Synthetic Control of Thorium Metal-Organic Frameworks for Sequencing and Sensing of Radioiodine Species

Exploring the physiochemical properties and expanding the applications of actinide-containing materials is paramount to address the escalating challenge of radioactive waste accumulation. However, unlocking the full potential of these materials is largely crippled by the radiotoxicity of the actinides. We report here two porous and luminescent thorium-based metal-organic frameworks (Th-BITD-1 and Th-BITD-2) that serve as a bifunctional platform for sequencing and sensing of radioiodine, a much more radioactive fission product discharged during the nuclear fuel reprocessing. In particular, Th-BITD-1 displays better iodine uptake performance than Th-BITD-2 via the solution-based process and vapor diffusion with the maximum adsorption capacities of 831 and 1099 mg/g, respectively. Furthermore, Th-BITD-1 can function as a highly sensitive luminescence sensor for iodate with a quenching constant (K_SV) of 6.6(5) × 10³ M⁻¹ and a detection limit of 2.02 μM, respectively, outperforming 2.96(6) × 10³ M⁻¹ and 10.5 μM of Th-BITD-2. Moreover, a positive correlation between the sensing efficacy and the iodate adsorption capacity has been revealed. This work highlights the opportunity in designing novel actinide-based MOFs for their potential applications in radiological fields, e.g., radionuclide separation and detection.