Novel Dual-Mode Fluorescent Sensor for Detecting Chlorpyrifos and Cu(II)

Hazardous chemicals are a widespread concern owing to their toxicity to humans, creatures, and the environment. The latter can be exposed to these chemicals when they are released through many industrial and agricultural practices. Therefore, a new fluorescent sensor was developed for the sensitive and selective detection of chlorpyrifos (CP) and Cu²⁺ under different working conditions. This study successfully synthesized a dual-analyte fluorescent sensor based on oxime-functionalized carbazole (<b>PK</b>) that exhibited fluorescence quenching during the detection of CP and Cu²⁺. <b>PK</b> distinguished CP from other organophosphates in a basic buffer solution with a detection limit of 0.485 ppm. The binding was verified to be in a 1:1 stoichiometric ratio by Job's plot, and the mechanism was confirmed via infrared spectroscopy and mass spectrometry. <b>PK</b> also distinguished Cu²⁺ from other interfering metal ions in an aqueous organic solution with a detection limit of 15.19 ppb. The binding was in a 1:1 stoichiometric ratio, as verified by Job's plot, and the mechanism was confirmed via ¹H nuclear magnetic resonance (NMR) spectral analysis and density functional theory (DFT) calculations.