Water-Soluble Pillar[7]arene: Synthesis, pH-Controlled Complexation with Paraquat, and Application in Constructing Supramolecular Vesicles

By the introduction of 14 anionic carboxylate groups at its two rims, a water-soluble pillar[7]arene (WP7) was synthesized. Its pH-controlled complexation with paraquat G, in water was investigated. Host WP7 and guest G, formed a 1:1 [2]pseudorotaxane with a high association constant of(2.96 +/- 0.31) x 10(9) M-1 in water. Furthermore, we took advantage of this novel molecular recognition motif to fabricate a supra-amphiphile based on WP7 and an amphiphilic paraquat derivative G(2). The morphologies and sizes of self-assemblies of G(2) and WP7DG(2) were identified by transmission electron microscopy and dynamic light scattering.