Self-Assembly of Macrocyclic Hosts with Kinetic Inertness

A dynamic covalent reaction, namely, oxime condensation, was employed here to synthesize macrocycles, using strong acid to catalyze oxime exchange. When formyl precursors with lower water solubility were used, condensation reaction proceeded in a heterogeneous manner. In this case, slow addition of the acid catalyst was crucial to avoid rapid polymerization. These hosts become kinetically inert upon acid removal, which turns OFF the dynamic nature of the oxime bond. Moreover, the macrocycles with relatively larger π-electron hydrophobic building blocks are able to accommodate guests via hydrophobic effect.