Stable, triplet ground state BODIPY-TEMPO diradical as a selective turn on fluorescence sensor for intracellular labile iron pool

Intracellular labile iron pool (LIP) has been associated with cellular toxicity, and regarded as one of the factors affecting many diseases. However, fluorescence probes for detection of LIP are limited. Herein, we present a novel, BODIPY based, triplet ground state pro-fluorescent dinitroxide, as a turn on sensor for similar purpose. The biradical probe has been synthesized, and was seen to be highly effective in detecting LIP, more importantly in a concentration-dependent manner, in a variety of cell lines. The probe showed high sensitivity with Fe(II)-selective turn-on response via reduction of the biradical. This is a first example of a BODIPY based fluorescence turn-on sensor selective towards Fe(II). [Display omitted] •For the first time, a triplet stable diradical was demonstrated as fluorescent turn-on sensor for intracellular Fe+2.•This is the first example of a turn-on fluorescence probe for Fe+2 based on a BODIPY dye.•The probe shows high selectivity towards Fe+2 with high fold increase in fluorescence.•This probe shows linear response to varying concentration of intracellular labile iron.•The probe is equally effective in detection of intracellular labile iron pool in a diverse array of cell lines.