The quenching of anthracene fluorescence and biacetyl and 1-bromonaphthalene phosphorescence by MIs (I-picoli~~e),(NCS)~ complexes, where M"is Ni", Co" or Mn", respectively, has been studied in liquid and glassy solutions and the data are compared with theoretical energy-transfer mechanisms.The chosen donor-acceptor pairs form, in the solid state, clathrates with significant ground-state interactions: no such association was observed in solution that might influence the luminescence decay processes. In particular, a diffusion-controlled process occurred for the systems involving excited singlet anthracene-M" complexes in methanol and in cyclohexanol and its mixtures ; an encountercontrolled process of an exchange nature occurred for the system triplet biacetyl-MI1 complex in water ; finally a dipolar and/or exchange quenching process took place in the system triplet 1-bromonaphthalene-M" complex. These results correlated satisfactorily with an electronic energy transfer mechanism ; alternative quenching processes were also considered, i.e. electron transfer, heavy-atom effect, spin-catalysed deactivation and exciplex formation, but were found to correlate poorly with the observed behaviour of thevarious systems studied.

No abstract

No abstract

No abstract

No abstract