Computation-informed optimization of Ni(PyC)(2) functionalization for noble gas separations

N Gantzler and MB Kim and A Robinson and MW Terban and S Ghose and RE Dinnebier and AH York and D Tiana and CM Simon and PK Thallapally, CELL REPORTS PHYSICAL SCIENCE, 3, 101025 (2022).

DOI: 10.1016/j.xcrp.2022.101025

Our objective is to tune a "lead "metal-organic framework, Ni(PyC)(2) (pyridine-4-carboxylate PyC), by functionalizing its PyC ligands to maximize its adsorptive selectivity for xenon over krypton at room temperature. To guide experiments, we (1) construct a library of Ni(PyC-X)(2) (X = functional group) crystal structure models then (2) use molecular simulations to predict their noble gas adsorption and selectivity at room temperature. Motivated by our virtual screening, we synthesize Ni(PyC-m-NH2)(2), determine its crystal structure by X-ray powder diffraction, measure its Xe, Kr, and Ar adsorption isotherms (298 K), and indeed find that its dilute Xe/Kr selectivity at 298 K (20) exceeds that of its parent Ni(PyC)(2) (17). Corroborated by molecular models, in situ X-ray diffraction shows that Ni(PyC-m-NH2)2 organizes well-defined, Xe-tailored binding pockets along its one-dimensional channels. Our study illustrates the computation-informed optimization of a "lead "metal-organic framework.

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