Unique binding behaviour of water-soluble polycationic oxacalix[4]arene tweezers towards the paraquat dication

Abstract

The first water-soluble polycationic oxacalix[4]arene molecular tweezers able to recognize - under pH control - the paraquat dication as a result of a delicate balance between electrostatic repulsion, Coulombic shielding and attractive π-stacking interactions are reported.