O–B ← N perturbed polycyclic aromatic hydrocarbons: a straightforward synthesis strategy, and their photophysical and optical waveguide properties

Polycyclic aromatic hydrocarbons (PAHs) containing O-B ← N groups in the backbone have demonstrated excellent optical properties but two-dimensionally (2D) extended O-B ← N perturbed PAHs have been rarely reported due to synthetic challenges. Moreover, the applications of these O-B ← N perturbed PAHs have been primarily limited to electroluminescent devices, highlighting the urgent need to explore novel functions of this class of heteroaromatic molecules. This work develops a straightforward synthesis strategy toward O-B ← N perturbed PAHs through 2-3 steps, creating a series of tetra-cycle, octa-cycle, and deca-cycle fused molecules. Photophysical characterization and theoretical simulations of these O-B ← N perturbed PAHs reveal several distinct properties, <i>e.g.</i>, high fluorescence quantum yields (70%), aggregation induced emission (AIE) effects, and anti-Kasha emission. Then, through classic solvent diffusion or volatilization methods, these O-B ← N perturbed PAHs further self-assemble into 1D microstructures, <i>e.g.</i>, rod or sheet shaped microwires in solutions. These microwires were, for the first time, subjected to optical waveguide measurements, revealing low optical loss coefficients ranging from 10^-2 to 10^-3 dB μm^-1. This work develops an efficient synthesis strategy for 2D extended O-B ← N perturbed PAHs and demonstrates their pioneering applications in optical waveguides, demonstrating the great potential of these O-B ← N perturbed PAHs for micro/nanophotonics.