Neutral redox-active hydrogen- and halogen-bonding rotaxanes for the electrochemical sensing of chloride†
The first examples of redox-active ferrocene-functionalised neutral rotaxanes have been synthesised via chloride anion templation. 1H NMR spectroscopic titrations reveal that these rotaxane host systems recognize chloride selectively over other halides and oxoanions in highly-competitive aqueous media. By replacing the hydrogen bonding prototriazole units of the rotaxane axle component with iodotriazole halogen bond-donor groups, the degree of chloride selectivity of the rotaxanes is modulated. Electrochemical voltammetric experiments demonstrate that the rotaxanes can sense chloride via cathodic perturbations of the respective rotaxanes' ferrocene–ferrocenium redox-couple upon anion addition.