Rational design of phosphonocarboxylate metal–organic frameworks for light hydrocarbon separations

Abstract

Metal–organic frameworks (MOFs) provoke intensive research interests on separations of small gas molecules. By introducing a coordinative phosphate group into a carboxylic acid linker, a ligand 4,4′-(hydroxyphosphoryl) dibenzoic acid (H₃hpda) was successfully synthesized and used to construct microporous phosphonocarboxylate framework [Cu₃(hpda)₂·DMF·2H₂O]·3DMF·H₂O (DMF = N,N-dimethylformamide) and [Mg₃(μ₂-OH₂)₂(OH₂)₂(hpda)₂]·3DMF·2H₂O. Both of them possess narrow approachable channels and exhibit excellent performance on selective separation of light hydrocarbons (C₁–C₂), presenting a promising ligand design strategy for the construction of porous material aiming for natural gas upgrading.