Innovative molecular architecture of a new Hg2+/Cu2+-dual chemosensor based on functionalizable chromenylium-cyanine framework

Abstract

A novel chromenylium-cyanine based near-infrared (NIR) and dual chemosensor (NIR9) has been developed for the highly sensitive and selective detection of mercury (Hg2+) and copper (Cu2+) ions. The NIR9 is the first example of NIR probes developed for independently analysis of Hg2+ and Cu2+ in real samples. The probe exhibits turn-on fluorescence and ratiometric UV–Vis absorption and colorimetric responses for Hg2+. It also displays a turn-off UV–Vis absorption signal to Cu2+. Upon interaction with Hg2+, NIR9 undergoes a desulfurization-induced spirolactam ring opening, resulting in a strong fluorescence emission at 750 nm and a visible color change from yellow to green, with a detection limit as low as 0.02 μM. For Cu2+ detection, the probe shows a unique absorbance decrease at 380 nm, enabling quantification with a detection limit of 0.01 μM. The sensing capability of NIR9 is supported by theoretical DFT studies and further validated through successful applications in real environmental (water and food) and biological (A549 cells) samples. Additionally, the probe enables smartphone-assisted detection of Hg2+, promoting field-deployable analytical capabilities. This work introduces a next-generation multiplexed NIR chemosensor with high versatility, selectivity, and sensitivity for environmental and biomedical applications.