Internally BN-Doped Coronene

Abstract

We present the first synthesis of internally BN-doped coronenes (B2N2-C, H-B2N2-C, and 2H-B2N2-C) with two covalent B─N units embedded on the central axis of coronene. The B─N doping leads to unique electronic structures with distinct charge distribution, conjugation, aromaticity, and photophysical properties. The structures were successfully identified by the single-crystal X-ray scattering. B2N2-C without sidechains retains the structure of coronene but exhibits stronger π-π stacking, higher electronic coupling, and a narrowed solid-state bandgap. Driven by the B─N dipole-dipole interaction, all B2N2-coronene derivatives exhibit more ordered assembly with excimer emission in solution, which is absent in coronene. Notably, two stable polymorphs emerge in single crystals of 2H-B2N2-C with two hexyl chains: a kinetically stable rod phase and a thermodynamically stable plate phase, where variations in processing conditions direct the formation of different phases.

Keywords: BN compounds; Coronene; Dipole; Excimer; Organic semiconductor.