A novel "on-off-on" near-infrared fluorescent probe for Cu 2+ and S 2- 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 2+ and S 2- . The results show that after adding Cu 2+ to the DL solution of the near-infrared fluorescent probe, Cu 2+ forms a [DL + Cu 2+ ] complex with the probe, which leads to fluorescence quenching due to the paramagnetism of Cu 2+ . The probe can be used for the quantitative detection of Cu 2+ with a detection limit of 1.26 × 10 -9 M. According to the Job's plot curve the binding stoichiometry between DL and Cu 2+ is 1 : 1. Subsequently, S 2- was added to the [DL + Cu 2+ ] solution, because the precipitation dissolution equilibrium constant of CuS was K sp = 1.27 × 10 -36 , so the binding capacity between Cu 2+ and S 2- was stronger, CuS precipitation was formed, and red fluorescence was re-released, and the quantitative detection of S 2- was realized, and the detection limit was 3.50 × 10 -8 M. Through bacterial imaging experiments, we found that the probe can accomplish the fluorescence imaging experiments of Staphylococcus aureus , 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 2+ and S 2- detection in real samples.