SENSITIZATION OF THE PHOSPHORESCENCE OF INDOLE THROUGH INTRAMOLECULAR ENERGY TRANSFER FROM THE TRIPLET STATE OF COVALENTLY LINKED ACETOPHENONE IN RIGID MEDIA AT 77 K

Abstract— In an attempt to study the quenching of the triplet state of acetophenone by indole, we have prepared the compounds containing these chromophores intramolecularly. The emission measurements in rigid glasses at 77 K have indicated that the quenching of the triplet acetophenone is due to intramolecular triplet-triplet energy transfer to the indole chromophore, resulting in the sensitization of the indole phosphorescence. The efficiency of the energy transfer has reached ca. 100% in ethanol glasses, while it has been suggested that in methylcyclohexane glasses, the indole chromophore except for 1-methyl derivative is subjected to strong interaction with the acetophenone chromophore other than electronic energy transfer.