A novel "on-off-on" near-infrared fluorescent probe for Cu and S continuous detection based on dicyanoisoflurone derivatives, and its application in bacterial imaging.

We have successfully synthesized a near-infrared fluorescent probe for the continuous detection of copper and sulfur ions. The probe has good selectivity and anti-interference ability against Cu and S. The results show that after adding Cu to the DL solution of the near-infrared fluorescent probe, Cu forms a [DL + Cu] complex with the probe, which leads to fluorescence quenching due to the paramagnetism of Cu. The probe can be used for the quantitative detection of Cu with a detection limit of 1.26 × 10 M. According to the Job's plot curve the binding stoichiometry between DL and Cu is 1 : 1. Subsequently, S was added to the [DL + Cu] solution, because the precipitation dissolution equilibrium constant of CuS was = 1.27 × 10, so the binding capacity between Cu and S was stronger, CuS precipitation was formed, and red fluorescence was re-released, and the quantitative detection of S was realized, and the detection limit was 3.50 × 10 M. Through bacterial imaging experiments, we found that the probe can accomplish the fluorescence imaging experiments of , indicating that the probe has good biopenetration and biocompatibility, and has application prospects in bioimaging and environmental monitoring. In addition, the probe DL has good suitability for Cu and S detection in real samples.