Polyaminocyclodextrin nanosponges: synthesis, characterization and pH-responsive sequestration abilities

New pH-responsive nanosponges were obtained by reacting four different polyaminocyclodextrins with heptakis-(6-bromo)-(6-deoxy)-beta-cyclodextrin. The materials obtained were characterized by various techniques (FT-IR, potentiometric titration, differential scanning calorimetry (DSC), porosimetry (BET), C-13 {H-1} CP-MAS NMR). Their adsorption abilities at different pH values were verified towards a suitable set of model guests, and seem mainly controlled by electrostatic interactions, as a function of the protonation/charge status of the polymer matrix. By contrast, data positively point out a lesser importance assumed by the induced-fit effect, important in affecting the formation of host-guest complexes in solution. The frequency-switched Lee-Goldburg (FSLG) heteronuclear correlation solid-state NMR technique was exploited in order to assess the possible location of the guests within the polymer matrix.