Crystallographic Visualization of Distinct Iodic Aggregations in Isostructural Metal–Organic Frameworks
Yi Han, Yiwen He, Yu Xiang Fu, Hongliang Huang, Hongdong Li, Jiong‐Peng Zhao, Lei Wang, Qian Niu, Nathaniel L. Rosi
Abstract
High Resolution Image Download MS PowerPoint Slide Precisely determining the location of adsorbed molecules is essential for illuminating the mechanisms underlying molecular confinement within porous metal–organic frameworks (MOFs). Here, we present the pore-filling and reactive adsorption of iodine in ALP-MOF-1 and its isostructural redox-active ALP-MOF-2. The adsorbed iodine molecules (I 2 ) are unaffected by Zn(II) in ALP-MOF-1 and are exclusively confined into an unusual three-dimensional (3D) iodine aggregation due to the 3D cross-linked pore topology and multiple I 2 -framework interactions. Conversely, in ALP-MOF-2, the adsorbed I 2 enables the oxidation of Co(II) to Co(III), which is accompanied by the reduction of I 2 to I 3 – and the formation of I 5 – and I 2 during continuous I 2 loading. Identification of distinct iodine adsorption processes in ALP-MOF-1 and −2 motivated tuning of the metal ion composition to adjust the adsorption mechanism. The iodic aggregations in both MOFs are unambiguously confirmed by the combination of single crystal X-ray diffraction and spectroscopic characterization. The presence of multiple adsorption sites facilitate rapid iodine uptake of ∼179 wt % in ALP-MOF-1 and ∼150 wt % in ALP-MOF-2 within ∼5 h, which could be advantageous for applications requiring rapid and energy-efficient iodine capture.