[Cu ₁₂ L ₈ ] Coordination Cage-Based Metal–Organic Framework for Iodine Capture

The electron-rich moieties and aromatic conjugated units are beneficial for promoting the adsorption and capture of iodine. Based on this principle, this study uses a triazine derivative poly(carboxylic acid) ligand H₆TMTTA as an organic ligand and Cu²⁺ as a metal node to construct a novel cage-based MOF material (IHEP-52). This (4, 6)-connected soc net features a cage-like structure [Cu₁₂L₈]. The dynamic nanochannel architecture of IHEP-52 facilitates rapid guest exchange while exhibiting exceptional iodine capture under ambient conditions. Quantitative adsorption studies reveal a maximum capacity of 366.4 mg·g⁻¹ for iodine in cyclohexane solution (298 K) and 1763.9 mg·g⁻¹ for iodine vapor (353 K), with equilibration achieved within 6 h at 393 K. Raman spectra and X-ray photoelectron spectroscopy (XPS) analysis demonstrate that adsorbed iodine undergoes framework-mediated disproportionation to form costabilized I₃⁻ and I₅⁻ anions within the pore structures of IHEP-52.