Ionic pseudopolyrotaxanes bearing a chromophore in the side chain – A spectroscopic study in water

The formation of pseudopolyrotaxanes based on a polyelectrolyte, a surfactant and α-cyclodextrin (α-CD) in aqueous solution is investigated. The polyelectrolyte and the surfactant form an ionic complex the side chains of which interact with each other. These interactions are strongly influenced by the formation of inclusion complexes with α-CD. It is shown by 1H NMR and UV–vis spectroscopy that threading of the α-CD rings onto the side chains causes a shielding effect which increases the mobility of the side chains. The structure of the pseudopolyrotaxanes is concluded from ROESY spectra and their stoichiometry is determined by Job plots based on shift effects observed in the 1H NMR spectra.