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

• Published in: Journal of luminescence 2020-03, Vol.219, p.116909, Article 116909
• Main Authors: Nazarov, V.B., Avakyan, V.G., Alfimov, M.V.
• Format: Article
• Language: English
• Subjects: 4′-t-butylacetophenone; ab initio CIS; DFT; Naphthalene-d8; Photosensitized long-lived phosphorescence at room temperature; Quantum-chemical calculations (PM3; TD TDF; Triplet–triplet energy transfer; β-Cyclodextrin
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2019.116909

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 Å) than in free state (5.19 Å), which ensures efficient transfer of triplet excitation to naphthalene-d8. •A based on beta-cyclodextrin complex with unique properties was implemented.•A process of a T-T excitation energy transfer was carried out within complex.•This results in lengthy (4.7 s) room temperature phosphorescence in presence of O2.•Phosphorescence time is increased to 12.8 s after deleting O2 from solution.