A new set of metal–organic frameworks synthesised from diisophthalate-based, 2′-phosphorus-substituted m-terphenyl linker molecules

Abstract

Four metal–organic frameworks employing the m-terphenyl diisophthalate linker molecule with 2′ substitution by P(V)-based functional groups of the central aryl have been synthesised. The dense packing of POMe₂/PSMe₂ functional groups within UHM-60/UHM-61 (UHM: University of Hamburg Materials) with an underlying net of ucp topology was overcome by increasing the sterical demand of phosphorus substituents. Replacement of the PEMe₂ (E = O, S) functional groups by POEt₂ or POPh₂ gave UHM-62 and UHM-63, respectively, where valid deconstructions of the underlying topology to types 3,3,4,4T199, tim, and tst were found. The potential influence of the now-accessible phosphoryl functional group towards CO₂ and CH₄ adsorption as well as the selectivity towards CO₂/CH₄ separation was studied. Based on a comprehensive survey of literature-known Cu(II)-based MOFs with m-terphenyl-based linker molecules, we propose the deconstruction of inter-isophthalate plane angles to angular components of twist and fold allowing for the sophisticated classification of topologies that can be realised in Cu(II)-based MOFs using the m-terphenyl tetracarboxylate linker molecule.