Highly selective and effective mercury(ii) fluorescent sensors

Abstract

A novel mercury non-sulfur and simple fluorescent chemosensor L based on the benzimidazole group and quinoline group as the fluorescence signal group has been designed and synthesized. The receptor could instantly detect the Hg²⁺ cation over other cations such as Fe³⁺, Ag⁺, Ca²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺, and Mg²⁺ by fluorescence spectroscopy changes in H₂O/DMSO (1 : 9, v/v) solution with specific selectivity and high sensitivity. The fluorescence color of the solution containing sensor L showed a remarkable change from blue to colorless only after the addition of Hg²⁺ in aqueous media while other cations did not cause obvious color changes. Moreover, further study demonstrates that the detection limit on the fluorescence response of the sensor to Hg²⁺ is down to 9.56 × 10⁻⁹ M, which is far lower than the maximum level for mercury of 0.01 M in drinking water, from EPA guidelines. Test strips based on L were fabricated, which could act as convenient and efficient Hg²⁺ test kits. Thus, the probe should have potential applications in an aqueous environment for the monitoring of mercury.