Design and synthesis of two iridium(Ⅲ) complex probes for rapid sensing of hydrogen sulfide

Hydrogen sulfide (H2S) is an important sulfur-containing signaling molecule in the human body, as well as a highly toxic gas that is soluble in water. A variety of pathological processes are associated with abnormal metabolism of hydrogen sulfide, so it is very important to develop an assay that can rapidly and specifically detect H2S. In this work, two iridium(Ⅲ) complexes were designed and synthesized using ester groups as reaction sites for recognition of H2S. As the H2S concentration increased, the photoluminescence of the probe was rapidly quenched within 5 s, with a detection limit as low as 0.45 μM. Among them, the probe Ir1, whose luminescence was located in the visible region, had been successfully used for the detection of trace amounts of H2S in water samples with a recovery rate of 92.5 ∼ 104.0% and a relative standard deviation (RSD, n = 5) of < 2.8%. The luminescence of probe Ir2 was located in the near-infrared region, which could avoid the interference of biological autofluorescence and be successfully used for luminescence imaging of H2S in HeLa cells. This study provided a promising method for rapid detection of trace H2S in water samples and cellular microenvironments.