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

• A simple cycloruthenated complex for detecting Hg2+/Cu2+ was synthesized. • It can detect Hg2+/Cu2+ by significant spectral and color changes in water. • Slips of paper dyed with the complex were successfully used to recognize Hg2+ and Cu2+ by naked eyes, respectively. A cyclometalated ruthenium complex (1) with 2-phenylbenzimidazole as the ligand was synthesized and used as a colorimetric chemosensor to detect Hg2+ and Cu2+. It is interesting that the presence of Hg2+ 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 Cu2+ 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 Hg2+ and 0.45 µM for Cu2+, respectively. Moreover, the slips of paper were dyed with complex 1 and then successfully used to recognize Hg2+ and Cu2+ by naked eyes, respectively. Furthermore, 1 was also used to determine Hg2+ and Cu2+ in some spiked water samples, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]