EXCITED STATE INTRAMOLECULAR PROTON TRANSFER (ESIPT) IN 6- HYDROXY-7H-BENZO[C] FLUOREN-7-ONE: SUBSTITUENT EFFECT

In this work, intramolecular photo-induced proton transfers in 6-hydroxy-7H-benzo[c]fluoren-7- one (HBFO) and its substituted compound in gas phase are investigated using TD-DFT method at M06-2X/6-311++G(d,p) level of theory. The results show that the ground state intramolecular proton transfer (GSIPT) in the studied species is impossible. Excited states potential energy surface calculations support the existence of ESIPT process. The calculated fluorescence emission wavelength for both molecules is 700 nm. Both compounds exhibit unusually high Stokes shifts fluorescence. Structural parameters, absorption and emission bands, vertical excitation and emission energies, oscillator strength, and dipole moment were calculated.