Internal Dynamics and Modular Peripheral Binding in Stimuli-Responsive 3: 2 Host:Guest Complexes

Now that the chemistry of 1 : 1 host:guest complexes is well-established, it is surprising to note that higher stoichiometry (oligomeric) complexes, especially those with excess host, remain largely unexplored. Yet, proteins tend to oligomerize, affording new functions for cell machinery. Here, we show that cucurbit[n]uril (CB[n]) macrocycles combined with symmetric, linear di-viologens form unusual 3 : 2 host:guest complexes exhibiting remarkable dynamic properties, host self-sorting, and external ring-translocation. These results highlight the structural tunability of cucurbit[8]uril (CB[8]) based 3 : 2 host:guest complexes in water and their responsiveness toward several stimuli (chemicals, pH, redox). A family of versatile 3 : 2 host/guest complexes has been prepared by combining cucurbit[n]urils with symmetric, linear diviologens. These assemblies have properties typical of 1 : 1 complexes, but also show a new type of supramolecular translational-rotational coupling, peripheral complexation amenable to proximal or distal binding, and controllable peripheral ring translocation.image