A novel ratiometric fluorescent sensor based on terpyridine derivatives for Zn 2+ in aqueous solution

Terpyridine and its derivatives have good binding affinity for most transition metal ions due to the arrangement of their three pyridine nitrogen atoms. In this work, a new ratiometric fluorescent probe G, which is based on a styrylpyridinium attached to a terpyridine fluorophore, was synthesized and characterized. The fluorescence spectrum of probe G shows a good response to Zn²⁺ by an intramolecular charge transfer effect. On increasing the concentration of Zn²⁺, the fluorescence color of probe G changes from blue to yellow. Importantly, probe G has a high selectivity for Zn²⁺and is not affected by other metal ions, including Cd²⁺. In addition, the limit of detection (LOD) of probe G for Zn²⁺ was found to be up to 0.17 µM. The results show that probe G has the ability to selectively recognize Zn²⁺ in aqueous solution.