A colorimetric sensor based on 2,3-bis(6-chloropyridin-2-yl)-6-fluoroquinoxaline for naked-eye detection of Iron (III) and its application in real sample analysis

Abstract

Iron ions are crucial for numerous biological processes, and the levels of these ions have a significant impact on human well-being. Hence, it is essential to identify the level of Iron ions using a suitable technique. A new colorimetric sensor, namely “2,3-bis(6-chloropyridin-2-yl)-6-fluoroquinoxaline” (CF), has been introduced to detect Fe³⁺ through naked-eye observation. The sensor exhibits remarkable specificity towards Fe³⁺ compared to other metal ions in aqueous environments. Furthermore, it undergoes a substantial color change from colorless to yellow, which is visible without needing additional equipment. The complex formation was proposed to be in 1:1 ratio based on the Job’s plot and molar ratio plot. The maximum sensitivity of CF towards Fe³⁺ was found at pH 6 to 8. Minimal or negligible interference was noticed from different metal ions in the detection of Fe³⁺. The binding constant using Benesi-Hildebrand was estimated at 1.434 × 10⁴ M⁻¹. Gibbs free energy was determined –23.728 kJ/Mol. The LOD and LOQ were calculated at 0.378 and 1.26 µM, respectively. The probe CF was utilized to recover Fe³⁺ in tap water, resulting in recovery percentages ranging from 99.44 to 103.61. This indicates that the CF has the ability to identify Fe³⁺ in environmental samples.