Functionalization of mono- and bimetallic MIL-100(Al,Fe) MOFs by ethylenediamine: post-functionalization, Brønsted acido-basicity and unique CO2 sorption behaviour

19 July 2021, Version 1

Abstract

The metal sites of MIL-100(Fe), MIL-100(Fe,Al) and MIL-100(Al) MOFs were decorated with ethylenediamine (EN). Interestingly, the Al-containing MOFs presented hierachized porosity, and their structural integrity was maintained upon functionalization. Solution and solid-state NMR confirmed the grafting efficiency in the case of MIL-100(Al) and the presence of a free amine group. It was shown that MIL-100(Al) can be functionalized by only one EN molecule by trimeric Al3O cluster unit, whereas the two other aluminium sites are occupied by an hydroxyl and a water molecule. The -NH2 sites of the grafted ethylenediamine can be used for further post-functionalization through amine chemistry and is responsible for basicity of the functionalized material. Furthermore, the presence of coordinated water molecules on the Al-MOF is responsible for simultaneous Brønsted acidity and for a unique carbon dioxide sorption mecanism, that distinguishes this material from its iron and chromium counterparts.

Keywords

Metal-Organic Framework
MOF
Functionalization
Post-functionalization
Acid-base
CO2
Carbon dioxide
Aluminum
Iron
Bimetallic

Supplementary materials

Title
Description
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Title
Supporting Information for Functionalization of mono- and bimetallic MIL-100(Al,Fe) MOFs by ethylenediamine: post-functionalization, Brønsted acido-basicity and unique CO2 sorption behaviour
Description
Supporting Information. PXRD patterns, FTIR spectra, nitrogen adsorption isotherms, TGA curves and NMR spectra of the pristine and functionalized MOFs, diffuse reflectance spectra of bromothymol blue adsorbed MOFs and gravimetric CO2 sorption curves.
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