A simple pincer-type chemosensor for reversible fluorescence turn-on detection of zinc ion at physiological pH range

Abstract

A new, highly selective and sensitive pincer-type chemosensor (Y) for zinc ion with turn-on fluorescence behavior in physiological pH range solution was developed. Y is based on bi-hydrazone derivatives, which contain pyridine as the fluorescent group and a hydrazone bond as recognition site. The selectivity mechanism of Y for zinc is based on the combined effects of the inhibition of excited-state intramolecular proton transfer (ESIPT) and –HCN– isomerization, as well as chelation-enhanced fluorescence. The entire process takes less than 15 seconds. The minimum detection limit of Y for zinc reaches 1.39 × 10⁻⁸ M. Moreover, Y can conveniently detect zinc in test strip form, and it can be recycled.