Mutual Induced Fit in a Synthetic Host–Guest System

Mutual induced fit is an important phenomenon in biological molecular recognition, but it is still rare in artificial systems. Here we report an artificial host–guest system in which a flexible calix[4]­arene is enclathrated in a dynamic self-assembled host and both molecules mutually adopt specific three-dimensional structures. NMR data revealed the conformational changes, and crystallographic studies clearly established the precise structures at each stage.