Accurate identification of cysteine by a nucleophilic-reaction-induced conversion of an open-shell luminescent radical into closed-shell molecule

Sensors based on the disappear of unique optical and magnetic signals of luminescent radicals caused by the conversion from open-shell into closed-shell molecules have not been realized. Here, we report a multiplechannel Cysteine (Cys) probe by a luminescent tris(2,4,6-trichloro-3-nitrophenyl) methyl radical (TTM center dot-3NO2) with good selectivity and high sensitivity. Cys has been confirmed to react with TTM center dot-3NO2 and generate closedshell molecules, which causes the changes of fluorescence, colorimetry and electron paramagnetic resonance (EPR) of the radical. Interestingly, based on the above multiple-channel signal, we expanded the application of the radical sensor in RGB pattern, simulated clinical laboratory and fluorescent imaging. Our results not only display a promising Cys probe but also show a novel route for the application of organic radicals in sensing.