Center for Molecular Modeling - B. Van de Voorde

Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH2 metal organic frameworks

michel — Wed, 24 Jun 2015 09:17:46 +0000

J. Hajek, M. Vandichel, B. Van de Voorde, B. Bueken, D. De Vos, M. Waroquier, V. Van Speybroeck

Journal of Catalysis

331, 1-12

2015

Abstract

A full mechanistic investigation is proposed for the industrially important cross-aldol condensation reaction of heptanal with benzaldehyde on the UiO-66 and the amino-functionalized UiO-66-NH2 metal–organic frameworks to form jasminaldehyde. Several experimental studies indicate that the activity for the aldol condensation reaction can be increased by proper functionalization of the material, e.g. by introducing an additional basic amino site and thus creating a bifunctional acid–base catalyst for the aldol condensation. The precise molecular level origin for this behavior is to date unclear. Herein state-of-the-art Density-Functional Theory (DFT) calculations have been performed to unravel the mechanism of the cross- and self-aldol condensations of benzaldehyde and propanal. To this end free energy calculations have been performed on both extended cluster and periodic models. It is found that the mechanism on both catalysts is essentially the same, although a slightly stronger adsorption of the reactants and slightly lower barriers were found on the amino functionalized material, pointing toward higher initial activities. New experiments were performed to confirm these observations. It is indeed found that the initial activity toward cross-aldol condensation on the amino functionalized material is higher, although after about 40 min of reaction both materials become equally active. Our results furthermore point out that the basic amino groups may promote side reactions such as imine formation, which is induced by water. The study as presented can assist to engineer materials at the molecular level toward the desired products.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1016/j.jcat.2015.08.015

Private attachment

15-JCatalysis-331-1-Hajek.pdf

Synthesis modulation as a tool to increase the catalytic activity of MOFs: the unique case of UiO-66(Zr)

michel — Sat, 18 May 2013 19:26:34 +0000

F. Vermoortele, B. Bueken, G. Le Bars, B. Van de Voorde, M. Vandichel, K. Houthoofd, A. Vimont, M. Daturi, M. Waroquier, V. Van Speybroeck, C. Kirschhock, D. De Vos

JACS (Journal of the American Chemical Society)

135 (31), 11465–11468

2013

Abstract

The catalytic activity of the zirconium terephthalate UiO-66(Zr) can be drastically increased by using a modulation approach. The combined use of trifluoroacetic acid and HCl during the synthesis results in a highly crystalline material, with partial substitution of terephthalates by trifluoroacetate. Thermal activation of the material leads not only to dehydroxylation of the hexanuclear Zr cluster but also to post-synthetic removal of the trifluoroacetate groups, resulting in a more open framework with a large number of open sites. Consequently, the material is a highly active catalyst for several Lewis acid catalyzed reactions.

DOI

http://dx.doi.org/10.1021/ja405078u

Private attachment

13_jacs_135_11465_Vermoortele.pdf

Electronic effects of linker substitution on Lewis acid catalysis with Metal-organic frameworks

michel — Wed, 30 Nov 2011 14:44:33 +0000

F. Vermoortele, M. Vandichel, B. Van de Voorde, R. Ameloot, M. Waroquier, V. Van Speybroeck, D. De Vos

Angewandte Chemie int. Ed.

51(20), 4887-4890

2012

Abstract

Functionalized linkers can greatly increase the activity of metal–organic framework (MOF) catalysts with coordinatively unsaturated sites. A clear linear free-energy relationship (LFER) was found between Hammett σm values of the linker substituents X and the rate kX of a carbonyl-ene reaction. This is the first LFER ever observed for MOF catalysts. A 56-fold increase in rate was found when the substituent is a nitro group.

DOI

http://dx.doi.org/10.1002/anie.201108565

Private attachment

12 angewandte chem int ed 51(20)4887 Vermoortele.pdf

Mechanistic studies of reactions on UiO-66 type Metal-Organic Frameworks

wim — Wed, 12 Aug 2015 07:11:59 +0000

J. Hajek, M. Vandichel, M. Waroquier, V. Van Speybroeck, B. Van de Voorde, B. Bueken, D. De Vos

ISBN/ISSN:

Poster

Conference / event / venue

EUROMOF2015

Potsdam am Templiner See (Berlin), Germany

Sunday, 11 October, 2015 to Wednesday, 14 October, 2015

Conference reference

EUROMOF2015

Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH2

julianna — Wed, 10 Jun 2015 12:51:50 +0000

J. Hajek, M. Vandichel, B. Van de Voorde, B. Bueken, D. De Vos, M. Waroquier, V. Van Speybroeck

ISBN/ISSN:

Talk

Conference / event / venue

IAP work meeting of WP2 “Supramolecular catalysis, photocatalysis and advanced separations"

Leuven, Belgium

Monday, 11 May, 2015

Electronic modification and controlled defect introduction improve the catalytic activity of Zr-MOFs

mat — Thu, 20 Sep 2012 08:34:44 +0000

F. Vermoortele, B. Van de Voorde, B. Bueken, R. Ameloot, D. De Vos, M. Vandichel, M. Waroquier, V. Van Speybroeck

p. 121

Talk

Conference / event / venue

MOF2012

Edinburgh, UK

Sunday, 16 September, 2012 to Wednesday, 19 September, 2012

Abstract (private)

4170.pdf

Conference reference

MOF2012

Modeling Lewis acid catalyzed reactions in MOFs: How to solve the challenges?

mat — Tue, 07 Aug 2012 08:01:54 +0000

M. Vandichel, F. Vermoortele, B. Van de Voorde, S. Cottenie, D. De Vos, M. Waroquier, V. Van Speybroeck

p. 37

Talk

Conference / event / venue

MOF2012

Edinburgh, UK

Sunday, 16 September, 2012 to Wednesday, 19 September, 2012

Abstract (private)

4183.pdf

Conference reference

MOF2012

Electronic effects of ligand substitution on Lewis acid catalysis with metal-organic frameworks

wim — Tue, 20 Mar 2012 08:22:21 +0000

M. Vandichel, F. Vermoortele, B. Van de Voorde, R. Ameloot, D. De Vos, M. Waroquier, V. Van Speybroeck

Poster

Conference / event / venue

IAP Annual Meeting

Leuven, Belgium

Monday, 21 November, 2011 to Tuesday, 22 November, 2011

Abstract (private)

IAP_2011_Vandichel_UiO_NO2_UiO.pdf

Conference reference

Annual Meeting for Interuniversity Attraction Poles (IUAP) 2011