successfully synthesized to improve the thermally stability of nonlinear optical chromophores. Several polyurethanes bearing pendant benzoxazole chromophores were obtained by polyaddition of the diol to various aromatic diisocyanates. The thermal stability of these polyurethanes were monitored by thetrnogravimetry and IR spectroscopy, and compared with other polyurethanes having general pendant azo chromophores. The poled polyurethane films exhibited large and stable second-order nonlinear optical properties.     

The synthesis,electrochemical and theoretical nonlinear optical properties of push–pull chromophores for photorefractive composites

Four chromophores, of different dipole moment and polarizable anisotropy and which comprised conjugation bridges of both benzene and polyene with strong electron-donor and electron-acceptor groups, were characterized using ¹H NMR, FT-IR, UV–vis, and electrochemical analyses. The electric dipole moment (μ), polarizability (α) and the first hyperpolarizability (β) values of the chromophores were examined using computational methods. The contribution of orientational birefringence to total birefringence was estimated from the calculated molecular parameters of the chromophores; these parameters are important factors for predicting photorefractive efficiency.     

Push–pull bithiophene azo-chromophores bearing thiazole and benzothiazole acceptor moieties: Synthesis and evaluation of their redox and nonlinear optical properties

Three series of bithiophene azo dyes functionalized with thiazol-2-yl or benzothiazol-2-yl-diazene acceptor moieties were synthesized through azo coupling reaction using 2,2′-bithiophene, 5-alkoxy-2,2′-bithiophenes, 5-N,N-dialkylamino-2,2′-bithiophenes and thiazolyl- and benzothiazolyl diazonium salts as coupling components. The 5-alkoxy-2,2′-bithiophene precursors yielded the 5-thiazolylazo-5′-alkoxy-2,2′-bithiophenes, while the azo coupling reaction of 5-N,N-dialkylamino-2,2′-bithiophenes with the thiazolyl diazonium salt gave 4-thiazolyl-azo-5-N,N-dialkylamino-2,2′-bithiophenes. A different reactivity behavior was observed for 2,2-bithiophene with thiazolyl diazonium salts which gave rise to the expected azo dyes together with several arylation products. The redox behavior, thermal stability, and the first hyperpolarizability of the novel chromophores were evaluated through cyclic voltammetry, thermogravimetric analysis (TGA) and hyper-Rayleigh scattering (HRS) respectively. By varying the position of the thiazolyldiazene acceptor group on the bithiophene system, the electrochemical behavior as well as the optical (linear and nonlinear) properties of the donor–acceptor π-conjugated systems can readily be tuned. Push–pull 5-thiazolylazo-5′-alkoxy-2,2′-bithiophenes exhibit the most promising redox and the solvatochromic properties and second-order nonlinear optical response. The redox and the optical properties also show notable variations for the different heterocyclic spacers and were also sensitive to the electronic acceptor strength of the (benzo)thiazolyldiazene moieties.     

Push-pull bithiophene azo-chromophores bearing thiazole and benzothiazole acceptor moieties: Synthesis and evaluation of their redox and nonlinear optical properties

Three series of bithiophene azo dyes functionalized with thiazol-2-yl or benzothiazol-2-yl-diazene acceptor moieties were synthesized through azo coupling reaction using 2,2′-bithiophene, 5-alkoxy-2,2′-bithiophenes, 5-N,N-dialkylamino-2,2′-bithiophenes and thiazolyl- and benzothiazolyl diazonium salts as coupling components. The 5-alkoxy-2,2′-bithiophene precursors yielded the 5-thiazolylazo-5′-alkoxy-2,2′-bithiophenes, while the azo coupling reaction of 5-N,N-dialkylamino-2,2′-bithiophenes with the thiazolyl diazonium salt gave 4-thiazolyl-azo-5-N,N-dialkylamino-2,2′-bithiophenes. A different reactivity behavior was observed for 2,2-bithiophene with thiazolyl diazonium salts which gave rise to the expected azo dyes together with several arylation products. The redox behavior, thermal stability, and the first hyperpolarizability of the novel chromophores were evaluated through cyclic voltammetry, thermogravimetric analysis (TGA) and hyper-Rayleigh scattering (HRS) respectively. By varying the position of the thiazolyldiazene acceptor group on the bithiophene system, the electrochemical behavior as well as the optical (linear and nonlinear) properties of the donor-acceptor π-conjugated systems can readily be tuned. Push-pull 5-thiazolylazo-5′-alkoxy-2,2′-bithiophenes exhibit the most promising redox and the solvatochromic properties and second-order nonlinear optical response. The redox and the optical properties also show notable variations for the different heterocyclic spacers and were also sensitive to the electronic acceptor strength of the (benzo)thiazolyldiazene moieties.     

Fluorescence and photophysical properties of D-π-A push-pull systems featuring a 4,5-dicyanoimidazole unit

Absorption and fluorescence spectra and fluorescence quantum yields of 18 D-;π-A push-pull compounds were measured. The investigated chromophores consist of 4,5-dicyanoimidazole — bearing donor — substituted and systematically extended π-conjugated spacers. The influence of temperature and solvent polarity on the spectral and photophysical properties was investigated. Employing INDO/S calculations, the structure–property relationships were discussed.     

Fluorescence and photophysical properties of D-π-A push-pull systems featuring a 4,5-dicyanoimidazole unit

Absorption and fluorescence spectra and fluorescence quantum yields of 18 D-;π-A push-pull compounds were measured. The investigated chromophores consist of 4,5-dicyanoimidazole — bearing donor — substituted and systematically extended π-conjugated spacers. The influence of temperature and solvent polarity on the spectral and photophysical properties was investigated. Employing INDO/S calculations, the structure-property relationships were discussed.     

Photoinduced orientation and cooperative motion of three epoxy-based azo polymers

In this work, photoinduced orientation of three epoxy-based polymers bearing different type azo chromophores was studied. The epoxy-based azo polymers were synthesized through post-polymerization azo-coupling reactions based on an epoxy-based precursor polymer (BP-AN), which was synthesized by the step polymerization between bisphenol-A diglycidyl ether and aniline. The chromophore orientation and cooperative motion of the main-chain groups were studied by birefringence characterization, polarized infrared spectroscopy, and two-dimensional (2D)-IR correlation spectroscopy (COS). The results show that the orientation behavior of the epoxy-based azo polymers is closely related with the electron-withdrawing groups on the azo chromophores. The azo polymer BP-AZ-CN, which contains azo chromophores with cyano as the electron-withdrawing group, shows the fastest birefringence growth rate. The azo polymer BP-AZ-CA, containing carboxyl as the electron-withdrawing group, possesses high birefringence residual value and the highest saturated orientation degree in the series. Cooperative motion between azobenzene moieties and non-photochromic polymer backbone was revealed by polarized FTIR and 2D-IR COS. The photoinduced anisotropy is a result of the orientation of both azo chromophore and polymer main-chain. The understanding of the structure–property relationships can be used to develop materials with better performance for data storage and other applications.     

New crosslinked polymer systems with high and stable optical nonlinearity

Thermo-crosslinkable copolymers (PGMAA and PGMAS) of glycidyl methacrylate containing azobenzene chromophores (20 mol%) and stilbene chromophores (19 mol%) respectively were synthesized and characterized. In order to obtain crosslinked polymers with high and stable second-order nonlinear optical (NLO) property, PGMAA and PGMAS were doped with a reactive nonlinear optical (NLO) dye, 4-nitro-4′-aminobiphenyl (20 mol% of the glydidyl group). In the poled state, these doped polymers systems (PGMAD and PGMSD) can be thermo-crosslinked to yield materials with high second-order (NLO) coefficient (d₃₃) of 4.33×10⁻⁷ esu and 4.74×10⁻⁷ esu respectively. The investigation of SHG decay at room temperature and 100°C showed that the polymer networks much improved the SHG stability.