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

Abstract T–T energy transfer inside the supramolecular system has been performed resulting in photosensitized long-lived room-temperature phosphorescence of naphthalene-d8 included to the complex 4′-t-butylacetophenone–naphthalene-d8–2β-cyclodextrine (tBA⋅Nph-d8@2βCD). In this system, formed by self-assembly, the donor (D) of triplet energy was tBA, the acceptor (A) was naphthalene-d8. 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 β-cyclodextrine dimer, D and A of triplet excitation are located closer (4.81 A) than in free state (5.19 A), which ensures efficient transfer of triplet excitation to naphthalene-d8.