Synthesis of 2,6,9-substituted xanthen-3-one and solvent effect on structural and photophysical properties

The synthesis of donor-π-donor type 2,6,9-substituted xanthen-3-one and its solvent effect on both the structural and photophysical properties were revealed. The keto-enol isomerization behavior and red-shift of the emission wavelengths were observed depending on the solvent polarity. This observation indicated that twisted intramolecular charge transfer (TICT) occurs in this system. This is probably due to the electron donating aryl group at 2-position of the xanthene skeleton, which could rotate in the excited state. The luminescence of the compound was also confirmed in a living cell. •The donor-π-donor type 2,6,9-substituted xanthen-3-one was newly synthesized.•The keto-enol isomerization behavior was observed depending on the solvent polarity.•Twisted intramolecular charge transfer (TICT) was observed due to the rotation of the electron donating aryl group.