Inclusion complexes of coumarin in cucurbiturils

Coumarin was found to form stable inclusion complexes with cucurbiturils. In the presence of cucurbit[7]uril(CB[7]), 1 : 1 inclusion complexes were observed in aqueous solution, as monitored by H-1 NMR and UV-visible absorption spectroscopies, and further supported by ab initio calculations, whereas with cucurbit[8] uril (CB[8]) a solid phase 1 : 2 host : guest complex was found in a single crystal X-ray diffraction structure determination.