EXCITED TRIPLET-STATES AS PROBES IN ORGANIZED SYSTEMS - AN OVERVIEW OF RECENT RESULTS

Triplet molecules have been employed as probes in organized systems in solution and in the solid state. This article presents an account of our recent work in this area. In particular, these probes are very useful when studying processes involving relatively slow mobility, where the short lifetime of singlet states would make fluorescence a poor monitoring technique. Among the molecules examined, xanthone and 4,4'-dimethylbenzophenone have proven useful in cyclodextrin complexes, leading to information on polarity, mobility and excited state reactivity. Other triplet probes based on the beta-phenylpropiophenone moiety yield information on intracavity mobility, inclusion geometries and generally on the importance of steric factors in the formation and stability of cyclodextrin complexes. Finally, delayed fluorescence from pyrene derivatives has been employed as a probe for mobility and exchange in reversed micelles.