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Covalent organic framework as an efficient, metal-free, heterogeneous photocatalyst for organic transformations under visible light
摘要： Visible-light active, heterogeneous, and organic photocatalysts exhibit a more sustainable and environmentally friendly alternative to classical metal-based catalysts. Two-dimensional covalent organic frameworks (2D-COFs) with permanent porosity, columnar π-arrays and excellent stability, that can become an excellent platform for heterogeneous photocatalysis of organic transformations. Here we report a predesigned imine-based COF with electron donor and acceptor structure. And new framework possesses large surface area, high crystallinity, outstanding stability and broad absorption range in the visible-light region as well as good photoelectric response characteristics. Importantly, it was found to be a highly effective heterogeneous photocatalyst for reductive dehalogenation of phenacyl bromide derivatives and α-alkylation of aldehydes under irradiation of visible-light. In addition, the COF gave good recyclability and could be reused after a simple separation manipulation. The current present still reveals a great prospect for 2D-COFs as metal-free, heterogeneous photocatalysts for organic transformations.
关键词： visible light,photocatalysis,heterogeneous catalysis,metal-free,covalent organic frameworks
更新于2025-09-23 15:23:52
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Electrochemiluminescence sensor based on upconversion nanoparticles and oligoaniline-crosslinked gold nanoparticles imprinting recognition sites for the determination of dopamine
摘要： For the determination of dopamine (DA) in serum samples, a quenching-type electrochemiluminescence sensor was constructed in this study. Upconversion nanoparticles (UCNPs) enhanced by covalent organic frameworks (COFs)-based hybrid and oligoaniline-crosslinked gold nanoparticles (AuNPs) imprinting recognition sites were introduced in electrochemiluminescence (ECL) system at first time. The porous COFs-based hybrid with large specific surface area was modified on the electrode firstly to hold more UCNPs and imprinting recognition sites. AuNPs, here, was employed in developed sensor for two objectives: 1) AuNPs on COFs-based hybrid enabled the hybrid to tunnel the electrons, which helped to improve the ECL intensity; 2) AuNPs-based thioaniline units (PATP@AuNPs) electropolymerized on the electrode in the presence of template to form oligoaniline-crosslinked AuNPs matrix. Then the exclusion of template from matrix yielded molecularly three-dimensional imprinted contours with conductivity, conducive to specific recognition and further amplify the ECL. The double recognition mode in this work involves the recognition effect of imprinted contours and quenching effect of o-benzoquinone species. The quantum chemical calculation was performed to analyzing the possible recognition and binding mechanisms of molecularly three-dimensional imprinted contours. The results showed imprinted contours could bind the target by complementary spatial cavities and weak interactions. The proposed approach yields a wide detection range (10-14-10-6 M), low limit of detection (LOD=2×10-15 M) and acceptable recoveries (93.25%-112.97%) in rat serum sample, demonstrating that the developed method holds great promise to be applied to DA detection in practical samples.
关键词： Electroconductibility molecular imprinting polymer,Covalent organic frameworks,Oligoaniline-crosslinked gold nanoparticles,Dopamine,Electrochemiluminescence
更新于2025-09-23 15:23:52
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Q-graphene-scaffolded covalent organic frameworks as fluorescent probes and sorbents for the fluorimetry and removal of copper ions
摘要： Metal-free fluorescent covalent organic frameworks (COFs) were synthesized initially with Q-Graphene (QG) scaffolds by the one-step covalent reactions of melamine-aldehyde and phenol-aldehyde poly-condensations using paraformaldehyde. It was discovered that onion-like hollow QG, which consists of multi-layer graphene and different carbon allotropes having a high proportion of folded edges and surface defects, could endow the scaffolded COFs with enhanced green fluorescence and environmental stability. Unexpectedly, they could exhibit the powerful absorption for Cu2+ ions resulting in the specific quenching of fluorescence. A fluorimetric strategy with QG-scaffolded COFs was thereby developed to probe Cu2+ ions separately in blood and wastewater with the linear concentration ranges of 0.0010 - 10.0 μM (limit of detection of 0.50 nM) and 0.0032 - 32.0 μM (limit of detection of 2.4 nM), respectively, promising the potential applications for the field-applicable monitoring of Cu2+ ions in the clinical and environmental analysis fields. In addition, the prepared COFs sorbents were employed to absorb Cu2+ ions in wastewater showing high removal efficiency. More importantly, such an one-pot fabrication route with hollow QG scaffolds may be tailorable extensively for the preparation of a variety of metal-free multifunctional COFs with enhanced fluorescence, water solubility, environmental stability, and metal removal capability.
关键词： Q-Graphene Scaffold；Covalent Organic Frameworks；Fluorescent Analysis；Removal Sorbents；Copper Ions
更新于2025-09-23 15:23:52
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Boosting the photocatalytic performances of covalent organic frameworks enabled by spatial modulation of plasmonic nanocrystals
摘要： Plasmonic Au nanocrystals (NCs) are incorporated into covalent organic frameworks (COFs) with precisely modulated distributions to improve the efficiency of electron-hole separation covalent reactions and assembly of NCs, sparsely dispersed Au NCs (AuSP/COFs) or the close packed ones (AuCP/COFs) in COFs are fabricated, in which the contributions of electron acceptors/cocatalysts on the catalytic properties of Au/COFs composites are addressed by EPR, PL, phenacyl bromide (conversion >99%, selectivity of acetophenone ~92.8%) under visible light irradiation, which are associated with accelerated electron transfer, increased available Au/COFs and optimize the charge-carrier utilization. Specifically, through balancing the rate of dynamic Schottky junctions and boosted interfacial reaction kinetics. Overall, this work contributes to the fundamental understanding of the how spatial distributions of NCs in COFs affect the photocatalytic performances.
关键词： metallic nanocrystals,heterojunctions,covalent organic frameworks,photocatalysis,inorganic/organic hybrids
更新于2025-09-23 15:19:57
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Platform for molecular-material dual regulation: A direct Z-scheme MOF/COF heterojunction with enhanced visible-light photocatalytic activity
摘要： Series of novel metal-organic framework/covalent organic framework (MOF/COF) hybrid materials were constructed by encapsulating MOF with highly stable TTB-TTA (a COF synthesized from 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TTB) and 4,4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline (TTA)) layer, inheriting their merits of high crystallinity, large surface area, outstanding visible-light response and tunable band gaps. The introduction of NH2-MIL-125(Ti) into the hybrid materials could modulate their optical, electronic and redox properties, and promote the charge separation owing to the formation of heterojunction, thus resulting in an enhanced photocatalytic performance for organic pollutant decomposition. As such, NH2-MIL-125(Ti)/TTB-TTA composite has a much higher photodegradation kinetic of methyl orange (MO) which is over 9 and 2 times the rates of pure NH2-MIL-125(Ti) and TTB-TTA, respectively. This versatile molecular-material platform can achieve dual adjusting modes consisting of a COF molecular engineering and a MOF type screening strategy, which will be applicable to a wide range of fields.
关键词： metal-organic frameworks,covalent organic frameworks,heterogeneous photocatalysis,Z-scheme heterojunction,visible-light-driven
更新于2025-09-19 17:15:36
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Rapid detection of tryptamine by optosensor with molecularly imprinted polymers based on carbon dots-embedded covalent-organic frameworks
摘要： A rapid optosensing detection method for tryptamine (TRY) based on one-pot surface-imprinting synthesis methods has been developed. The optosensor consists of molecularly imprinted polymers (MIPs) based on carbon dots (CNs)-embedded covalent-organic frameworks (COFs). The principle of operation depends on adsorbents providing a large number of accessible recognition sites with high affinity and specificity, to achieve both a rapid uptake of and high capacity for TRY. After removing the template molecules, the desired molecular cavities were selected and fixed in a distinct manner to provide a defined chemical microenvironment for the reversible binding of the TRY target molecules. The optosensing system relied on the linear relationship between the fluorescence intensity of the TRY-imprinted polymers and the concentration of TRY in the range of 0.025–0.4 mg kg-1 with a detection limit of 7 μg kg-1. The system was used for efficiently detecting TRY in meat samples with recovery values from 91.42% to 119.80%.
关键词： covalent organic frameworks,meat,molecularly imprinted polymers,tryptamine,carbon nanodots
更新于2025-09-19 17:15:36
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Molecular Recognition and Band Alignment in 3D Covalent Organic Frameworks for Cocrystalline Organic Photovoltaics
摘要： Covalent organic frameworks (COFs) have emerged as versatile, functional materials comprised of low-cost molecular building blocks. The permanent porosity, long-range order, and high surface area of 3D-COFs permit co-crystallization with other materials driven by supramolecular interactions. We designed a new subphthalocyanine-based 3-D covalent organic framework (NEUCOF1) capable of forming co-crystals with fullerene (C60) via periodic ball-and-socket binding motifs. The high co-crystalline surface area and long-range order of NEUCOF1 eliminates the typical surface area vs. structural order trade-off in organic photovoltaics (OPVs). We used plane-wave density functional theory (PBE) to minimize NEUCOF1 and NEUCOF1–C60 co-crystals and determine their electronic band structures. Molecular dynamics (MD) simulations showed that dispersive interactions promoting co-crystallinity NEUCOF1–C60 are stable up to 350 K. The band structures at 0 and 350 K suggest that there is a driving force of 0.27 eV for exciton charge transfer to the pocket-bound fullerenes. Charge separation could then occur at the COF-C60 D-A interface, followed by the transfer of the free electron to the nanowire of C60 acceptors with a driving force of 0.20 eV.
关键词： fullerene,subphthalocyanine,co-crystallization,density functional theory,molecular dynamics,Covalent organic frameworks,organic photovoltaics
更新于2025-09-19 17:13:59
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Ultrahigh Responsivity Photodetectors of 2D Covalent Organic Frameworks Integrated on Graphene
摘要： 2D materials exhibit superior properties in electronic and optoelectronic fields. The wide demand for high-performance optoelectronic devices promotes the exploration of diversified 2D materials. Recently, 2D covalent organic frameworks (COFs) have emerged as next-generation layered materials with predesigned π-electronic skeletons and highly ordered topological structures, which are promising for tailoring their optoelectronic properties. However, COFs are usually produced as solid powders due to anisotropic growth, making them unreliable to integrate into devices. Here, by selecting tetraphenylethylene monomers with photoelectric activity, elaborately designed photosensitive 2D-COFs with highly ordered donor-acceptor topologies are in situ synthesized on graphene, ultimately forming COF-graphene heterostructures. Ultrasensitive photodetectors are successfully fabricated with the COFETBC–TAPT-graphene heterostructure and exhibited an excellent overall performance with a photoresponsivity of ≈3.2 × 107 A W?1 at 473 nm and a time response of ≈1.14 ms. Moreover, due to the high surface area and the polarity selectivity of COFs, the photosensing properties of the photodetectors can be reversibly regulated by specific target molecules. The research provides new strategies for building advanced functional devices with programmable material structures and diversified regulation methods, paving the way for a generation of high-performance applications in optoelectronics and many other fields.
关键词： photodetectors,graphene,covalent organic frameworks,2D materials
更新于2025-09-16 10:30:52
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Two-Dimensional Covalent Organic Framework–Graphene Photodetectors: Insight into the Relationship between the Microscopic Interfacial Structure and Performance
摘要： Graphene is an attractive material for photodetection and optoelectronic applications because it offers a broad spectral bandwidth and ultrafast response speed. However, because of the broad light absorption characteristic, graphene has a lack of selectivity to the wavelength, which limits the performance of graphene-based photodetectors. Here, we demonstrate a novel hybrid photodetector with monolayer graphene covered with an ultrathin film of surface covalent organic frameworks (COFs) with variable structures as the light-harvesting materials. Photodetectors based on surface COF?G show enhanced responsivity in comparison with unmodified graphene and graphene modified with monomers. The submolecular resolution of scanning tunneling microscopy allows us to get a direct insight into the relationship between the microscopic interfacial structure and the performance of the device. We prove that the enhancement in the device performance is directly related with the orderliness of surface COFs, which influences the interfacial charge transfer by tuning π?π stacking between surface COF and graphene.
关键词： covalent organic frameworks,photodetector,charge transfer,interfacial structure,graphene
更新于2025-09-11 14:15:04
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Aptamer-gold nanoparticle doped covalent organic framework followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for selective enrichment and detection of human insulin
摘要： In this work, we introduced an aptamer modified Au nanoparticles doped covalent organic frameworks composite (IBAs-AuNPs/COF) to improve the property of selective enrichment of insulin from serum samples. The Au nanoparticles were immobilized on imine-based COF by in-situ reduction reaction via mussel inspired polydopamine coating, and then sulfhydryl-containing aptamers were bonded to the surface of AuNPs through an Au-S linkage. Due to the excellent adsorption property of COF and specific recognition between insulin and IBAs, the IBAs-AuNPs/COF composites show selective and satisfactory extraction property to insulin in serum samples. Excellent specificity was obtained for insulin in the presence of 50-fold interfering substances including human immunoglobulin, lysozyme and biotin. The concentrations of insulin in the range of 1.0 to 50.0 μg L ?1 show good linear relationship ( R 2 = 0.9917) with limit of detection and limit of quantitation of 0.28 μg L ?1 and 0.93 μg L ?1 , respectively. Then, the IBAs-AuNPs/COF composites were applied to enrich insulin in serum samples followed by analysis with matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). After the recovery experiment, the developed method shows good recoveries in range of 91.6%–112.4% with low RSD value (2.4%–9.4%, n = 3) for diabetic and healthy serum samples. The developed IBAs-AuNPs/COF composites propose a new perspective for selective and efficient enrichment of biomarkers in serum samples by functionalized COF.
关键词： Composites,Insulin aptamer,Covalent organic frameworks,Serum samples,Biomolecule,MALDI-TOF-MS
更新于2025-09-11 14:15:04