Construction of Isonicotinic Acid Derivative-Based Hydrogen-Bonded Organic Frameworks for Selective Detection and Adsorption of Radionuclide Th(IV)

Abstract Th(IV) poses severe radioactive hazards once released into the environment due to its long half-life and potential bioaccumulation. Therefore, the development of multifunctional materials capable of simultaneous detection and removal of Th(IV) becomes an urgent research priority. Herein, by introducing pyrazole-functionalized isonicotinic acid monomers, a hydrogen-bonded organic framework (DPIA-HOF) with strong stability under acidic conditions was successfully constructed by a simple solvent evaporation method. The π···π interactions and multiple hydrogen bonds in DPIA-HOF suppress the rotation and vibration of the intramolecular pyrazole ring, thereby stabilizing the three-dimensional monoclinic structure and significantly improving the rigidity of the framework. Experimental and theoretical calculations indicate that DPIA-HOF can achieve sensitive fluorescent detection of Th(IV) via photoinduced electron transfer (PET) mechanism, with a detection limit of 5.5 ppb. Furthermore, the coordination interactions between Th(IV) and nitrogen/oxygen atoms enable selective adsorption and efficient removal of Th(IV) with rapid kinetics and excellent selectivity that is applicable to real rare earth tailings leachate treatment. This work proposes a new strategy to construct functionalized HOFs for the selective detection and efficient removal of radioactive nuclides.