An inorganic phosphate (Pi) sensor triggers ‘turn-on’ fluorescence response by removal of a Cu2+ ion from a Cu2+-ligand sensor: determination of Pi in biological samples

A fluorescent ligand that displays a high selectivity for Cu2+ has been synthesized. On complexation with Cu2+, the fluorescence of the ligand is quenched. Inorganic phosphate ions decomplex Cu2+ displaying a fluorescence enhancement that can even be seen with naked eyes. The method was successfully used in quantitative determination of inorganic phosphates in serum, urine, and saliva samples.