Affiliation: | 1. Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, 610064 China These authors contributed equally to this work.;2. Institute of Environmental Sciences, Shanxi University, China;3. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, China;4. Comprehensive Analysis Center, ISIR, Osaka University, Japan;5. Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, 610064 China Sino-British Materials Research Institute, College of Physical Sciences & Technology, Sichuan University, Chengdu, 610064 China;6. Department of Chemistry, Tokyo Institute of Technology, Japan;7. Department of Applied Chemistry, Osaka University, Japan;8. Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu, 610064 China |
Abstract: | The study of an enantiopure bicyclic pillar[5]arene-based molecular universal joint (MUJ) by single-crystal X-ray diffraction allowed for the first time the unequivocal assignment of the absolute configuration of a planar chiral pillar[5]arene by circular dichroism spectroscopy. Crucially, the absolute configuration of the MUJ was switched reversibly by temperature, with an accompanying sign inversion of the anisotropy factor that varied by as much as 0.03, which is the largest value ever reported. Mechanistically, the reversible chirality switching of the MUJ is driven by the threading/dethreading motion of the fused ring and hence is dependent on both the size and nature of the ring and the solvent employed, reflecting the critical balance between the self-complexation of the ring by pillar[5]arene, the solvation to the excluded ring, and the inclusion of solvent molecules in the cavity. |