A novel “on−off−on” fluorescent probe with high selectivity for continuous identification of Cu2+ and S2− and its applications

Abstract

A BODIPY-derived fluorescent probe (B-2) was developed to recognize Cu2+ and S2− sequentially in the CH3CN/HEPES (7:3 v/v, pH=7.27) buffer solution. After Cu2+ was added, the fluorescence was quenched, where the quenching rate was 95.3 %, and the detection limit was 0.36 μmol/L. The binding mechanism between B-2 and Cu2+ was elucidated using IR spectra, 1H NMR titration, DFT study, and Job's plot analysis. The complex B-2-Cu2+ formed from B-2 and Cu2+ could continuously recognize S2−, where the recovery rate was 90.6 %, and the detection limit was 0.01 μmol/L. In the pH range of 3∼9, probe B-2 had a high recognition ability for Cu2+ and S2−, which could be recycled four times. Furthermore, a cheap medical cotton swab can confirm that probe B-2 can continuously detect Cu2+ and S2−. Meanwhile, the applicability of B-2 for Cu2+ detection was verified in actual water samples with good precision and accuracy.