A high connectivity metal–organic framework with exceptional hydrogen and methane uptake capacities

Abstract

A 6,8-connected 3-dimensional metal–organic framework (2) of the tph topology was constructed from a new aromatic-rich, tetraphenylmethane-derived octa-carboxylate bridging ligand and trizinc cluster secondary building units (SBUs), and exhibited exceptionally high hydrogen (58 mg g⁻¹ and 39 g L⁻¹ at 52 bar and 77 K) and methane (276 mg g⁻¹ and 189 g L⁻¹ at 80 bar and 298 K) uptake capacities. 2 has the highest hydrogen uptake at 298 K among all of the MOFs that have been examined to date. The gravimetric and volumetric methane uptake capacities for 2 are the highest among thousands of MOFs that have been evaluated. We attribute the exceptionally high gas uptake capacities of 2 to the highly branched, aromatic-rich nature of the bridging ligand, optimal pore size, and the open metal sites in the trizinc SBUs in a stable high-connectivity MOF.