Complexation of a pentiptycene-derived trans-bis(crown ether) host with different terminally functionalized paraquat derivatives in solution and the solid state: a switchable complexation process controlled by potassium ions.

The complexation behaviour of a pentiptycene-derived bis(crown ether), containing two 24-crown-8 moieties in a trans arrangement, and a series of paraquat derivatives with different terminal functional groups was investigated. It was found that all of the paraquat derivatives could form stable 2 : 1 complexes with the pentiptycene-derived host both in solution and the solid state, where multiple non-covalent interactions between the host and the guests played an important role. Moreover, the binding and release of the guests in the complexes could also be efficiently controlled by the removal and addition of potassium ions.