Signal-dependent reactivity of host-guest complexes controls supramolecular aggregate formation

Living systems can respond to their environment through signal transduction cascades. In these cascades, original stimuli are amplified and translated into reaction or assembly events. In an effort to instill synthetic materials with biomimetic responsivity, we report an aggregation process forming a supramolecular network held together by host-guest interactions that is responsive to nucleophilic chemical signals through a chemical reaction-assembly cascade. In particular, we developed a signal-induced switch between cucurbit[8]uril binary and ternary complexes with cationic bipyridine derivatives where the charge on the bipyridine can be changed through an allylic substitution reaction with the nucleophilic signal. When applied to a multitopic bipyridine guest, the reaction with the nucleophile signals leads to supramolecular network formation where the aggregation rates and final structure depend on the nucleophilicity of the signal. This work opens the door to new opportunities for signal-responsive synthetic materials and interactions with biological systems.