Two New 1D Supramolecular Compounds Based on PbI₂ for Efficient Iodine Capture

Two new inorganic-organic hybrid crystals based on PbI₂ were assembled through the solvent evaporation method, namely, {[L1]·[Pb₂I₆]}_n (1) and {[L2]₂·[Pb₃I₁₀]}_n (2). L1-L2 are a series of multivalent nitrogen-containing cationic ligands. Compounds 1-2 were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR, powder X-ray diffraction, and thermogravimetric microanalysis. The results showed that the adsorption rate of 80 mg compound 1 to iodine reached 96.59%, indicating a high iodine capture performance in cyclohexane solution. In the meantime, the adsorption kinetics is most suitable for a pseudo-second-order model, and the adsorption process is mainly chemisorption. Adsorption thermodynamics is most suitable for the Langmuir model, indicating that adsorption occurs on the surface of the monolayer. According to the adsorption mechanism, it can be inferred that the structure of compound 1 contains amino, benzene, N heterocyclic, and other active groups, that is, indirectly increases the adsorption site with iodine, and the chemical reaction with iodine improves the removal rate of iodine in cyclohexane solution. In addition, compound 1 was found to have good iodine adsorption and recyclability by cyclic experiments. Therefore, the synthesized compound 1 can be used as a potential and excellent iodide capture adsorbent, which may have a good application prospects in the future.