Electrochemical Bromide Sensing with a Halogen Bonding [2]Rotaxane

The selective electrochemical sensing of heavy halides, such as bromide, over more charge-dense counterparts, like chloride, using mechanically-interlocked structures remains a formidable challenge. Using the active-metal templation methodology, the first redox-active ferrocene-appended rotaxane containing an all-halogen bonding anion binding cavity was synthesised. H-1 NMR binding studies in aqueous-organic solvent media demonstrated a marked recognition bias for heavy halides, facilitating the selective redox sensing of bromide over chloride to be demonstrated for the very first time with an interlocked host molecule.