A Schiff-based sensor with turn-on fluorescence for selective detection of Hg2+

Reaction-based highly selective and sensitive monomer/polymer probes with Schiff base groups for the detection of Hg2+ and Fe3+ ions

It is urgent and important to detect heavy metals in environments. In this work, novel reaction-based fluorescent probes were obtained by Schiff base reaction. The probes with Schiff base moiety (-C=N-) undergo irreversible hydrolysis in the presence of Hg²⁺ and Fe³⁺. They exhibit perfect high selectivity and sensitivity to Hg²⁺and Fe³⁺ ions. Upon the addition of Hg²⁺and Fe³⁺, fluorescence intensity of the probes increased notably. And the color of the probe changes from brown to bright green under UV light, which can realize "naked eye" detection. In addition, Schiff base group was introduced into polyurethane chain through condensation polymerization reaction. As expected, the fluorescent polyurethane probe (P2) maintained the detection performance of its original small molecules (BSD). Even more P2 showed a more sensitive detection effect than BSD, and the detection limits of P2 for Hg²⁺ and Fe³⁺ reach 0.19 μM and 0.21 μM, respectively. It indicates that Reaction-based probes could be a useful tool for the detection of Hg²⁺ and Fe³⁺.