N-Rich Porphyrin-Functionalized Tröger’s Base Covalent Organic Polymer for Selective and Reversible Sensing of Roxarsone in Water

Roxarsone (ROX), a commonly used organoarsenic feed additive in poultry and pig farming, poses significant environmental risks due to the widespread practice of applying animal waste containing ROX as fertilizer. This results in arsenic contaminating soil, surface water, and groundwater. Detecting ROX at trace levels in water systems is therefore critical but remains challenging. In this study, we introduce a novel porphyrin-functionalized Tröger’s base covalent organic polymer (Por-TB-COP) for selective and reversible fluorescent “turn-off” detection of ROX in water. Fluorescence titration results show that Por-TB-COP preferentially binds to ROX over other analytes, with a high Stern–Volmer quenching constant (KSV) of 8.58 × 103 M–1 and a low detection limit of 14.7 nM. The effectiveness of Por-TB-COP was confirmed in phosphate-buffered saline and real pond water samples, highlighting its potential for monitoring ROX in complex environmental conditions. These results indicate that Por-TB-COP is a promising fluorescent material for the selective and trace detection of ROX in water.