Iridium(III) complex-based phosphorescent and electrochemiluminescent dual sensor for selective detection of glutathione

Glutathione (GSH) is the most abundant biological thiol and involved in antioxidant defense systems in human cells. Lack of GSH increases the risk of oxidative stress, resulting in the progression of cancer. Therefore, a selective detection method for GSH is highly required. Herein, we report phosphorescent and electrochemiluminescent dual sensors (1-3) based on iridium complexes for the selective detection of GSH. These sensors have a 1,10-phenanthroline-5,6-dione (pdo) ancillary ligand as a common reaction site for GSH. Reduction of the pdo moiety to 1,10-phenanthroline-5,6-diol (phen(OH)2) upon reaction of sensors with GSH triggered fluorescence turn-on response and electrochemiluminescence turn-off response with high selectivity for GSH. Sensing mechanisms were elucidated by DFT calculations and cyclic voltammetry. Sensor 1 was successfully applied to determination of GSH concentrations in human serum samples by ECL methods.N