A Multistate Molecular Switch Based on the 6,8-Rearrangement in Bromo-apigeninidin Operated with pH and Host- Guest Inputs

The equilibrium between 6- and 8-bromo-apigeninidin is quantitatively displaced toward the formation of the former in the presence of cucurbit[7]uril because of the selective recognition of the 6-bromo isomer by the host. This phenomenon permits us to conceive a unidirectional multistate switch addressed with host guest inputs and enables the reversible activation and deactivation of the 6-/8-bromo-apigeninidin dynamic molecular multistate through coupled host-guest and pH inputs.