Bifunctional acetylindole-driven ring expansion accessing new asymmetric indole-quinolinone boron fluorophores with PMMA-triggered solid fluorescence enhancement.

Herein, we report an unprecedented one-carbon ring expansion using bifunctional acetylindoles to construct functional quinolinones, affording novel mBODs and BODIPY analogues via condensation and boron chelation. DFT calculations verify the reaction pathway, and spectroscopic analyses clarify their poly(methyl methacrylate) (PMMA)-triggered solid fluorescence enhancement and chromic switching, providing a concise route to new boron luminescent materials.