De Vos, Dirk

Hajek, Julianna

Van Speybroeck, Veronique

Vandichel, Matthias

Vermoortele, Frederik

Waroquier, Michel

Ghent University Academic Bibliography

Modeling aldol condensations in UiO-66 type materials  Julianna Hajek,† Matthias Vandichel,† Frederik Vermoortele,‡ Michel Waroquier,† Dirk De Vos,‡ Veronique Van Speybroeck,† †Center for Molecular Modeling, Ghent University, Technologiepark 903, B-9052 Zwijnaarde, Belgium   ‡Centre for Surface Chemistry and Catalysis, University of Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium   Hybrid framework compounds including both inorganic and organic moieties have recently developed into an important new class of crystalline porous materials, also known as metal organic frameworks (MOFs) [1]. MOFs contain many metal sites, which might be catalytically active. This implies that MOFs have the potential to replace homogenous catalysts in important industrial applications [2]. Notwithstanding the catalytic activity of some of them- it is not always clear what the active sites are and how the reactions are catalyzed. In this contribution, we will focus on certain variations of the UiO-66. Recently, the UiO-66-NH2 has successfully been applied experimentally for the synthesis of Jasminaldehyde from benzaldehyde and heptanal [3]. The presence of the coordinatively unsaturated Lewis acid sites in the material could be increased using a monocarboxylate modulation approach and post synthetic heat treatment [4]. To fully understand the mechanism of Jasminaldehyde condensation on such open active Zr-sites, we applied molecular modeling techniques on extended cluster as well as on periodic models of the UiO-66-X materials. On an extended cluster, the most plausible condensation reaction mechanism was found, showing that benzaldehyde and heptanal are adsorbed and activated on adjacent Zr sites before the coupling reaction. On the UiO-66-NH2 model, there should be also an alternative reaction route, where one of the two aldehydes is activated on the amino group, explaining the higher selectivity of the UiO-66-NH2 compared to the UiO-66 [3]. Deeper insight into these complex mechanisms allows us to explain the selectivity and activity on the UiO-66 type materials.   [1]  Férey, G., Chemical Society Reviews 37 (2008) 191. [2] Czaja, A. U., Trukhan, N. and Muller, U., Chem. Soc. Rev. 38 (2009) 1284. [3] Vermoortele, F., Ameloot, R., Vimont, A., Serre, C., De Vos, D., Chemical Communications 47 (2011) 1521. [4] Vermoortele, F., Bueken, B. Le Bars, G., Van de Voorde, B., Vandichel, M., Houthoofd, K., Vimont, A., Daturi, M., Waroquier, M., Van Speybroeck, V., Kirschhock, C., De Vos, D., Journal of the American Chemical Society 135 (2013) 11465.  

Modeling aldol condensations in UiO-66 type materials

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Modeling aldol condensations in UiO-66 type materials

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Ghent University Academic Bibliography