Construction Archimedean tiling patterns based on soft materials from block copolymers and covalent organic frameworks

Sol-gel processing of a covalent organic framework for the generation of hierarchically porous monolithic adsorbents

Covalent organic frameworks (COFs) are emerging as promising electrode materials due to their high surface area, tunable porosity, and design flexibility. However, their practical use in energy storage remains limited by their poor stability and electrochemical performance. Here, we report a nitrogen-rich COF, synthesized via an irreversible aromatic nucleophilic substitution between hexaazatriphenylenehexacarbonitrile and 3,3′-diaminobenzidine (HAT-DAB COF), forming stable – C═N– and −C–N– linkages. The framework integrates redox-active phenazine and arylamine units, offering a porous, crystalline, and nitrogen-rich architecture. Structural and morphological analyses confirm its robust and porous nature. As a bifunctional electrode, HAT-DAB COF shows excellent performance in lithium-ion batteries, with a specific capacity of 265 mAh/g, an energy density of ∼607 Wh/kg, and ∼98% Coulombic efficiency over hundreds of cycles. As a supercapacitor, it delivers 110.5 mF/cm2 at 1 mV/s, with ∼95% capacitance retention and 100% Coulombic efficiency over 8000 cycles. Capacitance arises from a synergy of electric double-layer and redox (Faradaic) processes, with the diffusive component retained even at high scan rates, indicating strong pseudocapacitor behavior. This work demonstrates the value of irreversible linkages and rational redox-active design in achieving durable, high-performance COFs for next-generation energy storage applications.

Covalent organic frameworks (COFs) are a family of crystalline porous networks having applications in various fields, including gas and energy storage. Despite respectable progress in the synthesis of such crystalline materials, examples of the use of template-free methods to construct COFs having hollow nano- and microstructures are rare. Furthermore, all reported methods for synthesizing these hollow structural COFs have involved [4 + 2] and [3 + 2] condensations. Herein, we report the synthesis of hollow microspherical and microtubular carbazole-based COFs through template-free, one-pot, [3 + 3] condensations of the novel triamine 9-(4-aminophenyl)-carbazole-3,6-diamine (Car-3NH2) and triformyl linkers with various degrees of planarity. Depending upon the monomer's planarity, a unique morphological variety was observed. A time-dependent study revealed that each COF formed through an individual mechanism depended on the degree of planarity of the triformyl linker; it also confirmed that the hollow structures of these COFs formed through inside-out Ostwald ripening. Our COFs exhibited high Brunauer-Emmett-Teller surface areas (up to ca. 1400 m2 g-1), excellent crystallinity, and high thermal stability. Moreover, the CO2 uptake capacities of these COFs were excellent: up to 61 and 123 mg g-1 at 298 and 273 K, respectively. The high surface areas facilitated greater numbers of strong interactions with CO2 molecules, leading to high CO2 uptake capacities. Moreover, the prepared COFs exhibited redox activity because of their redox-active triphenylamine and pyridine groups, which can be utilized in electrochemical energy storages. Accordingly, such hollow COFs having high surface areas appear to be useful materials for industrial and biological applications.

Modulated construction of imine-based covalent organic frameworks for efficient adsorption of polycyclic aromatic hydrocarbons from honey samples

Covalent organic frameworks (COFs) are periodic porous polymers with relatively high crystallinity, which have become a newly emerging family of materials. The COF materials are constructed by covalent bonds (B–O, C–C, C–N etc.) of light elements, and by using various organic building blocks we can create versatile COFs with diverse topology and functionalities. The COFs often possess the characteristics of low density, high porosity and large specific surface area, and have therefore been widely applied in gas adsorption and separation, energy chemistry and the environmental fields. To develop COF materials with appreciable functionalities, extensive experimental and theoretical techniques are being employed. In particular, multiscale simulation methods have been proven to be an efficient tool to design and investigate the properties of new COFs. This article mainly introduces two rational strategies to design new COF materials. One is linker replacement or the node replacement strategy to achieve high performance gas storage COF materials with large surface areas and pore volumes. The other is functional group modification or the metal doping strategy to design functionalized COFs with strong affinity towards gases. For the two design strategies, we also give a corresponding example for further analysis. Finally, we summarize the applications of COFs in hydrogen and methane storage, as well as CO2 capture.

Introduction Nitrogen-doped carbon materials have been attracting great attention as one of the promising metal-free oxygen reduction reaction (ORR) catalysts due to the abundant resources, chemical stability, and high electronic conductivity, which could replace the high cost platinum-based materials limiting expansion of application fields of the fuel cells. Generally, nitrogen-doped carbons have been prepared by chemical vapor deposition with precursors containing nitrogen (pyridine or acetonitrile, etc.)[i], or by thermal/plasma treatment using graphitic carbons.[ii] The active site of nitrogen-doped carbons is yet controversial, though it has been suggested that incorporation of nitrogen atoms in the sp2 carbon network structures enhances ORR activity through active site formation by produced pyridinic N or graphitic N.1 Together with the nitrogen doped structures, the amount of the doped nitrogen atoms, surface area and degrees of graphitization can affect the ORR performance[iii] and control techniques of these factors are crucial to achieve the higher catalytic activity. Herein we fabricated the nitrogen-doped carbon from covalent organic frameworks (COFs) which have molecularly-ordered structures constructed by covalent linkage of organic building blocks. Due to the above unique structures and properties, COFs are promising for potential applications in gas storage, optoelectronic devices and catalysis.[iv] In this study, we focus on the structural features of COFs, which are versatile molecular design based on various combination of the building block molecules and the covalent bonding and highly porous structures. Thus we have been examining carbonization of COFs having hetero atoms such as N and B to create hetero atom doped carbon materials from the molecularly-ordered starting materials, COFs. Herein we synthesized two types of the nitrogen atom-containing COFs as the precursors. After carbonization, we found that the nitrogen-doped porous carbons were fabricated with high surface areas. The obtained materials would be useful to examine the effect of structural differences of the resulting nitrogen-doped structures on ORR activity to develop highly active carbon catalysts. Experiment Synthesis of COF1[v]Benzene-1,3,5-tricarboxylate (1, 24 mg) and phenylendiamine (2, 24 mg) were dissolved in dioxane (2.5 ml), respectively. After mixing the solutions, 3.0 M aqueous acetic acid (0.25 ml) was added. Two-day storage at 25 °C was found to generate a precipitate, which was collected by filtration, then washed with acetone. The obtained solid was dried overnight in vacuo at 80 °C to provide a yellow powder (COF1). Synthesis of ACOF-1 1 (24 mg) and hydrazine (3, 19 ml) were dissolved in dioxane (1.0 ml). Then 6.0 M tetrafluoroacetic acid (0.13 ml) was added. The solution was heated at 120 °C in a pressure resistant vessel yielding a precipitate, which was collected by filtration, then washed with acetone. The obtained solid was dried overnight in vacuo at 80 °C to provide a pale yellow powder (ACOF-1). Carbonization of COFs The obtained COF1 and ACOF-1 were heated at 800 °C for 3 h under N2 flow. Result and Discussion The XRD patterns of the obtained COFs show obvious diffraction peaks, which indicate crystalline structure formation. For porous structure investigation, N2 gas adsorption measurements were conducted. Based on the BET analysis, the surface area of COF1 and ACOF-1 were estimated to be 1528 m2/g and 1484 m2/g respectively. These results reveal that the prepared COFs have highly ordered structures with large surface areas. After carbonization of the both COFs, in Raman spectra, two peaks were observed at around 1300 cm-1 and 1590 cm-1, which are attributed to D band and G band of graphitic carbon structures. From deconvoluted XPS spectra of the N1s, three peaks were observed at 398, 400, and 402 eV ascribable to pyridinic, pyrrolic, and graphitic N. The results exhibit that the carbonized COFs have nitrogen-doped graphitic structures. The BET surface area of the carbonized COF1 and the carbonized ACOF-1 were calculated to be 538 m2/g and 1257 m2/g, respectively. Interestingly, the carbonized ACOF-1 showed a similar surface area to one before carbonization. This result indicates that COFs would be capable of producing porous carbon structures. The electrocatalytic properties of the carbonized ACOF-1 for ORR were investigated by cyclic voltammetry (CV) in 0.1M KOH saturated with N2 or O2 gas. Though no peak was observed in a N2 atmosphere condition, a significant reduction peak appeared at -0.198 V under an O2 atmosphere, which indicates ORR catalytic activity from the material. [i] M. Kawaguchi et al. Chem. Mater. 1996, 8, 1197. [ii] X. Wang et al. Science, 2009, 324, 768. [iii] C. H. Choi et al. ACS nano, 2 012, 6, 7084. [iv] A. P. Cote et al. Science, 2005, 310, 1166. [v] T. Shiraki et al. Chem. Lett. 2015, 44, 1488. Figure 1

ConspectusAs one of the most attractive members in the porous materials family, covalent organic frameworks (COFs) have been reported thousands of times since their first discovery in 2005, covering their design, synthesis, and applications. However, an overwhelming majority of these COFs are based on two-dimensional (2D) topologies while three-dimensional (3D) COFs are numbered fewer than 100 up to date. In fact, baring enhanced specific surface area, interconnected channels, well-exposed functional moieties, and highly adjustable structures, 3D COFs are often more competitive in various application fields like adsorption, separation, chemical sensing, and heterogeneous catalysis compared with their 2D counterparts. However, significant crystallization problems and poor chemical stabilities, which might be attributed to the highly void frameworks and the absence of π-π stacking, have raised severe limitations over the research and application of 3D COFs. To solve these problems, more elaborate synthesis regulations or more moderate functionalization conditions are required. More importantly, the strategies for enhancing chemical stabilities of 3D COFs are of vital importance for their further development and practical applications.In this Account, we review the design principles, functional approaches, and stability regulation methods toward functional 3D COFs. We begin the discussion with some essential elements in the construction of 3D COF structures, including topologies, interpenetrations, linkages, and synthetic methods. After that, we focus on several strategies for the functionalization of 3D COFs, including in situ approaches (utilizing in situ generated COF linkages as the active sites), bottom-up synthesis (embedding functional moieties from predesigned building blocks), and postsynthesis modification (covalent modification or metalation of pristine frameworks). At last, we highlight some approaches toward the durable amplification of 3D COFs, which is highly important for framework functionalization and practical application. This target could be achieved through not only the introduction of some extra strengthening force, such as hydrophobic effects, coulomb repulsion, and steric hindrance effects, but also the utilization of robust linkages, which could enhance the stability from material nature.Due to their high surface area, various interpenetrated channels, multifarious functionalities, and promising stabilities, 3D COFs demonstrated excellent performance and have great potential in a wide range of application fields including adsorption and separation, heterogeneous catalysis, energy storage, and so on. Although the development of these materials has been limited by serious crystallization problems and stability restriction, great efforts have been devoted by researchers in the past decade, and a mass of strategies have been developed in synthesis control, functionalization regulation, and stability enhancement for 3D COFs. We expect 3D COFs to be practically utilized in the future with further advances in the design, preparation, and functionalization of these materials.

As a subseries of the covalent organic framework (COF) material family, polyimide-based covalent organic framework (PI-COF) material, which has the advantages of high stability of polyimide, high specific surface area, and controllable pores of COF material, is expected to be a new type of porous material with potential applications. Although the development of PI-COF is in the early stages during the past decade, it has attracted extensive attention and is widely used in heterogeneous catalysis, gas separation, and storage fields. Therefore, this review is aiming to give a comprehensive understanding of the recent progress of PI-COFs. This article summarizes the progress of PI-COF from three aspects: controllable structure design, synthesis method, and application. First of all, under the guidance of network chemical design principles, the topology type of PI-COF and the size and shape of the formed pores are summarized in terms of different organic monomers. Then the five synthetic strategies for the synthesis of PI-COF are analyzed. Finally, the applications of PI-COF in adsorption and separation, drug delivery, solar-to-electrochemical energy storage, photocatalysis, and electrocatalyst are introduced.

BackgroundProduction of biodiesel from renewable sources such as inedible vegetable oils by enzymatic catalysis has been a hotspot but remains a challenge on the efficient use of an enzyme. COFs (Covalent Organic Frameworks) with large surface area and porosity can be applied as ideal support to avoid aggregation of lipase and methanol. However, the naturally low density limits its application. In this work, we reported a facile synthesis of core–shell magnetic COF composite (Fe3O4@COF-OMe) to immobilize RML (Rhizomucor miehei lipase), to achieve its utilization in biodiesel production.ResultThis strategy gives extrinsic magnetic property, and the magnetic COFs is much heavier and could disperse in water medium well, facilitating the attachment with the enzyme. The resultant biocomposite exhibited an excellent capacity of RML due to its high surface area and fast response to the external magnetic field, as well as good chemical stability. The core–shell magnetic COF-OMe structure not only achieved highly efficient immobilization and recovery processes but also maintained the activity of lipase to a great extent. RML@Fe3O4@COF-OMe performed well in practical applications, while free lipase did not. The biocomposite successfully achieved the production of biodiesel from Jatropha curcas Oil with a yield of about 70% in the optimized conditions.ConclusionMagnetic COFs (Fe3O4@COF-OMe) for RML immobilization greatly improved catalytic performance in template reaction and biodiesel preparation. The magneticity makes it easily recovered and separated from the system. This first successful attempt of COFs-based immobilized enzyme broadened the prospect of biodiesel production by COFs with some inspiration.

Covalent organic frameworks (COFs) have emerged as a versatile class of crystalline reticular materials distinguished by their high surface area, permanent porosity, and atomically precise structural tunability. Their modular synthesis enables precise control over pore size, geometry, and surface functionality, while offering excellent chemical stability and intrinsic biocompatibility. These attributes make COFs uniquely suited for applications as precision nanocarriers in targeted drug delivery. Recent advances demonstrate that COFs can encapsulate therapeutic agents with high loading efficiency and facilitate controlled, stimuli-responsive release profiles. Furthermore, the incorporation of targeting moieties through linker design or post-synthetic modification enables site-specific delivery, minimizing off-target cytotoxicity and enhancing therapeutic efficacy-particularly in oncological contexts. This review critically evaluates the current landscape of COF-based drug delivery systems, detailing structural design strategies, loading and release mechanisms, and functionalization approaches for precision targeting. We also highlight key challenges-such as scalable synthesis, pharmacokinetics, and in vivo stability-and outline promising research directions toward the clinical translation of COF nanocarriers for personalized medicine.

Covalent organic frameworks (COFs) are a type of crystalline porous polymers that possess ordered structures and eternal pores. Because of their unique structural characteristics and diverse functional groups, COFs have been used in various application fields, such as adsorption, catalysis, separation, ion conduction, and energy storage. Among COFs, the fluorine-containing COFs (fCOFs) have been developed for special applications by virtue of special physical and chemical properties resulting from fluorine element, which is a nonmetallic halogen element and possesses strong electronegativity. In the organic chemistry field, introducing fluorine into chemicals enables those chemicals to exhibit many interesting properties, and fluorine chemistry increasingly plays an important role in the history of chemical development. The introduction of fluorine in COFs can enhance the crystallinity, porosity, and stability of COFs, making COFs having superior performances and some new applications. In this review, the synthesis and application of fCOFs are systematically summarized. The application involves photocatalytic production of hydrogen peroxide, photocatalytic water splitting, electrocatalytic CO2 reduction, adsorption for different substances (H2 , pesticides, per-/polyfluoroalkyl substances, polybrominated diphenyl ethers, bisphenols, and positively charged organic dye molecules), oil-water separation, energy storage (e.g., zinc-ion batteries, lithium-sulfur batteries), and proton conduction. Perspectives of remaining challenges and possible directions for fCOFs are also discussed.

Covalent organic frameworks (COFs) are crystalline and porous materials formed from periodically organized organic molecules bonded covalently to create highly stable architectures. Their mechanical properties can be precisely adjusted through structural modifications, making COFs exceptionally suitable for applications in cancer treatment and drug delivery. This review summarizes strategies for controlling the mechanical properties of COFs, including adjustments in structural dimensions, pore sizes and host-guest interactions. The remarkable advancements in drug delivery, cancer therapy, photodynamic therapy and photothermal therapy achieved through COFs with tunable mechanical properties are then discussed. By providing deeper insights into the biomedical applications of COF systems, this review aims to foster interdisciplinary research combining nanomedicine and COF materials. Additionally, the review explores recent studies and discoveries on COFs' potential as innovative drug carriers capable of biological overcoming barriers such as the blood-brain barrier, nasal mucosa, cutaneous layers and oral mucosa. Greater insight into both the limitations and potential of COFs could pave the way for developing more effective and targeted strategies within this challenging field.

Per‐ and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that pose significant health risks, prompting urgent efforts to develop effective removal methods and adsorbers. Covalent organic frameworks (COFs) are metal‐free adsorbers with high stability and tunable porosity. A highly crystalline COF is synthesised mechanochemically using 1,3,5‐tris(4‐aminophenyl)benzene (TAPB) and 1,3,5‐triformylbenzene (TFB). The formation dynamics are monitored in real time with time‐resolved in situ synchrotron X‐ray diffraction. The TAPB‐TFB COF demonstrates good efficiency in eliminating PFAS from water. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are effectively extracted, and most of the adsorption occurred within the first 10 min. Additionally, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and DFT calculations are employed to elucidate the molecular interactions between PFAS and the COF framework. The rapid and efficient removal of PFAS makes TAPB‐TFB COF a promising material for water treatment applications.

Covalent organic frameworks (COFs) are designable polymers that have received great research interest and are regarded as reliable supercapacitor (SC) electrode materials. However, the poor capacitive performance in pristine form due to their insoluble non-conductive nature is the primary concern that restricts their long term use for energy storage applications. Owing to the increased requirements for electrochemical energy storage systems, exploiting porous architectures with abundant channels, high surface areas, and electrical conductivities as a type of promising electrode material for pseudocapacitors is vital. Keeping this in mind, Phosphine (PPh3)-based COF denoted as (Phos-COF-1) is being reported for the first time for SCs application. The as-prepared material was characterized by various characterization tools to gain insight into its textural and structural properties. The structural analysis revealed the crystalline nature of the sample. Remarkably, the BET analysis indicated a high surface area of ~ 818 m2 g−1 with the pore diameter centered at 1.56 nm, demonstrating the microporous structure of the sample. The SEM and TEM analysis further confirm the ordered micropore structure of the as-prepared sample as one of the most characteristic features of COFs materials. The average particle size ranges from 11 to 13 μm. The electrochemical analysis showed the pseudocapacitive nature of the Phos-COF-1 electrode with improved reversible redox properties that originated from the phosphine moieties. More importantly, when Phos-COF-1 was employed as an electrode material for SCs exhibited a specific capacitance of 100 F g−1 at the current density of 1 A g−1, a high energy density of 32 Wh kg−1 at the power density 0.4 W kg−1 within a potential window of 0.8 V. We discovered that the Phos-COF-1 electrode provides fast pathways for ion transport and shorten the ion diffusion path owing to its high surface area, and porous structure, demonstrating its great potential for electrochemical energy storage systems in the future.

Crown ethers are a class of macrocyclic molecules with unique flexible structures but they are rarely integrated in covalent organic frameworks (COFs). To date, employing flexible organic units such as crown ethers to construct COFs with high crystallinity and surface area are still a challenge. In this work, two new COFs with different flexible crown ethers as backbone rather than side chains are synthesized and further employed for alkali metal ions separation. Both of COFs possess high surface areas, good crystallinity, and excellent chemical stability. Interestingly, these two new COFs with 18‐crown‐6 or 24‐crown‐8 units showed remarkable binding ability of K+ or Cs+ owing to the size‐fit effect. This work demonstrated that the unique structural features of crown ethers will lead to increase interest in fabricating COFs with crown ethers.