Role of a Modulator in the Synthesis of Phase-Pure NU-1000

Thomas E. Webber, Wei-Guang Liu, Sai Puneet Desai, Connie C Lu, Donald G Truhlar, Lee Penn

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61 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)39342-39346
Number of pages5
JournalACS Applied Materials and Interfaces
Issue number45
StatePublished - Nov 15 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.


  • NU-1000
  • metal infiltration
  • metal-organic frameworks
  • modulator
  • phase-pure synthesis


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