Interplay between a Foldamer Helix and a Macrocycle in a Foldarotaxane Architecture

The design and synthesis of a novel rotaxane/foldaxane hybrid architecture is reported. The winding of an aromatic oligoamide helix host around a dumbbell‐shaped thread‐like guest, or axle, already surrounded by a macrocycle was evidenced by NMR spectroscopy and X‐ray crystallography. The process proved to depend on the position of the macrocycle along the axle and the associated steric hindrance. The macrocycle thus behaves as a switchable shield that modulates the affinity of the helix for the axle. Reciprocally, the foldamer helix acts as a supramolecular auxiliary that compartmentalizes the axle. In some cases, the macrocycle is forced to move along the axle to allow the foldamer to reach its best recognition site. Novel foldarotaxanes have been synthesized that combine both the mechanically interlocked rotaxane architecture and the foldaxane supramolecular assembly. The localization of the encircling macrocycle influences the association between the helix and the axle, while the helix is able to displace the macrocycle elsewhere than its preferred site of interaction through the compartmentalization of the axle.