新型手性有机阴离子自由基的精准合成与自组装研究

One of the most appealing challenges for contemporary molecular magnetics is the combination and synergy of magnetism and chirality to result in magneto-optical effects. However, the massive challenge in chiral molecular-based magnetism lies in the difficulties in obtaining persistent organic radicals. This project dedicates to develope a new family of persistent chiral anionic radicals as building blocks for multifunctional self-assembly based on the benzene triimide backbone, an unique planar moiety with C3 symmetry and electron-deficient nature. Various chiral benzene triimide derivatives could be synthesized through a highly efficient one-step condensation or post-modification of an unsubstituted benzene triimide core. Transformations of the chiral benzene triimide with various strategies including reducing agent, electrochemical reduction, intramolecular and intermolecular charge transfers are expected to provide chiral anionic radicals. The consequence of magnetic properties including bistability, multistability and circularly polarized luminescence will be pursued in detail. Applying the radicals as building block, self-assembly and preparation of molecular materials that might display magneto-optical effects will be systematically investigated.

以稳定的手性有机自由基物种为组装基元，通过非共价相互作用构筑兼具磁性-光学效应的功能材料无疑是非常具吸引力的课题，但在稳定的手性自由基组装基元的设计与合成方面存在巨大挑战。本项目拟以苯三酰亚胺为骨架，开发稳定的手性有机阴离子自由基组装基元，并系统研究其自组装行为和功能。苯三酰亚胺是具有C3对称性和缺电子性的平面骨架分子，易被还原成阴离子自由基物种。利用我们发展的苯三酰亚胺的高效合成方法，通过在单体或通过后修饰引入手性取代基构筑手性苯三酰亚胺化合物库，进而利用不同的方法如化学还原、电化学还原、分子内和分子间电荷转移手段制备手性阴离子自由基，系统建立分子结构与双稳态或多稳态磁性、圆偏振发光特性以及磁圆偏振发光特性等的相关关系，利用自由基之间的相互作用和次级非共价相互作用构建组装体，探索组装体的磁性、光学特性和反应活性等功能。

苯三酰亚胺是一类具有C3对称性的缺电性骨架，能够经化学或电化学还原形成稳定的阴离子自由基，其稳定性无需大位阻基团的保护，BTI骨架的N端可同时引入三个取代基，可作为研究自由基与手性之间相互作用的平台分子。本项目基于丙基取代的苯三酰亚胺阴离子自由基pimer实现了多稳态磁性首次实现了有机自由基的多稳态磁性，进一步通过系统的取代基变化，总结了取代基对自由基-自由基相互作用、磁性和导电性的影响规律。在此基础上，将不同手性元素引入到苯三酰亚胺骨架，进一步通过还原，构建了手性苯三酰亚胺阴离子自由基或手性分子笼自由基，研究了手性取代基对自由基堆积结构、自由基-自由基相互做哟个和磁学性质的影响，借助自由基在近红外处的紫外吸收（SOMO轨道跃迁），利用CD光谱和理论计算，揭示了自由基与手性相互作用的本质；利用MCD光谱技术，展示了磁场方向对手性自由基CD光谱的影响。