A turn-off fluorescence sensor for cyanide detection which in turn inhibit 2-way ESIPT investigated by experimental and theoretical study

A ligand based on 3-((quinoline-7-yl) methyeleneamino) phenazine-2-ol) (HAPQA) has been synthesized and used for the selective detection of cyanide ions. The ligand has been designed in such a way so that the excited state intramolecular proton transfer (ESIPT) of the HAPQA moiety gets blocked. The deep orange (λem = 575 nm) fluorescence of HAPQA in acetonirile turns into bright green fluorescence (λem = 505 nm) in presence of the cyanide (detection limit = 0.60 μM).100