A cycloruthenated complex: Detecting Hg2+ by Hg2+‐promoted coordination switch and Cu2+ by coordination

A new cycloruthenated complex Ru1 with a ditopic thienyl–NHC ligand has been designed to recognize Hg2+ by a blue shift in absorption and evident solution color change in aqueous system. However, the time‐dependent absorption spectral changes of Ru1 with Hg2+ and H+ as well as MS and 1H NMR spectra demonstrated a possible Hg2+‐promoted coordination switch from Ru‐C to Ru‐S. Moreover, it should be noted that different color and absorption spectral changes were also observed in the presence of Cu2+. The reversible behavior between Ru1‐Cu2+ and HS− indicated a simple coordination between Ru1 and Cu2+. As a result, the different interactions between Ru1 and the two metal ions demonstrated a possible way for Ru1 to detect Hg2+ and Cu2+, respectively. Furthermore, Ru1 was also used to determine Hg2+ and Cu2+ in some spiked water samples, respectively. A cycloruthenated complex can be used as an irreversible probe to detect Hg2+ by an Hg2+‐promoted coordination switch. However, the simple coordination between Cu2+ and the complex provided reversibility at least five times to detect Cu2+.