A large Stokes shift, sequential, colorimetric fluorescent probe for sensing Cu2+/S2- and its applications

Abstract

Copper ions (Cu2+) and sulfide (S2−) are important markers in many physiologies and pathological processes. In this work, a new near-infrared fluorescent probe 1 for colorimetric and sequential detection of Cu2+/S2− was designed and developed. The probe showed a rapid (less than 1 min), highly selective and sensitive response toward copper ions. Notably, the probe could also be applied to detect S2− through reversible formation-separation of complex 1-Cu2+ and CuS with a large Stokes shift of 234 nm. The detection limit for Cu2+ and S2− was found to be 1.8 × 10-8 M and 1.5 × 10-8 M, respectively. Furthermore, the binding stoichiometry between 1 and Cu2+ was found to be 1:1, the binding mode was also demonstrated using density functional theory (DFT) calculations and contrastive compound research. In addition, the probe was successfully applied in real water samples assay for the detection of Cu2+, and the strip papers experiments also showed that probe 1 can be used to detect Cu2+ and S2−.