A ratiometric fluorescence probe for monitoring cyanide ion in live cells

Abstract

A ratiometric emission fluorescent probe 1,1-dimethyl-3-ethyl-2-(2-(N-ethyl-carbazol-3-yl)-vinyl)-1H-benzo[e]indolium iodide (Probe) is facilely synthesized via the ethylene bridging of N-ethylcarbazole-3-formaldehyde and 1,1,2-trimethyl-3-ethyl-1H-benz[e]indolium iodide, which is a useful fluorescent probe for monitoring cyanide ion at extremely low concentrations, quantitatively. The detection of cyanide is performed via the nucleophilic attack of cyanide toward the benzo[e]indolium group of the probe, resulting in a prominent fluorescence ratiometric change and a color change. The titration experiments for CN− show that it exhibits a large Stokes shift (92nm), high selectivity, excellent sensitivity and good stability for CN− sensing in DMSO system. The detection limit of Probe for CN− is found to be 0.23μM. Furthermore, the probe has excellent cell membrane permeability and is applied successfully to rapidly detect CN− in living cells.