In this study, we synthesized dibenzo [22–30] crown ethers and dumbbell-like secondary ammonium salts having stoppers of varying bulk. These crown ethers formed pseudorotaxanes with the ammonium ions in solution and in the gas phase, as evidenced using NMR spectroscopy and MS/MS spectrometry, respectively. The association constants in solution were obtained through regulation of the association and dissociation rates by ...
[Gibson, Harry W.; Jones, Jason W.; Zakharov, Lev N.; Rheingold, Arnold L.; Slebodnick, Carla Chemistry - A European Journal, 2011 , vol. 17, # 11 p. 3192 - 3206]