Inner-Bond-Cleavage Approach to Figure-Eight Macrocycles from Planar Aromatic Hydrocarbons

• Published in: Journal of the American Chemical Society 2024-10, Vol.146 (43), p.29383-29390
• Main Authors: Yoshina, Reiji, Hirano, Junichiro, Nishimoto, Emiko, Sakamoto, Yuki, Tajima, Keita, Minabe, Shunsuke, Uyanik, Muhammet, Ishihara, Kazuaki, Ikai, Tomoyuki, Yashima, Eiji, Omine, Takuya, Ishiwari, Fumitaka, Saeki, Akinori, Kim, Jinseok, Oh, Juwon, Kim, Dongho, Liu, Guanting, Yasuda, Takuma, Shinokubo, Hiroshi, Fukui, Norihito
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.4c07985

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.