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.