Salt-dependent switching of crystal packing in cucurbituril–antidepressant crystals

Abstract

Across the CB[8]–imipramine and CB[6]–amitriptyline systems, addition of KI or ZnCl₂ as salt additives can change packing topology, crystal stoichiometry, and channel architecture, while preserving the underlying CB[n]–guest–CB[n] recognition motif. Structural and interaction-energy analyses show that robust local recognition is retained, whereas weaker secondary interactions drive the differences in crystal packing.