New Supercage Metal-Organic Framework Based on Allopurinol Ligands Showing Acetylene Storage and Separation

To develop efficient adsorbent materials for storage and separation of C₂ H₂ , an unprecedented supercage MOF, [Me₂ NH₂ ]⋅[Zn₃ (ALP)(TDC)_2.5 ]⋅3.5DMF⋅2 H₂ O (1) was constructed through medicinal molecule allopurinol (ALP) and S-containing 2,5-thiophenedicarboxylic acid (H₂ TDC). 1 contains a novel linear trinuclear cluster that is composed by ALP and carboxylates and forms a final uncommon 5-connected yfy topological framework. The framework possesses three types of interlinked cages decorated by rich functional sites, and reveals not only high adsorption capacity for C₂ H₂ but also excellent selective separation for C₂ H₂ /CO₂ and C₂ H₂ /CH₄ at 298 K. Dynamic breakthrough experiments on C₂ H₂ /CO₂ (1:1) mixture and C₂ H₂ /CH₄ (1:1) mixture also demonstrated the potential of the material to separate C₂ H₂ from CO₂ or CH₄ mixtures. Molecular simulations were also studied to identify the different CO₂ - and C₂ H₂ - binding sites in 1, such as carboxylate groups, S atoms and carbonyl groups.