A mutually stabilized host-guest pair

By using click chemistry, a hexacationic cage was synthesized. The cage contains two triscationic pi-electron-deficient trispyridiniumtriazine (TPZ(3+)) platforms that are bridged in a face-to-face manner by three ethylene-triazole-ethylene linkers. A diversity of pi-electron-rich guests can be recognized within the pocket of the cage, driven by host-guest pi-pi interactions. The cage cavity acts as a protecting group, preventing an anthracene guest from undergoing Diels-Alder reaction. Under ultraviolet (UV) light, the pyridinium C-N bonds in TPZ(3+) platforms are polarized and weakened, resulting in the occurrence of cage decomposition via beta-elimination. Guest recognition could help to prevent this UV-stimulated cage decomposition by suppressing the excitation of the TPZ(3+) units.