A Boron‐Doped Buckybowl with a C ₄₂ B ₂ Core: Synthesis, Crystal Structure, and Optoelectronic Properties

Abstract Constructing curved topologies of and/or doping heteroatoms into molecular carbons are of importance for synthetic chemistry and materials science. Herein, we disclose a boron‐doped buckybowl, which was realized by region‐cyclization‐induced curvature of an organoboron π‐system. Its synthesis was enabled by consecutive alkyne‐based annulation and palladium‐catalyzed regional C–H arylation. This molecule features a C 42 B 2 polycyclic π‐skeleton containing two pentagonal rings, and has a highly stable bowl‐shaped geometry, thus representing an unprecedented kind of curved heterocyclic molecular carbons. Notably, a few unexpected photophysical properties were achieved, including narrowband red fluorescence, stimulated emission, and amplified spontaneous emission. All of these properties have never been reported in other all‐carbon and heterocyclic buckybowls, and demonstrate that such boron‐doped buckybowls are promising for use as narrowband emitters and optical‐gain materials. Additionally, it shows a four‐step reversible reduction activity, revealing its efficient electron‐accepting capability contributed by the boron atoms and pentagonal rings.