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Exploring the role of cluster formation in UiO family Hf metal–organic frameworks with in situ X-ray Pair Distribution Function analysis

DOI: 10.1021/jacs.1c06990 DOI Help

Authors: Francesca C. N. Firth (University of Cambridge) , Michael W. Gaultois (University of Cambridge) , Yue Wu (University of Liverpool) , Joshua M. Stratford (University of Birmingham) , Dean S. Keeble (Diamond Light Source) , Clare P. Grey (University of Cambridge) , Matthew J. Cliffe (University of Nottingham)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: November 2021
Diamond Proposal Number(s): 18630

Open Access Open Access

Abstract: The structures of Zr and Hf metal–organic frameworks (MOFs) are very sensitive to small changes in synthetic conditions. One key difference affecting the structure of UiO MOF phases is the shape and nuclearity of Zr or Hf metal clusters acting as nodes in the framework; although these clusters are crucial, their evolution during MOF synthesis is not fully understood. In this paper, we explore the nature of Hf metal clusters that form in different reaction solutions, including in a mixture of DMF, formic acid, and water. We show that the choice of solvent and reaction temperature in UiO MOF syntheses determines the cluster identity and hence the MOF structure. Using in situ X-ray pair distribution function measurements, we demonstrate that the evolution of different Hf cluster species can be tracked during UiO MOF synthesis, from solution stages to the full crystalline framework, and use our understanding to propose a formation mechanism for the hcp UiO-66(Hf) MOF, in which first the metal clusters aggregate from the M6 cluster (as in fcu UiO-66) to the hcp-characteristic M12 double cluster and, following this, the crystalline hcp framework forms. These insights pave the way toward rationally designing syntheses of as-yet unknown MOF structures, via tuning the synthesis conditions to select different cluster species.

Journal Keywords: Cluster structure; Metal clusters; Metal organic frameworks; Solvents; Cluster chemistry

Subject Areas: Chemistry, Materials

Instruments: I15-1-X-ray Pair Distribution Function (XPDF)

Added On: 19/11/2021 08:43


Discipline Tags:

Materials Science Metallurgy Metal-Organic Frameworks Chemistry Organometallic Chemistry

Technical Tags:

Scattering Pair Distribution Function (PDF) Total Scattering