Colorimetric determination of Hg2+ via thiosemicarbazide-to-oxadiazole transformation of a coumarin-benzopyrylium dye

A dual signaling reaction-based probe derived from a hybrid coumarin-benzopyrylium dye was developed for Hg2+ signaling. The probe exhibited selective colorimetric Hg2+ signaling via the Hg2+-induced thiosemicarbazide-oxadiazole transformation. Interference from Cu2+ ions was successfully circumvented using a citrate buffer as a masking agent. The detection limit for Hg2+ ions was found to be 1.88 × 10–7 M. Practical application to Hg2+ detection in simulated wastewater was realized using a typical smartphone as a stand-alone data capture and data processing device.