A Mitochondria-Targeted Iridium(iii) Phosphorescent Probe for Selective Detection of Hypochlorite in Living Cells

Hypochlorous acid(HClO)/hypochlorite ion (ClO-) is a highly reactive oxygen species (ROS) that play a crucial role in various biological processes. In this paper, a "turn-on" phosphorescent probe (Ir-TPP) for detecting ClO- in mitochondria was designed and synthesized. In solution, Ir-TPP is minimal emission due to rapid isomerization of C=N-OH as an efficient non-radiative decay process. When Ir-TPP was reacted with ClO- to form an oxidized carboxylate product, there is a significant enhancement both in absorbance and emission intensity, resulting in approximately 19-fold increase in phosphorescence signal. Furthermore, the probe demonstrates high selectivity towards other anions and ROS. It also exhibits specific targeting ability towards mitochondria with a co-staining coefficient of 94% compared to commercial dyes, enabling "turn-on" detection of ClO- within mitochondria.