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A smart self-indicating metal–organic framework with real-time fluorochromic response for ultraselective thorium remediation

Nature Water (2026)Cite this article

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Abstract

The efficient separation and simultaneous detection of thorium from complex aqueous environments remain a critical challenge in radioactive waste management, where minimizing secondary waste and reducing adsorbent consumption are paramount. Here we report a fluorochromic metal–organic framework (MOF), Eu-NDC, that functions as a self-indicating adsorbent for ultraselective Th(IV) sensing and separation. Eu-NDC exhibits a distinctive red-to-blue emission transition upon Th(IV) binding, achieving an ultralow detection limit of 9.2 nM while selectively distinguishing Th(IV) from other tetravalent cations. Furthermore, the material combines high Th(IV) adsorption capacity (504.3 mg g−1) with superior selectivity, indicated by a distribution coefficient of 2.8 × 106 ml g−1 and a Th(IV)/U(VI) separation factor of 1,806. Mechanistic studies reveal that Th(IV) uptake occurs via a dissolution–recrystallization process. Importantly, the fluorochromic response of Eu-NDC provides a self-indicating capability, whereby changes in emission colour directly reflect adsorption progress. This dual-functionality, integrating ultraselective adsorption with direct optical feedback, establishes MOFs as a multifunctional platform for smart, self-indicating radionuclide separation and environmental remediation.

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Fig. 1: Structural and physicochemical characterization of Eu-NDC.
Fig. 2: Fluorochromic detection of Th(IV) by Eu-NDC.
Fig. 3: Mechanistic investigation of selective Th(IV) detection by Eu-NDC.
Fig. 4: Adsorption performance of Eu-NDC towards Th(IV).
Fig. 5: Self-indicating Th(IV) separation.

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Data availability

The data that support the findings of this study are available in the article and its Supplementary Information. The X-ray crystallographic coordinates for structures reported in this study have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition numbers 2485502-2485503. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Source data are provided with this paper.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (grant nos. 22322609, U22B20139 and 22506141) and the New Cornerstone Science Foundation through the New Cornerstone Investigator Program and the XPLORER PRIZE. SCXRD data were collected using a Bruker D8 Quest diffractometer in the State Key Laboratory of Multiphase Flow in Power Engineering. We thank Z. Pan at the National Innovation Platform for Industry-Education Integration of Energy Storage Technology of Xi’an Jiaotong University for assistance with variable-temperature PXRD and SEM-EDS measurements.

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Authors and Affiliations

  1. School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, People’s Republic of China

    Yunyi Cui, Yaoyao Bai, Junpu Yang, Guangtao Zhang, Chengyan Yu, Jie Qiu & Jian Lin

  2. State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, People’s Republic of China

    Yaxing Wang & Shuao Wang

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Contributions

J.L. and S.W. conceived and supervised the project. Y.C. participated in all aspects of the study. Y.B., J.Y. and G.Z. conducted the Th(IV) adsorption experiments. C.Y. performed the Th(IV) detection experiments. J.Q. and Y.W. contributed to the study of the detection mechanism. J.L., Y.C. and S.W. wrote the paper. All authors analysed the results and provided critical feedback on the paper.

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Correspondence to Shuao Wang or Jian Lin.

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Competing interests

J.L. and Y.C., in conjunction with Xi’an Jiaotong University, have filed a patent (202511992028.2) in China based on the results presented in this study. The other authors declare no competing interests.

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Nature Water thanks Xiaojun Wang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Cui, Y., Bai, Y., Yang, J. et al. A smart self-indicating metal–organic framework with real-time fluorochromic response for ultraselective thorium remediation. Nat Water (2026). https://doi.org/10.1038/s44221-026-00612-1

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