Jin Ke, Xiao Zuo, Xie Huidong, Shen Xingxing, Wang Jizheng, Chen Xiangyu, Wang Zhijie, Zhao Zujin, Yan Keyou, Ding Yong, Ding Liming
Center for Excellence in Nanoscience (CAS), Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS), National Center for Nanoscience and Technology Beijing 100190 China
University of Chinese Academy of Sciences Beijing 100049 China.
Chem Sci. 2024 Sep 24;15(41):17128-49. doi: 10.1039/d4sc04796f.
A new design concept, tether-entangled conjugated helices (TECHs), is introduced for helical polyaromatic molecules. TECHs consist of a linear polyaromatic ladder backbone and periodically entangling tethers with the same planar chirality. By limiting the length of tether, all tethers synchronously bend and twist the backbone with the same manner, and change it into a helical ribbon with a determinate helical chirality. The 3D helical features are customizable modular synthesis by using two types of synthons, the planar chiral tethering unit ( symmetry) and the docking unit ( symmetry), and no post chiral resolution is needed. Moreover, TECHs possess persistent chiral properties due to the covalent locking of helical configuration by tethers. Concave-type and convex-type oligomeric TECHs are prepared as a proof-of-concept. Unconventional double-helix π-dimers are observed in the single crystals of concave-type TECHs. Theoretical studies indicate the smaller binding energies in double-helix π-dimers than conventional planar π-dimers. A concentration-depend emission is found for concave-type TECHs, probably due to the formation of double-helix π-dimers in the excited state. All TECHs show strong circularly polarized luminescence (CPL) with dissymmetric factors (| |) generally over 10. Among them, the ()-T4-Bu shows the highest | | of 1.0 × 10 and a high CPL brightness of 316 M cm.
本文为螺旋状多芳族分子引入了一种新的设计概念——系链缠结共轭螺旋（TECHs）。TECHs由线性多芳族梯形主链和具有相同平面手性的周期性缠结系链组成。通过限制系链长度，所有系链以相同方式同步弯曲和扭曲主链，将其转变为具有确定螺旋手性的螺旋带。利用两种合成子，即平面手性系链单元（ 对称性）和对接单元（ 对称性），可通过模块化合成实现3D螺旋特征的定制，且无需进行后期手性拆分。此外，由于系链对螺旋构型的共价锁定，TECHs具有持久的手性性质。作为概念验证，制备了凹型和凸型低聚TECHs。在凹型TECHs的单晶中观察到了非常规的双螺旋π二聚体。理论研究表明，双螺旋π二聚体中的结合能比传统平面π二聚体小。发现凹型TECHs具有浓度依赖性发射，这可能是由于在激发态形成了双螺旋π二聚体。所有TECHs均表现出强烈的圆偏振发光（CPL），不对称因子（| |）通常超过10。其中，（）-T4-Bu的| |最高，为1.0×10 ，CPL亮度高达316 M cm 。
