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

Tian‐Yi Xu,Qi Zhang,Shang‐Wu Zhou,Chang‐Shun Ma,Zhao‐Tao Shi,Xiu‐Kang Zhang,Stefano Crespi,Ben L Feringa,He Tian,Shaoyu Chen,Da‐Hui Qu,Yue Liu

doi:10.1002/ange.202104285

Tian‐Yi Xu, Qi Zhang + Show 10 more

Open Access

https://doi.org/10.1002/ange.202104285

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Abstract

AbstractDesigning 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.

Highlights

Since the pioneering developments in supramolecular chemistry by Cram, Lehn, and Pedersen,[1] the design and synthesis of macrocycle-based host–guest systems have taken a prominent position at the frontiers of chemistry.[2]
We report the combination of molecular motors with crown-ether-based host–guest chemistry in a system that functions as photo-responsive host with switchable, multiple and reversible chiral guest recognition. (Figure 1) A series of motorized macrocycles was synthesized by intramolecular cyclization of first-generation molecular motors with oligoethylene glycol chains
Angewandte Chemie International Edition published by Wiley-VCH GmbH www.angewandte.org 16135

Summary

Introduction

Since the pioneering developments in supramolecular chemistry by Cram, Lehn, and Pedersen,[1] the design and synthesis of macrocycle-based host–guest systems have taken a prominent position at the frontiers of chemistry.[2]. Light-driven molecular motors[12] based on overcrowded alkenes have been developed as a unique family of photoresponsive units in the last decades Due to their intrinsic feature of performing unidirectional rotation, molecular motors have been explored as robust and versatile functional units to fabricate many photo-responsive materials, including liquid crystals,[13] soft actuators,[6b,14] gels,[15] foams,[16] membranes,[17] solid-state surfaces,[18] porous frameworks,[19] and nanocars.[20] The intrinsic axial chirality and photoswitching ability of molecular motors, resulting in multiple stable chiral states with precise control over the sequence of chiral isomer formation, are the key features of asymmetric catalysts and phosphate receptors with adaptive chirality.[21] These fascinating applications stimulated the introduction of molecular motors into macrocyclic host–guest systems, which might give access to an intriguing family of intrinsic motorized macro-. Combined with the ability of the motorized macrocycles to invert chirality by an external trigger (i.e. light or heat), this unique host–guest system controlled by molecular motors can be a starting point to design more complex mechanically interlocked molecules and functional molecular machines

Results and Discussion

Conclusion

Conflict of interest