Search Results (258)

Covalent organic frameworks (COFs) are promising crystalline porous polymers for photocatalysis, yet their strong excitonic effects and rapid carrier recombination limit efficiency. However, strong excitonic effects and rapid electron–hole recombination remain key challenges. Herein, we employ density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to systematically investigate the structure–activity relationships of three D–π–A-type COFs (COF-alkene, TapbBtt-COF, and TtaTpa-COF) for photocatalytic overall water splitting. Benchmarking identifies the M06L functional, SMD solvent model, and 6-311+G(2d,p) basis set as optimal. Our results reveal that molecular planarity, D–π–A configuration, and charge separation collectively govern performance. TtaTpa-COF exhibits the narrowest E_ex (2.47 eV), longest absorption wavelength (502.15 nm), and lowest hole–electron overlap (0.51), enabling efficient carrier separation. For the hydrogen evolution reaction (HER), TtaTpa-COF shows the most favorable *H adsorption free energy (0.04 eV) and lowest LUMO level (−2.8 eV), yielding the highest activity. Notably, the D–π–A system governs active-site selectivity: COF-alkene favors the alkene-linked carbon, whereas the other two favor imine nitrogen. For the oxygen evolution reaction (OER), all follow the adsorbate evolution mechanism with *OOH formation as the rate-determining step. TtaTpa-COF exhibits the lowest limiting potential (4.33 eV), indicating superior water oxidation kinetics. This work establishes a clear structure–activity relationship linking D–π–A architecture to photocatalytic performance, providing a rational design framework for high-activity COF-based photocatalysts. Full article

Chirality is a cornerstone of biological systems and pharmaceutical activity, driving a critical need for rapid and sensitive enantioselective analytical methods. Covalent organic frameworks (COFs) have emerged as versatile porous materials, and their chiral counterparts, chiral COFs (CCOFs), uniquely combine high surface area, pre-designable pores, and a confined chiral microenvironment, making them exceptional platforms for enantioselective fluorescence sensing. This review systematically summarizes recent advances in the construction and application of CCOFs for enantioselective fluorescence sensing. We first outline the primary synthetic strategies for CCOFs, including direct synthesis, post-synthetic modification, and chiral induction. Subsequently, based on the direction of fluorescence signal change upon analyte binding, we classify the sensing mechanisms into three categories: “turn-off” (quenching via static complexation or photoinduced electron transfer), “turn-on” (enhancement through rigidification or suppression of electron transfer), and ratiometric (self-calibrating dual-emission response). Representative examples for the detection of amino acids, amino alcohols, terpenes, and saccharides are highlighted for each mode. Special emphasis is placed on structure–property relationships, such as the synergistic roles of hydrogen bonding, π–π stacking, and framework confinement in amplifying enantioselectivity. Finally, we discuss current challenges and future perspectives, including the rational design of ratiometric sensors, integration into practical devices, and the convergence with machine learning to advance the field of smart chiral sensing. Full article

Effective regulation of the adsorption strength of oxygen reduction reaction (ORR) intermediates on active sites is the key to enhancing their catalytic performance. This study proposes an axial coordination modulation strategy by successfully anchoring the dioxin-linked FePcF₁₆-based covalent organic frameworks (COFs) onto amino-functionalized multi-walled carbon nanotubes (NH₂-MWCNTs), constructing a FePcF₁₆-COF/NH₂-MWCNT hybrid catalyst. Experimental results demonstrate that the catalyst exhibits outstanding ORR activity (E_1/2 = 0.901 V; J_L = 5.133 mA cm⁻²), outperforming commercial 20% Pt/C and most reported Fe-based non-precious metal catalysts. Furthermore, the robust dioxin-linked COF skeleton endows the catalyst with excellent electrochemical stability. A zinc–air battery using this catalyst as the cathode also demonstrates superior power density and cycling performance. This work provides a new strategy for designing highly efficient ORR catalysts through axial coordination environment engineering. Full article

Covalent organic frameworks (COFs) are one of the most important crystalline structures, having high porosity, and are mostly composed of lighter elements, such as H, C, N, O, etc., with covalent bonds between them. They are chemically synthesized in a repetitive arrangement and create a highly effective porous surface area that plays a fundamental role in various applications including sensing and biomedical applications. This study offers an overview of COFs in sensing and biomedical applications and provides a detailed overview of various synthesis procedures of COFs. Next, we explore their innovative sensing performances in the cases of various gases, ions and metals. Finally, it is emphasized that the major biomedical applications of COFs have been addressed regarding diseases and treatment strategies. Overall, this review offers an overview of COFs’ capabilities and promising behaviors in enhancing and revolutionizing sensing and biomedical technologies. Full article

Covalent organic framework materials (COFs) are promising for pollutant adsorption owing to their high specific surface area, tunable pores and functional designability, but their microcrystalline powder form leads to poor mechanical strength and processability, limiting practical applications. This study presents a mild, eco-friendly strategy using polysulfonamide fiber (PSA) with excellent mechanical and thermal stability as the core matrix, and room-temperature-synthesized sulfonic acid-functionalized TFP-DABA-COFs as the shell layer. Via coaxial wet spinning, core–shell structured PSA-COF composite fibers were fabricated without harsh solvothermal conditions, improving COF dispersion and interfacial bonding. Characterizations revealed the fibers possessed favorable comprehensive properties: fracture strength of 14.97 MPa, elongation at break of 32.84%, specific surface area of 8 m²/g, and hierarchical porous structures dominated by micropores, with enhanced hydrophilicity beneficial to aqueous adsorption. Adsorption experiments on woven fabrics showed 93.6% methylene blue removal in 40 min and 98.9% in 120 min, following the quasi-second-order kinetics, indicating chemisorption (electrostatic attraction) as the main mechanism. This work provides a mild, green approach to prepare PSA-COFs core–shell fibers, effectively solving the formability and processing issues of COFs. Full article

Alzheimer’s disease (AD) seriously affects human health worldwide. Nicotinamide adenine dinucleotide (NADH) and glutamate are important biomarkers of AD, which play an indispensable role in the pathogenesis of AD. Herein, two ligands were used to synthesize a layered covalent organic framework (TPCOF) via amide bond formation, which was loaded with cobalt to obtain Co-TPCOF. TPCOF has a twisted 2D layered structure, along with large interlayer spacing and porosity, enabling precise Co coordination and stable loading of metal nanoparticles/enzymes to support electrocatalysis. A Co-TPCOF was immobilized on a screen-printed electrode (SPE) to catalyze the oxidation of NADH. After that, the oxidation product NAD⁺ of NADH and the NAD⁺-dependent dehydrogenase immobilized on the electrode jointly catalyzed the glutamate in the solution. COFs’ unique structures endow Co-TPCOFs with excellent NADH catalytic activity. The Co-TPCOF/SPE showed good linearity for NADH (10 nM-5 mM, LOD 7.07 nM) and GDH/Co-TPCOF/SPE for glutamate (50 μM-5 mM, LOD 3.74 μM). The biosensor can sensitively detect trace NADH and glutamate in human serum, providing an adequate technical means and theoretical reference for the pathological research of AD. Full article

Unsafe food poses a significant threat to global public health and the economy, making the early detection of food spoilage an ongoing and critical imperative. Herein, we report the design of a straightforward and highly effective fluorescence sensor for monitoring histamine (HI), a key biomarker of food deterioration, utilizing the direct interaction between the analyte and the sensor. We demonstrate that the inherently weak luminescent covalent organic framework (COF), TpPa-1, functions as a highly responsive “turn-on” luminescent switch in the presence of HI. Upon interaction with HI, the luminescence of TpPa-1 is significantly enhanced; this phenomenon is attributed to the generation of anionic N⁻ species via the deprotonation of the N−H unit, which effectively suppresses the electron transfer pathway from the nitrogen lone pair to the COF backbone. The TpPa-1 sensor exhibits excellent sensitivity and reproducibility for HI detection. Furthermore, we developed a reusable, fluorescent COF-based film that displays a distinct, naked-eye visible color transition from red to yellow-green upon exposure to histamine, establishing a robust platform for rapid, and preliminary food quality assessment. This work presents a novel, COF-based strategy for HI detection, offering substantial significance for public health and food safety monitoring. Full article

To address the critical challenges of sluggish C-C coupling kinetics and the propensity for over hydrogenation to ethane (C₂H₆) in the photocatalytic CO₂ reduction to ethylene (C₂H₄), this study designed a synergistic bimetallic Pt/Co cluster catalyst supported on a covalent organic framework (COF), designated as PtCo-TpBD COF. This catalyst is designed to modulate the adsorption of key intermediates via Co clusters to suppress over-hydrogenation, while leveraging Pt clusters to promote C-C coupling, thereby achieving highly selective C₂H₄ production. Through a series of structural characterization analyses, it was confirmed that Pt/Co clusters were successfully confined within the pores of the COF, and significant electronic interactions were observed. In situ infrared spectroscopy revealed that the introduction of Co clusters effectively weakens the adsorption strength of the CO* intermediate, while the incorporation of Pt clusters promotes C-C coupling. In visible-light-driven gas-phase CO₂ reduction, this catalyst delivered exceptional activity, reaching an C₂H₄ formation rate of 7.54 μmol g⁻¹ h⁻¹ and an C₂H₄ selectivity of 90.1%, along with remarkable inhibition of deep hydrogenation byproducts including C₂H₆. This study not only provides a successful example for constructing efficient bifunctional photocatalysts to achieve highly selective conversion of CO₂ to C₂H₄, but also highlights the great potential of COFs as advanced platforms for integrating multifunctional metal clusters and precisely tuning catalytic selectivity. Full article

Covalent organic frameworks (COFs) have emerged as promising materials for the capture and photoluminescent detection of pharmaceutical contaminants in aquatic environments due to their tunable porosity, high surface area, and structural versatility. This review summarizes recent advances in pristine COFs and COF-based hybrid materials for water treatment, focusing on both the adsorption and photoluminescent sensing of pharmaceutical pollutants. The influence of framework design, linkage type, and functionalization on adsorption performance and selectivity is discussed, together with the main interaction mechanisms involved. In addition, recent developments in photoluminescent COFs for sensitive and rapid drug detection are highlighted. Attention is given to dual-function materials capable of simultaneous capture and detection, which represent an emerging strategy for efficient water remediation. Finally, current challenges related to stability, selectivity, and real-world applicability are outlined, providing perspectives for the design of next-generation COF-based systems. Full article

Background: Pancreatic cancer is an aggressive malignancy with poor survival. Most patients are diagnosed at advanced or metastatic stages because early disease is often asymptomatic and effective screening tools are lacking. We evaluated a three-marker model comprising serum CA19-9 in combination with the plasma proteins ITIH3 and CEACAM1 for pancreatic ductal adenocarcinoma (PDAC) detection. Methods: Matched plasma and serum samples were collected from 649 participants (250 PDAC cases and 399 controls). Plasma proteins were enriched using high-surface area magnetic covalent organic framework (COF) polymers. Serum CA19-9 was measured using the Tosoh Bioscience immunoassay. The marker panel was trained using a radial-based SVM with repeated 10-fold cross-validation using a set-aside training sample set. The derived model along with a fixed cutoff corresponding to 95% sensitivity in training samples were independently validated using a blinded sample set. Results: In the independent blinded validation, the combined panel of serum CA19-9 with plasma ITIH3 and CEACAM1 achieved an AUC of 0.917 indicating that the three-marker panel maintained strong performance in distinguishing PDAC from controls. At the prefixed threshold, the three-marker panel had a specificity of 53.3% (95% CI: 46.8–59.7%), significantly outperforming CA19-9 alone at 14.5% (95% CI: 10.4–19.7%). Conclusions: In independently blinded validation, combining plasma ITIH3 and CEACAM1 with serum CA19-9 substantially improved diagnostic performance for PDAC, achieving high specificity while maintaining 95% sensitivity compared with serum CA19-9 alone. These findings support further validation of this three-marker panel as a potential PDAC monitoring and detection approach in larger, multicenter studies. Full article

Achieving selective SO₂ capture at low pressures is pivotal and challenging for possible flue gas desulfurization and air pollution control. In this study, we synthesized a series of ionic covalent organic frameworks (iCOFs) with β-ketoenamine linkages and sulfonic acid groups using a solvothermal method. TpPa-SO₃H and TpBD-(SO₃H)₂ show a higher SO₂ uptake of 4.46 and 5.24 mmol g⁻¹ than TpPa-1 (4.24 mmol g⁻¹) at 1 bar and 298 K, respectively, due to the combination of the good SO₂ affinity of the polar sulfonic acid groups, higher pore volumes, and the good stability of β-ketoenamine COFs. TpBD-(SO₃H)₂ captured 2.83 mmol g⁻¹ of SO₂ at 0.1 bar and 298 K, which is 1.6 times higher than TpPa-1 (1.82 mmol g⁻¹) under the same conditions. Notably, the IAST SO₂/CO₂ selectivity of TpBD-(SO₃H)₂ and TpPa-1 are 61 and 51, respectively, reflecting the impact of the incorporated SO₃H groups’ higher affinity toward SO₂. Notably, the multicomponent gas mixture breakthrough experiments confirm that TpBD-(SO₃H)₂ displays longer breakthrough time than TpPa-1 (987 vs. 311 min g⁻¹). These β-ketoenamine iCOFs demonstrate nearly complete retention of crystallinity and porosity after exposure to dry or humid SO₂. This work demonstrates that iCOFs are promising adsorbents for SO₂ capture due to their high capacity, stability, and affinity for SO₂ at low pressure. Full article

Application of porous coordination polymers (PCPs), which include metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) in sensors for detection of toxicant pollutants in water is discussed. Particular attention is given to electrochemical and photoluminescent sensors because PCPs/MOFs demonstrate good selectivity towards adsorption of molecules in combination with outstanding luminescent properties and electroconductivity in composite materials. The use of PCPs/MOFs as pre-concentrators of the compounds to be analyzed is also outlined. The review covers the results described in the literature over the past 5 years in such diverse fields as the determination of metal ions and anions, drugs, mycotoxins, pesticides, explosives, bacteria, etc. Thus, the review demonstrates the proliferation of MOF applications and the universal nature of sensors based on them. Full article

The excessive accumulation of biogenic amines (BAs) in aquatic products poses serious health risks, necessitating the development of rapid and sensitive detection methods. This study reports the synthesis of a novel fluorescent nanocomposite, carbon-dot-embedded covalent organic frameworks (CDs@COFs). Comprehensive characterization (TEM, XPS, FTIR, UV–Vis, and fluorescence spectroscopy) confirmed the successful fabrication of the nanocomposites, which exhibited excellent thermal and optical stability. A significantly enhanced quantum yield of 36.22% (compared with 12.92% for pure carbon dots) was obtained. As a fluorescent probe, the composite enabled the detection of nine BAs based on a fluorescence quenching mechanism. The proposed method demonstrated good linearity (1~100 ng/mL) and low detection limits of 0.58~0.98 ng/mL. The method was successfully applied to analyze tyramine in large yellow croaker, showing accurate spike recoveries ranging from 91.93% to 101.43% and excellent reproducibility (RSD < 3%). These results highlight the great potential of the developed method as a powerful tool for the rapid screening of BAs in aquatic products. Full article

The global energy transition and the implementation of carbon capture, utilization, and storage (CCUS) strategies require energy-efficient and scalable CO₂ separation technologies. Mixed-matrix membranes (MMMs), combining polymer matrices with functional inorganic or hybrid nanofillers, have emerged as advanced separation platforms capable of surpassing the conventional permeability–selectivity trade-off observed in neat polymer membranes. This review critically evaluates recent developments in modern hybrid membranes for CO₂ separation from synthetic and industrial gas mixtures, including CO₂/N₂ (flue gas), CO₂/CH₄ (natural gas and biogas upgrading), and syngas systems. Particular emphasis is placed on MMMs incorporating covalent organic frameworks (COFs), metal–organic frameworks (MOFs), graphene oxide (GO), MXenes, transition metal dichalcogenides (TMDs), carbon nanotubes (CNTs), g-C₃N₄, layered double hydroxides (LDH), zeolites, metal oxides, and magnetic nanoparticles. Reported performance ranges include CO₂ permeability (P_CO2) typically between 100 and 800 Barrer, CO₂/N₂ selectivity up to 319, and CO₂/CH₄ selectivity up to 249, depending on filler chemistry, loading, and interfacial compatibility. The mechanisms governing gas transport—molecular sieving, selective adsorption, facilitated transport, and diffusion-pathway engineering—are systematically discussed. Key challenges addressed include filler dispersion, polymer–filler interfacial defects, physical aging, moisture sensitivity, oxidation (particularly in MXenes), and scalability toward industrial membrane modules. Future perspectives focus on sub-nanometer pore engineering, surface functionalization to enhance CO₂ affinity, controlled alignment of 2D nanosheets to promote directional transport, multifunctional core–shell and hollow structures, and the integration of computational modeling and machine learning for accelerated material design. Modern hybrid MMMs are identified as strategically important materials enabling high-efficiency CO₂ separation processes aligned with decarbonization and energy transition objectives. Full article

High-sensitivity rapid detection of ammonia (NH₃) in environmental monitoring, industrial safety, early diagnosis, and other fields is of great significance. Covalent organic frameworks (COFs) have shown great potential in the field of gas sensing due to their designable porous structure and active sites. However, the traditional solvothermal synthesis method of COFs has problems such as cumbersome steps, high energy consumption and serious environmental pollution. Therefore, it is of great significance to invent a new method for COF synthesis that is green and efficient and makes it easy to conduct flexible ammonia gas sensing. This study first reported a solvent-free synthesis of imine connection 1,3,5-Triformylbenzene (TFB) and p-Phenylenediamine (PDA)—a new strategy for COF. This method innovatively employs zinc trifluoromethyl sulfonate (Zn(OTf)₂) as a bifunctional catalyst. This catalyst not only efficiently catalyzes para-phenylenediamine, but its zinc ions also play a unique structural guiding role, guiding the reactants to be arranged in a directional manner, thereby constructing a highly ordered porous crystal structure. A series of characterizations confirmed that the obtained TFB-PDA-COF had good crystallinity and a high proportion of imine bonds (C=N). The powder material was coated onto a flexible polyimide (PI) substrate, successfully constructing a resistive ammonia gas sensor that operates at room temperature. The test results show that this sensor has a high response value, rapid response/recovery capability, and good selectivity for ammonia gas. More importantly, based on a flexible PI substrate, the device can maintain stable sensing performance even under repeated bending conditions, demonstrating its great potential in practical flexible electronic applications. This work not only provides a brand-new “zinc ion-guided” paradigm for the green and controllable synthesis of COF but also lays a material foundation for their application in the next-generation flexible sensing field. Full article