Rare 3D Heterometallic–Organic Frameworks Built from [M 6 ] (M = Zr, Hf) and [Cu 2 I 2 ] Clusters for Iodine Vapor Capture

Precisely synthesizing Zr/Hf-oxo and 3d metal cluster-based heterometallic–organic frameworks (HMOFs) still faces huge challenges: coordination competition between Zr 4+ /Hf 4+ and 3d metal ions toward ligands and crystallization difficulties inherent to Zr/Hf-oxo cluster systems. Herein, we chose an eight-connected [M 6 (μ 3 -O) 4 (μ 3 -OH) 4 (OH) 4 (H 2 O) 4 ] 8+ (M = Zr, Hf) motif and a four-connected [Cu 2 I 2 ] cluster as second building units and linear isonicotinate (INA) as an organic linker to construct two rare three-dimensional HMOFs {[Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (OH) 4 (H 2 O) 4 ][(Cu 2 I 2 )(INA) 4 ] 2 ·8H 2 O·7DMF} n ( NS-7 ) and {[Hf 6 (μ 3 -O) 4 (μ 3 -OH) 4 (OH) 4 (H 2 O) 4 ][(Cu 2 I 2 )(INA) 4 ] 2 ·8H 2 O·7DMF} n ( NS-8 ) via self-assembly under solvothermal condition. Activated NS-7 and NS-8 with amorphous nonmicroporous structures still exhibited high iodine adsorption capacities of 2.09 and 1.87 g·g –1 via the confirmation of static iodine vapor adsorption experiments, respectively, being superior to most previously reported pure Zr-/Hf-oxo or copper(I)-iodide cluster-based metal–organic frameworks. Our work not only enriches the documents of Zr-/Hf-oxo cluster-based HMOFs but also provides some instructive suggestions in the design and synthesis of novel multicomponent cluster-based metal–organic frameworks.