Center for Molecular Modeling - FWO COK (3G033808)

The remarkable amphoteric nature of defective UiO-66 in catalytic reactions

michel — Fri, 23 Dec 2016 15:56:00 +0000

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

ChemCatChem

9 (12), 2203-2210

2017

Abstract

One of the major requirements in solid acids and bases catalyzed reactions is that the reactants, intermediates or activated complexes cooperate with several functions of catalyst support. In this work the remarkable bifunctional behavior of the defective UiO-66(Zr) metal organic framework is shown for acid-base pair catalysis. The active site relies on the presence of undercoordinated zirconium sites, which may be tuned by removing framework linkers and by removal of water from the inorganic bricks using a dehydration treatment. To elucidate the amphoteric nature of defective UiO-66, the Oppenauer oxidation of primary alcohols has been theoretically investigated using density functional theory (DFT) and the periodic approach. The presence of acid and basic centers within molecular distances has been shown crucial for determining the catalytic activity of the material. Hydrated and dehydrated bricks have a distinct influence on modulation of the acidity and basicity of the active sites. In any case both functions need to cooperate in a concerted way to enable the chemical transformation.

Open Access version available at UGent repository

Gold Open Access

DOI

http://dx.doi.org/10.1002/cctc.201601689

Private attachment

Hajek_et_al-2017-ChemCatChem.pdf

Towards metal–organic framework based field effect chemical sensors: UiO-66-NH2 for nerve agent detection

michel — Sat, 09 Jul 2016 19:53:21 +0000

L. Stassen, B. Bueken, H. Reinsch, J.F.M. Oudenhoven, D. Wouters, J. Hajek, V. Van Speybroeck, N. Stock, P.M. Vereecken, R. Van Schajik, D. De Vos, R. Ameloot

Chemical Science

7, 5827-5832

2016

Abstract

We present a highly sensitive gas detection approach for the infamous ‘nerve agent’ group of alkyl phosphonate compounds. Signal transduction is achieved by monitoring the work function shift of metal–organic framework UiO-66-NH2 coated electrodes upon exposure to ppb-level concentrations of a target simulant. Using the Kelvin probe technique, we demonstrate the potential of electrically insulating MOFs for integration in field effect devices such as ChemFETs: a three orders of magnitude improvement over previous work function-based detection of nerve agent simulants. Moreover, the signal is fully reversible both in dry and humid conditions, down to low ppb concentrations. Comprehensive investigation of the interactions that lead towards this high sensitivity points towards a series of confined interactions between the analyte and the pore interior of UiO-66-NH₂.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1039/C6SC00987E

Private attachment

c6sc00987e.pdf

Meeting at COK

wim — Tue, 02 Jul 2013 11:35:47 +0000

Leuven, Belgium

Tuesday, 2 July, 2013

Participant(s)

L. Joos, V. Van Speybroeck

Project ref.

IAP VII P7/05 B/12909/*, FWO mandaat, FWO COK (3G033808)

Meeting at COK

wim — Tue, 07 May 2013 06:50:15 +0000

Leuven, Belgium

Tuesday, 7 May, 2013

Participant(s)

L. Joos

Project ref.

wim — Tue, 19 Feb 2013 09:03:55 +0000

Leuven, Belgium

Wednesday, 10 October, 2012

Participant(s)

L. Joos

Project ref.

FWO COK (3G033808), FWO mandaat, IAP VII P7/05 B/12909/*