Search results for "pseudostoppers"

Dual-stimuli pseudorotaxane switches under kinetic control

2021

A series of dumbbell-shaped sec-ammonium salts with bulky (pseudo)stoppers (‘speed bumps’) were tested for their ability to form pseudorotaxanes with a redox-switchable, tetrathiafulvalene (TTF)-decorated [24]crown-8 ether. Depending on the size of the pseudostoppers, fast (less than ten minutes), slow (hours to days) and very slow (no pseudorotaxanes observed) threading has been observed. NMR spectroscopy as well as tandem mass spectrometry indicate the formation of non-threaded face-to-face complexes prior to pseudorotaxanes formation. Both isomers can be distinguished by their substantially different stability in collision-induced dissociation (CID) experiments. Two external stimuli affe…