INFLUENCE OF HYDROGEN-BONDED DIMERS ON THE LUMINESCENCE OF 2-PYRIDONE

Fluorescence and phosphorescence quantum yield and lifetime data for 2 -pyridone in a variety of solvents provide evidence that in non-polar solvents a C2h hydrogen-bonded dimer contributes to electronic relaxat ion and fluoresces via a double-proton transfer in the excited state. In basic media where dimer formation is prevented, the luminescence ap pears at a higher energy. The dramatic increases in the phosphorescenc e yield and lifetime of the anion relative to the neutral molecule are due to an excited state protonation. The larger wavelength shifts in luminescence, when compared to absorption wavelength shifts, are consi stent with a structural change in the excited state.