| Abstract: | The photochemistry of 3- and 4-benzoylpyridine-cyclodextrin inclusion complexes (BPyCDx) was examined by nanosecond laser flash-photolysis and stationary techniques. The lifetimes of the triplet complex and of the triplet radical pair, formed by H-abstraction from a glucose unit of the CDx, have been measured in β-CDx complexes. The reactivity of the heterocyclic ketones with CDx is higher than that of benzophenone, but the lower binding ability of the macrocycle toward these more hydrophylic molecules induces faster separation of the geminate radicals. The quantum yields of the escaped radicals and their decay kinetics have been determined. The β-CDx cage favours geminate recombination reactions, while α- and -γ-CDx tend to release the guest molecule. Cage products have been spectroscopically characterized in the case of the 3-BPy-β-CDx system. |
