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

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 (H(3)hpda) was successfully synthesized and used to construct microporous phosphonocarboxylate framework [Cu-3(hpda)(2)DMF2H(2)O]3DMFH(2)O (DMF = N,N-dimethylformamide) and [Mg-3((2)-OH2)(2)(OH2)(2)(hpda)(2)]3DMF2H(2)O. Both of them possess narrow approachable channels and exhibit excellent performance on selective separation of light hydrocarbons (C-1-C-2), presenting a promising ligand design strategy for the construction of porous material aiming for natural gas upgrading.