In situ Electron Magnetic Resonance study of coordinative and structural transformations in paramagnetically doped Metal Organic Frameworks

by EMR and COMOC research teams of UGent

This project of the EMR and COMOC teams of Ghent University aimed to gain insight in the catalytic activity and structural flexibility of metal-organic frameworks (MOFs). These porous network structures, built up from metal centres and organic linkers, allow tayloring structure, pore size and shape to desired functionality. They have potential applications in diverse fields (adsorption, catalysis, separations, ...).

Elementary reaction steps during catalysis and structural transformations were investigated on a selection of Al(III)-OH-, isostructural V(IV)=O-MOFs, and their mixtures. Electron magnetic resonance (EMR) was used as primary spectroscopic tool, as it provides quantitative and structural information on the metal complexes in MOFs, including their valence state and ligand structure. V(IV)=O EMR spectra can be detected in a wide temperature range, but in fully concentrated MOFs, they show limited resolution. Hence, EMR experiments on V(IV)=O-doped Al(III)-OH-MOFs have been used to monitor changes in the metal-ligand structure, during and after catalysis and framework transformations. The selection of studied MOFs includes one flexible Al(III)-OH-MOF for which the isostructural V(IV)=O-MOF has a rigid structure, and two for which the reverse behaviour is encountered. Studying V(IV)=O-doped Al(III)-OH-MOFs as function of concentration may therefore also elucidate the relation between metal-linker interactions and flexibility.

The research within this project resulted in the PhD theses of Irena Nevjestic and Hannes Depauw. Follow-up research led to the PhD thesis of Kwinten Maes.

Perspective view of MIL-47 (VIV=O(BDC))
Perspective view of MIL-47 (VIV=O(BDC))

In collaboration with COMOC, the radical reactions catalyzed by covalent organic frameworks (COFs) have recently also been studied using spin-trapping EPR.

Selected publications

Identification of vanadium dopant sites in the metal-organic framework DUT-5(Al)

Kwinten Maes (UGent) , Lisa Martin (UGent) , Samira Khelifi (UGent) , Alexander Hoffman (UGent) , Karen Leus (UGent) , Pascal Van Der Voort (UGent) , Etienne Goovaerts, Philippe Smet (UGent) , Veronique Van Speybroeck (UGent) , Freddy Callens (UGent) , et al.

(2021) PHYSICAL CHEMISTRY CHEMICAL PHYSICS. 23(12). p.7088-7100

 

Metal-free activation of molecular oxygen by covalent triazine frameworks for selective aerobic oxidation

Sara Abednatanzi (UGent) , Parviz Gohari Derakhshandeh (UGent) , Karen Leus (UGent) , Henk Vrielinck (UGent) , Freddy Callens (UGent) , Johannes Schmidt, Aleksandr Savateev and Pascal Van Der Voort (UGent)

(2020) SCIENCE ADVANCES. 6(14).

 

Elucidating the promotional effect of a covalent triazine framework in aerobic oxidation

Sara Abednatanzi (UGent) , Parviz Gohari Derakhshandeh (UGent) , Pieter Tack (UGent) , Francesco Muniz Miranda (UGent) , Ying-Ya Liu, Jonas Everaert (UGent) , Maria Meledina, Flore Vanden Bussche (UGent) , Laszlo Vincze (UGent) , Christian Stevens (UGent) , et al.

(2020) APPLIED CATALYSIS B-ENVIRONMENTAL. 269.