Unique catalytic effect of a cyclodextrin host on photodimerization of coumarin in nonpolar solvents

Heptakis(6-O-tert-butyldimethylsilyl)-β-cyclodextrin (TBDMS-β-CD) formed inclusion complexes with coumarin in benzene and cyclohexane. The inclusion mode of coumarin within the TBDMS-β-CD cavity was different between these solvents. Photodimerization of coumarin in the solvents was remarkably accelerated by the inclusion within the TBDMS-β-CD cavity. In particular, the largest rate increase was observed when 1.0 equiv of TBDMS-β-CD was added to coumarin.