title: Highly efficient singlet-singlet energy transfer in light-harvesting [60,70]fullerene-4-amino-1,8-naphthalimide dyads.
abstract: New C60 and C70 fullerene dyads formed with 4-amino-1,8-naphthalimide chromophores have been prepared by the Bingel cyclopropanation reaction. The resulting monoadducts were investigated with respect to their fluorescence properties (quantum yields and lifetimes) to unravel the role of the charge-transfer naphthalimide chromophore as a light-absorbing antenna and excited-singlet-state sensitizer of fullerenes. The underlying intramolecular singlet-singlet energy transfer (EnT) process was fully characterized and found to proceed quantitatively (Φ(EnT)≈1) for all dyads. Thus, these conjugates are of considerable interest for applications in which fullerene excited states have to be created and photonic energy loss should be minimized. In polar solvents (tetrahydrofuran and benzonitrile), fluorescence quenching of the fullerene by electron transfer from the ground-state aminonaphthalimide was postulated as an additional path.
authors.affiliation: CIQSO-Center for Research in Sustainable Chemistry and Department of Chemical Engineering, Physical Chemistry and Organic Chemistry, University of Huelva, Campus de El Carmen s/n, 21071 Huelva, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Remón
authors.forename: Cátia
authors.initials: C
authors.lastname: Parente Carvalho
authors.forename: Carlos
authors.initials: C
authors.lastname: Baleizão
authors.forename: Mario Nuno
authors.initials: MN
authors.lastname: Berberan-Santos
authors.forename: Uwe
authors.initials: U
authors.lastname: Pischel
keywords: electron transfer; energy transfer; fluorescence; fullerenes; solvent effects