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A new cryptand/paraquat [2]pseudorotaxane and its crown ether analog were synthesized and characterized by proton NMR, mass spectrometry, and single crystal X-ray analysis. The Job plots based on proton NMR data demonstrated that both the complex between cryptand 1 and paraquat derivative 2a and the complex between bis(p-phenylene)-34-crown-10 (3) and paraquat derivative 2b have 1:1 stoichiometry in solution. The apparent association constants (Ka,exp) of 1·2a and 3·2b calculated for 1:1 complexes were 1.4 (±0.2) × 104 and 4.7 (± 0.5) × 102 M-1, respectively. X-ray analysis showed that 1·2a is stabilized by ten hydrogen bonds and face-to-face π-stacking interactions in the solid state, while 3·2b is stabilized by four hydrogen bonds and face-to-face π-stacking interactions. As well as in the X-ray structure of 1·2c, a water molecule acts as a hydrogen bridge between the β-pyridinium protons of 2a and the ether oxygen atoms of 1 in 1·2a. The successful preparation of 1·2a demonstrated that the tert-butyl group is not big enough to be a stopper for rotaxanes based on 1.
A new cryptand / paraquat [2] pseudorotaxane and its crown ether analog were synthesized and characterized by proton NMR, mass spectrometry, and single crystal X-ray analysis. The Job plots based on proton NMR data for that both the complex between cryptand 1 and paraquat derivative 2a and the complex between bis (p-phenylene) -34-crown-10 (3) and paraquat derivative 2b have 1: 1 stoichiometry in solution. 2b calculated for 1: 1 complexes were 1.4 (± 0.2) × 104 and 4.7 (± 0.5) × 102 M-1, respectively. X-ray analysis showed that 1 · 2a is stabilized by ten hydrogen bonds and face-to-face π-stacking interactions in the solid state, while 3 · 2 2 is stabilized by four hydrogen bonds and face-to-face π-stacking interactions. As a result of the X-ray structure of 1 · 2c, a water molecule acts as a hydrogen bridge between the β-pyridinium protons of 2a and the ether oxygen atoms of 1 in 1 · 2a. The successful preparation of 1 · 2a demonstrated that the tert-butyl group is not big enough to be a stopper for rotaxanes based on 1.