Fluorene-based chemodosimeter for “turn-on” sensing of cyanide by hampering ESIPT and live cell imaging

A new salicylaldehyde appended fluorene-based chemodosimeter (FSal) has been designed by taking consideration of the special nucleophilicity of cyanide ion. FSal shows selective affinity towards CN− over other anions (namely F−, Br−, NO3−, ClO4−, N3−, H2PO4−, AcO−, I−, Cl−, and NO2−) through turn-on fluorescence with a minimum detection limit of 0.06 ppm. The turn-on fluorescence of the FSal–CN complex resulting from hampering ESIPT is also supported by DFT and TDDFT calculations. Biological compatibility and live cell imaging of this unique probe have also been explored.