Tuning colourimetric indicator displacement assays for naked-eye sensing of pyrophosphate in aqueous media

A library of anion receptors comprising cyclic peptide scaffolds bearing two (ZnII-DPA) anion binding sites have been synthesised and their anion binding abilities evaluated using colourimetric indicator displacement assays with three different indicators. The resulting chemosensing ensembles provided excellent discrimination between polyphosphate ions, with several of the receptor:indicator combinations providing naked-eye sensing of pyrophosphate ions in aqueous solutions containing more than 100 fold excess of ATP.