Naked-eye detection of Fe3+ and Ru3+ in water: Colorimetric and ratiometric sensor based on per-6-amino-β-cyclodextrin/p-nitrophenol

Using per-6-amino-β-cyclodextrin as a supramolecular host and p-nitrophenol as a spectroscopic probe, a novel, colorimetric and ratiometric sensor is developed for transition metal cations Fe3+ and Ru3+ in water. Binding of these cations causes an appreciable color change from intense yellow to colorless. This naked-eye sensing of Fe3+ and Ru3+ is rationalized on the basis of electronegativity and HSAB theory.