A supramolecular switch based on three binding states of a pyrene derivate: a reversible three-state switch with only two stimuli

Abstract

A fluorescent molecule, N-methyl-pyrenemethylammonium (MPA⁺), can be encapsulated inside cucurbit[8]uril's (CB[8]) cavity to form a binary host–guest complex. And the binary complex can further binds methyl viologen (MV²⁺), yielding a ternary complex. With only two chemical stimuli, cucurbit[7]uril (CB[7]) and amantadine hydrochloride (AD), the three binding states of MPA⁺, unbound MPA⁺, the binary complex and the ternary complex, can transform reversibly and exert three different fluorescence outputs.