title: Stepwise Motion in a Multivalent [2](3)Catenane.
abstract: The motions of biomolecular machines are usually multistep processes, and are involved in a series of conformational changes. In this paper, a novel triply interlocked [2](3)catenane composed of a tris(crown ether) host eTC and a circular ditopic guest with three dibenzyl ammonium (DBA) sites and three N-methyltriazolium (MTA) sites was reported. Due to the multivalency nature of the catenane, the acid-base triggered motion was performed by a stepwise manner. The coconformations of the four related stable states have been directly identified and quantified which confirmed the multistep process. In order to quantify the dynamics with environmental acidity changes, the values of the three levels of dissociation constant pKa have been determined. The special interlocked topology of the [2](3)catenane also endows the motion of each crown ether ring in the host with unexpected selectivity for the MTA sites. This study provides clues to comprehend the underlying motion mechanism of intricate biological molecular machines, and further design artificial molecular machine with excellent mechanochemistry properties.
authors.affiliation: †Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.|§University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Meng
authors.affiliation: †Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Han
authors.affiliation: ‡Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Wang
authors.affiliation: ‡Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Xiang
authors.affiliation: ‡Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Sheng-Gui
authors.initials: SG
authors.lastname: He
authors.affiliation: †Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Chuan-Feng
authors.initials: CF
authors.lastname: Chen
mesh_terms: D000873:Anthracenes / Q000737:chemistry*; D043844:Crown Ethers / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D014230:Triazoles / Q000737:chemistry
chemical_list: D000873:Anthracenes; D043844:Crown Ethers; D000644:Quaternary Ammonium Compounds; D014230:Triazoles; C467767:catenane