Modification of Chemical Reactivity via Inclusion Complex Formation: Photochemistry of Dibenzyl Ketones and Benzyl Phenylacetates

In the context of employing "inclusion complexes" as a medium for organic photochemical reactions, we have investigated the photochemical behavior of dibenzyl ketones and benzyl phenylacetates using deoxycholic acid (DCA), Dianin's compound, and cyclodextrin (CD) as hosts in the solid state. Results on cage effect suggest that the translational motion of the benzyl radical pairs is restricted in all three media and totally in Dianin's compound. Products resulting from rearrangement of dibenzyl ketones were formed upon photolysis in Dianin's compound and cyclodextrin and were absent in deoxycholic acid. The absence of rearrangement in DCA and its presence to varied extents in Dianin's compound and cyclodextrin is suggested to be an indication of the restriction imposed by the host on the reorientational process of geminate radical pairs.