AM1 AND INDO/S CALCULATIONS ON ELECTRONIC SINGLET AND TRIPLET-STATES INVOLVED IN EXCITED-STATE INTRAMOLECULAR PROTON-TRANSFER OF 3-HYDROXYFLAVONE

Energies and geometries of the electronic ground states and vertical transition energies and oscillator strengths of singlet-singlet and triplet-triplet transitions have been calculated for both tautomer forms of 3-hydroxyflavone. The resulting energy level diagram and calculated excited-state spectra yield a consistent interpretation of the data from transient absorption measurements. It is concluded that all long-lived transient absorptions are due to triplet species and that an intrinsic barrier to proton transfer exists in the lowest triplet state. © 1990 American Chemical Society.