三芳基硼衍生物激发态性质的调控及应用

Triarylboron derivatives have recently emerged as an important class of molecules with many applications in materials sciences. The empty p orbital on the boron center makes these compounds excellent electron acceptors. When accompanied by electron donors, these compounds possess large electrical dipoles, which promote donor-acceptor charge-transfer upon excitation with light, and result in some intriguing electronic and photophysical properties. These properties enable their use in such diverse fields as nonlinear optics, anion sensing, hydrogen activation and storage, and as emitters and electron transport materials in organic light-emitting diodes (OLEDs). . The photophysics and spectroscopy of donor (D)-acceptor (A) molecules, which are capable of photoinduced intramolecular charge transfer (ICT), are the subject of continuing theoretical and experimental interest. The character of ICT depends on the D-A molecular structure including electronic structure and molecular geometry. Respite the numerous investigations of ICT behavior in a conjugated D-A system, however, to predict excited-state properties (LE, TICT and other ICT states) simply based on the molecular structure remains to be a challenging task. In this project, we will synthesize various triarylboron derivatives, and investigate their photophysical and photochemical properties as well as electrochemical properties experimentally and theoretically. Furthermore, kinetics in the formation and decay will be observed using femtosecond spectroscopy, and mechanistic models of photophysical and photochemical processes will be demonstrated. The excited states of these compounds will be characterized, and thier interconversions in different conditions will be investigated. The correlation of the excited-state properties with molecular structures will be found. By the study of this project, we will establish a structure-property relationship of triarylboron derivatives, and achieve to predict the excited-state properties of a triarylboron compounds based on their molecular structures. Meanwhile, we will explore applications of these compounds in materials science.

光诱导分子内电荷转移（ICT）在诸多应用领域尤其是材料科学扮演着关键角色。有机共轭分子的激发态性质，特别是ICT特征决定其发光性质，比如授-受体（D-A）扭曲的TICT态，具有大的溶致变色效应和低的荧光效率。然而，从分子结构来预测其激发态特征（包括LE，TICT及其他ICT态）至今仍是一个挑战。本项目选择有诸多应用的三芳基硼衍生物为研究对象，合成系列结构的三芳基硼衍生物，研究它们的光物理、光化学性质，表征其激发态的特征；研究外界因素对各激发态间的平衡与相互转化的影响；运用超快光谱观察激发态的形成及其演变过程，阐明三芳基硼化合物各激发态的生成及相互转化的热力学；通过电化学方法获得相关热力学数据，建立评价三芳基硼化合物的ICT过程的热力学，阐明三芳基硼ICT过程的热力学与激发态特征之间的关系，初步实现由分子设计即可构建预期ICT特征的功能分子。同时，探索合成的三芳基硼化合物的应用。

光诱导分子内电荷转移（ICT）在诸多应用领域尤其是材料科学扮演着关键角色。本项目开展的主要研究内容是1）设计合成了多个系列三芳基硼，并研究了它们的激发态性质，结果发现，这些三芳基硼的激发态呈现不同程度的分子内电子转移（ICT），包括LE，PICT和TICT三种典型的电荷转移态，有迥然不同的光物理性质。三芳基硼的电荷转移态的性质取决于分子结构（包括授、受体结构及空间位置）和所处环境介质的性质。通过有关热力学数据的测定，我们建立了一个判别授-受（D-A）分子是否形成TICT态的热力学方程，该方程可定性分析三芳基硼化合物的电荷转移态的性质。这一方程对光电功能有机分子的设计具有重要的指导意义。进一步，我们探索了这些三芳基硼的应用，作为阴离子探针和荧光温度计。并将上述结构与性质的关系运用于太阳电池染料、荧光分子探针的设计合成。2）设计合成了新型2,6-授受体修饰的BODIPY太阳电池染料。以这些染料作为敏化剂使太阳电池的光电转换效率大幅提高，远高于文献报道的其他二种设计策略的BODIPY染料。从文献最高值1.88%，逐步提高至5.31%。3）设计合成了多种生物活性分子荧光探针（硫醇、H2S和NO）重要的金属离子（Au+/Au3+, Cu2+）和阴离子CN-、F-等探针，这些分子荧光探针基于分子内电荷转移调控策略，呈现多种响应模式，对探测对象具有高灵敏、高选择性。这些探针分子具有潜在的应用价值。