Two new, isostructural UiO-66-type metal–organic frameworks (MOFs), Zr-PyDC (Zr6O4(OH)5(pyridine-2,5-dicarboxylate)4(formate)3(H2O)34) and Zr-PzDC (Zr6O4(OH)4.75(pyrazine-2,5-dicarboxylate)4.5(formate)2.25(H2O)33) have been synthesised via an unusual high acidity route. Despite the chelating capability of the ligands, which incorporate pyridine and pyrazine N-functionalities, these robust MOFs are linked exclusively through carboxylate donors to leave free Lewis base donor sites. Both MOFs show increased heats of adsorption and higher loadings of CO2 and H2 than UiO-66. High-conversion post-synthetic modification of Zr-PyDC and Zr-PzDC yielded charged, N-methylated frameworks with enhanced gas adsorption capacities. Further, the metal binding properties of Zr-PyDC have been probed by post-synthetic metallation with CuII.
