A porous mixed-valent iron MOF exhibiting the acs net: Synthesis, characterization and sorption behavior of Fe3O(F4BDC)3(H2O)3·(DMF)3.5

A new mixed-valent iron MOF, formulated as Fe3O(F4BDC)3(H2O)3·(DMF)3.5 (1), has been synthesized by using a perfluorinated linear dicarboxylate to link trigonal prismatic Fe3(μ3-O)(O2C–)6 clusters. The structure refinement based on single crystal X-ray diffraction data collected from 1 reveals the material exhibits the acs topology with large channels along the crystallographic c-axis. Due to the presence of fluorine atoms the organic link, 2,3,5,6-tetrafluorobenzene-1,4-dicarboxylate (F4BDC), has a 63° torsion angle between the carboxylate and aromatic planes, resulting in larger channels compared to those in the isoreticular material MOF-235. While few iron-based MOFs have demonstrated porosity, nitrogen and hydrogen sorption experiments carried out at 77 K proved the porosity of outgassed 1, which has a Langmuir surface are of 635 m2/g and a gravimetric capacity of 0.9 wt% of hydrogen at 1 bar.