Singlet oxygen phosphorescence photosensitized in nano-aggregates of C buckminsterfullerene is insensitive to solvent and quenchers and strongly red-shifted indicating highly polarizable interior.

We investigated the strongly red-shifted singlet oxygen (O) phosphorescence spectra in an aqueous preparation of C buckminsterfullerene. The 10 nm red shift was associated with HO dispersions of C nanoaggregates (C) that can photosensitize O in their polarizable cores. In contrast to O produced by the water-soluble C-(γ-cyclodextrin) complex, O trapped inside (C) was short-lived (2-3 μs), insensitive to solvent and O quenchers, and did not induce photocytotoxicity. To our knowledge, O spectrum from (C) is the most red-shifted O spectrum recorded to date and it may be used to probe the inner polarizability of carbon (nano)aggregates.