Two heterovalent copper–organic frameworks with multiple secondary building units: high performance for gas adsorption and separation and I₂ sorption and release

Abstract

With the help of the multiple Secondary Building Unit (SBU) strategy, two novel heterovalent Cu–MOFs, [(C₄I₄)Cu₄L₄ (DABCO) ₂]•16DMF (JLU-Liu31) and [(Cu₄I₄)Cu₃L₃ (DABCO)(DMF) ₂]•18DMF (JLU-Liu32) [H₂L = pyridine-3,5-bis(phenyl-4-carboxylic acid), DABCO = 1,4-diazabicyclo[2.2.2]-octane], have been successfully solvothermally synthesized and structurally characterized. Both of the two compounds feature multiple SBUs and exhibit novel topologies. JLU-Liu31 possesses the largest sustainable pore volume among the MOFs based on Cu₄I₄ clusters. Moreover, the adsorption behaviours of the desolvated JLU-Liu31 material for some small gases (H₂, O₂, CO₂, CH₄, C₂H₆ and C₃H₈) have been analysed in low pressure regions; meanwhile, it exhibits commendable selectivity for O₂ over N₂ and C₃H₈ over CH₄. The remarkable results illustrate that JLU-Liu31 is a good candidate for application in the separation of light hydrocarbons. Additionally, JLU-Liu32 exhibits impressive performance for I₂ sorption and release in solvents.