Phosphorescence of bicyclic enones at low temperatures

Abstract

Phosphorescence spectra, degree of polarization and decay times of three bicyclic enones in a variety of glassy solvents at 77 K are reported, and emission shown to be characteristic of that from ³ππ* states. The phosphorescence was quenched efficiently by a well-known triplet quencher cyclo-octadiene (COD). Analysis of the quenching using the models of Perrin or Hirayama–Inokuti gave similar results in all cases, in that the critical distance for half-quenching was found to be 12–13 Å, typical of that for the exchange-interaction expected for the triplet–triplet energy transfer.