Stable Microporous Metal–Organic Framework Based on Tritopic Pyrazolate Ligand for Xe/Kr Separation

Pyrazolate ligands, renowned for their potent electron-donating capabilities, have emerged as promising building blocks for the construction of stable metal-organic frameworks (MOFs) particularly when paired with late transition metals. While a plethora of diverse MOFs have been meticulously crafted using ditopic pyrazolate ligands, the realm of multidentate pyrazolate-based MOF structures remains relatively unexplored. This research unveils a notable achievement in the synthesis of a novel three-dimensional microporous MOF, characterized by its single-crystal form, meticulously assembled from a tritopic pyrazole ligand and cobalt ions. This structure exhibits high structural robustness, withstanding pH conditions ranging from 4 to 12. The robust framework, adorned with micropores, bestows upon it an exceptional ability to perform durable and efficient xenon (Xe)-krypton (Kr) separation. It demonstrates a high Xe uptake of 23.80 cm³ g^-1 (1.06 mmol g^-1) at 0.1 bar and 55 cm³ g^-1 (2.46 mmol g^-1) at 1 bar, along with a notable selectivity of 13 for Xe over Kr.