A zirconium metal-organic framework with an exceptionally high volumetric surface area

A zirconium metal-organic framework (MOF), PCN-111, has been synthesized by using an elongated ditopic carboxylate linker, 4,4'-(buta-1,3-diyne-1,4-diyl)dibenzoate. Single crystal X-ray diffraction characterization indicates that the noninterpenetrated microporous structure of PCN-111 is isoreticular to UIO MOFs with 12 connected Zr₆O₄(OH)₄(CO₂)₁₂ clusters and a fcu topology. It was successfully activated through a solvent exchange with acetone followed by controlled evacuation and its gas sorption was reported. By using 77 K nitrogen adsorption isotherm and strictly applying three consistency criteria, the BET surface area for PCN-111 was calculated to be 4825 m² g^-1. Pore size distribution analysis suggests that the sizes of cavities contributing to nitrogen adsorption are predominately in the range of 15 to 20 Å, which are in good agreement with the two polyhedral cages (15.6 and 20.2 Å, respectively) in the single crystal X-ray solved structure. Owing to its relatively high crystal density (0.42 g cm^-3), the volumetric surface area for PCN-111 was calculated to be 2026 m² cm^-3. The value is among the highest of all the reported ultrahigh surface area MOF materials. The exceptionally high microporosity of PCN-111 has also been validated by comparison with the simulated nitrogen adsorption isotherm derived from multipurpose simulation code MUSIC.