Size Control of the MOF NU-1000 through Manipulation of the Modulator/Linker Competition

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 mono-disperse NU-1000 from 300 nm to almost 10 mu m 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.