New coumarin-[60]fullerene dyads connected by an alkynyl linkage: Synthesis and fluorescence studies. Evidence for efficient singlet–singlet energy transfer

Abstract

a b s t r a c tTwo new coumarin-[60]fullerene dyads, in which an alkyne group covalently links C 60 to coumarin, are synthesized via 1,3-dipolar cycloaddition and spectroscopically characterized. Their photophysical properties in apolar (toluene) and polar (THF and benzonitrile) solvents are studied at room temperature, revealing the nature and polarity dependence of the excited-state interactions between the coumarin and C 60 moieties. In both dyads and in all solvents, a strong quenching of the coumarin emission by C 60 was observed. It mainly results from a fast and efficient singletesinglet resonance energy transfer from the coumarin moiety to the C 60 moiety, but an electron transfer contribution, enhanced in polar solvents, also exists. In toluene, the fluorescence emission of the fullerene moiety is increased by the nonradiative energy transfer process, which occurs mainly by a dipoleedipole (FRET) mechanism. In polar solvents (THF and benzonitrile), fast electron transfer from ground-state coumarin to excited fullerene is significant, leading to a partial or complete quenching of the fullerene emission, depending on the dyad.

Transition-Metal-Catalyzed C–H Activation Reactions for the Creation and Modification of Organic Fluorophores

“…Review / Short Review Template for SYNTHESIS Thieme reaction as the key step (Scheme 15). 48 The characteristics of their light-induced properties are investigated at room temperature in nonpolar (toluene) and polar (THF and benzonitrile) solvents. This examination unveils the type and sensitivity of the interactions occurring in the excited state between the coumarin and C60 components.…”

“…In 2015, Brites, Berberan-Santos, and co-workers developed coumarin-[60]fullerene dyads by utilizing the Sonogashira cross-coupling reaction as the key step (Scheme 15 ); 51 their light-induced properties were investigated at room temperature in nonpolar (toluene) and polar (THF and benzonitrile) solvents. This examination unveiled the type and sensitivity of the interactions occurring in the excited state between the coumarin and C 60 components.…”

Coumarin–Tetrapyrrolic Macrocycle Conjugates: Synthesis and Applications

“…In this article, we review primarily the synthetic approaches leading to coumarin–porphyrin, coumarin–phthalocyanine, and coumarin–corrole conjugates. A range of other coumarin–chromophore conjugates, such as coumarin–bodipy [ 18 , 31 ], coumarin–fullerene [ 32 , 33 , 34 ], coumarin–perylene [ 35 , 36 , 37 ], etc. have also been reported and exhibit highly interesting photophysical properties.…”