title: Cyclodextrin-based size-complementary [3]rotaxanes: selective synthesis and specific dissociation.
abstract: α-Cyclodextrin (CD)-based size-complementary [3]rotaxanes with alkylene axles were prepared in one-pot by end-capping reactions with aryl isocyanates in water. The selective formation of [3]rotaxane with a head-to-head regularity was indicated by the X-ray structural analyses. Thermal degradation of the [3]rotaxanes bearing appropriate end groups proceeded by stepwise dissociation to yield not only the original components but also [2]rotaxanes. From the kinetic profiles of the deslippage, it turned out that the maximum yield of [2]rotaxane was estimated to be 94 %. Thermodynamic studies and NOESY analyses of such rotaxanes revealed that [2]rotaxanes are specially stabilized, and that the dissociation capability of the [3]rotaxanes to the components can be adjusted by controlling the structure of the end groups, direction of the CD groups, and length of the alkylene axle.
authors.affiliation: Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan), Fax: (+81) 3-5734-2888.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Akae
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Koyama
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kuwata
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Takata
keywords: cyclodextrin; rotaxane; size-complementary groups; supramolecular chemistry; thermodynamics