A colorimetric chemosensor for Cu2+/Hg2+ based on a cycloruthenated 2-phenylbenzimidazole

A cyclometalated ruthenium complex ( 1 ) with 2-phenylbenzimidazole as the ligand was synthesized and used as a colorimetric chemosensor to detect Hg 2+ and Cu 2+ . It is interesting that the presence of Hg 2+ caused a blue-shifted absorption of 1 from 560 to 450 nm resulting in a solution color change from red to yellow, while the addition of Cu 2+ resulted in an attenuated absorption along with the solution color changing from red to colorless. Their corresponding detection limits were calculated to be 0.25 µM for Hg 2+ and 0.45 µM for Cu 2+ , respectively. Moreover, the slips of paper were dyed with complex 1 and then successfully used to recognize Hg 2+ and Cu 2+ by naked eyes, respectively. Furthermore, 1 was also used to determine Hg 2+ and Cu 2+ in some spiked water samples, respectively.