Solvent-tunable exciton-charge transfer mixed state enhances emission of functionalized benzo[ rst ]pentaphene through symmetry breaking.

A benzo[]pentaphene (BPP) substituted by two bis(methoxyphenyl)amino (MeOPA) groups (BPP-MeOPA) was synthesized and clearly characterized by NMR and single-crystal X-ray analysis. Detailed investigations of its photophysical properties, including transient absorption spectroscopy analyses, revealed that the introduction of the MeOPA groups breaks the symmetry of the BPP core, improving its absorption and emission from an S state with both excitonic and charge-transfer character.