Pyrophosphate Detection in Water by Fluorescence Competition Assays: Inducing Selectivity through the Choice of the Indicator.

Displacement of the previously bound, and quenched, fluorescent indicator (I) by coordination of the pyrophosphate ion to the two CuII centers of the receptor R results in the generation of the natural fluorescence of the indicator, and thus signals pyrophosphate recognition (see scheme). Discrimination from interfering anions (HPO42−, SO42−, NO3−, Cl−, NCO−, N3−, acetate, benzoate) can be achieved by tuning the indicator affinity towards the receptor.