Direct detection of singlet oxygen (1O2) production under irradiation of molecular micelle-like hexa(sulfo-n-butyl)fullerene (FC4S) self-assembled nanospheres at 500-600 nm was obtained by the measurement of its near-infrared luminescence at 1270 nm. This photocatalytic effect makes FC4S a potential alternative sensitizer to TiO 2 and feasible for use in the visible region in addition to its intrinsic high UV efficiency. Despite having a relatively low optical absorption of FC4S at 600 nm, appreciable 1O2 signal was detected comparable to that of hematoporphyrin derivatives Photofrin at the same molar concentration, but less than sulfonated aluminium phthalocyanine, AlS4Pc. The quantum yield of FC4S for the generation of 1O2 in H2O was roughly estimated to be 0.36 using the relative correlation to that of C60/γ-CD. The absolute value is not available. These results demonstrated efficient triplet energy transfer from 3FC4S* to molecular oxygen in the nanosphere structure. We also confirmed certain retention between photocatalytic characteristics of underivatized C60 with that of FC4S, a C60 hexaadduct containing a single covalent bond between each addend and the fullerene cage, in contrast to other Bingel-type hexamalonate adducts of C60 in the literature with a low 1O2 yield.
ASJC Scopus subject areas
- Materials Chemistry