Linli Hou,Yonghai Song,Yingjie Xiao,Rong Wu,Li Wang
Fluorescent metal-organic frameworks (MOFs) have attracted wide attention in fluorescence detection. Herein, a novel sensing platform for highly selective and sensitive detection of Fe 3+ in aqueous solution was proposed based on 2,5-dihydroxyterephthalic acid (DOBDC)-Zn 2+ 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 Fe 3+ , the cation exchange between Fe 3+ and Zn 2+ 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 Fe 3+ 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 Fe 3+ in real river water and human serum with good recovery and accuracy. This work provided a good Fe 3+ sensor based on ZnMOF-74 due to high affinity between phenolic hydroxyl group and Fe 3+ .
The detection of S 2− is of great significance because excess S 2− can lead to a variety of serious physiological diseases. Here, two metal-organic frameworks (MOFs), ZnMOF-74 and CuMOF-74, were synthesized by using 2,5-dihydroxy terephthalic acid with strong fluorescence as organic ligand and Zn 2+ or Cu 2+ as central coordination ions for S 2− detection. Both as-prepared ZnMOF-74 and CuMOF-74 displayed nanospheres with a diameter of about 100 nm. Under the excitation of 353 nm, the ZnMOF-74 had a characteristic emission peak at 537 nm and the CuMOF-74 had a characteristic emission peak at 528 nm under excitation of 356 nm. The interaction of S 2− and Zn 2+ weakened the fluorescence of ZnMOF-74 but the interaction of S 2− with Cu 2+ to form CuS restored the fluorescence of CuMOF-74, so the ZnMOF-74 and CuMOF-74 were exploited as a fluorescent nanosensor for sensing S 2− . The ZnMOF-74 sensor has a good linear range of 19.6 nmol L −1 -90.0 μmol L −1 , and the limit of detection was as low as 6.53 nmol L −1 . The CuMOF-74 sensor has a good linear relationship with I I 0 in the S 2− concentration range of 1.50 nmol L −1 -125 μmol L −1 , and the limit of detection was 1.50 nmol L −1 . The proposed ZnMOF-74 and CuMOF-74 sensor could also detect S 2− in actual samples.
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