Complexation between Pentiptycene Derived Bis(crown ether)s and CBPQT<sup>4+</sup> Salt: Ion-Controlled Switchable Processes and Changeable Role of the CBPQT<sup>4+</sup> in Host−Guest Systems
mono(crownether)s. For the pentiptycene derived bis(crownether) with two 24-crown-8 moieties in the trans position, it formed a 1:2 stable complex with the CBPQT4+ salt in solution and in the solid state, in which the pentiptycene moiety played an important role in stabilizing the complex. Moreover, binding and release of the CBPQT4+ ring in the complexes based on the pentiptycene-derived crown ethers