Rotaxane-mediated suppression and activation of cucurbit[6]uril for molecular detection by 129Xe hyperCEST NMR

We report a method for blocking interactions between 129Xe and cucurbit[6]uril (CB6) until activation by a specific chemical event. We synthesized a CB6–rotaxane that allowed no 129Xe interaction with the CB6 macrocycle component until a cleavage event released the CB6, which then produced a 129Xe@CB6 NMR signal. This contrast-upon-activation 129Xe NMR platform allows for modular synthesis and can be expanded to applications in detection and disease imaging.