Abstract
We investigated the strongly red-shifted singlet oxygen ((1)O(2)) phosphorescence spectra in an aqueous preparation of C(60) buckminsterfullerene. The ~10 nm red shift was associated with H(2)O dispersions of C(60) nanoaggregates (C(60))(n) that can photosensitize (1)O(2) in their polarizable cores. In contrast to (1)O(2) produced by the water-soluble C(60)-(γ-cyclodextrin)(2) complex, (1)O(2) trapped inside (C(60))(n) was short-lived (~2-3 μs), insensitive to solvent and (1)O(2) quenchers, and did not induce photocytotoxicity. To our knowledge, (1)O(2) spectrum from (C(60))(n) is the most red-shifted (1)O(2) spectrum recorded to date and it may be used to probe the inner polarizability of carbon (nano)aggregates.