Redox-Active Europium-Based MOFs Showing Ratiometric Fluorescence Sensing for the Anthrax Biomarker and Oxytetracycline, and Proton Conduction.

Redox-active metal-organic frameworks have received increasing attention for potential applications in conductivity, sensing, catalysis, and magnetism. In this work, a novel redox-active europium-based metal-organic framework, {[(CH)NH][Eu(BTA-2OH)(HO)]·2HO} (, HBTA-2OH = 2,3,5,6-tetrakis(-carboxyphenyl)hydroquinone), is prepared and structurally characterized. The is characterized by a well-defined structure featuring a two-dimensional channel along the -axis. can be converted into through the oxidation of hydroquinone to benzoquinone, which can maintain structural stability and enhance fluorescence emission. Compared with , displays a more sensitive visual identification of 2,6-pyridine dicarboxylic acid (DPA) or oxytetracycline (OTC) as a ratiometric fluorescent sensor with lower detection limits of 0.013 and 0.071 μM, respectively. Fluorescent composite films and smartphone-based readout systems based on s have been constructed to achieve rapid on-site quantification and testing. Moreover, displays a more outstanding proton conductivity value of 1.16 × 10 S cm than (2.01 × 10 S cm) at 50 °C and 100% RH, indicating its high performance and potential application in the field of proton conduction. Therefore, the is a potential bifunctional material for fluorescence sensing and proton conduction.