Synthesis and activation of phase-pure and defect-free metal–organic frameworks (MOFs) are essential for establishing accurate structure–property relationships. Primarily suffering from missing linker and/or node defects, Zr6-based MOFs can have polymorphs, structures with the identical linker and node but different connectivity, which can create multiple phases in a sample that complicate the characterization. Here, we report the synthesis of phase-pure NU-1000, a mesoporous Zr6-based MOF that typically contains a significant secondary phase within the individual crystallites. Large biomolecules and smaller inorganic molecules have been installed in NU-1000 as probes to verify the near elimination of the microporous secondary-phase. Obtaining structurally homogenous MOFs will assist the design of new materials with distinct structural features.
