圆偏振发光的新型手性三芳基硼pi-共轭分子的研究

The organic optoelectronic materials exhibiting circularly polarized luminescence (CPL) are potentially applied in a wide range of fields, such as 3D optical displays, optical storage and processing systems, biological probes and signatures, light-emission systems for asymmetric photosynthesis and circularly polarized luminescence microscopes. The organic molecules enabling CPL generally shows low fluorescence quantum yield, especially low fluorescence quantum yield in the solid state, and low luminescence dissymmetric factor. In addition, the structural diversity of this kind of molecules is very poor and the structure-property relationships are very unclear. Based on our recent research on the solid-state emissive organoboron materials, we are herein proposing to obtain organic functional materials with high performance of CPL via construction of novel chiral triarylboron pi-conjugated systems. We will firstly design and synthesize a series of novel chiral triarylborons, including those containing chiral units and achiral triarylboron luminophores, boron-doped helicenes and those, in which the rotation of aryl substituents on tri-coordinate boron is highly restricted. On this base, we will systematically investigate the relationships between the molecular structure and optoelectronic properties, especially chiral optical properties. We also aim to obtain some chiral triarylborons with high performance of CPL through optimized design of molecular structures. We believe that the results from this project will provide some important theoretical basis for the rational design of organic functional materials with high performance of circularly polarized luminescence and make great contributions to the development of organoboron-based optoelectronic materials.

有机圆偏振发光材料在3D光显示、光电信息存储和处理、生物探针和印迹以及圆偏振光激光器等方面具有诱人的应用前景，但目前对有机圆偏振发光材料的研究仍存在结构类型非常有限、构效关系不够明确、荧光量子效率尤其是固态荧光效率低以及发光不对称因子比较低等问题，基于这一研究现状并结合申请人多年来在有机硼固态发光材料方面的研究积累，申请人提出通过构筑新型的手性三芳基硼分子体系来获得高性能有机圆偏振发光材料的工作设想。首先，本项目将设计合成一系列新型的手性三芳基硼化合物，其中包括含有非手性三芳基硼发光团和手性结构单元的化合物、硼杂螺烯类化合物以及硼中心芳基旋转受阻的化合物，在此基础上，研究分子结构对光电性能尤其是手性光学性能的影响规律，并进一步优化分子结构设计以获得一些高性能的圆偏振发光材料。该项工作的顺利完成将为发展高性能的有机圆偏振发光材料提供一定的理论依据，并为丰富和发展有机硼光电材料作出贡献。

在本项目的支持下，我们针对有机小分子圆偏振发光材料研究中所存在的结构类型有限、难以兼具高发光量子效率（F）和高发光不对称因子（glum）等问题，以联萘、螺烯和[2.2]环仿作为手性共轭单元，通过引入大位阻吸电性的二米基硼取代基并同时引入给电性的氨基，构筑了一系列手性三芳基硼化合物，研究发现：（1）我们所构筑的手性三芳基硼化合物大都具有良好的圆偏振发光性能，有的可以同时兼具高荧光量子效率和高发光不对称因子的特点，发光不对称因子最高可达10-2的级别，这在有机小分子中是比较高的数值；（2）而且由于硼取代基位阻效应的影响，可以有效地抑制固态下的荧光淬灭现象，使得所获得的手性三芳基硼化合物在固态下也可以保持高的发光效率；（3）另外通过调控激发态动力学，还可以实现溶致圆偏振发光手性反转以及温敏荧光双发射。上述这些性质是利用其它基团进行结构的修饰难以获得的，进而也说明硼取代基在构筑有机小分子圆偏振发光体系具有非常独特的优势。这些系统的研究结果将为有机小分子圆偏振发光体系的进一步结构优化设计提供重要的理论依据。