Development of a novel ICT-ESIPT-based NIR ratiometric fluorescent probe for specific detection of Hg²⁺ in the environment and living organisms

As a heavy metal contaminant, mercury ion (Hg²⁺) has caused great harm to environment and life. Mercury ions will migrate and transform in the environment and eventually accumulate in the human body, thus causing human poisoning. Therefore, it is of great significance to detect Hg²⁺ in the environment and living bodies. Based on this, we constructed an example of reactive near-infrared ratiometric fluorescent probe NIRPC-Hg based on the ICT-ESIPT mechanism. The probe could not only effectively overcome the effects of environmental changes, thus realizing the accurate detection of Hg²⁺ in the environment, but also possessed the advantages of large emission wavelength shift (130 nm red shift). In addition, the probe NIRPC-Hg was constructed with the classical recognition structure of Hg²⁺ and NIR fluorophore, which could detect Hg²⁺ sensitively with a low detection limit (9.21 nM). The satisfactory experimental results of environmental water samples proved that the probe had high application potential in the environment. At the same time, the probe NIRPC-Hg had the characteristics of smaller photo-toxicity and lower autofluorescence interference in the bioimaging applications, which could conveniently realize the sensitive detection of Hg²⁺ in cells and zebrafish. Therefore, the construction of probe NIRPC-Hg provided an effective tool to detect Hg²⁺ in the environment and living organisms.