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Van 't Hoff Institute for Molecular Sciences Van 't Hoff Institute for Molecular Sciences

Synthesis of chiral metal-organic frameworks by post‐synthetic modification

27 May 2020

Using a combination of synthetic, spectroscopic and theoretical approaches, HIMS researchers have demonstrated that the post‐synthetic modification of MOFs is an effective approach for the synthesis of chiral materials. The study was carried out in collaboration with the group of Prof. Sharon Ashbrook at the University St Andrews.
molecule image
Image: HIMS

Abstract

The synthesis of chiral metal‐organic frameworks (MOFs) is highly relevant for asymmetric heterogeneous catalysis, yet very challenging. Chiral MOFs with MOF‐74 topology were synthesized using post‐synthetic modification with proline. Vibrational circular dichroism studies demonstrate that proline is the source of chirality. The solvents used in the synthesis play a key role in tuning the loading of proline and its interaction with the MOF‐74 framework. In N,N’‐dimethylformamide, proline coordinates monodentate to the Zn2+ ions within the MOF‐74 framework, whilst it is only weakly bound to the framework when using methanol as solvent. Introducing chirality within the MOF‐74 framework also leads to the formation of defects, with both the organic linker and metal ions missing from the framework. The formation of defects combined with the coordination of DMF and proline within the framework leads to a pore-blocking effect. This is confirmed by adsorption studies and testing of the chiral MOFs in the asymmetric aldol reaction between acetone and para ‐nitrobenzaldehyde.

Publication

Andreea Gheorghe, Benjamin Strudwick, Sander Woutersen, David Dubbeldam, Stefania Tanase, Synthesis of chiral MOF-74 frameworks using post-synthetic modification by an amino acid. Chemistry - A European Journal, Accepted 27 May 2020, DOI: 10.1002/chem.202002293.