Immobilised photosensitisers for continuous flow reactions of singlet oxygen in supercritical carbon dioxide

Photosensitisers have been incorporated into both polymer and aerogel supports for the photochemical generation of singlet oxygen, ¹O₂, in supercritical carbon dioxide, scCO₂. These systems showed high activity and an acceptable lifetime for the photo-oxidation of a-terpinene and of citronellol in continuous reactors over a period of at least 5 h. The most effective photosensitiser was a covalently coupled analogue of tetradi(2,6)chloro-phenylporphyrin (TDCPP) on polyvinyl chloride (PVC). This immobilisation removes the need to separate the photosensitiser from the downstream solution.