P. Van der Voort

ReDD-COFFEE: A ready-to-use database of covalent organic framework structures and accurate force fields to enable high-throughput screenings

J. De Vos, S. Borgmans, P. Van der Voort, S.M.J. Rogge, V. Van Speybroeck
J. Mater. Chem. A
11, 14, 7468-7487
2023
A1

Abstract 

Covalent organic frameworks (COFs) are a versatile class of building block materials with outstanding properties thanks to their strong covalent bonds and low density. Given the sheer number of hypothetical COFs envisioned via reticular synthesis, only a fraction of all COFs have been synthesized so far. Computational high-throughput screenings offer a valuable alternative to speed-up such materials discovery. Yet, such screenings vitally depend on the availability of diverse databases and accurate interatomic potentials to efficiently predict each hypothetical COF’s macroscopic behavior, which is currently lacking. Therefore, we herein present ReDD-COFFEE, the Ready-to-use and Diverse Database of Covalent Organic Frameworks with Force field based Energy Evaluation, containing 268 687 COFs and accompanying ab initio derived force fields that are shown to outperform generic ones. Our structure assembly approach results in a huge amount of computer-ready structures with a high diversity in terms of geometric properties, linker cores, and linkage types. Furthermore, the textural properties of the database are analyzed and the most promising COFs for vehicular methane storage are identified. By making the database freely accessible, we hope it may also inspire others to further explore the potential of these intriguing functional materials.

 

Gold Open Access

DOI 

http://dx.doi.org/10.1039/D3TA00470H

Pyrene-Based Covalent Organic Frameworks for Photocatalytic Hydrogen Peroxide Production

J. Sun, H. S. Jena, C. Krishnaraj, K. S. Rawat, S. Abednatanzi, J. Chakraborty, A. Laemont, W. Liu, H. Chen, Y.-Y. Liu, K. Leus, H. Vrielinck, V. Van Speybroeck, P. Van der Voort
Angewandte Chemie int. Ed.
Volume: 62; Issue: 19
2023
A1

Abstract 

Four highly porous covalent organic frameworks (COFs) containing pyrene units were prepared and explored for photocatalytic H2O2 production. The experimental studies are complemented by density functional theory calculations, proving that the pyrene unit is more active for H2O2 production than the bipyridine and (diarylamino)benzene units reported previously. H2O2 decomposition experiments verified that the distribution of pyrene units over a large surface area of COFs plays an important role in catalytic performance. The Py-Py-COF, though contains more pyrene units than other COFs, induces a high H2O2 decomposition due to a dense concentration of pyrene in small proximity over a limited surface area. Therefore, a two-phase reaction system (water-benzyl alcohol) was employed to inhibit H2O2 decomposition. This is the first report on applying pyrene-based COFs in a two-phase system for photocatalytic H2O2 generation.

DOI 

http://dx.doi.org/10.1002/anie.202216719

Linker Engineering of 2D Imine Covalent Organic Frameworks for Heterogeneous Palladium-catalyzed Suzuki Coupling Reaction

C. Krishnaraj, H. S. Jena, K. S. Rawat, J. Schmidt, K. Leus, V. Van Speybroeck, P. Van der Voort
ACS Applied Materials & Interfaces
14, 45, 50923-50931
2022
A1

Abstract 

Covalent organic frameworks (COFs) are an emerging class of porous organic polymers that have been utilized as scaffolds for anchoring metal active species to act as heterogeneous catalysts. Though several examples of such COFs exist, a thorough experimental and computational analysis on such catalysts is limited. In this work, a series of two-dimensional (2D) imine COFs (TTA–DFB COF (N), TTA–TBD COF (N∧O), and TTA–DFP COF(N∧N)) were synthesized by using suitable building units to obtain three different coordination sites (N, N∧O, and N∧N). These were post-modified with Pd(II) to catalyze the Suzuki–Miyaura coupling reaction. Pd@TTA–DFB COF, where Pd(II) was coordinated to N sites, showed the fastest reactivity and lower stability. Pd@TTA–DFP COF showed highest stability but slowest reactivity. Pd@TTA–TBD COF was the best among the three with both high stability and fast reactivity. By combining both experimental and computational results, we conclude that the Pd(II) to Pd(0) reduction is a key step in the difference between the catalytic reactivities of the three COFs. This study demonstrates the importance of the building block approach to design COFs for efficient heterogeneous catalysis and to understand the fate of the reaction profile.

DOI 

https://doi.org/10.1021/acsami.2c14882

Covalent Organic Framework supported Palladium Catalysts

H. Salemi, M. Debruyne, V. Van Speybroeck, P. Van der Voort, M. D'Hooghe, C. Stevens
Journal of Materials Chemistry A
10, 39, 20707-20729
2022
A1

Abstract 

Covalent organic frameworks (COFs), as highly porous crystalline structures, are newly emerging materials designed with tuneable features. They have a high potential to be a host to immobilize metal catalysts. The unique property of these materials, such as their high surface area, oriented channels, and heteroatom enrichment, make them promising materials to improve some disadvantages of heterogeneous metal catalysts. In this review, the fabrication and application of Pd anchored COFs as one of the most critical transition-metal catalysts that play a crucial role in a wide range of reactions is summarized.

DOI 

https://doi.org/10.1039/D2TA05234B

Exploring the phase stability in interpenetrated diamondoid covalent organic frameworks

S. Borgmans, S.M.J. Rogge, J. De Vos, P. Van der Voort, V. Van Speybroeck
Communications Chemistry
6, 1, 5
2023
A1

Abstract 

Soft porous crystals, which are responsive to external stimuli such as temperature, pressure, or gas adsorption, are being extensively investigated for various technological applications. However, while substantial research has been devoted to stimuli-responsive metal-organic frameworks, structural flexibility in 3D covalent organic frameworks (COFs) remains ill-understood, and is almost exclusively found in COFs exhibiting the diamondoid (dia) topology. Herein, we systemically investigate how the structural decoration of these 3D dia COFs—their specific building blocks and degree of interpenetration—as well as external triggers such as temperature and guest adsorption may promote or suppress their phase transformations, as captured by a collection of 2D free energy landscapes. Together, these provide a comprehensive understanding of the necessary conditions to design flexible diamondoid COFs. This study reveals how their flexibility originates from the balance between steric hindrance and dispersive interactions of the structural decoration, thereby providing insight into how new flexible 3D COFs can be designed.

Open Access version available at UGent repository
Gold Open Access

DOI 

http://dx.doi.org/10.1038/s42004-022-00808-y

How the Layer Alignment in Two-dimensional Nanoporous Covalent Organic Frameworks Impacts Its Electronic Properties

K. S. Rawat, S. Borgmans, T. Braeckevelt, C.V. Stevens, P. Van der Voort, V. Van Speybroeck
ACS Applied Nano Materials
5, 10, 14377-14387
2022
A1

Abstract 

Two-dimensional nanoporous covalent organic frame-works (2D COFs) have gathered significant interest due to their wide range of applications. Due to the lack of strong covalent interlayer interactions, their layers can be stacked in countless ways, each resulting in unique nanoscale characteristics impacting the structural, chemical, and electronic properties. To characterize and understand the layer stacking in 2D COFs and its effect on the structural and electronic properties, we carried out a detailed density functional theory investigation on four materials, CTF-1, COF-1, COF-5, and Pc-PBBA. This entailed an in-depth evaluation of the potential energy as a function of the interlayer distance and offset, the powder X-ray diffraction (PXRD) pattern, and the electronic properties. From the potential energy surfaces, the typical slipped AA-stacking configuration was confirmed as optimal for each of the 2D COFs, with a slight offset from a perfect alignment of the layers. The statically calculated PXRD patterns based on these optimized stacking configurations showed discrepancies when compared to experimental data. Instead, when properly accounting for dynamic fluctuations by calculating the average diffraction pattern over the course of a molecular dynamics simulation, a better agreement with the experiment is obtained. Different stacking configurations also profoundly affected the electronic band structure of COFs as the interlayer pi-pi interactions are significantly impacted by the layer offset. Evidently, with decreasing layer offsets, the pi-pi interactions increase due to the layer alignment, leading to a decrease in the band gap and an increase in interlayer charge mobility. Our study highlights the need for accurate modeling of the stacking configuration in 2D COFs as a small-scale deviation in the adjacent layer position can significantly affect the structural and electronic properties.

DOI 

https://doi.org/10.1021/acsanm.2c02647

Porous organic polymers as metal free heterogeneous organocatalysts

M. Debruyne, V. Van Speybroeck, P. Van der Voort, C. Stevens
Green Chemistry
Volume 23, Issue 19, Page 7361-7434
2021
A1

Abstract 

Efficient catalysis is essential from a green chemistry perspective. Porous organic polymers (POPs) have recently emerged as highly effective materials for catalytic applications. POPs possess controllable compositions and functionalities, high surface areas and can be very stable. In this review we focus on the application of POPs as metal free heterogeneous organocatalysts, a booming field in green chemistry. Acid, base, combined acid-base and hydrogen bonding catalysis are addressed. In addition, chiral catalysis and CO2 utilization with POPs are discussed. The aim is to provide a comprehensive overview of the field, exploring all different types of POPs as metal free catalysts. Special attention is given to the synthesis conditions to provide the reader with more insight into the construction of these types of materials.

DOI 

10.1039/d1gc02319e

Synthesis of Nitrile-Functionalized Polydentate N-Heterocycles as Building Blocks for Covalent Triazine Frameworks

J. Everaert, M. Debruyne, F. Vandenbussche, K. Van Hecke, T.S.A Heugebaert, P. Van der Voort, V. Van Speybroeck, C. Stevens
Synthesis-Stuttgart
2021
A1

Abstract 

Covalent triazine frameworks (CTFs) based on polydentate ligands are highly promising supports to anchor catalytic metal complexes. The modular nature of CTFs allows to tailor the composition, structure, and function to its specific application. Access to a broad range of chelating building blocks is therefore essential. In this respect, we extended the current available set of CTF building blocks with new nitrile-functionalized N-heterocyclic ligands. This paper presents the synthesis of the six ligands which vary in the extent of the aromatic system and the denticity. The new building blocks may help in a rational design of enhanced support materials in catalysis.

DOI 

http://dx.doi.org/10.1055/a-1626-5749

Hydrogen Clathrates: Next Generation Hydrogen Storage Materials

A. Gupta, G.V. Baron, P. Perreault, S. Lenaerts, R.-G. Ciocarlan, P. Cool, P. M. Mileo, S.M.J. Rogge, V. Van Speybroeck, G. Watson, P. Van der Voort, M. Houlleberghs, E. Breynaert, J.A. Martens, J.F.M. Denayer
Energy Storage Materials
41, 69-107
2021
A1

Abstract 

Extensive research has been carried on the molecular adsorption in high surface area materials such as carbonaceous materials and MOFs as well as atomic bonded hydrogen in metals and alloys. Clathrates stand among the ones to be recently suggested for hydrogen storage. Although, the simulations predict lower capacity than the expected by the DOE norms, the additional benefits of clathrates such as low production and operational cost, fully reversible reaction, environmentally benign nature, low risk of flammability make them one of the most promising materials to be explored in the next decade. The inherent ability to tailor the properties of clathrates using techniques such as addition of promoter molecules, use of porous supports and formation of novel reverse micelles morphology provide immense scope customisation and growth. As rapidly evolving materials, clathrates promise to get as close as possible in the search of “holy grail” of hydrogen storage. This review aims to provide the audience with the background of the current developments in the solid-state hydrogen storage materials, with a special focus on the hydrogen clathrates. The in-depth analysis of the hydrogen clathrates will be provided beginning from their discovery, various additives utilised to enhance their thermodynamic and kinetic properties, challenges in the characterisation of hydrogen in clathrates, theoretical developments to justify the experimental findings and the upscaling opportunities presented by this system. The review will present state of the art in the field and also provide a global picture for the path forward.

Gold Open Access

DOI 

http://dx.doi.org/10.1016/j.ensm.2021.05.044

Overview of N-rich antennae investigated in lanthanide-based temperature sensing

F. Vanden Bussche, A.M. Kaczmarek, V. Van Speybroeck, P. Van der Voort, C.V. Stevens
Chemistry - A European Journal
27 (25), 7214-7230
2021
A1

Abstract 

The market share of noncontact temperature sensors is expending due to fast technological and medical evolutions. In the wide variety of noncontact sensors, lanthanide‐based temperature sensors stand out. They benefit from high photostability, relatively long decay times and high quantum yields. To circumvent their low molar light absorption, the incorporation of a light‐harvesting antenna is required. This Review provides an overview of the nitrogen‐rich antennae in lanthanide‐based temperature sensors, emitting in the visible light spectrum, and discusses their temperature sensor ability. The N‐rich ligands are incorporated in many different platforms. The investigation of different antennae is required to develop temperature sensors with diverse optical properties and to create a diverse offer for the multiple application fields. Molecular probes, consisting of small molecules, are first discussed. Furthermore, the thermometer properties of ratiometric temperature sensors, based on di‐ and polynuclear complexes, metal–organic frameworks, periodic mesoporous organosilicas and porous organic polymers, are summarized. The antenna mainly determines the application potential of the ratiometric thermometer. It can be observed that molecular probes are operational in the broad physiological range, metal–organic frameworks are generally very useful in the cryogenic region, periodic mesoporous organosilica show temperature dependency in the physiological range, and porous organic polymers are operative in the cryogenic‐to‐medium temperature range.

Open Access version available at UGent repository

DOI 

10.1002/chem.202100007

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