Photoprocesses in styryl dyes and their pseudorotaxane complexes with cucurbit[7]uril

The formation of inclusion complexes between styryl dyes containing a dimethylamino group or azacrown-ether residue and cucurbit[7]uril (CB[7]) in aqueous solution was studied by 1H NMR spectroscopy and quantum chemistry. The complexes are characterized by 1:1 composition and the pseudorotaxane structure, which was confirmed by quantum chemical calculations. The free dyes and dye@CB[7] complexes exhibit both prompt fluorescence and an ability to intersystem crossing. The triplet–triplet absorption spectra and the triplet lifetime of the free dyes and dye@CB[7] were measured by ns-laser photolysis.