Influence of functionalization of terephthalate linker on the catalytic activity of UiO-66 for epoxide ring opening

• Published in: Journal of molecular catalysis. A, Chemical Vol. 425; pp. 332 - 339
• Main Authors: Blandez, Juan F., Santiago-Portillo, Andrea, Navalón, Sergio, Giménez-Marqués, Mónica, Álvaro, Mercedes, Horcajada, Patricia, García, Hermenegildo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-12-2016
• Subjects: Epoxide ring opening; Heterogeneous catalysis; Metal organic frameworks; UiO-66; Heterogeneous catalysis; Epoxide ring opening; UiO-66; Metal organic frameworks
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2016.10.022

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•UiO–66s with substituents on the terephthalate (H, Br, Cl, NO2 and SO3H) linker were prepared.•The reaction tested with epoxide ring opening.•Substituted UiO-66 preserve crystallinity and do not leach Zr to the liquid phase.•The activity of substituted UiO-66 increases with substituent electron withdrawing strength.•Bromo substituted UiO-66 is the most active catalyst of the series.
A series of five isostructural zirconium terephthalate UiO-66 metal organic frameworks bearing different functional groups on the terephthalate linker (UiO-66-X; X=H, NH2, NO2, Br, Cl,) have been successfully prepared and characterized. UiO-66-X materials were evaluated as heterogeneous catalysts for the epoxide ring opening of styrene oxide by methanol, observing an increase in the initial reaction rate from UiO-66-H to UiO-66-Br, over one order of magnitude. The reactivity order, however, does not follow a linear relationship between the Hammett constant value of the substituent and the initial reaction rate. UiO-66-Br exhibits a wide scope, its activity depending on the structure of epoxide and nucleophile. The absence of Zr leaching to the solution together with the preservation of the UiO-66-X crystallinity confirms the stability of the framework under the reaction conditions. Nevertheless, UiO-66 undergoes a progressive deactivation upon reuse that was attributed to a strong adsorption of the reaction product.