Contrasting anion recognition behaviour exhibited by halogen and hydrogen bonding rotaxane hosts

摘要

A rotaxane host system containing a novel halogen bonding (XB) 5-iodo-1,2,3-triazole functionalised pyri-dinium motif, within its axle component, has been prepared via a ring closing metathesis reaction, using chloride as a template. Proton NMR titration experiments, in competitive 1:1 CDCl_3-CD_3OD solvent media, showed the XB rotaxane selectively bound halides over larger, more basic oxoanions. An all hydrogen bonding proto-triazote containing rotaxane analogue was also prepared, which in stark contrast demonstrated a reversal in the anion selectivity trend, with a preference for dihydrogen phosphate over the halides which is unprecedented for an interlocked host system.