Anionic porous metal-organic framework materials for dual-mode detection and removal of Cu²

Controlling heavy metal ions is crucial, as prolonged exposure to Cu²⁺ can cause neurodegenerative diseases and severe organ damage. To address this global issue, we have developed two anionic lanthanide-based metal-organic frameworks (Ln-MOFs), designated as University of Macau-1 (UM-1) and University of Macau-2 (UM-2), with porous structures. The synthesized UM-1 and UM-2 exhibit high specificity in recognizing and adsorbing Cu²⁺ ions. To expand the application of Cu²⁺ monitoring, a dual-mode rapid detection method integrating fluorescence and colorimetric techniques has been developed. In fluorescence, both Ln-MOFs exhibited high sensitivity with detection limits of 0.34 μM for UM-1 and 0.56 μM for UM-2. Then, a smartphone-assisted method was established for on-site colorimetric detection of Cu²⁺. Additionally, UM-1 and UM-2 achieved good removal efficiencies of 77.4% and 80.7%, respectively, in 30 min, when the concentration of Cu²⁺ was elevated to 25 mM. In conclusion, the porous anionic Ln-MOF showcases remarkable capabilities in the detection, separation, and removal of Cu²⁺. This innovative work not only provides an invaluable reference but also offers an effective solution for tackling the pressing issue of heavy metal pollution.