Photosensitized long-lived room-temperature phosphorescence of naphthalene-d8 as a result of T-T energy transfer inside the 4′-tret-butylacetophonone- naphthalene-d8@2β-cyclodextrin inclusion complex

T-T energy transfer inside the supramolecular system has been performed resulting in photosensitized long-lived room-temperature phosphorescence of naphthalene-d(8) included to the complex 4'-t-butylacetophenone-naphthalene-d(8)-2 beta-cyclodextrine (tBA center dot Nph-d(8)@2 beta CD). In this system, formed by self-assembly, the donor (D) of triplet energy was tBA, the acceptor (A) was naphthalene-d(8). Upon deleting dissolved atmospheric oxygen with added sodium sulfite, the phosphorescence lifetime increased from 4.7 to 12.8 s. A mono-exponential character of decay curves was indicative of a uniform structure of the emitting species. Our quantum-chemical simulations have shown that, in the cavity of beta-cyclodextrine dimer, D and A of triplet excitation are located closer (4.81 angstrom) than in free state (5.19 angstrom), which ensures efficient transfer of triplet excitation to naphthalene-d(8).