A sulfur-free iridium(III) complex for highly selective and multi-signaling mercury(II)-chemosensors

A sulfur-free iridium(III) complex (pbi)(2)Ir(mtpy) (1) was successfully prepared and adopted as a Hg(II)-chemosensor with high selectivity and sensitivity. Multi-signaling responses towards Hg(II) ions were observed by UV-vis absorption, phosphorescence and electrochemistry measurements. With addition of Hg(II) ions, complex 1 presented quenched emission in its phosphorescence spectrum and the detection limit was as low as 2.5 x 10(-7) M. Additionally, its redox peak currents showed a broad linear relationship with the concentration of Hg(II) ions ranging from 0 to 500 mu M, which was beneficial for the quantitative detection. Based on the H-1 NMR and ESI-MS analyses, the probing mechanism was tentatively supposed to be the Hg2+-induced changes in the local environment of complex 1. Such a response process was useful for achieving simple and effective detection of Hg(II) ions as well as developing more chemosensors.