Novel ratiometric turn-on fluorescent probe for selective sensing of cyanide ions, effect of substitution and bio-imaging studies

Abstract

Novel fluorogenic receptors S1-S4 (imidazo anthraquinone derivatives) were synthesized from o-substituted benzaldehyde and 1,2-diaminoanthraquinone and characterised with various spectroanalytical techniques. In the case of S1, the selectivity towards cyanide ions with turn-on fluorescence output among other anions, due to the inhibition of the twisted intramolecular charge transfer (TICT) mechanism. The effect of substitution was successfully compared with sensing studies of S2-S4. S1 showed a good binding constant with a 1 : 1 stoichiometric ratio and micromolar detection limit. The sensing behaviour was further supported by H-1 NMR titration, TD-DFT calculations and lifetime measurement studies. S1 was applied for the bio-imaging of the cell line RAW264.7 and successfully sensed cyanide ions under physiological conditions.