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Close Proximity Dibenzo[ a , c ]phenazine–Fullerene Dyad: Synthesis and Photoinduced Singlet Energy Transfer
Author(s) -
Dubey Rajeev K.,
Kumpulainen Tatu,
Efimov Alexander,
Tkachenko Nikolai V.,
Lemmetyinen Helge
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201000136
Subject(s) - chemistry , singlet fission , excited state , photochemistry , phenazine , chromophore , singlet state , fullerene , intramolecular force , stereochemistry , organic chemistry , atomic physics , physics
A dibenzo[ a , c ]phenazine–fullerene (DBPZ‐C 60 ) dyad in which two chromophores are linked in close proximity to each other has been synthesized and studied in detail by optical spectroscopy to explore a new energy donor–acceptor system. The dyad was prepared by Prato reaction between 11‐formyldibenzo[ a , c ]phenazine and fullerene. 3,5‐Di‐ tert ‐butylbenzyl group was introduced onto the fulleropyrrolidine unit to achieve adequate solubility of the dyad. A thorough study of the photophysical properties of the dyad and relevant reference compounds, performed by means of steady state and time resolved spectroscopic measurements, has revealed the presence of highly efficient (ca. 98 %) and extremely fast ( k en = 5 × 10 11 s –1 ) intramolecular photoinduced singlet–singlet energy‐transfer process from singlet excited state of the DBPZ moiety to fullerene. In both polar and nonpolar environment transduction of singlet excited state energy governs the excited state deactivation, but the efficiency and rate of energy transfer were found to be higher in nonpolar solvents in comparison to polar. The DBPZ singlet excited state decays within 2 and 4.7 ps in toluene andbenzonitrile, respectively, via singlet–singlet energy transfer to produce a fullerene singlet excited state which decays with a life time of 1.5 ns to give a very long‐lived fullerene triplet state as final populated excited state.