A (3,6)-connected metal–organic framework with high CH4 binding affinity and uptake capacity

Abstract

A (3,6)-connected metal–organic framework with a fit-3 topology, [CuL(NO₃)]·2DMF·H₂O (NJU-Bai16), has been synthesized by self-assembly of binuclear [Cu₂(COO)₂N₄] building blocks and heterofunctional ligand 3,5-di(pyridin-4-yl) benzoic acid (HL). The small pores within the framework have enabled their strong interactions with CH₄ molecules. NJU-Bai16 was thereby found to exhibit high isosteric heats of CH₄ adsorption (23.3 kJ mol⁻¹) and uptake capacity (50.3 cm³ g⁻¹ at 1 bar and 273 K). Additionally, NJU-Bai16 demonstrates high CO₂ uptake (22.4 wt% at 1 bar) with excellent selectivity for CO₂ over N₂ (29.7) at 273 K.