title: Tetranitro-oxacalix[4]crown-Based Host-Guest Recognition Motif and a Related [2]Rotaxane-Based Molecular Switch.
abstract: Different from so far reported oxacalix[4]crown-based host-guest motifs in which oxacalix[4]crowns act only as hydrogen bond acceptors, a [2]pseudorotaxane-type tetranitro-oxacalix[4]crown/urea host-guest recognition motif was developed in which tetranitro-oxacalix[4]crown played a role as both a hydrogen bond donor and an acceptor to stabilize the resulting supramolecular complex. Furthermore, on the basis of a [2]pseudorotaxane complex formed from a tetranitro-oxacalix[4]crown and an axle containing a secondary ammonium ion and a urea group, a [2]rotaxane-based molecular switch was created, in which the oxacalix[4]crown wheel was able to reversibly translocate between the secondary ammonium binding site and the urea binding site of the axle under acid-base stimulation.
authors.affiliation: Shanghai Advanced Research Institute, Chinese Academy of Science , Shanghai 201210, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Liu
authors.affiliation: Shanghai Advanced Research Institute, Chinese Academy of Science , Shanghai 201210, China.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Hu
authors.affiliation: Medicinal Chemistry, ChemBridge Research Laboratories , San Diego, California 92127, United States.
authors.forename: Yahu A
authors.initials: YA
authors.lastname: Liu
authors.affiliation: Shanghai Advanced Research Institute, Chinese Academy of Science , Shanghai 201210, China.
authors.forename: Jiu-Sheng
authors.initials: JS
authors.lastname: Li
authors.affiliation: Shanghai Advanced Research Institute, Chinese Academy of Science , Shanghai 201210, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Shanghai Advanced Research Institute, Chinese Academy of Science , Shanghai 201210, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Wen