A Highly Sensitive Benzoxazole‐Based Fluorescent Probe for Hg2+ Detection Supported by Mechanistic Studies

Abstract In this research study, we report the synthesis and application of a newly designed fluorophore for the detection of Hg 2+ ions. The sensing system consisted of the synthesized organic entity, ( E )‐2‐(4‐(4‐bromostyryl) phenyl) benzo[ d ]oxazole ( BO1 ), which was thoroughly characterized using various analytical and spectroscopic techniques to confirm its structure and purity. Spectroscopic analysis revealed that BO1 exhibits maximum absorption at 352 nm with an emission wavelength of 416 nm. Subsequently, the fluorescence behavior of BO1 in the presence of Hg 2+ ions was investigated using photoluminescence. The increase in concentration of mercuric ions (2–20 µM) decreases the emission intensity of BO1 linearly, confirming a steady interaction between BO1 and the analyte. Hence, the Hg 2+ ions act as an effective quencher for BO1 . The limit of detection (LOD) value of the sensor is calculated to be 1.85 µM, associated with a limit of quantification (LOQ) of 5.60 µM. Additionally, density functional theory (DFT) was employed to gain an insight into the photophysical properties of the fluorophore and its interaction mechanism with Hg 2+ ions. This comprehensive investigation sheds light on the potential application of BO1 as a sensitive fluorophore for the detection of mercuric ions and highlights the potential nucleophilic moieties involved in the charge transfer. The synthesized molecule BO1 is therefore considered an effective fluorescent sensor for the detection of mercuric ions.