Colorimetric detection of chromium( vi ) using copper-based porphyrin organic framework materials and 8-hydroxyquinoline via a ‘signal inhibition-target activation’ response mode

= 0.999) with a low detection limit (LOD) of 22.3 nM, demonstrating excellent selectivity even in the presence of multiple interfering ions. The proposed intelligent response mechanism provided a visual, rapid, and user-friendly solution for on-site monitoring of Cr(VI) contamination, showing promising application potential in environmental analysis.