A turn-on fluorescent chemodosimeter based on detelluration for detecting ferrous iron (Fe2+) in living cells.

A turn-on fluorescent probe for the detection of Fe2+ is facilely synthesized via a nucleophile substitution reaction. The fluorescent probe, N-butyl-4-phenyltellanyl-1,8-naphthalimide (Naph-Te), shows excellent selectivity to Fe2+ in a mixed solution of acetonitrile and phosphate buffer under aerobic conditions. The coexistence of biological abundant metal ions such as Na+, K+, Ca2+ and Mg2+ has little effect on the fluorescence signal. This turn-on response is achieved via a redox-involved reaction triggered by Fe2+ at neutral pH and room temperature, which removes the heavy-atom effect of the tellurium atom on the naphthalimide fluorophore to afford a fluorescent product (N-butyl-4-hydroxyl-1,8-naphthalimide). The probe has excellent cell membrane permeability and is further applied successfully to monitor supplementary Fe2+ in live HL-7702 cells using a laser confocal fluorescence microscope.