3-(pyridine-4-thione) BODIPY as a chemodosimeter for detection of Hg(II) ions

Abstract

A new chemodosimeter for detection of Hg(II) ions based on boron-dipyrromethene (BODIPY) is developed. The 3-(pyridine-4-thione) BODIPY was synthesized in high yield by treating 3-(pyridine-4-one) BODIPY with Lawesson's reagent. The 3-(pyridine-4-thione) BODIPY was confirmed by HR-MS mass, ¹H, ¹H–¹H COSY, ¹⁹F and ¹¹B NMR techniques. In ¹H NMR, the protons which are adjacent to sulfur in 3-(pyridine-4-thione) BODIPY showed ∼1 ppm downfield shift compared to equivalent protons in 3-(pyridine-4-one) BODIPY. The absorption and electrochemical properties experienced slight changes in 3-(pyridine-4-thione) BODIPY compared to 3-(pyridine-4-one) BODIPY. The compound 3-(pyridine-4-thione) BODIPY is very weakly fluorescent compared to 3-(pyridine-4-one) BODIPY. Furthermore, 3-(pyridine-4-thione)BODIPY can be used as an exclusive chemodosimeter for Hg²⁺ ion as it shows significant enhancement in the fluorescence intensity and a dramatic visible color change from pink to fluorescent green in the presence of Hg(II) ions.