title: Chloride Selective Macrocyclic Bisurea Derivatives with 2,2'-Binaphthalene Moieties as Spacers.
abstract: A cyclic bisurea derivative 2a has been successfully prepared from the corresponding diamine and diisocyanate in the presence of tetrabutylammonium chloride as a template. A more soluble cyclic bisurea 2b has also been prepared by introduction of sterically bulky tert-butyl groups. X-ray crystal analyses of [2a·Cl]-and [2b·Cl]-revealed that overall structure was saddle like and the chloride anion was located in the center of the cavity. The bound chloride anion was hydrogen bonded by four N-H of urea groups and weakly hydrogen bonded by four 1-C-H of naphthyl groups, respectively. After removal of the bound chloride anions of [2b·Cl]-with silver nitrate, two different X-ray crystals of free 2b were obtained; one was intermolecular hydrogen bonded shrunken structure and the other was extended structure. Receptor 2b showed large binding ability for Cl-, however, the selectivity for Cl-against basic anions, such as AcO-and F-, has been insufficient. In aqueous MeCN, the association constant of 2b for Cl-was reduced but still large, and the selectivity for hydrophobic Cl-was greatly improved. In this solvent, 2b also selectively recognized alkaline metal chloride salts. Therefore, cyclic bisurea 2b is highly selective and effective Cl-selective receptor.
authors.affiliation: Department of Material and Biological Chemistry, Faculty of Science, Yamagata University , Yamagata-shi, Yamagata 990-8560, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Satake
authors.affiliation: Department of Material and Biological Chemistry, Faculty of Science, Yamagata University , Yamagata-shi, Yamagata 990-8560, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ishizawa
authors.affiliation: Graduate School of Science and Engineering, Yamagata University , 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katagiri
authors.affiliation: Department of Material and Biological Chemistry, Faculty of Science, Yamagata University , Yamagata-shi, Yamagata 990-8560, Japan.|Institute for Regional Innovation, Yamagata University , Kanakame, Kaminoyama, Yamagata 999-3101, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Kondo