Electronic Substituent Effects of Guests on the Conformational Network and Binding Behavior of Oxatub[4]arene.

A series of quaternary ammonium guests have been synthesized, and their binding behavior with oxatub[4]arene have been studied. In particular, remote electronic substituents of the guests can significantly affect the binding affinities mainly through a field/inductive effect by following a linear free energy relationship. More surprisingly, oxatub[4]arene, with a complex conformational network, shows a large amplitude of conformational change in response to the remote electronic substituents on the guests. This novel mode of synthetic molecular recognition may also have biological relevance.