Role of a Modulator in the Synthesis of Phase-Pure NU-1000
Citations Over TimeTop 11% of 2017 papers
Abstract
NU-1000 is a robust, mesoporous metal-organic framework (MOF) with hexazirconium nodes ([Zr6O16H16]8+, referred to as oxo-Zr6 nodes) that can be synthesized by combining a solution of ZrOCl2·8H2O and a benzoic acid modulator in N,N-dimethylformamide with a solution of linker (1,3,6,8-tetrakis(p-benzoic acid)pyrene, referred to as H4TBAPy) and by aging at an elevated temperature. Typically, the resulting crystals are primarily composed of NU-1000 domains that crystallize with a more dense phase that shares structural similarity with NU-901, which is an MOF composed of the same linker molecules and nodes. Density differences between the two polymorphs arise from the differences in the node orientation: in NU-1000, the oxo-Zr6 nodes rotate 120° from node to node, whereas in NU-901, all nodes are aligned in parallel. Considering this structural difference leads to the hypothesis that changing the modulator from benzoic acid to a larger and more rigid biphenyl-4-carboxylic acid might lead to a stronger steric interaction between the modulator coordinating on the oxo-Zr6 node and misaligned nodes or linkers in the large pore and inhibit the growth of the more dense NU-901-like material, resulting in phase-pure NU-1000. Side-by-side reactions comparing the products of synthesis using benzoic acid or biphenyl-4-carboxylic acid as a modulator produce structurally heterogeneous crystals and phase-pure NU-1000 crystals. It can be concluded that the larger and more rigid biphenyl-4-carboxylate inhibits the incorporation of nodes with an alignment parallel to the neighboring nodes already residing in the crystal.
Related Papers
- → SF5-Synthons: Pathways to Organic Derivatives of SF6(2005)31 cited
- → Supramolecular Synthons: Will Giant Rigid Superspheres Do?(2016)16 cited
- → A mathematical model of the synthon(1988)11 cited
- → Mathematical Model of Synthon Reactions(1989)1 cited
- → ChemInform Abstract: Ethynylglycine Synthon, a Useful Precursor for the Synthesis of Biologically Active Compounds: an Update ‐ Part I: Preparations of Ethynylglycine Synthon(2015)