Guest-Controlled Formation of a Hydrogen-Bonded Molecular Capsule

The dimerization of the self-complementary resorcarene tetraesters is triggered by the entrapment of a tropylium cation in the π-basic cavity. Eight intermolecular OH⋅⋅⋅OC hydrogen bonds together with host–guest interactions such as charge transfer and C−H⋅⋅⋅π bonding are responsible for the high stability of this assembly (see picture). Hereby neither the host–guest interaction nor the interaction of two resorcarene molecules through hydrogen bonds is sufficient by itself to form the complex.