Switching between Non-isoenergetic Dynamic Covalent Re-actions using Host-guest Chemistry

CO2 reacts with simple amines in presence of water to generate dynamic combinatorial libraries of majority (i.e., am-monium carbamates) and minority (i.e., ammonium carbonates) non-isoenergetic covalent adducts. Over the past decade, our laboratory has reported a new class of cavitands, namely dyn[n]arenes, from which a polyanionic macro-cycle is an highly efficient receptor for linear poly-ammoniums to form [2]pseudorotaxanes in water at neutral pH. Herein, we demonstrate that this formation of [2]pseudorotaxanes shifts the equilibrium of CO2 capture by polyam-ines in water towards the quasi-exclusive formation of carbonate adducts, providing the first example of a switch between two competitive and reversible covalent processes triggered by host-guest interactions. In addition, this su-pramolecular approach to CO2 capture exhibits enhanced capture efficiency by increasing the state of protonation of complexed vs. uncomplexed polyamines. Altogether, we report here that a templating approach can divert the out-come of two reversible covalent chemistries involving nucleophilic additions and acid-base reactions, challenging therefore the common knowledge that non-covalent interactions are weaker bonds than covalent ones.