Fluorescent chitosan-BODIPY macromolecular chemosensors for detection and removal of Hg and Fe ions.

The detection of heavy metals, such as Hg and Fe, is of great significance. In this work, fluorescent small-molecule BODIPY (BY-3) bearing CC group was synthesized firstly. And then, the chitosan-based polymer sensor CY-1 was synthesized through the spontaneous NH/C≡C click reaction. The synthesized CY-1 can effectively bind and recognize Hg/Hg by the -C=N groups formed in the click reaction. Moreover, the macromolecular sensors CS-1 and CS-2 were synthesized by incorporating another recognition sites to CY-1. These synthesized macromolecular sensors can not only recognize Hg/Hg, but also effectively recognize Fe/Fe. All of them exhibited significant quenching effect, visible to the naked eye under UV irradiation. The detection limit of CY-1 for Hg was 1.51 × 10 mol/L, and the detection limit of CS-2 for Fe was 2.30 × 10 mol/L. The BODIPY-chitosan sensors synthesized in this work have the functions of removing heavy metal ions besides the identifying ability. The maximum adsorption capacity of 1 g chitosan to Hg was 108 mg as the best one. This article provides a new method to prepare macromolecular sensors for the detection and removal of heavy metal ions. As a useful natural polymer, chitosan's application scope was enlarged.