Cation recognition by cationic receptors is typically challenging due to coulombic repulsion.In this study,we designed a hexacationic receptor,namely,3NDI^(6+).This tricycle naturally adopts a sandwichlike conformatio...Cation recognition by cationic receptors is typically challenging due to coulombic repulsion.In this study,we designed a hexacationic receptor,namely,3NDI^(6+).This tricycle naturally adopts a sandwichlike conformation as its hexafluorophosphate salt([3NDI^(6+)@2PF6^(−)]·4PF6^(−))but then recognizes two chloride anions upon treatment with a chloride anion source.The recognition of the first chloride anion(as an allosteric modulator)facilitates conformational regulation fromthe sandwich-like conformation with a collapsed cavity to a preorganized capsule-like conformation.After conformational switching,the second chloride anion is further recognized to form the inclusion complex[3NDI^(6+)⊃2Cl^(−)]^(4+).The chloridecontaining hexacationic capsule([3NDI^(6+)⊃2Cl^(−)]^(^(4+)))was found to recognize various cations(e.g.,K+from KCl),as supported by the crystal structure of the potassium complex,which revealed a single anionic[KCl_(2)]–entity within the capsule.Prior to conversion to the chloride anion-bound capsule-like form,no evidence of cation recognition is seen by[3NDI^(6+)@2PF_(6)^(−)]·4PF6^(−).The ability to accommodate a cation within the cationic framework of 3NDI^(^(6+))(as[3NDI^(^(6+))⊃2Cl^(−)]·4Cl^(−))is ascribed to specific anion(as Cl^(−))recognition and formation of a capsule-like species,rather than simple charge balance effects.This study presents a new strategy for cation recognition by a cationic capsule that underscores the promise of allosteric control over small-molecule receptor systems.展开更多
基金the National Key Research and Development Program of China(grant no.2021YFA0910100)the National Natural Science Foundation of China(grant nos.22035006,22320102001,and 22350007)+3 种基金the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study(grant no.SN-ZJU-SIAS-006)the“pioneer”and“Leading Goose”R&D Program of Zhejiang(grant no.2025C04010)the Leading Innovation Team grant from the Department of Science and Technology of Zhejiang Province(grant no.2022R01005)for financial support.F.Hthanks the Chemistry Instrumentation Center of Zhejiang University for technical support.We are grateful for the access to the research facilities in Chemistry Department of the University of Hong Kong(HKU).Thework in Austinwas supported by the Robert A.Welch Foundation(F-0018 to J.L.S.).We thank HKU for their continued support of this research.
文摘Cation recognition by cationic receptors is typically challenging due to coulombic repulsion.In this study,we designed a hexacationic receptor,namely,3NDI^(6+).This tricycle naturally adopts a sandwichlike conformation as its hexafluorophosphate salt([3NDI^(6+)@2PF6^(−)]·4PF6^(−))but then recognizes two chloride anions upon treatment with a chloride anion source.The recognition of the first chloride anion(as an allosteric modulator)facilitates conformational regulation fromthe sandwich-like conformation with a collapsed cavity to a preorganized capsule-like conformation.After conformational switching,the second chloride anion is further recognized to form the inclusion complex[3NDI^(6+)⊃2Cl^(−)]^(4+).The chloridecontaining hexacationic capsule([3NDI^(6+)⊃2Cl^(−)]^(^(4+)))was found to recognize various cations(e.g.,K+from KCl),as supported by the crystal structure of the potassium complex,which revealed a single anionic[KCl_(2)]–entity within the capsule.Prior to conversion to the chloride anion-bound capsule-like form,no evidence of cation recognition is seen by[3NDI^(6+)@2PF_(6)^(−)]·4PF6^(−).The ability to accommodate a cation within the cationic framework of 3NDI^(^(6+))(as[3NDI^(^(6+))⊃2Cl^(−)]·4Cl^(−))is ascribed to specific anion(as Cl^(−))recognition and formation of a capsule-like species,rather than simple charge balance effects.This study presents a new strategy for cation recognition by a cationic capsule that underscores the promise of allosteric control over small-molecule receptor systems.
