Photocatalysis on magnetic supports for singlet oxygen generation: Role of immobilization and photobleaching

Abstract

Organometallic photosensitizers are very efficient triplet sensitizers that have found wide use in photocatalysis, but they are scarce, toxic, and expensive. Organic fluorophores have also been used in several systems, but they can suffer from lower efficiency and sensitivity to photobleaching. In this work, we immobilized ruthenium (II) tris(bipyridine) and rose bengal on magnetic nanosupports and compared their activity and photostability in the singlet oxygen mediated photooxidation of citronellol. Both systems can perform the transformation with equivalent turnover frequencies and be magnetically recovered. We studied their long-term stability and found photobleaching to be a major cause of photocatalyst deactivation over time for both systems, and we were able to improve their photostability upon immobilization on solid supports.