Four-State Molecular Shuttling of [2]Rotaxanes in Response to Acid/Base and Alkali-Metal Cation Stimuli

作者：Kimura Masaki; Mizuno Takuma; Ueda Masahiro; Miyagawa Shinobu; Kawasaki Tsuneomi; Tokunaga Yuji

来源：Chemistry-An Asian Journal, 2017, 12(12): 1381-1390.

DOI：10.1002/asia.201700493

• alkali metals
• macrocycles
• molecular recognition
• molecular shuttles
• rotaxanes

In this study, we synthesized [2]rotaxanes possessing three recognition sitesa dialkylammonium, an alkylarylamine, and a tetra(ethylene glycol) stationsin their dumbbell-like axle component and dibenzo[24]crown-8 (DB24C8) as their macrocyclic component. These [2]rotaxanes behaved as four-state molecular shuttles: i)under acidic conditions, the DB24C8 unit encircled both the dialkylammonium and alkylarylammonium stations; ii)under neutral conditions, the dialkylammonium unit was the predominant station for the DB24C8 component; iii)under basic conditions, when both ammonium centers were deprotonated, the alkylarylamine unit became a suitable station for the DB24C8 component; and iv)under basic conditions in the presence of an alkali-metal cation, the tetra(ethylene glycol) unit recognized the DB24C8 component through cooperative binding of the alkali-metal ion. In addition, we observed that the [2]rotaxanes exhibited selective recognition for metal cations. These shuttling motions of the macrocyclic component proceeded reversibly.

• 出版日期2017-6-19