pH-Responsive polypseudorotaxane synthesized through cucurbit[6]uril catalyzed 1,3-dipolar cycloaddition

Abstract

A pH-responsive polypseudorotaxane has been synthesized via cucurbit[6]uril (CB6)-catalyzed 1,3-dipolar cycloaddition using diazide and dialkyne monomers, which contain a long aliphatic-spacer. The polypseudorotaxane was characterized by spectroscopic techniques (¹H, ¹³C NMR and FT-IR) and matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS). The experimental results reveal that this polypseudorotaxane behaves as a pH-driven polymeric switch. Thus, when amine groups are protonated at an appropriate pH, CB6s are located on the triazole rings due to ion–dipole interaction, whereas at high pH they move onto the hydrophobic aliphatic spacer rather than slipping off the polypseudorotaxane.