Dual signaling of Hg2+ ions by selective cleavage of thiophosphinated rhodol

A new Hg2+-selective reaction-based probe based on thiophosphinated N,N-diethylrhodol was developed. Thiophosphinated rhodol showed prominent chromogenic and fluorogenic signaling for the Hg2+ ions. Signaling is due to the Hg2+-assisted hydrolysis of the thiophosphinated group to generate the rhodol fluorophore. An optical signaling with a detection limit of 13 nM, detectable with unaided eyes, was realized in a mixed aqueous environment. Selective Hg2+ signaling by thiophosphinated rhodol was not significantly affected by the presence of background common metal ions. Signaling was completed within 3 min and constant under the measuring conditions between pH 6.2 and 8.0. The Hg2+ signaling based on hydrolysis of the thiophosphinated rhodol was confirmed by 1H, 13C, and 31P NMR spectroscopy. Application of the designed probe to practical samples of tap water and wastewater was also tested.