Correlated Defects in Metal Organic Frameworks Using Theory-guided Inelastic Neutron Scattering

January 31, 2023
Correlated Defects in Metal Organic Frameworks Using Theory-guided Inelastic Neutron Scattering
Experimental neutron spectra of UiO66 (blue curve, exp(AA)) and simulations with introduction of different defects. Simulations include the bcu unit cell with 4 missing linker sites occupied by formate ligands (bcu-4F), acetate ligands (bcu-4A), two formate groups and two acetate groups in a diagonal fashion (bcu-2A2F), and a 2x1x1 supercell with diagonal and off-diagonal defects (bcu-2A2F-2F2A).The vibrational mode corresponding to the “a” peak in the bcu-2A2F simulation is shown on the left.

Scientific Achievement

A combination of inelastic neutron scattering (INS) and density functional theory (DFT) is used to characterize the arrangement of node defects around the metal oxide core of a typical metal-organic framework (MOF) (UiO66).

Significance and Impact

The demonstrated INS / DFT approach for spectroscopic defect characterization provides unprecedented molecular details about the organization and coordination of defects in MOFs which play an important role in the stability of these materials for potential applications.

Research Details

  • UiO66 has Zr-oxide nodes with 12 possible linker attachment sites. Acetate and formate defects were introduced in varying amounts and INS from these samples was measured at VISION.
  • DFT simulations examined defect-induced topologies and identified fingerprint modes in the far-IR INS spectra that correlate unambiguously with defect types.

“Elucidating correlated defects in metal organic frameworks using theory-guided inelastic neutron scattering spectroscopy”
Lucas S. R. Cavalcante, Makena A. Dettmann, Tyler Sours, Dong Yang, Luke L. Daemen, Bruce C. Gates, Ambarish R. Kulkarni and Adam J. Moule
Materials Horizons (2022). DOI: https://doi.org/10.1039/d2mh00914e.