Oxazolidine Transient Bases as Molecular Platforms for Testing Dynamic CO₂ Capture in Biochemical Systems

Understanding the dynamic processes of CO₂ capture in biosystems is important because of the great effect CO₂ has on the carbon cycle, human health, the global climate, and living environments. After years of multidisciplinary studies, researchers have gained only basic mechanistic knowledge about how enzymes or protein-aggregates capture and deliver CO₂, a process involving reversible bonding of CO₂ with basic amino acid residues. However, vital mechanistic details of how the activated basic residues within these enzymes or protein-aggregates are initially formed, a crucial step for CO₂ capture, are still lacking. Herein, we designed specific molecules, i.e., oxazolidines, which are able to reversibly change their alkalinity via ultrafast isomerizations. Serving as so-called transient bases, these oxazolidines mimic the activated/deactivated states of enzymes or protein-aggregates responsible for dynamic CO₂ capture/release. A detailed mechanism for CO₂ capture, which involves dynamic covalent bonding and multimolecular cooperative interactions among functional groups that occur with the help of a polyhydroxyl environment, is demonstrated by UV-vis and multiple NMR spectroscopies as well as theoretical calculations. Using suitable oxazolidine transient bases, applications for visual CO₂ detection under different detection limit requirements were also developed. Insights for further understanding the process of dynamic CO₂ capture in biosystems are also discussed. This oxazolidine-inspired biomimetic CO₂ capture serves as a platform for the future development of additional biomimicking systems, as well as offers unique perspectives for other complicated life processes.