Construction of Unsaturated Coordinated Cu-Metal–Organic Frameworks for Iodine Adsorption

Radioactive iodine from nuclear energy poses serious risks to aquatic environments, driving the need for efficient adsorbents for nuclear wastewater treatment. Metal–organic frameworks (MOFs) have shown promise in iodine capture due to their tunable pores and functional surfaces. In this work, three copper-triazolate-based MOFs with unsaturated coordination (CuCl 2 (TRZ) for 1, Cu 4 OCl 3 (TRZ) 3 for 2, Cu 3 HOCl 2 (TRZ) 3 ·2.4H 2 O for 3; TRZ = 1,2,4-triazole) were synthesized and characterized. Compound 1 exhibits a one-dimensional chain structure, compound 2 exhibits a two-dimensional layer, and compound 3 exhibits a three-dimensional cage architecture featuring a 10 Å molecular cage with two kinds of window sizes at 5 and 7.8 Å, respectively. In the evaluation of iodine adsorption in aqueous solution, compound 3 demonstrated outstanding iodine adsorption, removing 95% of iodine from aqueous solution within 200 min and maintaining high efficiency and structural stability over four adsorption–desorption cycles. This study offers a new strategy for designing radioactive iodine adsorbents and enhances the understanding of interactions between unsaturated metal sites and iodine species.