Hydrolytically Stable Zr-Based Metal-Organic Framework as a Highly Sensitive and Selective Luminescent Sensor of...

Effective detections of radionuclides including uranium and its predominant fission products, for example, iodine, are highly desired owing to their radiotoxicity and potential threat to human health. However, traditional analytical techniques of radionuclides are instrument-demanding, and chemosensors targeted for sensitization of radionuclides remain limited. In this regard, we report a sensitive and selective sensor of UO₂²⁺ and I^- based on the unique quenching behavior of a luminescent Zr-based metal-organic framework, Zr₆O₄(OH)₄(OH)₆(H₂O)₆(TCPE)_1.5·(H₂O)₂₄(C₃H₇NO)₉ (Zr-TCPE). Immobilization of the luminescent tetrakis(4-carboxyphenyl)ethylene (TCPE^4-) linkers by Zr₆ nodes enhances the photoluminescence quantum yield of Zr-TCPE, which facilitates the effective sensing of radionuclides in a "turn-off" manner. Moreover, Zr-TCPE can sensitively and selectively recognize UO₂²⁺ and I^- ions with the lowest limits of detection of 0.67 and 0.87 μg/kg, respectively, of which the former one is much lower than the permissible value (30 μg/L) defined by the U.S. EPA. In addition, Zr-TCPE features excellent hydrolytic stability and can withstand pH conditions ranging from 3 to 11. To facilitate real-world applications, we have further fabricated polyvinylidene fluoride-integrating Zr-TCPE as luminescence-based sensor membranes for on-site sensing of UO₂²⁺ and I^-.