Three-dimensional Covalent Organic Frameworks Research Articles

Three-Dimensional Covalent Organic Framework with Tty Topology for Enhanced Photocatalytic Hydrogen Peroxide Production

Three-Dimensional Covalent Organic Framework with Tty Topology for Enhanced Photocatalytic Hydrogen Peroxide Production

Molecularly Engineered Three-Dimensional Covalent Organic Framework Protection Films for Highly Stable Zinc Anodes in Aqueous Electrolyte

Molecularly Engineered Three-Dimensional Covalent Organic Framework Protection Films for Highly Stable Zinc Anodes in Aqueous Electrolyte

Sustained-release nanocapsule based on a 3D COF for long-term enzyme prodrug therapy of cancer.

A well-designed three-dimensional (3D) covalent organic framework (COF) was constructed as a nanocapsule for the encapsulation of horseradish peroxidase (HRP), which could realize sustained release of HRP to prolong the duration of the therapeutic agents and promote long-term enzyme prodrug therapy.

Solvent-Free and in Situ Synthesis of Three-Dimensional Covalent Organic Frameworks Thin Films on Zn Anodes for Zn–Air Batteries

Solvent-Free and in Situ Synthesis of Three-Dimensional Covalent Organic Frameworks Thin Films on Zn Anodes for Zn–Air Batteries

Highly conjugated three-dimensional covalent organic frameworks with enhanced Li-ion conductivity as solid-state electrolytes for high-performance lithium metal batteries

An effective strategy to explore the potential of three-dimensional (3D) COFs with well-designed ion channels for fast transport of Li+ is developed.

Building-block exchange synthesis of amino-based three-dimensional covalent organic frameworks for gas chromatographic separation of isomers.

Thermally stable three-dimensional covalent organic frameworks (3D COFs) with rich pores of channels and cages are promising as stationary phases for gas chromatography (GC), which has not been explored. Here we synthesize the first amino-based 3D COF and its covalently bonded capillary via building-block exchange for GC separation of isomers.

Construction of a Three-dimensional Covalent Organic Framework via the Linker Exchange Strategy

Construction of a Three-dimensional Covalent Organic Framework via the Linker Exchange Strategy

Three-Dimensional Covalent Organic Frameworks with hea Topology

Three-dimensional (3D) covalent organic frameworks (COFs) are a new type of crystalline organic porous material, which have great application potential in various fields due to their complex pore s...

Tailoring the Pore Surface of 3D Covalent Organic Frameworks via Post‐Synthetic Click Chemistry

AbstractThree‐dimensional covalent organic frameworks (3D COFs) have gained increasing attention for their attractive features. However, the development of 3D COFs is strongly restricted, mainly due to their synthetic difficulty and complicated structure determination. Post‐synthetic modification, which can avoid these problems by incorporating functional moieties into a predetermined framework, provides an alternative way to construct 3D COFs with specific functions. Herein, we report the designed synthesis and characterization of a series of highly crystalline 3D COFs with different loadings of ethynyl groups. Notably, these alkyne‐tagged 3D COFs provide a platform for targeted anchoring various specific groups onto the pore walls via click reactions. Moreover, the pore surface engineering can accordingly change their properties, for example, the obtained click products exhibited higher CO2/N2 selectivity. We describe a simple but powerful strategy to build functional 3D COFs, which will certainly advance them for a ranging of interesting applications in the future.

Analysis of mycotoxins in grain samples using 3D covalent organic frameworks and stable isotope labeling technique

A new three-dimensional (3D) covalent organic framework (COF) tris (4-formylphenyl) amine-tetra (4-aminophenyl) methane (TFPA-TAM) was designed and synthesized. It was used in the dispersed solid-phase extraction (DSPE) of mycotoxins from grain sample extractant. The adsorption performance of 3D COF (TFPA-TAM) was compared with four kinds of different COFs with various spatial structures and steric hindrances to illustrate the key factors in the adsorption process. Stable isotope labeling (SIL) strategy with dansyl chloride (DNS-Cl) and deuterated dansyl chloride (d6-DNS-Cl) as labeling agents was applied for the first time in the high-performance liquid chromatography-tandem mass spectrometry (HPLC–MS/MS) quantitation of mycotoxins. SIL strategy enhanced the mass spectrometry (MS) sensitivity and minimized matrix effects. The optimized adsorption conditions were sample solution pH 7; adsorbent amount, 20 mg; desorption time, 5 min; elution volume, 1 mL. The limits of detection (LODs) of mycotoxins in grain samples were in the range of 4–7 µg/kg, while limits of quantification (LOQs) were in the range of 13–24 µg/kg. The linearity coefficients for all analytes were higher than 0.9977. The recoveries of this method were in the range of 90.3–94.3% with relative standard deviations of <6.3%, and the matrix effects were in the range of 93.5–98.8%.

Flexible and Robust Three-Dimensional Covalent Organic Framework Membranes for Precise Separations under Extreme Conditions.

Membranes based on covalent organic frameworks (COFs) have demonstrated huge potential to resolve the long-standing bottlenecks in separation fields due to their structural and functional attributes. Herein, a three-dimensional COF featuring interpenetrated apertures, 3D-OH-COF, is rationally synthesized on polyimide supports to generate flexible, robust membranes. The resultant 3D-OH-COF presents excellent crystallinity, prominent porosity, and exceptional solvent resistance, enabling the produced membrane a sharp and durable selectivity to small molecules in water and organic solvents. Impressively, the membrane also exhibits excellent flexibility and robustness as verified by the well-maintained performances after serious bending and solvent soaking under elevated temperatures. We further chemically convert 3D-OH-COF into the carboxyl-decorated 3D-COOH-COF by a postsynthetic strategy. The 3D-COOH-COF retains high crystallinity, and the converted membrane receives a remarkable capture ability for targeted multivalent ions over other competing ions. This study exploits a viable avenue to produce practical 3D COF membranes toward ultimate separations under extreme conditions.

Ultrahigh thermal conductivity in three-dimensional covalent organic frameworks

Covalent organic frameworks (COFs) are a new, growing class of crystalline polymers with exceptional characteristics such as low density, mechanical strength, and flexibility. Taking three-dimensional (3D) COF-300 derivatives as an example, we apply molecular dynamics simulations to show that ultrahigh thermal conductivity (>15 W/(mK)) is achieved at a pore size of d = 0.63 nm. This is the first observation of such an outstanding intrinsic thermal conductivity of a 3D polymer in all directions. Further temperature-dependent thermal conductivity calculations and X-ray diffraction (XRD) patterns highlight the importance of maintaining microscopic order for a large thermal conductivity. We also demonstrate that the tunability and anisotropy in COFs provide sufficient room to engineer and obtain desired thermal conductivity. These findings provide a fundamental understanding of structure-thermal conductivity relation in COFs and shine a light on high-thermal-conductivity COFs for thermal management applications.

A Three-Dimensional sp2 Carbon-Conjugated Covalent Organic Framework.

A first example of an sp2 carbon-conjugated three-dimensional (3D) covalent organic framework (COF) (BUCT-COF-4) is synthesized via the Knoevenagel condensation of the saddle-shaped aldehyde-substituted cyclooctatetrathiophene and 1,4-phenylenediacetonitrile. Ascribed to the extended π-conjugation and long-range ordered structures, BUCT-COF-4 displays high Hall electron mobility of 1.97 cm2 V-1 s-1 at room temperature. After it is doped with iodine, the material not only exhibits an enhanced electron mobility up to 2.62 cm2 V-1 s-1 in ambient air but also presents an unexpected metal-free ferromagnetic phase transition arising from the formation of aligned spins unidirectional across the whole sp2 carbon-conjugated 3D framework. This is the first report of a ferromagnetic phenomenon in 3D COF materials, which would broaden promising applications and open a new frontier in COF materials.

Three-Dimensional Covalent Organic Frameworks with Cross-Linked Pores for Efficient Cancer Immunotherapy.

We report the design and synthesis of a series of three-dimensional (3D) covalent organic frameworks (COFs) as immunogenic cell death (ICD) inducers for cancer immunotherapy. Three triple-topic amine building blocks, inactive to inducing ICD, were used to construct three COFs, COF-607, COF-608, and COF-609, with outstanding ICD eliciting efficiency. Mechanism studies revealed that after linking these ICD inert monomers into the COF backbone, the optical properties of these COFs could be systematically tuned to achieve excellent reactive oxygen species (ROS) production performance. This combined with 3D cross-linked pores, mimicking lung structure, favor the exchange and diffusion of oxygen and ROS, leading to excellent inducing ICD efficacy. One member, COF-609, is capable of triggering abscopal and long-lasting immune memory effects in a mouse model of breast cancer with >95% mice survival after being treated with COF-609+αCD47 for 110 days.

A Cubic 3D Covalent Organic Framework with nbo Topology.

The synthesis of three-dimensional (3D) covalent organic frameworks (COFs) requires high-connectivity polyhedral building blocks or the controlled alignment of building blocks. Here, we use the latter strategy to assemble square-planar cobalt(II) phthalocyanine (PcCo) units into the nbo topology by using tetrahedral spiroborate (SPB) linkages that were chosen to provide the necessary 90° dihedral angles between neighboring PcCo units. This yields a porous 3D COF, SPB-COF-DBA, with a noninterpenetrated nbo topology. SPB-COF-DBA shows high crystallinity and long-range order, with 11 resolved diffraction peaks in the experimental powder X-ray diffraction (PXRD) pattern. This well-ordered crystal lattice can also be imaged by using high-resolution transmission electron microscopy (HR-TEM). SPB-COF-DBA has cubic pores and exhibits permanent porosity with a Brunauer-Emmett-Teller (BET) surface area of 1726 m2 g-1.

Capillary coated with three-dimensional covalent organic frameworks for separation of fluoroquinolones by open-tubular capillary electrochromatography

The Schiff-base reaction of 1,3,5-triformylphloroglucinol (Tp) and tetra(4-aminophenyl)methane (TAM) was performed for the synthesis of a three-dimensional covalent organic framework named 3D TpTAM, which was obtained by an ultrasound-assisted method for the first time. The morphology and structure of the synthesized TpTAM were characterized through various methods. Then, TpTAM-coated capillary columns were subsequently prepared by a covalent bonding method within a short time and applied for the separation of fluoroquinolones by capillary electrochromatography (CEC) with good resolution and reproducibility. The intraday relative standard deviations (RSDs) of the retention time and peak areas were 0.88%–0.95% and 2.27%–3.81%, respectively. The interday RSDs of retention time and peak areas were 0.71%–0.89% and 0.88%–3.60%, respectively. The column-to-column RSDs of retention time and peak areas were less than 1.90% and 13.56%, respectively. The interbatch RSDs of retention time and peak areas were less than 3.48% and 3.89%, respectively. The TpTAM-coated capillary columns could be used for no less than 100 runs with no observable changes in the separation efficiency. The separation mechanism was also studied, which indicated that π-π stacking effects, hydrophobic interactions and hydrogen bonding were the main factors. The results revealed that 3D TpTAM should have superior potential as the stationary phase in CEC for chromatographic separation.

Three-Dimensional Radical Covalent Organic Frameworks as Highly Efficient and Stable Catalysts for Selective Oxidation of Alcohols.

With excellent designability, large accessible inner surface, and high chemical stability, covalent organic frameworks (COFs) are promising candidates as metal-free heterogeneous catalysts. Here, we report two 3D radical-based COFs (JUC-565 and JUC-566) in which radical moieties (TEMPO) are uniformly decorated on the channel walls via a bottom-up approach. Based on grafted functional groups and suitable regular channels, these materials open up the application of COFs as highly efficient and selective metal-free redox catalysts in aerobic oxidation of alcohols to relevant aldehydes or ketones with outstanding turn over frequency (TOF) up to 132 h-1 , which has exceeded other TEMPO-modified catalytic materials tested under similar conditions. These stable COF-based catalysts could be easily recovered and reused for multiple runs. This study promotes potential applications of 3D functional COFs anchored with stable radicals in organic synthesis and material science.

Postsynthetic modification of three-dimensional covalent organic frameworks

Postsynthetic modification of three-dimensional covalent organic frameworks

A 3D Anionic Metal Covalent Organic Framework with soc Topology Built from an Octahedral TiIV Complex for Photocatalytic Reactions.

The construction of three-dimensional (3D) covalent organic frameworks (COFs) remains challenging due to the limited types of organic building blocks. With octahedral TiIV complex as the building unit, this study reports on the first 3D anionic titanium-based COF (Ti-COF-1) with an edge-transitive (6, 4)-connected soc topology. Ti-COF-1 exhibits high crystallinity, superior stability, and large specific surface area (1000.4 m2 g-1 ). Moreover, Ti-COF-1 has a broad absorption band in the UV spectrum with an optical energy gap of 1.86 eV, and exhibits high photocatalytic activity toward Meerwein addition reactions. This research demonstrates an attractive strategy for the design of 3D functional COFs.

Imparting Ion Selectivity to Covalent Organic Framework Membranes Using de Novo Assembly for Blue Energy Harvesting.

It has long been a challenge to fabricate angstrom-sized functional pores for mimicking the function of biological channels to afford selective transmembrane transport. In this study, we describe a facile strategy to incorporate ionic elements into angstrom-sized channels using de novo encapsulation of charged dye molecules during the interface polymerization of a three-dimensional covalent organic framework (3D COF). We demonstrate that this approach is tailorable as it enables control over both the type and content of the guest and thus allows manipulation of the membrane function. The resulting membranes exhibit excellent permselectivity and low membrane resistance, thereby indicating the potential for harvesting salinity gradient (blue) energy. As a proof-of-concept study, the reverse electrodialysis device coupled with positive and negative dye encapsulated COF membranes afforded a power density of up to 51.4 W m-2 by mixing the simulated seawater and river water, which far exceeds the commercialization benchmark (5 W m-2). We envision that this strategy will pave the way for constructing new multifunctional biomimetic systems.