NU-1000 is a stable, zirconium-based metal–organic framework (MOF) that has been used extensively as a scaffold for the installation of catalytic species, among other applications. The synthesis of NU-1000 follows a two-step modulated procedure, whereby the MOF grows as modulator molecules bound to the node are replaced with organic linker molecules. Manipulating the competition between the modulator and linker molecules for the binding sites on the node leads to control of reaction rate and the resulting NU-1000 particle size. By modifying the linker, modulator, and base concentrations and zirconium precursor, we can synthesize high-purity and monodisperse NU-1000 from 300 nm to almost 10 μm in length. Despite a wide range of particle sizes and synthetic conditions, the uptake of a dicobalt complex remained consistent per node. Further control over particle size can lead to more facile high-resolution characterization using methods like electron microscopy and spectroscopy as well as open a wider range of potential applications, including nanoscale applications like biological imaging.

Water oxidation is catalysed in Nature by a redox cofactor embedded in a hydrogen-bonded network designed to orchestrate proton transfer throughout the challenging 4 electron reaction.

Metal–organic framework (MOF) materials have shown promise in many applications, ranging from gas storage to absorption and catalysis. Because of the high porosity and low density of many MOFs, densification methods such as pelletization and extrusion are needed for practical use and for commercialization of MOF materials. Therefore, it is important to elucidate the mechanical properties of MOFs and to develop methods of further enhancing their mechanical strength. Here, we demonstrate the influence of phase purity and the presence of a pore-reinforcing component on elastic modulus and yield stress of NU-1000 MOFs through nanoindentation methods and finite element simulation. Three types of NU-1000 single crystals were compared: phase-pure NU-1000 prepared with biphenyl-4-carboxylic acid as a modulator (NU-1000-bip), NU-1000 prepared with benzoic acid as a modulator (NU-1000-ben), which results in an additional, denser impurity phase of NU-901, and NU-1000-bip whose mesopores were infiltrated with silica (SiO x (OH) y @NU-1000) by nanocasting methods. By maintaining phase purity and minimizing defects, the elastic modulus could be enhanced by nearly an order of magnitude: phase-pure NU-1000-bip crystals exhibited an elastic modulus of 21 GPa, whereas the value for NU-1000-ben crystals was only 3 GPa. The introduction of silica into the mesopores of NU-1000-bip did not strongly affect the measured elastic modulus (19 GPa) but significantly increased the load at failure from 2000 μN to 3000–4000 μN.

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