联杂芳烃型小分子荧光骨架的构筑方法、性质与应用研究

The demanding for organic fluorophors is ever increasing because of the fast development (wide applications) in molecular sensing, bioimaging, optoelectronic devices and functional materials in recent years. The studies and applications of the known skeletons such as courmarin, fluorecein, rhodamine, cyanine and bodipy etc. have made great progresses. Although chemists never stop searching for new fluorogens, rare is comparative with the known ones, except hexaphenylsilole (HPS) and tetraphenylethene (TPE) possessing aggregation-induced emission (AIE) characteristic serendipitously discovered by Tang et al. This is probably because people still know very few about fluorescence and can hardly synthesize fluorogens with designed property. Due to our continuous interests in fluorescent materials, we find that some commercially available and famous fluoregens are all constituted as biheteroarene skeletons with peripheral functional groups. This enlightens us to ask: "whether biheteroarene skeleton could be a general strategy to construct fluorogens?" In this project, we will try to develop efficient methods for the biheteroarene construction and the functionalization of heteroarenes through C?H activation. These methods will provide us high throughput screening of various fluorogenic molecules and establish a full-colored library, in which stable, highly emissive fluorogens will possibly be found. The DFT theory calculation will then be used to disclose the structure-property relationship in expectation to provide general rules for the fluorogen design. We believe that our study will get a positive answer to the question we ask. Finally, the applications of these new fluorogens will be performed in the field of sensing, bioimaging and functional materials.

有机荧光材料的开发研究是当前有机化学的研究热点之一。目前的研究主要集中在对已知骨架的修饰与改造，而具有广泛应用前景的新骨架，由于理论认知的有限，缺乏系统而深入的研究，仍较稀少。同时，人们也难以设计合成具有特定功能的荧光分子。我们发现，一些商品化的和著名的小分子荧光化合物均是由联杂芳烃骨架连接功能基团构成。那么，联杂芳烃骨架是否能成为构筑荧光分子的一个普适策略？本课题将围绕这个问题，发展高效绿色的基于C?H活化的联杂芳烃构筑方法和杂芳烃功能化方法。在此基础之上，采用高通量筛选的办法，通过不同联杂芳烃和功能基的组合，建立全色发光的荧光分子库，寻求结构稳定，荧光性质突出的新型小分子荧光骨架。同时，结合理论计算研究此类分子的构效关系，以期为荧光分子的设计合成提供理论指导。最后，我们期望这些新型的荧光小分子能够在探针、生物标记以及功能材料等方面表现出优异的性能和应用前景。

本项目拟基于C-H键活化策略，发展构筑联杂芳烃骨架和多环杂芳烃骨架的简洁高效有机合成新方法。在此基础之上，寻求结构稳定，荧光性质突出的新型荧光功能骨架。我们发展了三氯化铑催化的咪唑鎓卡宾导向的两重C-H/C-H氧化交叉偶联反应，构筑了一系列阳离子型平面三亚杂芳烃化合物。我们发展了钯催化的吲唑与杂芳烃的C-H/C-H交叉偶联反应，快速构筑了联杂芳烃型荧光分子库Indazo-Fluors，提出了构筑近红外荧光小分子的“D-Het(ED)-Het(ER)-A”策略，并成功获得一个小分子量，光稳定性好，低毒性的近红外线粒体探针。我们系统研究了共轭不饱和羰基化合物的C-H键活化反应，实现了它们与炔的C-H环化反应和交叉偶联反应。我们实现了吲哚的自偶联反应用于构筑新型萘并四吲哚骨架，其表现出与常用Spiro-OMeTAD分子相当的空穴传输能力。我们发展了芳醛衍生物与炔的C-H串联环化反应，快速构筑了天然和非天然阳离子型多环杂芳烃荧光骨架。我们实现了咪唑鎓盐的直接C-H单、双和三芳基化反应，首次发现了共轭双咪唑鎓分子的电致变色性质。我们还发展了肟醚导向的C-H/C-H杂芳基化反应以及吡啶鎓与炔的C-H环化反应高效构筑12-氮杂苾荧光骨架。这些方法的建立将推动有机合成朝着更为简单高效的方向发展，而所得的具有优良荧光性质的新骨架分子，将启发人们对于荧光功能分子设计的新思维。