A photoluminescent and electrochemiluminescent probe based on an iridium(iii) complex with a boronic acid-functionalised ancillary ligand for the selective detection of mercury(ii) ions

Abstract

Exposure to mercury(II) ions (Hg²⁺) can cause various diseases such as Minamata disease, acrodynia, Alzheimer's disease, and Hunter–Russell syndrome, and even organ damage. Therefore, real-time and accurate monitoring of Hg²⁺ in environmental samples is crucial. In this study, we report a photoluminescent (PL) and electrochemiluminescent (ECL) probe based on a cyclometalated Ir(III) complex for the selective detection of Hg²⁺. The introduction of a reaction site, o-aminomethylphenylboronic acid, on the ancillary ligands allowed a prompt transmetalation reaction to take place between Hg²⁺ and boronic acid. This reaction resulted in significant decreases of the PL and ECL signals due to the photo-induced electron transfer from the Ir(III) complex to the Hg²⁺ ions. The probe was applied to the selective detection of Hg²⁺, and the signal changes revealed a linear correlation with Hg²⁺ concentrations in the range of 0–10 μM (LOD = 0.72 μM for PL, 8.03 nM for ECL). The designed probe allowed the successful quantification of Hg²⁺ in tap water samples, which proves its potential for the selective detection of Hg²⁺ in environmental samples.