Relay recognition of Cu2+ and S2− in water by a simple 2-(2′-aminophenyl)benzimidazole derivatized fluorescent sensor through modulating ESIPT

•A new phenylbenzimidazole derivatized sensor L has been designed and synthesized.•Sensor L displays relay recognition of Cu2+ and S2− in 100% water solution by fluorescence “on–off–on” functionality.•Sensor L exhibits excited-state intramolecular proton transfer behavior.•The Cu2+ and S2− recognition are highly selective and sensitive.

A new 2-(2′-aminophenyl)benzimidazole (2-APBI) derivatized fluorescent sensor (L) that behaves relay recognition of Cu2+ and S2− in water solution (pH 7.4) has been developed. Sensor L displays excited-state intramolecular proton transfer (ESIPT) featured two emission bands and performs highly selective and sensitive recognition to Cu2+ through two emissions simultaneous quenching. The on-site formed L-Cu2+ complex exhibits excellent selectivity to S2− with fluorescence “off–on” response via Cu2+ displacement approach, which exerts ESIPT recovery. Thus, through modulation the ESIPT state of sensor L, relay recognition of Cu2+ and S2− in water has been achieved.

Graphical abstractThe first phenylbenzimidazole based sensor L that exhibits highly selective relay recognition of Cu2+ and S2− in water (HEPES 10 mM, pH = 7.4) has been developed.Figure optionsDownload full-size imageDownload as PowerPoint slide