1,3,5-三芳基-2-吡唑啉化合物光物理行为的研究

近年来，在分子内电荷转移化合物发光行为的研究中，对分子激发态非辐射衰变通道问题的研究有了较大的进展［‘－’］．在分子结构和所处环境两因素对激发分子非辐射衰变过程影响的研究中，在结构方面已经认识到如化合物分子内双键的特性、杂原子的存在以及分子的几何构象等都可能对化合物的发光行为带来很大影响［’－’1．特别是分子立体几何构象问题，自F6rster－Hoffmarm提出他们的模型以来同，最近迅速发展起来的所谓“扭曲的分子内电荷转移（TICT）”概念同，使分子构象问题在荧光、激光染料的光物理研究中占有十分重要的位置．按…     

双(三氯甲基)三嗪类化合物光生酸反应的研究

对 3种具不同结构 (三氯甲基 )三嗪化合物的光致生酸及光敏化生酸问题进行了研究 .从其吸收光谱、荧光光谱、荧光猝灭以及光致生酸过程的测定结果表明 ,三嗪化合物的敏化光致生酸具有电子转移性质 .发现在三嗪化合物分子中存在着归属于核的局域发光以及分子内的电荷转移发光两个部分 .局域的激发与发光和化合物光致生酸有着密切的关系 ,而电荷转移发光则会增强或扩充化合物的吸收和发射光谱范围 ,在光致生酸中也有重要的作用 .一种完美的光致生酸化合物分子的设计和合成必须对上述两个方面均加以注意 ,使能达到互补和协同的作用     

受阻三芳基吡唑啉类化合物光物理行为的研究

1,3,5-三芳基-2-吡唑啉化合物因存在着广泛的应用前景,引起了人们极大的兴趣.吡唑啉类化合物不仅是良好的荧光增白剂,而且在静电复印中,它还是良好的光导材料.该类化合物具有强烈的荧光发射特性,因此许多研究都涉及其荧光光谱问题,在前人的报导中曾指出:芳基吡唑啉化合物所以具较强荧光,主要是由于其分子内存在着良好共平面性的“芳基—C=N—N—芳基”电荷转移发色团,而任何引起该发色团扭曲的效果都将对分子的发光能力带来影响.但对于这一看法,在对吡唑啉化合物发光行为的最近研究中已提出不     

结构受阻的取代的苯乙烯基吡嗪衍生物作为荧光探针的研究

本工作合成了两种旋转受阻取代的苯乙烯基吡嗪衍生物。详细研究了环境温度、极性和粘度对其光物理及发光行为的影响。结果表明两化合物在基态时可能存在着"平面构象与扭曲构象"间的平衡, 环境的温度、极性和粘度对于化合物存在的构象有很大影响。扭曲构象为较好的发光构象。分子受激后, 平面构象可经旋转松弛到扭曲构象。两化合物的荧光量子产率在室温条件下基本不随溶剂极性变化而变, 仅与溶剂粘度有关, 利用该性质可建议其作为一种有效的粘度荧光探针。     

4'-N,N-二甲氨基黄酮类衍生物的发光行为研究

共轭的分子内电荷转移化合物的光谱和光物理行为的研究，一直受到人们的关注[1-4]．特别在Grabowski、Rettig等人[5-6]提出了所谓“扭曲的分子内电荷转移”(TICT)激发态问题后更是受到重视，这不仅是由于这类化合物具有十分广泛的应用前景，如用作荧光、激光染料、有机非线性光学材料等，而且还存在着一系列有待解决的科学问题．如分子内的电子效应及构家效应等对分子内电荷转移过程及发光行为的影响，电荷转移化合物在经光照激发后可引起分予极化，在周围溶剂分子的作用下，可通过“自去偶”过程达到稳定的电行分离状态即所谓的TICT态…     

一种新型的可见光诱导电子转移生酸体系的研究

对 4种分子内共轭的电荷转移化合物和取代的双 (三氯甲基 ) 2 ,4,6 三嗪分子间的光诱导电子转移和光生酸反应进行了详细研究 .通过荧光猝灭和体系荧光随时间的变化可看到作为电子受体的三嗪分子和作为电子给体电荷转移化合物间的光诱导电荷转移作用 .在对体系酸度的测定中 ,可清楚地看到体系经光照后所发生的变化 .对所研究生酸体系引发酚醛树脂 六甲氧基甲基三聚氰胺交联反应的能力进行了初步研究 .对可能发生的反应机制进行了讨论     

D-A结构的9,9-二芳基芴类发光材料的合成、表征及性能

设计合成了一系列以三苯胺结构为核心的具有推电子-拉电子(D-A)结构的9,9-二芳基芴类有机小分子. 研究了介质极性对吸收与发射光谱行为的影响及分子结构与其发光能力的关系. 该类化合物荧光发射波长范围在430-530 nm. 并在特定极性溶剂中观察到双重荧光现象. 溶剂效应显示该类化合物随着介质极性的增加, 分子内电荷转移态(ICT)的荧光发射峰波长先红移后蓝移且荧光强度降低, 表现出扭曲的分子内电荷转移(TICT)行为. 该类化合物的最高占有分子轨道(HOMO)能级位于-5.24 - -5.50 eV, 且可以通过改变取代基电负性的强弱来调节. 所得化合物的玻璃化转变温度为192-206 °C, 热重分析(TGA)表明化合物的热分解温度都在400 °C以上, 具有良好的热稳定性.     

以吖啶染料荧光猝灭为基础的卤素阴离子检测研究

合成了两种吖啶及吖啶橙盐类小分子化合物和带有吖啶盐的三元共聚物.研究了它们在溶液中的荧光被卤素离子猝灭的问题.发现它们能强烈地被碘离子所猝灭而不易被氯离子猝灭,表明这类化合物有可能用于在有氯离子存在条件下对碘、溴离子的检测.对荧光猝灭机理进行的研究发现,卤素离子的猝灭能力并不和它们对发光化合物的系间窜越和三重态的生成等有关,而是和阴离子对极化分子的作用减弱了分子内的电荷转移能力相关.     

具有扭曲的分子内电荷转移的芳香酮衍生物的结构与光谱性能研究

设计合成了一系列基于芳香酮的具有分子内扭曲态电荷转移(TICT)特性的化合物,通过线性光物理性质与双光子吸收性质的表征,研究了分子结构中不同共轭基团和不同取代基位置对化合物光谱性能的影响,同时通过溶剂效应研究了化合物的分子内电荷转移性质。结合理论计算结果表明分子的共轭骨架和取代基的位置都能显著影响分子内电荷转移特征。其中芴酮系列的化合物表现出了较强的双光子吸收与聚集诱导荧光增强效应,在生物荧光成像领域有着潜在的应用价值。     

罗丹明-B及其烷基衍生物在表面活性剂溶液中探针功能的研究

近十年来,人们除对高度有序的分子晶体进行持续的深入研究外,对另一类有组织的分子集合体的研究也得到了蓬勃发展,特别是利用各种荧光化合物作为探针来研究微组织集合体(micro-organized assembly)的各种特性,更引起人们的光趣。用作荧光探针的化合物有一系列不同的类型,分别适用于不同的研究目的。某些对环境极性、粘度变化非常敏感的分子内电荷转移化合物探针的研究报道较多,对另一类探针化合物,其分子单体与聚集体有不同荧光特征,环境改变能影响探针分子单体与聚集体形成的条件,因此就可通过体系发光特性的变化来推断体系环境的改变,但对这类探针化合物的研究报道不多。已知罗丹明类染料的单体分子与其聚集体的发光行为有较大差别,将亲水性罗丹明化合物联以脂肪长链使之成为具有两亲性质的探针化合物已引起人们的注意,并在某些方面如研究细胞融合过程等取得了成功的应用,然而这类化合物某些基本物化性质的研究尚不够充分。本工作是在这样的背景下对几种带不同脂肪链的罗丹明化合物用作探针时的发光行为进行了比较研究。     

用荧光光谱法研究OLED用的新型蓝色发光染料和三-（8-羟基喹啉）铝(AlQ_3)的光诱导电子转移和激基复合物的生成

在合成了三种新型发射蓝光化合物的基础上，对它们在溶液中的光物理行为作 了详细研究。发现它们的荧光能强烈地被三-（8-羟基喹啉）铝所猝灭，并在荧光 光谱的长谱部分出现因发生光诱导电子转移而生成激基复合物的发光。几个方面的 工作-如猝灭常数的测定，电子转移过程自由能的计算，都表明化合物荧光猝灭过 程的电子转移性质。此外，还讨论了因出现光诱导电子转移和激基复合物给OLED器 件带来的影响，特别对三种作为器件发射蓝光化合物的优劣进行了讨论，表明化合 物DPF有着最佳的发光特征。     

Tunable Dual Fluorescence of 3‐(2,2′‐Bipyridyl)‐Substituted Iminocoumarin

3‐(2,2′‐Bipyridyl)‐substituted iminocoumarin molecules (compounds 1 and 2 ) exhibit dual fluorescence. Each molecule has one electron donor and two electron acceptors that are in conjugation, which leads to fluorescence from two independent charge transfer (CT) states. To account for the dual fluorescence, we subscribe to a kinetic model in which both CT states form after rapid decays from the directly accessed S₁ and S₂ excited states. Due to the slow internal conversion from S₂ to S₁, or more likely the slow interconversion between the two subsequently formed CT states, dual emission is allowed to occur. This hypothesis is supported by the following evidence: 1) the emission at short and long ends of the spectrum originates from two different excitation spectra, which eliminates the possibility that dual emission occurs after an adiabatic reaction at the S₁ level. 2) The fluorescence quantum yield of compound 2 grows with increasing excitation wavelength, which indicates that the high‐energy excitation elevates the molecule to a weakly emissive state that does not internally convert to the low‐energy, highly emissive state. The intensity of the two emission bands of 1 is tunable through the specific interactions between either of the two electron acceptors with another species, such as Zn²⁺ in the current demonstration. Therefore, the development of ratiometric fluorescent indicators based on the dual‐emitting iminocoumarin system is conceivable. Further fundamental studies on this series of compounds using time‐resolved spectroscopic techniques, and explorations of their applications will be carried out in the near future.     

Computational investigation of amine-oxygen exciplex formation

It has been suggested that fluorescence from amine-containing dendrimer compounds could be the result of a charge transfer between amine groups and molecular oxygen [Chu, C.-C.; Imae, T. Macromol. Rapid Commun. 2009, 30, 89.]. In this paper we employ equation-of-motion coupled cluster computational methods to study the electronic structure of an ammonia-oxygen model complex to examine this possibility. The results reveal several bound electronic states with charge transfer character with emission energies generally consistent with previous observations. However, further work involving confinement, solvent, and amine structure effects will be necessary for more rigorous examination of the charge transfer fluorescence hypothesis.     

几种方酸菁染料的NMR及光谱特性研究

研究了几种方酸菁染料的核磁、可见、荧光光谱。通过二维核磁共振谱和¹³CNMR确定了分子的结构和构型。测定了其在不同溶剂中吸收光谱和荧光发射光谱及其发射的荧光量子产率。发现它具有微弱的正向溶致变色特性,通过光谱特征分析得出整个分子处于平面结构并形成一个长的共轭体系,其激发态和基态的结构相近的结论。同时,讨论了结构对分子电荷分布及相应荧光光谱特征的影响。     

正己烷中对二烷基氨基苯甲酸的分子内电荷转移双重荧光

在非极性溶剂正己烷中,观察到了系列对二烷基氨基苯甲酸的双重荧光.皮秒激光诱导时间分辨荧光和溶剂极性效应研究证实:该双重荧光系由于激发态分子内电荷转移过程形成的电荷转移态和局部激发态所发射.超快反应动力学研究表明:在非极性溶剂中,对二烷基氨基苯甲酸分子内电荷转移过程是由较低的反应活化能所致.     

Synthesis and spectral characteristics of two novel intramolecular charge transfer fluorescent dyes

The synthesis and absorption/fluorescence properties of two novel intramolecular charge transfer (ICT) compounds of (fluorene-2-yl)-(9-ethylcarbazole-3-yl) ketene and 1-phenyl-3-(fluorenone-2-yl)-5-(9-ethylcarbazole-3-yl)-2-pyrazoline were reported. The primary structure of the target compounds was characterized by IR and ¹H NMR. The systems contained a fluorenone or a propenon group as an electron acceptor (A) and an N-ethylcarbazole and a pyrazoline group as electron donors (D). From the emissive properties it was concluded that the electronic coupling between D and A was sufficient to allow charge transfer in these molecules. The ICT maximal emission displayed a large wavelength shift and Stokes shifts increased in response to the increase of the solvent polarity. The highly solvatochromic properties made the two compounds of great interest as new classes of fluorescent probes, electroluminescent and electrofax materials.     

Restriction of Photoinduced Twisted Intramolecular Charge Transfer

An intensive investigation of structure–property relationships in the aggregation‐induced enhanced emission (AIEE) of luminescent compounds is essential for the rational design of highly emissive solid‐state materials. In the AIEE‐active compounds N,N′‐bis[3‐hydroxy‐4‐(2′‐benzothiazolyl)phenyl]isophthalamide and N,N′‐bis[3‐hydroxy‐4‐(2′‐benzothiazolyl)phenyl]‐5‐tert‐butylisophthalamide, fast photoinduced twisted intramolecular charge transfer (TICT) of the enol excited state is found to be mainly responsible for the weak emission of their dilute solutions. The photoinduced TICT enol excited state is formed with a greatly distorted configuration, due to the large rotation about the C? N single bond. This facilitates nonradiative TICT decay from the normal enol excited state to the highly twisted enol excited state, rather than proton‐transfer decay to the keto excited state. In aggregates, photoinduced nonradiative deactivation of TICT is strongly prohibited, so that excited‐state intramolecular proton transfer (ESIPT) becomes the dominant decay, and hence contributes greatly to the subsequent emission enhancement of the keto form. Molecular design and investigation of analogous single‐armed compounds further verifies this kind of AIEE mechanism.     

Amine‐Responsive Adaptable Nanospaces: Fluorescent Porous Coordination Polymer for Molecular Recognition

Flexible and dynamic porous coordination polymers (PCPs) with well‐defined nanospaces composed of chromophoric organic linkers provide a scaffold for encapsulation of versatile guest molecules through noncovalent interactions. PCPs thus provide a potential platform for molecular recognition. Herein, we report a flexible 3D supramolecular framework {[Zn(ndc)(o‐phen)]?DMF}_n (o‐phen=1,10‐phenanthroline, ndc=2,6‐napthalenedicarboxylate) with confined nanospaces that can accommodate different electron‐donating aromatic amine guests with selective turn‐on emission signaling. This system serves as a molecular recognition platform through an emission‐readout process. Such unprecedented tunable emission with different amines is attributed to its emissive charge‐transfer (CT) complexation with o‐phen linkers. In certain cases this CT emission is further amplified by energy transfer from the chromophoric linker unit ndc, as evidenced by single‐crystal X‐ray structural characterization.