Inner-Bond-Cleavage Approach to Figure-Eight Macrocycles from Planar Aromatic Hydrocarbons
Reiji Yoshina, Junichiro Hirano, Emiko Nishimoto, Yuki Sakamoto, Keita Tajima, Shunsuke Minabe, Muhammet Uyanik, Kazuaki Ishihara, Tomoyuki Ikai, Eiji Yashima, Takuya Omine, Fumitaka Ishiwari, Akinori Saeki, Jinseok Kim, Juwon Oh, Dongho Kim, Guanting Liu, Takuma Yasuda, Hiroshi Shinokubo, Norihito Fukui
Abstract
High Resolution Image Download MS PowerPoint Slide Figure-eight-shaped nonplanar π-systems adopt distinctive chiral D 2 -symmetric structures, which are ideal for realizing efficient circularly polarized luminescence (CPL). However, the short-step and enantioselective synthesis of figure-eight π-systems represents a considerable challenge for the conventional bottom-up synthetic strategy. Herein, we report that the oxidative cleavage of the internal double bond of a commercially available polycyclic aromatic hydrocarbon, i.e., dibenzo[ g, p ]chrysene (DBC), catalytically affords a figure-eight electron-accepting macrocycle, i.e., cyclobisbiphenylenecarbonyl (CBBC), with high scalability (up to 3.3 g) and excellent enantioselectivity (94% ee). This inner-bond-cleavage approach also applies to larger PAHs, affording highly distorted molecular frameworks that comprise two figure-eight subunits. Furthermore, we demonstrate that the peripheral functionalization of CBBC with carbazole afforded donor–acceptor-type emitter, which shows thermally activated delayed fluorescence and emits CPL with a g value of 1.0 × 10 –2 . This g value is ten times higher than those of previously reported chiral TADF-active emitters for circularly polarized organic light-emitting diodes. These results demonstrate that oxidative inner-bond cleavage is a powerful synthetic strategy for creating innovative materials that incorporate molecules with figure-eight structures.