Chelated charge assisted halogen bonding enhanced halide recognition by a pyridinium-iodotriazolium axle containing [2]rotaxane.

Four halogen and hydrogen bonding rotaxane host systems featuring pyridinium bis-amide-iodotriazole/prototriazole and pyridinium bis-amide-iodotriazolium/prototriazolium axle components have been synthesized by CuAAC-mediated mono-stoppering chloride anion templation and post-rotaxanation methylation reactions. In competitive 45 : 45 : 10 CDCl-CDOD-DO aqueous solvent media, the dicationic halogen bonding rotaxane displayed a notable enhanced binding affinity and marked selectivity for Br over other halides and nitrate and dihydrogen phosphate oxoanions in contrast to an all hydrogen bonding counterpart which is attributed to chelated charge assisted halogen bonding interactions.