Supramolecular Radical Switches Regulated by Host-Guest Chemistry

Water-soluble thermal initiators are important radical sources to be applied in various fields.However,the uncontrolled radical generation from the high sensitivity of initiators may cause disadvantages in the applications.Here,we present a series of supramolecular radical switches regulated by the host-guest chemistry between initiators and cucurbit[8]uril(CB[8]).Thermal initiators(VA-044,VA-056,VA-057)can be spontaneously encapsulated into the cavity of CB[8]to“turn off”their radical-generation ability.Their activity will instantaneously“turn on”in the presence of other competitors such as 1-adamantylamine(ADA).Further,we demonstrated the free radical polymerization of N-isopropylacrylamide using initiators,inhibiting its activity by binding with CB[8]and initiating reaction by adding ADA.These novel supramolecular radical switches provide a facile strategy to control the generation of free radicals in a“plug-and-play”manner,which may arouse research interests in polymerization,catalysis,and the biomedical field.