Motorized Macrocycle: A Photo‐responsive Host with Switchable and Stereoselective Guest Recognition

Designing photo‐responsive host–guest systems can provide versatile supramolecular tools for constructing smart systems and materials. We designed photo‐responsive macrocyclic hosts, modulated by light‐driven molecular rotary motors enabling switchable chiral guest recognition. The intramolecular cyclization of the two arms of a first‐generation molecular motor with flexible oligoethylene glycol chains of different lengths resulted in crown‐ether‐like macrocycles with intrinsic motor function. The octaethylene glycol linkage enables the successful unidirectional rotation of molecular motors, simultaneously allowing the 1:1 host–guest interaction with ammonium salt guests. The binding affinity and stereoselectivity of the motorized macrocycle can be reversibly modulated, owing to the multi‐state light‐driven switching of geometry and helicity of the molecular motors. This approach provides an attractive strategy to construct stimuli‐responsive host–guest systems and dynamic materials.