Band gap opening from displacive instabilities in layered covalent-organic frameworks

Huang, Ju; Golomb, Matthias; Kavanagh, Seán R.; Tolborg, Kasper; Ganose, Alex; Walsh, Aron

doi:10.1039/d2ta02993f

Cited by 10 publications

(14 citation statements)

References 66 publications

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“…The optimised structures agree with prior experiments in terms of similar intralayer metal‐to‐metal distances (7.77 for Ti and 7.67 for V) and interlayer distance (8.67 for Ti and a slightly deviating 8.01 Å for V). The Ti‐based structure however differs strongly from the reported layer stacking: instead of being eclipsed, subsequent layers are displaced (

{\alpha \approx {115}^{\circ }}

{\beta \approx {78}^{\circ }}

) by

{d\approx 2.9}

Å), as seems to be common in other layered frameworks [36] . For [Fe III 2 (Cl 2 dhbq 2− )(Cl 2 dhbq 3− ) 2 ] 2− , no combination of spin initialization or variation of the atomic relaxation parameters led to the reported hexagonal structure.…”

Section: Resultsmentioning

confidence: 70%

“…The Ti-based structure however differs strongly from the reported layer stacking: instead of being eclipsed, subsequent layers are displaced (a � 115 � , b � 78 � ) by d � 2:9 Å), as seems to be common in other layered frameworks. [36] For [Fe III 2 (Cl 2 dhbq 2À )(Cl 2 dhbq 3À ) 2 ] 2À , no combination of spin initialization or variation of the atomic relaxation parameters led to the reported hexagonal structure. Instead, the trifold symmetry around the metal node is found to be broken, leading to angles deviating from their quasi-hexagonal values of around 122°to 107 and 154°, respectively (Figure 2).…”

Section: Implicit Electrostatic Charge Compensationmentioning

confidence: 96%

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Role of Counterions in the Structural Stabilisation of Redox‐Active Metal‐Organic Frameworks**

Golomb

Tolborg

Calbo

et al. 2023

Chemistry A European J

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The crystal structures of metal‐organic frameworks (MOFs) are typically determined by the strong chemical bonds formed between the organic and inorganic building units. However, the latest generation of redox‐active frameworks often rely on counterions in the pores to access specific charge states of the components. Here, we model the crystal structures of three layered MOFs based on the redox‐active ligand 2,5‐dihydroxybenzoquinone (dhbq): Ti2(Cl2dhbq)3, V2(Cl2dhbq)3 and Fe2(Cl2dhbq)3 with implicit and explicit counterions. Our full‐potential first‐principles calculations indicate that while the reported hexagonal structure is readily obtained for Ti and V, the Fe framework is stabilised only by the presence of explicit counterions. For high counterion concentrations, we observe the formation of an electride‐like pocket in the pore center. An outlook is provided on the implications of solvent and counterion control for engineering the structures and properties of porous solids.

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{\alpha \approx {115}^{\circ }}

{\beta \approx {78}^{\circ }}

) by

{d\approx 2.9}

Section: Resultsmentioning

confidence: 70%

Section: Implicit Electrostatic Charge Compensationmentioning

confidence: 96%

Role of Counterions in the Structural Stabilisation of Redox‐Active Metal‐Organic Frameworks**

Golomb

Tolborg

Calbo

et al. 2023

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…The optimised structures agree with prior experiments in terms of similar intralayer metal-to-metal distances (7.77 Å for Ti and 7.67 Å for V) and interlayer distance (8.67 Å for Ti and a slightly deviating 8.01 Å for V). The Ti-based structure however differs strongly from the reported layer stacking: instead of being eclipsed, subsequent layers are displaced (α ≈ 115 • , β ≈ 78 • ) by d ≈ 2.9 Å), as seems to be common in other layered frameworks [36] . For [Fe III 2(Cl2dhbq 2− )(Cl2dhbq 3− )2] 2− , no combination of spin initialization or variation of the atomic relaxation parameters led to the reported hexagonal structure.…”

Section: Implicit Electrostatic Charge Compensationmentioning

confidence: 63%

Role of Counterions in the Structural Stabilisation of Redox-Active Metal-Organic Frameworks

Golomb

Tolborg

Calbo

et al. 2022

Preprint

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The crystal structures of metal-organic frameworks (MOFs) are typically determined by the strong chemical bonds formed between the organic and inorganic building units. However, the latest generation of redox-active frameworks often rely on counterions in the pores to access specific charge states of the components. Here, we model the crystal structures of three layered MOFs based on the redox-active ligand 2,5-dihyroxybenzoquinone (dhbq): Ti$_2$(Cl$_2$dhbq)$_3$, V$_2$(Cl$_2$dhbq)$_3$ and Fe$_2$(Cl$_2$dhbq)$_3$ with implicit and explicit counterions. Our full-potential first-principles calculations indicate that while the reported hexagonal structure is readily obtained for Ti and V, the Fe framework is stabilised only by the presence of explicit counterions. For high counterion concentrations, we observe the formation of an electride-like pocket in the pore center. An outlook is provided on the implications of solvent and counterion control for engineering the structures and properties of porous solids.

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“…The calculated chemical potentials for all elements are listed in Table S2. Interlayer binding energies were calculated as follows, E normalb = ( E M − 1 n E B ) / A where E M is the calculated energy of the monolayer, n is the number of layers in the bulk structure, E B is the calculated energy of the bulk structure, and A is the surface area of the monolayer. All the needed energetic data are extracted and calculated by our in-house codes.…”

Section: Computational Developmentsmentioning

confidence: 99%

In Silico High-Throughput Design and Prediction of Structural and Electronic Properties of Low-Dimensional Metal–Organic Frameworks

Zhang

Valente

Shi

et al. 2023

ACS Appl. Mater. Interfaces

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The advent of π-stacked layered metal–organic frameworks (MOFs), which offer electrical conductivity on top of permanent porosity and high surface area, opened up new horizons for designing compact MOF-based devices such as battery electrodes, supercapacitors, and spintronics. Permutation of structural building blocks, including metal nodes and organic linkers, in these electrically conductive (EC) materials, results in new systems with unprecedented and unexplored physical and chemical properties. With the ultimate goal of providing a platform for accelerated material design and discovery, here we lay the foundations for the creation of the first comprehensive database of EC-MOFs with an experimentally guided approach. The first phase of this database, coined EC-MOF/Phase-I, is composed of 1,057 bulk and monolayer structures built by all possible combinations of experimentally reported organic linkers, functional groups, and metal nodes. A high-throughput screening (HTS) workflow is constructed to implement density functional theory calculations with periodic boundary conditions to optimize the structures and calculate some of their most relevant properties. Because research and development in the area of EC-MOFs has long been suffering from the lack of appropriate initial crystal structures, all of the geometries and property data have been made available for the use of the community through an online platform that was developed during the course of this work. This database provides comprehensive physical and chemical data of EC-MOFs as well as the convenience of selecting appropriate materials for specific applications, thus accelerating the design and discovery of EC-MOF-based compact devices.

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Band gap opening from displacive instabilities in layered covalent-organic frameworks

Abstract: Symmetry breaking in covalent organic frameworks (COFs) lowers the energy and increases the valence to conduction band separation of the material.

Cited by 10 publications

References 66 publications

Role of Counterions in the Structural Stabilisation of Redox‐Active Metal‐Organic Frameworks**

Role of Counterions in the Structural Stabilisation of Redox‐Active Metal‐Organic Frameworks**

Role of Counterions in the Structural Stabilisation of Redox-Active Metal-Organic Frameworks

In Silico High-Throughput Design and Prediction of Structural and Electronic Properties of Low-Dimensional Metal–Organic Frameworks

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