A New Platform of B/N‐Doped Cyclophanes: Access to a π‐Conjugated Block‐Type B <sub>3</sub> N <sub>3</sub> Macrocycle with Strong Dipole Moment and Unique Optoelectronic Properties
Peng-Fei Li, Daisuke Shimoyama, Niu Zhang, Yawei Jia, Guo-Fei Hu, Chenglong Li, Xiaodong Yin, Nan Wang, Frieder Jäkle, Pangkuan Chen
Abstract
Abstract We herein describe a new design principle to achieve B/N‐doped cyclophane where an electron‐donor block of three triarylamines (Ar 3 N) and an acceptor block of three triarylboranes (Ar 3 B) are spatially separated on opposite sides of the π‐extended ring system. DFT computations revealed the distinct electronic structure of the block ‐type macrocycle MC‐ b ‐B3N3 with a greatly enhanced dipole moment and reduced HOMO–LUMO energy gap in comparison to its analogue with alternating B and N sites, MC‐ alt ‐B3N3 . The unique arrangement of borane acceptor Ar 3 B and amine donor Ar 3 N components in MC‐ b ‐B3N3 induces exceptionally strong intramolecular charge transfer in the excited state, which is reflected in a largely red‐shifted luminescence at 612 nm in solution. The respective linear open‐chain oligomer L‐ b ‐B3N3 was also synthesized for comparison. Our new approach to donor–acceptor macrocycles offers important fundamental insights and opens up a new avenue to unique optoelectronic materials.