Chemical tools for the generation and detection of singlet oxygen

Growing evidence indicates intermediacy of singlet dioxygen (¹O₂) in a variety of pathophysiological processes. ¹O₂ has also found great utility of destructive actions for clinical and environmental applications. However, many details of the molecular mechanisms mediated by ¹O₂ remain insufficiently understood. Efforts to elucidate the ¹O₂ chemistry have been hampered by the lack of chemical tools capable of generation and detection of ¹O₂. In this review, I summarize the recent advances in the development of the chemical tools of ¹O₂. This article focuses on two topics. The first part introduces chemical methods for ground-state generation of ¹O₂. Designs of the molecular carriers of ¹O₂ are also explained. The second part discloses molecular probes of ¹O₂. The probes are categorized into three groups, depending on signaling modalities: absorption-based probes, photoluminescent probes, and chemiluminescent probes. Focus is on the molecular design to maximize the signaling actions. Disadvantages of using the probes are also discussed to motivate the future research. I hope that this review will serve as helpful guidance to the exploitation and development of the chemical tools of ¹O₂.