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Manipulating excited-state dynamics through macrocycle positioning in a rotaxane for sensitive and discriminative
Yu Wang1, Yalei Ma1, Ruijuan Wen1
1Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Provincial Key Laboratory of New Concept Sensors and Molecular Materials, School of Chemistry and Chemical Engineering, Shaanxi Normal University Xi'an 710119 P. R. China miaorong2015@snnu.edu.cn.
None:
Precise control of excited-state dynamics is essential for advancing molecular materials. Herein, we present a supramolecular strategy utilizing mechanical interlocking to regulate photophysical pathways and molecular recognition. Three rotaxanes were synthesized by positioning a dibenzo-24-crown-8 macrocycle at specific sites along a naphthalimide-based axle. Femtosecond transient absorption spectroscopy revealed that the relaxation of the excited-state is critically governed by the spatial separation: the closer the macrocycle to the fluorophore, the slower the twisted intramolecular charge transfer process. Single-crystals of the rotaxane showed a lamellar architecture, where the macrocycle acts as a pre-organized gatekeeper for the fluorophore. Therefore, highly sensitive and selective detection of methanol vapor is realized based on the rotaxane film. In addition, a portable sensor for reliable (limit of detection: 0.099% vol.), rapid (<3 s), and reusable methanol detection in adulterated beverages is achieved. Our work establishes mechanical interlocking as a versatile approach to excited-state manipulating and sensor design.
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