RESUMEN

Recently, the misuse of organic arsenic feed additives, such as roxarsone (ROX), has increasingly jeopardized both human health and the environment. In response, a unique electron-rich pyrazine-cored fluorescent covalent organic framework (COF) nanosheet, named as COF-TMP, was synthesized using an alkali-catalyzed reaction between 2, 3, 5, 6-tetramethylpyrazine (TMP) and terephthalaldehyde (TPA). Characterization demonstrated that COF-TMP boasted high porosity, pronounced fluorescence, and an abundance of (E)-2-styrylpyrazine (SPA) groups. These attributes render it an exceptional fluorescent sensor for the ultrahigh sensitivity detection of electron-deficient ROX molecules. The limit of detection (LOD) for COF-TMP in detecting ROX was found to be 0.015 ppb through fluorescence-quenching titration experiments-surpassing all previously reported fluorescent sensors. A combination of experimental results and theoretical calculations suggests that the extraordinary detection capability of COF-TMP for ROX arises from a static quenching mechanism. This study paves the way not only for a novel pyrazine-based fluorescent COF nanosheet with high porosity, exceptional fluorescent capabilities, and abundant SPA groups suitable for highly sensitive and selective ROX detection but also hints at its potential application as a fluorescent sensor for environmental pollution management and related domains.