Anion recognition by halogen bonding and hydrogen bonding bis(triazole)-imidazolium [2]rotaxanes.

A novel halogen bonding (XB) bis(iodotriazole)-imidazolium motif is incorporated into the axle component of a [2]rotaxane via a discrete chloride anion template directed clipping methodology. 1H NMR anion titration experiments reveal the interlocked host is capable of strong halide and sulfate oxoanion binding in competitive aqueous-organic CDCl3/CD3OD/D2O (45 : 45 : 10 v/v) solvent mixtures. In comparison to a hydrogen bonding rotaxane analogue, which exhibited no pronounced selectivity between Cl-, I- and SO42-, the axle iodo-triazole donor motifs of the XB rotaxane modulate the anion recognition preference towards the lighter halides Cl- ≈ Br- > SO42- > I-.