Elucidating Lewis acidity of metal sites in MFU-4l metal-organic frameworks: N2O and CO2 adsorption in MFU-4l, CuI-MFU-4l and Li-MFU-4l

• Published in: Microporous and mesoporous materials 2015-11, Vol.216, p.146-150
• Main Authors: Denysenko, Dmytro, Jelic, Jelena, Magdysyuk, Oxana V., Reuter, Karsten, Volkmer, Dirk
• Format: Article
• Language: English
• Subjects: Adsorption; Copper; Metal-organic frameworks; Nitrous oxide
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2015.03.014

The interaction strength of N2O and CO2 molecules with different Lewis-acidic sites within MFU-4l–type metal-organic frameworks was studied via gas sorption measurements and density-functional theory calculations. MFU-4l comprising Zn–Cl units shows only physisorption of both gases. Introduction of Li into the parent MFU-4l framework leads to a remarkable increase of binding strength of both N2O and CO2 showing considerable Lewis acidity of LiI centers. CuI-MFU-4l shows even stronger binding of N2O, as compared to Li-MFU-4l, whereas CO2 doesn't bind to CuI centers. Preferential binding of N2O to CuI centers was also confirmed by in situ synchrotron X-ray powder diffraction measurements. These results show that CuI-MFU-4l can be considered as a material for selective N2O adsorption. [Display omitted] •Zn–Cl units within the MFU-4l framework possess only very weak Lewis acidity.•Introduction of Li+ leads to a considerable increase of Lewis acidity.•Li-MFU-4l shows weak and unselective binding of both, CO2 and N2O.•CuI-MFU-4l shows relatively strong and selective N2O binding.