Center for Molecular Modeling - A. De Vos

Optical Properties of Isolated and Covalent Organic Framework-Embedded Ruthenium Complexes

sven — Fri, 02 Aug 2019 15:36:39 +0000

F. Muniz-Miranda, L. De Bruecker, A. De Vos, F. Vanden Bussche, C.V. Stevens, P. Van der Voort, K. Lejaeghere, V. Van Speybroeck

Journal of Physical Chemistry A

123 (32), 6854-6867

2019

Abstract

Heterogenization of RuL3 complexes on a support with proper anchor points provides a route toward design of green catalysts. In this paper, Ru(II) polypyridyl complexes are investigated with the aim to unravel the influence on the photocatalytic properties of varying nitrogen content in the ligands and of embedding the complex in a triazine-based covalent organic framework. To provide fundamental insight into the electronic mechanisms underlying this behavior, a computational study is performed. Both the ground and excited state properties of isolated and anchored ruthenium complexes are theoretically investigated by means of density functional theory and time-dependent density functional theory. Varying the ligands among 2,2′-bipyridine, 2,2′-bipyrimidine, and 2,2′-bipyrazine allows us to tune to a certain extent the optical gaps and the metal to ligand charge transfer excitations. Heterogenization of the complex within a CTF support has a significant effect on the nature and energy of the electronic transitions. The allowed transitions are significantly red-shifted toward the near IR region and involve transitions from states localized on the CTF toward ligands attached to the ruthenium. The study shows how variations in ligands and anchoring on proper supports allows us to increase the range of wavelengths that may be exploited for photocatalysis.

Gold Open Access

DOI

http://dx.doi.org/10.1021/acs.jpca.9b05216

Electronic properties of heterogenized Ru(II) polypyridyl photoredox complexes on covalent triazine frameworks

kurt — Wed, 13 Mar 2019 07:02:04 +0000

A. De Vos, K. Lejaeghere, F. Muniz-Miranda, C. Stevens, P. Van der Voort, V. Van Speybroeck

Journal of Materials Chemistry A

7, 8433-8442

2019

Abstract

Ru(II) polypyridyl complexes have been successful for a wide range of photoredox applications thanks to their efficient light-induced metal-to-ligand charge transfer. Using the computational framework of density-functional theory, we report how these complexes can be anchored onto covalent triazine frameworks while maintaining their favorable electronic properties. We moreover show that variation of the nitrogen content of the framework linkers or complex ligands endows the heterogenized catalyst with a unique versatility, spanning a wide range of absorption characteristics and redox potentials. By judiciously choosing the catalyst building blocks, it is even possible to selectively guide the charge transfer toward either the scaffold or the accessible pore sites. Rational design of sustainable and efficient photocatalysts thus comes within reach.

DOI

http://dx.doi.org/10.1039/C9TA00573K

Private attachment

C9TA00573K.pdf

Exploring lanthanide doping in UiO-66: a combined experimental and computational study of the electronic structure

kurt — Fri, 23 Feb 2018 19:50:21 +0000

K. Hendrickx, J.J. Joos, A. De Vos, D. Poelman, P. F. Smet, V. Van Speybroeck, P. Van der Voort, K. Lejaeghere

Inorganic Chemistry

57, 5463-5474

2018

DOI

http://dx.doi.org/10.1021/acs.inorgchem.8b00425

Private attachment

Hendrickx_2018_InorgChem_lanthanide-UiO-electronic.pdf

Manuscript.pdf

Missing linkers: an alternative pathway to UiO-66 electronic structure engineering

kurt — Sun, 05 Feb 2017 10:38:54 +0000

A. De Vos, K. Hendrickx, P. Van der Voort, V. Van Speybroeck, K. Lejaeghere

Chemistry of Materials

29 (7), 3006–3019

2017

Abstract

UiO-66 is a promising metal-organic framework for photocatalytic applications. However, the ligand-to-metal charge transfer of an excited electron is inefficient in the pristine material. Herein we assess the influence of missing linker defects on the electronic structure of UiO-66 and discuss their ability to improve ligand-to-metal charge transfer. Using a new defect classification system, which is transparent and easily extendable, we identify the most promising photocatalysts by considering both relative stability and electronic structure. We find the properties of UiO-66 defect structures largely to depend on the coordination of the constituent nodes, and the nodes with the strongest local distortions to alter the electronic structure most. Defects hence provide an alternative pathway to tune UiO-66 for photocatalytic purposes, besides linker modification and node metal substitution. In addition, the decomposition of MOF properties into node- and linker-based behavior is more generally valid, so we propose orthogonal electronic structure tuning as a paradigm in MOF electronic structure engineering.

Open Access version available at UGent repository

Gold Open Access

DOI

http://dx.doi.org/10.1021/acs.chemmater.6b05444

Private attachment

acs%2Echemmater%2E6b05444(1).pdf

Water coordination and dehydration processes in defective UiO-66 type metal organic frameworks

michel — Sat, 09 Jul 2016 19:22:40 +0000

M. Vandichel, J. Hajek, A. Ghysels, A. De Vos, M. Waroquier, V. Van Speybroeck

CrystEngComm

18 (37), 7056-7069

2016

Abstract

The UiO-66 metal organic framework is one of the most thermally and chemically stable hybrid materials reported to date. However, it is also accepted that the material contains structurally embedded defects, which may be engineered to enhance properties towards specific applications such as catalysis, sensing, etc. The synthesis conditions determine to a large extent the level of perfection of the material and additionally the catalytic activity may be enhanced by post-synthesis activation at high temperature under vacuum, in which defect coordinating species (H2O, HCl, monocarboxylic modulators, etc.) evaporate. The molecular level characterization of defects is extremely challenging from both theoretical and experimental points of view. Such experimental endeavor was recently proposed via experimental SXRD measurements, also unraveling the coordination of water on the Zr–O–Zr defect sites [Angew. Chem., Int. Ed., 2015, 54, 11162–11167]. The present work provides a theoretical understanding of defect structures in UiO-66(Zr) by means of periodic density functional theory calculations and ab initio molecular dynamics simulations. A range of defect structures are generated with different numbers of missing linkers. For each of the defects, the free energetic and mechanical stability is discussed and the coordination of water and charge balancing hydroxide ions is studied. For catalysis applications, the material is mostly pretreated to remove water by dehydration reactions. For each of the proposed defect structures, mechanistic pathways for dehydration reactions of the Zr-bricks are determined employing nudged elastic band (NEB) calculations. During the dehydroxylation trajectory, loose hydroxyl groups and terephthalate decoordinations are observed. Furthermore, dehydration reactions are lower activated if terephthalate linkers are missing in the immediate environment of the inorganic brick. The creation of defects and the dehydration processes have a large impact on the mechanical properties of the material, which is evidenced by lower bulk moduli and elastic constants for structures with more defects.

DOI

10.1039/C6CE01027J

Private attachment

Vandichel-CrystEngComm-2016-SupportingInformation-c6ce01027j4.pdf

Vandichel et al.pdf

First-principles study of antisite defect configurations in ZnGa2O4:Cr persistent phosphors

kurt — Wed, 27 Jan 2016 11:24:02 +0000

A. De Vos, K. Lejaeghere, D.E.P. Vanpoucke, J.J. Joos, P.F. Smet, K. Hemelsoet

Inorganic Chemistry

55 (5), 2402–2412

2016

Abstract

First-principles simulations on zinc gallate solid phosphors (ZGO) containing a chromium dopant and antisite defects rationalize the attractive interactions between the various elements. A large number of antisite pair configurations is investigated and compared with isolated antisite defects. Defect energies point out the stability of the antisite defects in ZGO. Local structural distortions are reported, and charge transfer mechanisms are analyzed based on theoretical density of states and Hirshfeld-I charges.

DOI

http://dx.doi.org/10.1021/acs.inorgchem.5b02805

Private attachment

16-Inorganic-Chem-55(5)2402-DeVos.pdf

Computational spectroscopy: bridging theory and experiment

alexander — Mon, 17 May 2021 10:31:18 +0000

Como, Italy

Sunday, 9 September, 2018 to Friday, 14 September, 2018

Participant(s)

A.E.J. Hoffman, A. De Vos

Project ref.

None

MOFSIM2019

sven — Mon, 17 May 2021 10:11:33 +0000

Ghent, Belgium

Wednesday, 10 April, 2019 to Friday, 12 April, 2019

Participant(s)

V. Van Speybroeck, L. Vanduyfhuys, C. Caratelli, J. Cerutti Torres, R. Goeminne, J. Hajek, A. De Vos, K. Lejaeghere, S. Borgmans, K. Dedecker, J. De Vos, A.E.J. Hoffman, A. Lamaire, J. Wieme, M. Cools-Ceuppens, S.M.J. Rogge

Project ref.

ERC DYNPOR H20ERC2015000301

Orthogonal Electronic Structure Engineering in Nanoporous Frameworks

samuel — Thu, 01 Oct 2020 07:36:30 +0000

A. De Vos

Tue, 22/09/2020

Ghent University AULA, Voldersstraat, Ghent

https://biblio.ugent.be/publication/8676263

Supervisors

V. Van Speybroeck, K. Lejaeghere

Attachment (private)

PhD_ArthurDeVos_compressed2.pdf

Combined theoretical-experimental study of chromium doped zinc gallate phosphor

arthur — Mon, 24 Jun 2019 10:40:26 +0000

A. De Vos, K. Lejaeghere, D.E.P. Vanpoucke, J.J. Joos, P.F. Smet, K. Hemelsoet

ISBN/ISSN:

Poster

Conference / event / venue

MolSim 2016: Understanding Molecular Simulations

Amsterdam, Netherland

Wednesday, 6 January, 2016 to Friday, 15 January, 2016