Cage-Based Metal–Organic Framework Featuring a Double-Yolk Core–Shell U<sub>6</sub>L<sub>3</sub>@U<sub>18</sub>L<sub>14</sub> Structure for Iodine Capture
Shuang Deng, Xiang‐he Kong, Xuan Fu, Zhiwei Huang, Zhiheng Zhou, Lei Mei, Jipan Yu, Li‐Yong Yuan, Yanqiu Zhu, Nannan Wang, Kong‐Qiu Hu, Wei‐Qun Shi
Abstract
Cage-based MOFs, with their customizable chemical environments and precisely controllable nanospaces, show great potential for the selective adsorption of guest molecules with specific structures. In this work, we have constructed a novel cage-based MOF [(CH 3 ) 2 NH 2 ] 2 [(UO 2 ) 2 (TMTTA)]·11.5DMF·2H 2 O (IHEP-51), utilizing a triazine derivative poly(carboxylic acid), 4,4′,4″-(((1,3,5-triazine-2,4,6-triyl)tris(((4-carboxycyclohexyl)methyl)azanediyl))tris(methylene))tribenzoic acid (H 6 TMTTA), as an organic ligand and uranyl as a metal node. The 2-fold interpenetrated (3,6,6)-connected framework of IHEP-51 features two types of supramolecular cage structures: the Pyrgos[2]cage U 6 L 3 and the huge cage U 18 L 14 . They are further assembled into a double-yolk core–shell U 6 L 3 @U 18 L 14 structure, making it suitable for I 2 capture. The maximum adsorption capacities of IHEP-51 for iodine in solution and gaseous iodine are 420.4 and 1561.2 mg·g –1, respectively. XPS, Raman spectra, single-crystal X-ray diffraction, and DFT calculations reveal that the adsorbed iodine is located inside the U 6 L 3 Pyrgos[2]cage in the form of I 3 –, thus resulting in the formation of a (I 3 ) 2 @U 6 L 3 @U 18 L 14 ternary core–shell structure.