title: Five-State Molecular Shuttling of a Pair of [2]Rotaxanes: Distinct Outputs in Response to Acid and Base Stimuli.
abstract: In this study we synthesized two acid-/base-controllable [2]rotaxanes featuring aminodiazobenzene and aminocoumarin units, respectively, as chromophores and dibenzo[24]crown-8 and dibenzo[25]crown-8 units, respectively, as their macrocyclic components. Each [2]rotaxane contained N-alkylarylamine (ammonium) and N,N-dialkylamine (ammonium) centers as binding sites for their crown ether components. The absorption patterns of the chromophores were dependent on the position of the encircling macrocyclic component and the degree of protonation, with three distinct states (under acidic, neutral, and basic conditions) evident for each [2]rotaxane. The mixed [2]rotaxane system displayed stepwise and independent molecular shuttling behavior based on the degree of protonation of the amino groups in response to both the amount and strength of added acids or bases; as such, the system provided five different absorption signals as outputs that could be read using UV/Vis spectroscopy.
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ueda
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Shoya
authors.initials: S
authors.lastname: Terazawa
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Deguchi
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kimura
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Matsubara
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Miyagawa
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan.
authors.forename: Tsuneomi
authors.initials: T
authors.lastname: Kawasaki
authors.affiliation: University of Fukui, Department of Materials Science and Engineering, Bunkyo, Fukui, 910-8507, Japan. tokunaga@matse.u-fukui.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tokunaga
keywords: acid and base stimuli; crown ether; hydrogen bonds; rotaxanes