Despite recent progress in single-ring defect engineering, the fusion of a 5–7–7 ring system to a single HBC core remains unexplored. Herein, we report a π-extended HBC derivative 5a that incorporates a nitrogen-doped 5–7–7 ring fused to the HBC core. 5a adopts a saddle-planar hybrid geometry, exhibits good solubility even in n-hexane, shows enhanced photoluminescence, and forms a 1:1 complex with C60 in solution.
Ren et al. (2026) studied this question.