ZnMOF-74 responsive fluorescence sensing platform for detection of Fe3+

Fluorescent metal-organic frameworks (MOFs) have attracted wide attention in fluorescence detection. Herein, a novel sensing platform for highly selective and sensitive detection of Fe3+ in aqueous solution was proposed based on 2,5-dihydroxyterephthalic acid (DOBDC)-Zn2+ MOFs (ZnMOF-74). The as-prepared ZnMOF-74 exhibited uniform clavicorn nanostructures and high day-to-day stability in acidic aqueous solution (pH 4.0). Because of the special response of phenolic hydroxyl groups of DOBDC with Fe3+, the cation exchange between Fe3+ and Zn2+ occurred, which caused collapse of the skeleton and formed a blue weak-fluorescent iron(III)-phenol salt complex (Fe-DOBDC), which led to the effective fluorescence quenching of ZnMOF-74. ZnMOF-74 was used as a probe for detection of Fe3+ under relatively acidic condition with a good linear range of 0.1–100 μM and a low detection limit of 40 nM. The fluorescence probe was also applied to determine Fe3+ in real river water and human serum with good recovery and accuracy. This work provided a good Fe3+ sensor based on ZnMOF-74 due to high affinity between phenolic hydroxyl group and Fe3+.