Cage-like tris(salen)-type metallocryptand for cooperative guest recognition

A new cryptand-like tris(salen)-type ligand, H6L, was synthesized. Metalation of this ligand with zinc(II) acetate gave a trinuclear metallohost [LZn3] with a cage-like cavity surrounded by three metallosalen moieties. The metallohost [LZn3] showed unique binding behavior to MOAc (M = Na, K, Rb, Cs) as an ion pair due to the cage-like cavity for cationic guests as well as the zinc(II) centers for anionic guests.