Quenching of triphenylene phosphorescence in poly-(methylmethacrylate) at 77 K by ferrocene and ruthenocene

Abstract

Electronic energy transfer from the lowest triplet state of triphenylene to the transition metal complexes ferrocene and ruthenocene has been studied in poly-(methylmethacrylate) at 77 K. The mechanisms of energy transfer were determined by fitting the observed donor phosphorescence decay with decay functions predicted for exchange and dipole–dipole energy transfer mechanisms, by comparison of spectral overlap, and by comparing the variation of relative donor decay times and emission yields at different acceptor concentrations. Transfer to ruthenocene was shown to occur by the exchange mechanism, while transfer to ferrocene occurred predominantly by the dipole–dipole mechanism with a weaker transfer channel due to the polymer matrix. It is shown that comparison of the change in relative lifetimes and relative emission yields with acceptor concentration is not in itself sufficient to determine the mechanism of energy transfer when transition metal complexes are involved.