Crystalline Framework Materials Research Articles

Thickness-Driven Synthesis and Applications of Covalent Organic Framework Nanosheets.

Covalent organic frameworks (COFs) are two-dimensional, crystalline porous framework materials with numerous scopes of tunability like porosity, functionality, stability and aspect ratio (thickness to length ratio). The manipulation of π-stacking in COFs results in truly 2D materials, namely covalent organic nanosheets (CONs) adds advantages in many applications. In this review, we have discussed both top-down (COFs→CONs) and bottom-up (molecules→CONs) with precise information on thickness and lateral growth. We have showcased the research progress of CONs in few selected applications like batteries, catalysis, sensing and biomedical applications. This review specifically highlights the reports where the authors compare the performance of CONs with COFs by demonstrating the impact of thickness and lateral growth of the nanosheets. Eventually, we have provided the possible scope of exploration of CONs research in terms of inter-dimensional conversion like graphene to carbon nanotube and future technologies..

Thickness‐Driven Synthesis and Applications of Covalent Organic Framework Nanosheets

Covalent organic frameworks (COFs) are two‐dimensional, crystalline porous framework materials with numerous scopes of tunability like porosity, functionality, stability and aspect ratio (thickness to length ratio). The manipulation of π‐stacking in COFs results in truly 2D materials, namely covalent organic nanosheets (CONs) adds advantages in many applications. In this review, we have discussed both top‐down (COFs→CONs) and bottom‐up (molecules→CONs) with precise information on thickness and lateral growth. We have showcased the research progress of CONs in few selected applications like batteries, catalysis, sensing and biomedical applications. This review specifically highlights the reports where the authors compare the performance of CONs with COFs by demonstrating the impact of thickness and lateral growth of the nanosheets. Eventually, we have provided the possible scope of exploration of CONs research in terms of inter‐dimensional conversion like graphene to carbon nanotube and future technologies..

Charge-Assisted Ionic Hydrogen-Bonded Organic Frameworks: Designable and Stabilized Multifunctional Materials.

Hydrogen-bonded organic frameworks (HOFs) are a class of crystalline framework materials assembled by hydrogen bonds. HOFs have the advantages of high crystallinity, mild reaction conditions, good solution processability, and reproducibility. Coupled with the reversibility and flexibility of hydrogen bonds, HOFs can be assembled into a wide diversity of crystalline structures. Since the bonding energy of hydrogen bonds is lower than that of ligand and covalent bonds, the framework of HOFs is prone to collapse after desolventisation and the stability is not high, which limits the development and application of HOFs. In recent years, numerous stable and functional HOFs have been developed by π-π stacking, highly interpenetrated networks, charge-assisted, ligand-bond-assisted, molecular weaving, and covalent cross-linking. Charge-assisted ionic HOFs introduce electrostatic attraction into HOFs to improve stability while enriching structural diversity and functionality. In this paper, we review the development, the principles of rational design and assembly of charge-assisted ionic HOFs, and introduces the different building block construction modes of charge-assisted ionic HOFs. Highlight the applications of charge-assisted ionic HOFs in gas adsorption and separation, proton conduction, biological applications, etc., and prospects for the diverse design of charge-assisted ionic HOFs structures and multifunctional applications.

A Critical Assessment on Calculating Vibrational Spectra in Nanostructured Materials.

Vibrational spectroscopy is an omnipresent spectroscopic technique to characterize functional nanostructured materials such as zeolites, metal-organic frameworks (MOFs), and metal-halide perovskites (MHPs). The resulting experimental spectra are usually complex, with both low-frequency framework modes and high-frequency functional group vibrations. Therefore, theoretically calculated spectra are often an essential element to elucidate the vibrational fingerprint. In principle, there are two possible approaches to calculate vibrational spectra: (i) a static approach that approximates the potential energy surface (PES) as a set of independent harmonic oscillators and (ii) a dynamic approach that explicitly samples the PES around equilibrium by integrating Newton's equations of motions. The dynamic approach considers anharmonic and temperature effects and provides a more genuine representation of materials at true operating conditions; however, such simulations come at a substantially increased computational cost. This is certainly true when forces and energy evaluations are performed at the quantum mechanical level. Molecular dynamics (MD) techniques have become more established within the field of computational chemistry. Yet, for the prediction of infrared (IR) and Raman spectra of nanostructured materials, their usage has been less explored and remain restricted to some isolated successes. Therefore, it is currently not a priori clear which methodology should be used to accurately predict vibrational spectra for a given system. A comprehensive comparative study between various theoretical methods and experimental spectra for a broad set of nanostructured materials is so far lacking. To fill this gap, we herein present a concise overview on which methodology is suited to accurately predict vibrational spectra for a broad range of nanostructured materials and formulate a series of theoretical guidelines to this purpose. To this end, four different case studies are considered, each treating a particular material aspect, namely breathing in flexible MOFs, characterization of defects in the rigid MOF UiO-66, anharmonic vibrations in the metal-halide perovskite CsPbBr3, and guest adsorption on the pores of the zeolite H-SSZ-13. For all four materials, in their guest- and defect-free state and at sufficiently low temperatures, both the static and dynamic approach yield qualitatively similar spectra in agreement with experimental results. When the temperature is increased, the harmonic approximation starts to fail for CsPbBr3 due to the presence of anharmonic phonon modes. Also, the spectroscopic fingerprints of defects and guest species are insufficiently well predicted by a simple harmonic model. Both phenomena flatten the potential energy surface (PES), which facilitates the transitions between metastable states, necessitating dynamic sampling. On the basis of the four case studies treated in this Review, we can propose the following theoretical guidelines to simulate accurate vibrational spectra of functional solid-state materials: (i) For nanostructured crystalline framework materials at low temperature, insights into the lattice dynamics can be obtained using a static approach relying on a few points on the PES and an independent set of harmonic oscillators. (ii) When the material is evaluated at higher temperatures or when additional complexity enters the system, e.g., strong anharmonicity, defects, or guest species, the harmonic regime breaks down and dynamic sampling is required for a correct prediction of the phonon spectrum. These guidelines and their illustrations for prototype material classes can help experimental and theoretical researchers to enhance the knowledge obtained from a lattice dynamics study.

Water/Vapor Assisted Fabrication of Large-Area Superprotonic Conductive Covalent Organic Framework Membranes.

Fabrication of large-area ionic covalent organic framework membranes (iCOMs) remains a grand challenge. Herein, the authors report the liquid water and water vapor-assisted fabrication of large-area superprotonic conductive iCOMs. A mixed monomer solution containing 1,3,5-triformylphloroglucinol (TFP) in 1,4-dioxane and p-diaminobenzenesulfonic acid (DABA) in water is first polymerized to obtain a pristine membrane which subsequently underwent crystallization process in mixed vapors containing water vapor. During the polymerization stage, water played a role of a diluting agent, weakening the Coulombic repulsion between sulfonic acid groups. During the crystallization stage, water vapor played a role of a structure-directing agent to facilitate the formation of highly crystalline, large-area iCOMs. The resulting membranes achieved a proton conductivity value of 0.76 S cm-1 at 90 °C under 100% relative humidity, which is among the highest ever reported. Using liquid water and water vapor as versatile additives open a novel avenue to the fabrication of large-area membranes from covalent organic frameworks and other kinds of crystalline organic framework materials.

Smart crystalline framework materials with a triazole carboxylic acid ligand: fluorescence sensing and catalytic reduction of PNP.

Triazole polycarboxylic acid ligands are widely employed in the construction of MOFs due to their strong coordination ability and flexible coordination modes. In this work, three novel complexes (Pb(MCTCA)(H2O) (1), Co(HMCTCA)2(H2O)2 (2) and Cu(HMCTCA)2(H2O)2 (3)) based on the H2MCTCA ligand (5-methyl-1-(4-carboxyl)-1H-1,2,3-triazole-4-carboxylic acid) were successfully synthesized under hydrothermal conditions, respectively. X-ray single crystal structure analysis shows that complex 1 is a 3D network structure, where the central metal Pb(II) is six coordinated to form deformed triangular prism geometry. The complexes 2 and 3 are both 2D layer supramolecular structures connected through intermolecular hydrogen, where the central metals (Co/Cu) are six coordinated to form octahedral configuration geometry. Based on functional properties, it is found that complex 1 exhibits excellent detection ability for small-molecule drugs (azithromycin, colchicine and balsalazide disodium) and actinide cations (Th4+ and UO22+) within a lower concentration range without interference from other components. In particular, the detection limits of three small-molecule drugs are all lower than 0.30 μM. In addition, complexes 2 and 3 exhibited excellent catalytic reduction performance toward p-nitrophenol (PNP), with a reduction efficiency exceeding 98%. These experimental results evidence that complexes 1-3 have potential application prospects in fluorescence sensing and catalytic reduction.

Halogen hydrogen-bonded organic framework (XHOF) constructed by singlet open-shell diradical for efficient photoreduction of U(VI)

Synthesis of framework materials possessing specific spatial structures or containing functional ligands has attracted tremendous attention. Herein, a halogen hydrogen-bonded organic framework (XHOF) is fabricated by using Cl− ions as central connection nodes to connect organic ligands, 7,7,8,8-tetraaminoquinodimethane (TAQ), by forming a Cl−···H3 hydrogen bond structure. Unlike metallic node-linked MOFs, covalent bond-linked COFs, and intermolecular hydrogen bond-linked HOFs, XHOFs represent a different kind of crystalline framework. The electron-withdrawing effect of Cl− combined with the electron-rich property of the organic ligand TAQ strengthens the hydrogen bonds and endows XHOF-TAQ with high stability. Due to the production of excited electrons by TAQ under light irradiation, XHOF-TAQ can efficiently catalyze the reduction of soluble U(VI) to insoluble U(IV) with a capacity of 1708 mg-U g−1-material. This study fabricates a material for uranium immobilization for the sustainability of the environment and opens up a new direction for synthesizing crystalline framework materials.

Engineering Olefin-Linked Covalent Organic Frameworks for Photoenzymatic Reduction of CO2.

It is of profound significance concerning the global energy and environmental crisis to develop new techniques that can reduce and convert CO2 . To address this challenge, we built a new type of artificial photoenzymatic system for CO2 reduction, using a rationally designed mesoporous olefin-linked covalent organic framework (COF) as the porous solid carrier for co-immobilizing formate dehydrogenase (FDH) and Rh-based electron mediator. By adjusting the incorporating content of the Rh electronic mediator, which facilitates the regeneration of nicotinamide cofactor (NADH) from NAD+ , the apparent quantum yield can reach as high as 9.17±0.44 %, surpassing all reported NADH-regenerated photocatalysts constructed by crystalline framework materials. Finally, the assembled photocatalyst-enzyme coupled system can selectively convert CO2 to formic acid with high efficiency and good reusability. This work demonstrates the first example using COFs to immobilize enzymes for artificial photosynthesis systems that utilize solar energy to produce value-added chemicals.

Engineering Olefin‐Linked Covalent Organic Frameworks for Photoenzymatic Reduction of CO2

AbstractIt is of profound significance concerning the global energy and environmental crisis to develop new techniques that can reduce and convert CO2. To address this challenge, we built a new type of artificial photoenzymatic system for CO2 reduction, using a rationally designed mesoporous olefin‐linked covalent organic framework (COF) as the porous solid carrier for co‐immobilizing formate dehydrogenase (FDH) and Rh‐based electron mediator. By adjusting the incorporating content of the Rh electronic mediator, which facilitates the regeneration of nicotinamide cofactor (NADH) from NAD+, the apparent quantum yield can reach as high as 9.17±0.44 %, surpassing all reported NADH‐regenerated photocatalysts constructed by crystalline framework materials. Finally, the assembled photocatalyst–enzyme coupled system can selectively convert CO2 to formic acid with high efficiency and good reusability. This work demonstrates the first example using COFs to immobilize enzymes for artificial photosynthesis systems that utilize solar energy to produce value‐added chemicals.

Hot-electron leading-out strategy for constructing photostable HOF catalysts with outstanding H2 evolution activity

Improving photochemical stability of hydrogen-bonded organic frameworks (HOFs) is a prerequisite for design HOF photocatalysts for efficient solar energy conversion. Herein, efficiently leading-out hot-electrons was demonstrated as a new strategy for synthesizing photostable HOFs via introducing Pt nanoparticles as electron sinks into high crystalline nano-HOFs. The resulting Pt@nano-HOF exhibits extremely high hydrogen evolution activity and photochemical stability, subverting the traditional view of “frail HOFs”. Impressively, the maximum H2 evolution rate of 31.2 mmol/g/h represents the best performance among those of various crystalline framework materials. The acceleration of hot-electron transfer can be also achieved by introducing a planar [Co(qpy)(OH2)2]2+ molecule to form π-π stacking with framework, reaching a record H2 evolution rate of 14.8 mmol/g/h among all the covalent-/metal-organic framework and HOF-based photocatalysts without any noble metal components. This work highlights a new insight for improving the photochemcial stability of the catalysts, even for particularly unstable HOFs.

Copper triazine polycarboxylic acid crystalline framework materials: Synthesis, structure and multifunctional properties with the luminescent and catalytic reduction of 4-NP

Metal-organic frameworks are a class of promising materials that are widely used in various fields such as detection, catalysis, and adsorption. A new protonated coordination polymer [Cu2(H2TTHA)(H2O)6] (1) containing two uncoordinated carboxylate acid groups was synthesized under the condition of hydrothermal, and a series of characterizations including elemental analysis, infrared spectroscopy, PXRD, thermogravimetric analysis, and ultraviolet–visible spectroscopy were performed. It has a 3D supramolecular network structure. In order to further study the reproducible synthesis conditions, we unexpectedly got a partly protonated coordination polymer material [Cu3(H3TTHA)(μ3-O)(μ3-OH)(μ2-H2O)2(H2O)]·2H2O (2), which was different from the structure of 1 and contained three uncoordinated carboxylate acid groups in the framework structure. It was found that coordination polymer 1 has good catalytic activity for the catalytic reduction of 4-NP under mild reaction conditions. In the meantime, it can be used as a sensor to detect a small amount of Fe3+ (1 mM), and the detection limit for Fe3+ is 21 μM. The results show that 1 possesses a good application prospect in terms of fluorescence sensing and catalysis.

Copper Triazine Polycarboxylic Acid Crystalline Framework Materials：Synthesis, Structure and Multifunctional Properties with the Luminescent and Catalytic Reduction of 4-Np

Metal-organic frameworks are a class of promising materials that are widely used in various fields such as detection, catalysis, and adsorption. A new protonated Cu-MOF [Cu2(H2TTHA)(H2O)6] (1) containing two uncoordinated carboxylate acid groups was synthesized under the condition of hydrothermal, and a series of characterizations including elemental analysis, infrared spectroscopy, PXRD, thermogravimetric analysis, and ultraviolet-visible spectroscopy were performed. It has a 3D supramolecular network structure. In order to further study the reproducible synthesis conditions, we unexpectedly got a partly protonated Cu-MOF material [Cu3(H3TTHA)(μ3-O)(μ3-OH)(μ2-H2O)2(H2O)]·2H2O (2), which was different from the structure of 1 (Cu-MOF) and contained three uncoordinated carboxylate acid groups in the framework structure. It was found that complex 1 has good catalytic activity for the catalytic reduction of 4-NP under mild reaction conditions. In the meantime, it can be used as a sensor to detect a small amount of Fe3+ (1 mM), and the detection limit for Fe3+ is 21 μM. The results show that 1 possess a good application prospect in terms of fluorescence sensing and catalysis.

A New Group of Edge-transitive 3-Periodic Nets and Their Derived Nets for Reticular Chemistry

Edge-transitive and related minimal transitivity nets play a central role in the designed synthesis of crystalline framework materials (reticular chemistry), in particular, metal-organic frameworks...

Covalent organic framework mesocrystals through dynamic modulator manipulated mesoscale self-assembly of imine macrocycle precursors

Framework crystallization is an unresolved challenge in the chemistry of covalent organic frameworks (COFs) due to the poorly controlled simultaneous polymerization and crystallization processes. Here, we report the first morphogenesis of COF mesocrystals with two-dimensional hexagonal p6m symmetry through the combination of alkyl amine as a dynamic modulator and 2,4,6- triformylresorcinol imine as an asymmetrical building block. The amine modulator depresses the lateral growth of 2D sheets, and the slow kinetics combined with the asymmetrical conformation of 2,4,6-triformylresorcinol imine lead to the formation of transient imine macrocycles, which further undergo mesoscale self-assembly into nanotubular structures. The nanotubular structures tend to join together into rod-like bundles with ordered hexagonal rods, which finally grow into uniform hexagonal COF mesocrystals. The present strategy opens a nonclassical nucleation and crystal growth approach to create COFs with unexplored mesocrystal structures, which further extends the scope of crystalline framework materials and provides a new strategy for crystal morphogenesis.

Proximity Effect in Crystalline Framework Materials: Stacking‐Induced Functionality in MOFs and COFs

AbstractMetal–organic frameworks (MOFs) and covalent organic frameworks (COFs) consist of molecular building blocks being stitched together by strong bonds. They are well known for their porosity, large surface area, and related properties. The electronic properties of most MOFs and COFs are the superposition of those of their constituting building blocks. If crystalline, however, solid‐state phenomena can be observed, such as electrical conductivity, substantial dispersion of electronic bands, broadened absorption bands, formation of excimer states, mobile charge carriers, and indirect band gaps. These effects emerge often by the proximity effect caused by van der Waals interactions between stacked aromatic building blocks. Herein, it is shown how functionality is imposed by this proximity effect, that is, by stacking aromatic molecules in such a way that extraordinary properties emerge in MOFs and COFs. After discussing the proximity effect in graphene‐related materials, its importance for layered COFs and MOFs is shown. For MOFs with well‐defined structure, the stacks of aromatic building blocks can be controlled via varying MOF topology, lattice constant, and by attaching steric control units. Finally, an overview of theoretical methods to predict and analyze these effects is given, before the layer‐by‐layer growth technique for well‐ordered surface‐mounted MOFs is summarized.

A Chiral Bis-Naphthylated Tetrandrine Dibromide: Synthesis, Self-Assembly into an Organic Framework Based On Nanosized Spherical Cages, and Inclusion Studies.

Crystalline framework materials have gained interest because of their many potential applications. A novel chiral tetrandrine salt (DNT) has been synthesized and characterized by conventional analytical techniques and single-crystal X-ray diffraction analysis, and its self-assembly behavior studied. In the solid state, 48 molecules of the compound self-assemble into an organic framework based on nanospherical aggregates formed exclusively through weak noncovalent interactions. Additionally, it was demonstrated by UV-vis spectroscopy and TGA that assembled DNT can include the Nile Red dye, giving a fluorescent material. To the best of our knowledge, these spherical assemblies are the largest among the purely synthetic organic self-assembled molecular crystals reported to date.

Balancing Mechanical Stability and Ultrahigh Porosity in Crystalline Framework Materials.

A new mesoporous metal-organic framework (MOF; DUT-60) was conceptually designed in silico using Zn4 O6+ nodes, ditopic and tritopic linkers to explore the stability limits of framework architectures with ultrahigh porosity. The robust ith-d topology of DUT-60 provides an average bulk and shear modulus (4.97 GPa and 0.50 GPa, respectively) for this ultra-porous framework, a key prerequisite to suppress pore collapse during desolvation. Subsequently, a cluster precursor approach, resulting in minimal side product formation in the solvothermal synthesis, was used to produce DUT-60, a new crystalline framework with the highest recorded accessible pore volume (5.02 cm3 g-1 ) surpassing all known crystalline framework materials.

Synthesis and functionality of transition metal-centered polyoxometalate-based crystalline framework materials

Polyoxometalates, a class of discrete nanoscale molecular metal-oxo clusters, have excellent catalytic and photoelectric/electrochromic properties due to their excellent electronic storage and redox capacity. They possess of plenty of potential applications as efficient catalysts in the development of clean and green fuels. However, polyoxometalates are easy to agglomerate and deactivate in the catalytic process, and possess of low specific surface area. Therefore, it is extremely urgent to introduce polyoxometalates into crystalline porous materials with well-defined structure, modifiable channels and high porosity. The introduction of transition metal into polyoxometalates can not only regulate their charge number, but also optimize their band structure. As well known, polyoxometalates, as one kind of unique metal oxide cluster, have been considered as promising secondary building units for construction of porous frameworks because of their adjustable compositions, variable topologies and oxygen-rich surface as well as their diverse physical and chemical properties. Recently, more and more attention has been paid to introducing polyoxometalates into frameworks to functionalize porous frameworks materials. So, these transition metal-centered polyoxometalates should be ideal building units for the design and synthesis of porous crystalline framework materials. These crystalline materials are expected to be used in the fields of single-molecule magnets, photocatalytic water splitting, desulfurization and so on. This review is directed to cover the main advances on the development of transition metal-centered polyoxometalate-based framework materials. In the past several decades, researchers have synthesized 1:12 Keggin type and Silverton type polyoxometalate, Anderson type polyoxometalate Waugh type polyoxometalate, Evans-Showell type polyoxometalate and heteropolyvanadate-based framework materials by hydrothermal method and conventional aqueous solution method. The water oxidation and photocatalytic degradation of organic pollutants of the framework materials were detailly studied. For example, the Keggin anion [CoW12O40]6– turned into an efficient and robust electrocatalyst upon its confinement in the well-defined void space of metal-organic framework (ZIF-8). In the electrocatalytic process, the [H6CoW12O40]@ZIF-8 composite crystalline framework materials is very stable for water oxidation that could retain its initial activity even after 1000 catalytic cycles. The catalyst has a turnover frequency (TOF) of 10.8 mol O2 (mol Co) –1s–1, one of the highest TOFs for electrocatalytic oxygen evolution at neutral pH. Further, the POM-based crystalline framework materials were used for oxidative desulfurization and the decomposition of chemical warfare agent. In these fields, the porous frameworks with catalytic active manganese(IV)-containing heteropolyvanadate [MnV13O38]7- as nodes and rare earth ions as linking units have been successfully prepared. These multifunctional polyoxometalate-based porous framework materials exhibit selective adsorption behavior and remarkable catalytic activity as heterogeneous catalysts for the oxidation of sulfides. A novel manganese(IV)-containing symmetrical heteropolyvanadate K7 [ MnV13O38] · 18H2O to K4Li2[MnV14O40] · 21H2O was also prepared, which is an deficient catalyst for the oxidation of 2-chloroethyl ethyl sulfide with tert-butyl hydroperoxide oxidizing agent. In this catalytic process, a TON of 40 is achieved in 8 h, showing potential application toward air decontamination technology. The results show that the transition metal-centered polyoxometalate-based crystalline framework materials possess of many functionalities, especially as excellent catalysts. In this paper, the research progress of crystalline framework materials constructed from transition metal-centered polyoxometalates is systematically summarized, and the challenges and opportunities in this field are also presented.

Chiral Chemistry of Homochiral Porous Thin Film with Different Growth Orientations.

Chirality is one of the essential features in our living life and exerts a wide variety of applications in enantio-adsorption/separation. However, the mechanism between chirality and enantio-adsorption/separation is very significant in homochiral porous materials; in particular, the understanding of the relationship between crystalline orientations and chiral behavior is a challenging but important mechanism. In this work, homochiral porous crystalline metal organic framework (MOF) materials were grown on hydroxyl- and carboxyl-functionalized substrates, resulting in homochiral porous thin films with different orientations. The enantioselectivity and adsorption rates in two different oriented homochiral porous thin films were studied by using gas-phase quartz crystal microbalance (QCM) experiment of chiral probe molecules. The different mass uptake and time constant showed that the chiral behavior can be obviously influenced by the crystalline orientations on the same homochiral porous thin films. This study will not only offer a good model to understand the mechanism of chiral behavior in homochiral porous materials but also provide guidance for developing new homochiral-oriented porous thin films with high enantioselectivity or enantioseparation.

Superior Charge Storage and Power Density of a Conducting Polymer-Modified Covalent Organic Framework.

The low conductivity of two-dimensional covalent organic frameworks (2D COFs), and most related coordination polymers, limits their applicability in optoelectronic and electrical energy storage (EES) devices. Although some networks exhibit promising conductivity, these examples generally lack structural versatility, one of the most attractive features of framework materials design. Here we enhance the electrical conductivity of a redox-active 2D COF film by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) within its pores. The resulting poly(3,4-ethylenedioxythiophene) (PEDOT)-infiltrated COF films exhibit dramatically improved electrochemical responses, including quantitative access to their redox-active groups, even for 1 μm-thick COF films that otherwise provide poor electrochemical performance. PEDOT-modified COF films can accommodate high charging rates (10–1600 C) without compromising performance and exhibit both a 10-fold higher current response relative to unmodified films and stable capacitances for at least 10 000 cycles. This work represents the first time that electroactive COFs or crystalline framework materials have shown volumetric energy and power densities comparable with other porous carbon-based electrodes, thereby demonstrating the promise of redox-active COFs for EES devices.