Formation of 1:2 Host–Guest Complexes Based on Triptycene-Derived Macrotricycle and Paraquat Derivatives: Anion−π Interactions between PF<sub>6</sub><sup>–</sup> and Bipyridinium Rings in the Solid State

A triptycene-derived macrotricyclic host containing two dibenzo-[30]-crown-10 moieties forms stable 1:2 host–guest complexes with paraquat derivatives in both solution and the solid state, in which anion−π interactions between PF<sub>6</sub><sup>–</sup> and the bipyridinium rings play an important role. Moreover, it was found that binding and release of the guest molecules in the complexes could be easily controlled by the addition and removal of potassium ions.