Imidazole\nEncapsulation Enabled by Confinement for\nI<sub>2</sub> and CH<sub>3</sub>I Coremoval

Nitrogen-rich small molecules are frequently doped into\nporous\nmaterials to enhance their iodine adsorption properties. To explore\nhow imidazole confinement in metal–organic frameworks (MOFs)\naffects iodine adsorption, we obtained a UiO-66-based composite by\nembedding imidazole in UiO-66 pores via solid-phase adsorption (Im@UiO-66).\nCharacterization confirmed that imidazole was successfully confined\nwithin the UiO-66 pores, with each unit of UiO-66 accommodating up\nto 27 imidazole molecules. The density functional theory (DFT) calculations\nsuggested that the octahedral cages of UiO-66 are the primary sites\nfor iodine capture. The adsorption studies revealed that Im@UiO-66\nachieved maximum adsorption capacities for I<sub>2</sub> and CH<sub>3</sub>I that were 12 and 7.9 times higher than those of UiO-66,\nrespectively, reaching 6.42 g/g for I<sub>2</sub> and 553 mg/g for\nCH<sub>3</sub>I. The spectroscopic analysis indicated that Im@UiO-66\nabsorbed iodine vapor and methyl iodide via charge-transfer interactions\nand <i>N</i>-methylation reactions. This study demonstrates\nthat imidazole confinement can effectively enhance the adsorption\nperformance of MOF-based materials, offering valuable insights for\nthe design of iodine adsorbents.