Post-synthetic ligand exchange in the prototypical zirconium-based metal–organic framework (MOF) UiO-66 was investigated by in situ solution 1H NMR spectroscopy. Samples of UiO-66 having different degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect-free UiO-66, whereas monocarboxylates grafted at defect sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing-cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and showed that the physical-chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework.

Post-Synthetic Ligand Exchange in Zirconium-Based Metal–Organic Frameworks: Beware of The Defects!

Taddei M.
Co-primo
;
2018

Abstract

Post-synthetic ligand exchange in the prototypical zirconium-based metal–organic framework (MOF) UiO-66 was investigated by in situ solution 1H NMR spectroscopy. Samples of UiO-66 having different degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect-free UiO-66, whereas monocarboxylates grafted at defect sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing-cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and showed that the physical-chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework.
Taddei, M.; Wakeham, R. J.; Koutsianos, A.; Andreoli, E.; Barron, A. R.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/1024462
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