Abstract: Boron–nitrogen coordination (B←N) bonds have emerged as a versatile motif for engineering π-conjugated systems with tunable optoelectronic properties. Herein, we report the synthesis, structures, and properties of chiral heteroacenes ( 5a – 5c ) featuring B←N coordination within highly twisted π-frameworks. 5a – 5c were synthesized via a four-step approach, where the final cyclization simultaneously forged six- and five-membered rings bearing both B–N covalent and B←N dative bonds. Crystal structure analysis revealed the distorted backbone and intrinsically chiral character of 5a – 5c , which were successfully resolved into enantiomers by chiral-phase HPLC. The enantiomers of 5a – 5c were characterized by circular dichroism spectroscopy, and the enantiomers (+)-5a and (−)-5a exhibit circularly polarized luminescence with the luminescence dissymmetry factors ( g lum ) reaching 10 –3 in both solid state and solution phase. Furthermore, the B←N coordination unit induces strong intramolecular charge-transfer (ICT) transitions, resulting in low-energy absorption band at 420–600 nm. The ICT band can be reversibly modulated by acid–base treatment through dynamic cleavage and restoration of B←N bond. Moreover, 5a – 5c show strong third-order nonlinear optical responses, making them promising candidates for optical limiting materials. This study highlights the potential of B←N-embedded chiral heteroacenes as multifunctional materials.
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