GOA COFs BOFGOA2017000301

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High-Throughput Screening of Covalent Organic Frameworks for Carbon Capture Using Machine Learning

J. De Vos, S. Ravichandran, S. Borgmans, L. Vanduyfhuys, P. Van der Voort, S.M.J. Rogge, V. Van Speybroeck

Chemistry of Materials

36, 9, 4315-4330

2024

Abstract

Postcombustion carbon capture provides a high-potential pathway to reduce anthropogenic CO₂ emissions in the short term. In this respect, nanoporous materials, such as covalent organic frameworks (COFs), offer a promising platform as adsorbent beds. However, due to the modular nature of COFs, an almost unlimited number of structures can possibly be synthesized. To efficiently identify promising materials and reveal performance trends within the COF material space, we present a computational high-throughput screening of 268,687 COFs for their ability to efficiently and selectively separate CO₂ from the flue gas of power plants using a pressure swing adsorption process. Furthermore, we demonstrate that our screening can be significantly accelerated using machine learning to identify a set of promising materials. These are subsequently characterized with high accuracy, taking into account the effects of competitive adsorption and coadsorption. Our screening reveals that imide, (keto)enamine, and (acyl)hydrazone COFs are particularly interesting for carbon capture. Additionally, the best-performing materials are 3D COFs possessing strong CO₂ adsorption sites between aromatic rings at opposite sides of pores with a diameter of 1.0 nm. In 2D COFs, a significant influence of the framework chemistry, such as imide linkages or fluoro groups, is observed. Our design rules can guide experimental researchers to construct high-performing COFs for CO₂ capture.

Gold Open Access

DOI

http://dx.doi.org/10.1021/acs.chemmater.3c03230

OGRe: Optimal grid refinement protocol for accurate free energy surfaces and its application to proton hopping in zeolites and 2D COF stacking

S. Borgmans, S.M.J. Rogge, L. Vanduyfhuys, V. Van Speybroeck

Journal of Chemical Theory and Computation

19, 24, 9032-9048

2024

Abstract

While free energy surfaces are the crux of our understanding in many chemical and biological processes, their accuracy is generally unknown. Moreover, many developments to improve their accuracy are often complicated, impeding their general use. Luckily, several tools and guidelines are already in place to identify these shortcomings, but they are typically lacking in flexibility or fail to systematically determine how to improve the accuracy of the free energy calculation. To overcome these limitations, this work introduces OGRe--a python package for optimal grid refinement in an arbitrary number of dimensions. OGRe is based on three metrics which gauge the confinement, consistency, and overlap of each simulation in a series of umbrella sampling (US) simulations, an enhanced sampling technique ubiquitously adopted to construct free energy surfaces for hindered processes. As these three metrics are fundamentally linked to the accuracy of the weighted histogram analysis method, adopted to generate free energy surfaces from US simulations, they facilitate a systematic construction of accurate free energy profiles, where each metric is driven by a specific umbrella parameter. This allows for the derivation of a consistent and optimal collection of umbrellas for each simulation, largely independent of the initial values, thereby dramatically increasing the ease-of-use towards accurate free energy surfaces. As such, OGRe is particularly suited to determined complex free energy surfaces, with large activation barriers and shallow minima, which underpin many physical and chemical transformations, and hence to further our fundamental understanding of these processes.

Gold Open Access

DOI

https://doi.org/10.1021/acs.jctc.3c01028

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og-re-optimal-grid-refinement-protocol-for-accurate-free-energy-surfaces-and-its-application-to-proton.pdf

Exploring the Charge Storage Dynamics in Donor–Acceptor Covalent Organic Frameworks Based Supercapacitors by Employing Ionic Liquid Electrolyte

A. Chatterjee, J. Sun, K. S. Rawat, V. Van Speybroeck, P. Van der Voort

SMALL

Volume: 19, Issue: 46

2023

Abstract

Two donor–acceptor type tetrathiafulvalene (TTF)-based covalent organic frameworks (COFs) are investigated as electrodes for symmetric supercapacitors in different electrolytes, to understand the charge storage and dynamics in 2D COFs. Till-date, most COFs are investigated as Faradic redox pseudocapacitors in aqueous electrolytes. For the first time, it is tried to enhance the electrochemical performance and stability of pristine COF-based supercapacitors by operating them in the non-Faradaic electrochemically double layer capacitance region. It is found that the charge storage mechanism of ionic liquid (IL) electrolyte based supercapacitors is dependent on the micropore size and surface charge density of the donor–acceptor COFs. The surface charge density alters due to the different electron acceptor building blocks, which in turn influences the dense packing of the IL near its pore. The micropores induce pore confinement of IL in the COFs by partial breaking of coulomb ordering and rearranging it. The combination of these two factors enhance the charge storage in the highly microporous COFs. The density functional theory calculations support the same. At 1 A g⁻¹, TTF-porphyrin COF provides capacitance of 42, 70, and 130 F g⁻¹ in aqueous, organic, and IL electrolyte respectively. TTF-diamine COF shows a similar trend with 100 F g⁻¹ capacitance in IL.

DOI

http://dx.doi.org/10.1002/smll.202303189

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Small - 2023 - Chatterjee.pdf

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

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

Absorbing stress via molecular crumple zones: Strain engineering flexibility into the rigid UiO-66 material

S.M.J. Rogge, S. Borgmans, V. Van Speybroeck

Matter

6, 5, 1435-1462

2023

Abstract

Nanostructured materials such as metal-organic frameworks and perovskites can be tuned toward applications ranging from sensors to photovoltaic devices. Such design requires causal relations between a material’s atomic structure and macroscopic function, which remain elusive. Therefore, we herein introduce strain engineering as a general approach to rationalizing and designing how atomic-level structural modifications induce dynamically interacting strain fields that dictate a material’s macroscopic mechanical behavior. We first demonstrate the potential of strain engineering by designing shear instabilities in UiO-66, leading to counterintuitive behavior. The strain-engineered structures exhibit time- and space-dependent crumple zones that instill flexibility in the rigid material and locally focus the strain, partially preserving the material’s porosity under compression. Secondly, our strain fields help explain stimulus-induced phase coexistence in the flexible CoBDP, DMOF-1(Zn), and MIL-53(Al)-F materials. These examples demonstrate how strain engineering can be adopted to design state-of-the-art materials for challenging applications from the atomic level onward.

Gold Open Access

DOI

http://dx.doi.org/10.1016/j.matt.2023.02.009

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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

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

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340-2022-JChemMatA-COF-Pd catalyst.pdf

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

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

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acsanm.2c02647.pdf

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

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

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d1gc02319e_compressed.pdf

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

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

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a-1626-5749.pdf

Quantifying the likelihood of structural models through a dynamically enhanced powder X‐ray diffraction protocol

S. Borgmans, S.M.J. Rogge, J. De Vos, C.V. Stevens, P. Van der Voort, V. Van Speybroeck

Angewandte Chemie int. Ed.

60 (16), 8913-8922

2021

Abstract

Structurally characterizing new materials is tremendously challenging, especially when single crystal structures are hardly available which is often the case for covalent organic frameworks. Yet, knowledge of the atomic structure is key to establish structure‐function relations and enable functional material design. Herein a new protocol is proposed to unambiguously predict the structure of poorly crystalline materials through a likelihood ordering based on the X‐ray diffraction (XRD) pattern. Key of the procedure is the broad set of structures generated from a limited number of building blocks and topologies, which is submitted to operando structural characterization. The dynamic averaging in the latter accounts for the operando conditions and inherent temporal character of experimental measurements, yielding unparalleled agreement with experimental powder XRD patterns. The proposed concept can hence unquestionably identify the structure of experimentally synthesized materials, a crucial step to design next generation functional materials.

Gold Open Access

DOI

http://dx.doi.org/10.1002/anie.202017153

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anie.202017153.pdf

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