Kritchasorn Kantarod,^a Darunee Soorukram,^a Chutima Kuhakarn,^a Panida Surawatanawong,^a Worawat Wattanathana,^b Vichai Reutrakul,^a  and Pawaret Leowanawat*^a

^aCenter of Excellence for Innovation in Chemistry (PERCH-CIC) and Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.

^bDepartment of Materials Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900, Thailand.

Heptagon-embedded polycyclic aromatic dicarboximides were developed as new push–pull fluorescent dyes through palladium-catalysed [4+3] annulation followed by nucleophilic substitution. The introduction of a seven-membered ring in these push–pull systems can efficiently modulate the optical properties leading to an enhancement of the fluorescence quantum yields up to 0.93 with color tunable emission covering the visible-NIR spectrum.