Photochemistry of hypocrellin derivatives under aerobic conditions

Hypocrellins are a novel type of photosensitizers. A series of new hypocrellin B (HB) derivatives have been synthesized to overcome their limitations, i.e. to improve their red absorption and amphiphilicity. The generation of reactive oxygen species (including Superoxide anion radical, hydroxyl radical and singlet oxygen) is investigated in the presence of oxygen. The chemical structures of HB derivatives affect not only the generation efficiencies of Superoxide and hydroxyl radicals, but also quantum yields of singlet oxygen.