Controlling the Reactivity of the SeSe Bond by the Supramolecular Chemistry of Cucurbituril

We describe a new strategy to control the reactivity of Se?Se bond by using supramolecular chemistry of cucurbituril. We have demonstrated that selenocystamine (SeCy) and cucurbit6]uril (CB6]) can form a stable supramolecular complex (K_a=5.5×10⁶ M ^?1). Before complexation, the free Se?Se bond in SeCy is rather sensitive to redox stimuli and gets disrupted quickly with addition of reductant or oxidant. However, after binding with CB6], the Se?Se bond becomes quite inert and hardly reacts with reductant or oxidant. One advantage of this supramolecular protection is that it can be applied in a wide pH range from weakly acidic to basic. Additionally, the supramolecular complex formed by SeCy and CB6] can be reversibly dissociated simply with addition of Ba²⁺.