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Energy-Funneling-Based Broadband Visible-Light-Absorbing Bodipy-C60 Triads and Tetrads as Dual Functional Heavy-Atom-Free Organic Triplet Photosensitizers for Photocatalytic Organic Reactions
Auteur(s)
Date de parution
2013
In
Chem. - Eur. J.
Vol.
51
No
19
De la page
17472
A la page
17482
Résumé
C60-bodipy triads and tetrads based on the energy-funneling effect that show broadband absorption in the visible region have been prepd. as novel triplet photosensitizers. The new photosensitizers contain two or three different light-harvesting antennae assocd. with different absorption wavelengths, resulting in a broad absorption band (450-650 nm). The panchromatic excitation energy harvested by the bodipy moieties is funneled into a spin converter (C60), thus ensuring intersystem crossing and population of the triplet state. Nanosecond time-resolved transient absorption and spin d. anal. indicated that the T1 state is localized on either C60 or the antennae, depending on the T1 energy levels of the two entities. The antenna-localized T1 state shows a longer lifetime (?T=132.9 ?s) than the C60-localized T1 state (ca. 27.4 ?s). We found that the C60 triads and tetrads can be used as dual functional photocatalysts, i.e., singlet oxygen (1O2) and superoxide radical anion (O2.-) photosensitizers. In the photooxidn. of naphthol to juglone, the 1O2 photosensitizing ability of the C60 triad is a factor of 8.9 greater than the conventional triplet photosensitizers tetraphenylporphyrin and methylene blue. The C60 dyads and triads were also used as photocatalysts for O2.--mediated aerobic oxidn. of arom. boronic acids to produce phenols. The reaction times were greatly reduced compared with when [Ru(bpy)3Cl2
was used as photocatalyst. Our study of triplet photosensitizers has shown that broadband absorption in the visible spectral region and long-lived triplet excited states can be useful for the design of new heavy-atom-free org. triplet photosensitizers and for the application of these triplet photosensitizers in photo-organocatalysis. [on SciFinder(R)]
Identifiants
Type de publication
journal article
