Supramolecular amphiphilies based on water-soluble pillar[5]arene/paraquat derivatives and their self-assembly behaviour in water

Supramolecular amphiphilies based on water-soluble pillar[5]arene/paraquat derivatives were successfully prepared. We found that when the length of the alkyl chain on guest molecules shorter than C₁₂, it formed micelles, on the other hand, when the alkyl chain longer than C₁₂, vesicles were obtained. Furthermore, we have demonstrated that the resulting vesicles can respond to multiple external stimuli, including temperature, host–guest inclusion and pH. Methods of warming, decreasing the pH of the system and inclusion of α-cyclodextrins were then employed to disrupt the vesicle architecture. Finally, controlled release experiments were performed to evaluate the vesicles which could encapsulate calcein within their interiors under neutral conditions and release it in response to a decrease in pH.