Benzo-Extended Heli(aminoborane)s: Inner Rim BN-Doped Helical Molecular Carbons with Remarkable Chiroptical Properties.

Atomically precise synthesis of three-dimensional boron-nitrogen (BN)-based helical structures constitutes an undeveloped field with challenges in synthetic chemistry. Herein, we synthesized and comprehensively characterized a new class of helical molecular carbons, named benzo-extended [n]heli(aminoborane)s (s), in which the helical structures consisted of = 8 and = 10 -condensed conjugated rings with alternating BN atoms at the inner rims. X-ray crystallographic analysis, photophysical studies, and density functional theory calculations revealed the unique characteristics of this novel system. Owing to the high enantiomerization energy barriers, the optical resolution of and was achieved with chiral high-performance liquid chromatography. The isolated enantiomers of exhibited record absorption and luminescence dissymmetry factors (||=0.061; ||=0.048), and boosted CPL brightness up to 292 M cm, surpassing most helicene derivatives, demonstrating that the introduction of BN atoms into the inner positions of helicenes can increase both the || and || values.