Pentagon-embedded N-doped coumarinacenes: tandem synthesis and tunable photophysical attributes for biomolecular probing

We have synthesized a novel series of nitrogen-doped pentagon-embedded coumarinacenes, namely carbazole-coumarins, <i>via</i> a tandem 1,4-elimination Diels-Alder aromatization reaction. These planar, <i>N</i>-substituted carbazole-coumarins exhibit excellent functionalizability, enhanced photostability and solvent polarity-tunable absorption and blue-to-red emission with notably high fluorescence quantum yields, attesting to their remarkable photophysical properties. These attributes highlight the carbazole-coumarins' potential as robust and efficient fluorescent materials for diverse applications in various fields, including as probes for studying biomolecular systems and dynamics.