Thallium ions are widely used in chemical and industrial applications but are very toxic. Through this research, a novel dual signaling probe that is based on an oxidative cleavage reaction is examined. The probe showed selective and sensitive optical signaling behavior toward TI3+ through the oxidative hydrolysis of rhodamine–hydroxamate. The probe designed for this study exhibited a distinct colorimetric and fluorescence signaling activity for thallium ions compared to the ions of common metals and oxidants. In particular, the hypochlorous acid response of the probe was successfully suppressed using DMSO as a scavenger. The detection limit for thallium determination was 2.9 × 10−7 M and signaling was concluded within 5 minutes. The exploitation of the probe for the rapid screening of elevated urinary thallium levels due to thallium poisoning using smartphone images was also conducted.
