Structural analysis of interpenetrated methyl‐modified MOF‐5 and its gas‐adsorption properties

The first example of an interpenetrated methyl‐modified MOF‐5 with the formula Zn4O(DMBDC)3(DMF)2, where DMBDC2− is 2,5‐dimethylbenzene‐1,4‐dicarboxylate and DMF is N,N‐dimethylformamide (henceforth denoted as Me2MOF‐5‐int), namely, poly[tris(μ4‐2,5‐dimethylbenzene‐1,4‐dicarboxylato)bis(N,N‐dimethylformamide)‐μ4‐oxido‐tetrazinc(II)], [Zn4(C10H8O4)3O(C3H7NO)2]n, has been obtained from a solvothermal synthesis of 2,5‐dimethylbenzene‐1,4‐dicarboxylic acid and Zn(NO3)2·6H2O in DMF. A systematic study revealed that the choice of solvent is of critical importance for the synthesis of phase‐pure Me2MOF‐5‐int, which was thoroughly characterized by single‐crystal and powder X‐ray diffraction (PXRD), as well as by gas‐adsorption analyses. The Brunauer–Emmett–Teller surface area of Me2MOF‐5‐int (660 m2 g−1), determined by N2 adsorption, is much lower than that of nonpenetrated Me2MOF‐5 (2420 m2 g−1). However, Me2MOF‐5‐int displays an H2 uptake capacity of 1.26 wt% at 77 K and 1.0 bar, which is comparable to that of non‐interpenetrated Me2MOF‐5 (1.51 wt%). We report the controlled synthesis of non‐interpenetrated and interpenetrated methyl‐modified MOF‐5, which exhibit different pore structures. These compounds were prepared via a solvothermal synthesis, in which the choice of solvent is of critical importance.