Relay recognition by modulating ESIPT: A phenylbenzimidazole derived sensor for highly selective ratiometric fluorescent recognition of Zn2+ and S2− in water

A new phenylbenzimidazole derivatized fluorescent sensor (L) with 2-picolylamine as Zn2+ chaltor was designed and prepared. In buffered water solution (HEPES 10 mM, pH 7.4), sensor L displays highly selective, sensitive and ratiometric fluorescent recognition to Zn2+ based on inhibition of excited-state intramolecular proton transfer (ESIPT). In addition, the resultant L-Zn2+ complex exhibits ratiometric responses to S2− with excellent selectivity via S2− induced Zn2+ displacement approach. The results demonstrate that L can serve as a ratiometric fluorescent sensor for relay recognition of Zn2+ and S2− in water at physiological pH.