Photocatalytic Properties of a Palladium Metallosquare with Encapsulated Fullerenes via Singlet Oxygen Generation.

Singlet oxygen has recently attracted a great deal of attention due to its strong oxidizing properties, which makes it useful in organic synthesis and biological studies. However, the photosensitizers that are required for singlet oxygen generation remain inadequate due to their often low thermal and photochemical stabilities. Here we describe the use of a palladium-conjoined metallosquare with encapsulated fullerenes (C60 or C70), which behaves as an efficient and photochemically stable singlet oxygen photosensitizer. The metallocage with the encapsulated fullerenes can oxidize a series of cyclic and acyclic alkenes at room temperature via visible light-induced singlet oxygen generation, using oxygen molecules in air at atmospheric pressure. These reactions take advantage of the excellent spin-converting properties of fullerenes, which make them excellent agents for singlet oxygen production.