Exploring the Role of Hexanuclear Clusters as Lewis Acidic Sites in Isostructural Metal-Organic Frameworks

Jiafei Lyu, Xuan Zhang, Peng Li, Xingjie Wang, Cassandra T. Buru, Peng Bai, Xianghai Guo, Omar K. Farha*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Metal-organic frameworks (MOFs) have been extensively investigated as Lewis acidic catalysts for a variety of reactions. However, the identity and nature of the MOF nodes in the catalysis remain ill-defined. Herein, a series of isostructural MOFs (M-NU-1008), with M being hexanuclear clusters of transition metals (Zr and Hf), a lanthanide (Ce), or an actinide (Th), were successfully synthesized and evaluated as Lewis acid catalysts, and CO2 cycloaddition of styrene oxide was used as a test reaction. Superior catalytic activity was observed with Ce-NU-1008 over the other M6-based MOFs. In addition to the different Lewis acidities among the metals in the four M-NU-1008, the dissociation of terminal water molecules from the M6 clusters before exposing the Lewis acidic metal sites was found to vary between the MOFs, as supported by variable-temperature diffuse reflectance infrared Fourier transform spectroscopy studies. In the MOFs where water dissociation from the metal nodes readily occurs, the catalytic activity is higher than the MOFs where water is bound more strongly. Upon further investigation, Hf-NU-1008-dehy with terminal water partially removed was found to exhibit enhanced activity compared to the as-prepared catalyst.

Original languageEnglish (US)
Pages (from-to)4166-4172
Number of pages7
JournalChemistry of Materials
Volume31
Issue number11
DOIs
StatePublished - Jun 11 2019

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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