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

Journal Article · Wed Nov 01 00:00:00 EDT 2017 · ACS Applied Materials and Interfaces

DOI:https://doi.org/10.1021/acsami.7b11348· OSTI ID:1470050

Webber, Thomas E.  ^[1]; Liu, Wei-Guang  ^[2]; Desai, Sai Puneet ^[1]; Lu, Connie C.  ^[1]; Truhlar, Donald G.  ^[2]; Penn, R. Lee  ^[1]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry
2. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry, and Chemical Theory Center and Minnesota Supercomputing Inst.

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.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Energy Frontier Research Center for Inorganometallic Catalyst Design (ICDC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012702
• OSTI ID: 1470050
• Journal Information: ACS Applied Materials and Interfaces, Vol. 9, Issue 45; Related Information: ICDC partners with University of Minnesota(lead); Argonne National Laboratory; Clemson University; Dow Chemical Company; Northwestern University; Pacific Northwest National Laboratory; University of California Davis; University of Washington; ISSN 1944-8244
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
catalysis (heterogeneous)
materials and chemistry by design
synthesis (novel materials)