A reversible fluorescent chemosensor for cyanide in 100% aqueous solution

A new fluorescent chemosensor, sodium 2-(2-(1H-benzo[d]imidazol-2-yl)quinolin-8-yloxy)acetate (HL), based on 8-hydroxyquinoline derivative has been designed, synthesized and characterized. Once combined with Hg2+ in aqueous solution, HL displays a fluorescence quenching effect to form the compound mercury(II) 2-(2-(1H-benzo[d]imidazol-2-yl)quinolin-8-yloxy)acetate chloride (LHg), which could be fast dissociated by the addition of cyanide in this system so that “ON–OFF–ON” type fluorescence change can be achieved. Cyanide induces the revival of fluorescence of LHg and results in “OFF–ON” type sensing with high sensitivity and rapid response in 100% aqueous system. Furthermore, the fluorescence microscopic imaging also indicates that LHg is suitable for the detection of CN− in biological environment.