An iridium(III) complex-based chemosensor for the detection of thiourea in living cells

The adverse effects that thiourea can induce in biological systems demand the development of new methods for its detection. In this work, we present a iridium(III) complex-based chemosensor (1) containing a recognition unit for thiourea. The reaction of the recognition unit with thiourea affects the long-lived excited states of the complex, leading to an enhancement of luminescence. Complex 1 showed a 3.3-fold enhanced luminescence in the presence of thiorea and a good linear relationship with thiourea ranging from 10 to 200 μM, with a limit of detection (LOD) of 3.85 μM. By using time-resolved emission spectroscopy (TRES), complex 1 could detect thiourea in the presence of interfering fluorescence. Moreover, complex 1 offers the capability to image thiourea in living HeLa cells. To our knowledge, complex 1 is the first iridium(III) complex-based sensor reported for imaging thiourea in living cells.