Enhancing Proton Conduction in a Metal–Organic Framework by Isomorphous Ligand Replacement

Using the concept of isomorphous replacement applied to entire ligands, a <i>C</i>₃-symmetric trisulfonate ligand was substituted with a <i>C</i>₃-symmetric tris­(hydrogen phosphonate) ligand in a proton conducting metal–organic framework (MOF). The resulting material, PCMOF2¹/₂, has its proton conduction raised 1.5 orders of magnitude compared to the parent material, to 2.1 × 10^–2 S cm^–1 at 90% relative humidity and 85 °C, while maintaining the parent MOF structure