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As novel fluorescent-sensing materials, metal-organic frameworks (MOFs) have shown great potential in environmental monitoring. However, most of the researches are limited to traditional pollutants, whereas the application of MOFs to the detection of the pollutants with more complicated structures, such as endocrine disrupting chemicals (EDCs), has rarely been explored. The difficulties faced in the sensing of EDCs include their electronic stability and the structural similarity among homologues, which could be overcome by the incorporation of enzymatic reaction. In this work, the first example of enzyme-assisted MOF-fluorescent-sensing was developed for the analysis of diethylstilbestrol (DES, a synthetic estrogen). In this system, DES is first oxidized by HRP/H2O2 quantitatively to its quinone form, and then the quinone product is selectively captured by a stilbene based luminescent MOF to induce fluorescence response. By the tandem sensitization and filtration of enzymatic reaction and MOF adsorption, this method shows high sensitivity (DL=89 n m) and can distinguish DES from other similar-structured EDCs. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are emerging in recent years as a kind of versatile fluorescent sensing materials, but their application to enzyme assays has rarely been studied. Here, the first example of a MOF-based label-free enzyme assay system is reported. A luminescent MOF was synthesized and applied to the activity analysis of polyphenol oxidase (PPO). With its distinct responses to the phenolic substrate and o-quinone product, this MOF could transduce the extent of PPO-catalyzed oxidation to fluorescence signal and enable the real-time monitoring of this reaction. Wide substrate adaptability and high sensitivity (detection limit=0.00012 U mL−1) were exhibited by this method, which meets the requirement of common bioanalysis. Interestingly, by the comparison with molecular capturing reagents, the heterogeneous nature of this MOF-based assay effectively preventing the interaction with the enzyme was proven, thus ensuring the authenticity of results. [ABSTRACT FROM AUTHOR]

A MOF ‐ based label ‐ free enzyme assay was designed in this work. To analyze polyphenol oxidase (PPO) activity, a luminescent MOF in which the emission could be selectively quenched by the o ‐ quinone product was synthesized. With it, the kinetics of PPO ‐ catalyzed oxidation could be reflected with the fluorescence signal. This method exhibits the advantages of high sensitivity, wide substrate adaptability, and minimal effects on the enzymatic reaction. More information can be found in the Full Paper by W. ‐ J. Ruan, et al. on page 6562 ff. [ABSTRACT FROM AUTHOR]

The title compound, C(26)H(21)N(3)O(2), is an unsymmetrical tetra-dentate Schiff base ligand. The hydr-oxy group forms an intra-molecular O-H⋯N hydrogen bond with an adjacent N atom. An inter-molecular N-H⋯O hydrogen bond creates centrosymmetric dimers in the crystal packing.