Dual Capture of Iodine and Methyl Iodide Using Nonporous Nitrogen-Enriched Palladium(II) Assemblies

Abstract

The increasing reliance on nuclear energy amid fossil fuel depletion has intensified the demand for effective materials to capture and store radioactive species. Among these, molecular iodine and methyl iodide present serious environmental and health risks due to their volatility and persistence in nuclear waste. Herein, four nonporous self-assembled metallo-supramolecular assemblies (C1–C4) containing nitrogen-enriched cores (pyridyl, pyrimidine, or phenazine units) with distinct cavity sizes were investigated for their potential in simultaneous capture of both iodine and organic iodide. In the vapor phase, the assemblies achieved exceptional iodine uptake of up to 3.03 g g^–1 at 75 °C, and in n-hexane solution, capacities reached 493.5 mg g^–1, highlighting the materials’ efficiency across different phases facilitated by electron-pair interactions. Additionally, these materials exhibited excellent performance in capturing methyl iodide vapor, with adsorption capacities as high as 1.2 g g^–1 via methylation reactions. The assemblies proved to be robust and reusable, maintaining their efficacy over at least five cycles without significant degradation. This work presents the first report on an N-heteroatom functionalization approach to design recyclable coordination assemblies for the safe and efficient capture and storage of radioactive iodine and methyl iodide, contributing to the mitigation of nuclear energy-associated risks.