Redox-Active Metal-Covalent Organic Frameworks for Dendrite-Free Lithium Metal Batteries.

Lithium (Li) metal has gained attention as an anode material for lithium-metal batteries (LMBs) owing to its low electrochemical potential, high specific capacity, and low density. However, the accumulation of Li dendrites and unstable solid electrolyte interphases, caused by sluggish Li migration and uneven Li deposition, limit practical LMB applications. This study presents the first report on redox-active metal-covalent organic frameworks (MCOFs) with dual-active centers as functional separators for LMBs.

Tuning the interlayer stacking of a vinylene-linked covalent organic framework for enhancing sacrificial agent-free hydrogen peroxide photoproduction.

The layer-stacking mode of a two-dimensional (2D) material plays a dominant role either in its topology or properties, but remains challenging to control. Herein, we developed alkali-metal ion-regulating synthetic control on the stacking structure of a vinylene-linked covalent triazine framework (termed spc-CTF) for improving hydrogen peroxide (HO) photoproduction. Upon the catalysis of EtONa in Knoevenagel polycondensation, a typical eclipsed stacking mode (spc-CTF-4@AA) was built, while a staggered one (spc-CTF-4@AB) was constructed using LiOH.

Urea/Thiourea Imine Linkages Provide Accessible Holes in Flexible Covalent Organic Frameworks and Dominates Self-Adaptivity and Exciton Dissociation.

Unraveling the robust self-adaptivity and minimal energy-dissipation of soft reticular materials for environmental catalysis presents a compelling yet unexplored avenue. Herein, a top-down strategy, tailoring from the unique linkage basis, flexibility degree, skeleton electronics to trace-guest adaptability, is proposed to fill the understanding gap between micro-soft covalent organic frameworks (COFs) and photocatalytic performance. The thio(urea)-basis-dominated linkage within benzotrithiophene-based COFs induce the framework contraction/swelling (intralayer micro-flexibility) in response to tetrahydrofuran or water.

Three-Dimensional Covalent Organic Framework with Dense Lithiophilic Sites as Protective Layer to Enable High-Performance Lithium Metal Battery.

Lithium (Li) metal batteries with remarkable energy densities are restrained by short lifetime and low Coulombic efficiency (CE), resulting from the accumulative Li dendrites and dead Li during cycling. Here, we prepared a new three-dimensional (3D) covalent organic framework (COF) with dense lithiophilic sites (heteoatom weight contents of 32.32 wt %) as an anodic protective layer of Li metal batteries.

A Wurster-Type Covalent Organic Framework with Internal Electron Transfer-Enhanced Catalytic Capacity for Tumor Therapy.

The low immunogenicity of tumors, along with the abnormal structural and biochemical barriers of tumor-associated vasculature, impedes the infiltration and function of effector T cells at the tumor site, severely inhibiting the efficacy of antitumor immunotherapy. In this study, a cobaloxime catalyst and STING agonist (MSA-2)-coloaded Wurster-type covalent organic framework (Co-TB COF-M) with internal electron transfer-enhanced catalytic capacity was developed as a COF-based immune activator. The covalently anchored cobaloxime adjusts the energy band structure of TB COF and provides it with good substrate adsorption sites, enabling it to act as an electron transmission bridge between the COF and substrate in proton reduction catalytic reactions.

Cross-view motion consistent self-supervised video inter-intra contrastive for action representation understanding.

Self-supervised contrastive learning draws on power representational models to acquire generic semantic features from unlabeled data, and the key to training such models lies in how accurately to track motion features. Previous video contrastive learning methods have extensively used spatially or temporally augmentation as similar instances, resulting in models that are more likely to learn static backgrounds than motion features. To alleviate the background shortcuts, in this paper, we propose a cross-view motion consistent (CVMC) self-supervised video inter-intra contrastive model to focus on the learning of local details and long-term temporal relationships.

Mesoporous Vinylene-Linked Covalent Organic Frameworks with Heteroatom-Tuned Crystallinity and Photocatalytic Behaviors.

Owing to its prominent π-delocalization and stability, vinylene linkage holds great merits in the construction of covalent organic frameworks (COFs) with promising semiconducting properties. However, carbon-carbon double bond formation reaction always exhibits relatively low reversibility, unfavorable for the formation of high crystalline frameworks through self-error correction and assembling processes. In this work, we report a heteroatom-tuned strategy to build up a series of two-dimensional (2D) vinylene-linked COFs by Knoevenagel condensation of an electron-deficient methylthiazolyl-based monomer with different triformyl substituted (hetero-)aromatic derivatives.

Metal-insulator-semiconductor photoelectrodes for enhanced photoelectrochemical water splitting.

Photoelectrochemical (PEC) water splitting provides a scalable and integrated platform to harness renewable solar energy for green hydrogen production. The practical implementation of PEC systems hinges on addressing three critical challenges: enhancing energy conversion efficiency, ensuring long-term stability, and achieving economic viability. Metal-insulator-semiconductor (MIS) heterojunction photoelectrodes have gained significant attention over the last decade for their ability to efficiently segregate photogenerated carriers and mitigate corrosion-induced semiconductor degradation.

Crystalline Olefin-Linked Chiral Covalent Organic Frameworks as a Platform for Asymmetric Catalysis.

The construction of olefin-linked chiral covalent organic frameworks (COFs) with high crystallinity is highly desirable while remains great challenge due to the poor reversibility of the formation reaction for the olefin linkages during the in situ structural self-healing process. Herein, we successfully synthesized two sets of enantiomeric olefin-linked COFs. The chiral catalytic groups are uniformly distributed on the pore walls of COFs, resulting in the full exposure of catalytic sites to the reactants in asymmetric catalysis.

3D Crown Ether Covalent Organic Framework as Interphase Layer toward High-Performance Lithium Metal Batteries.

The practical application of lithium (Li) metal batteries is inhibited by accumulative Li dendrites and continuous active Li consumption during cycling, which results in a low Coulombic efficiency and short lifetime. Constructing artificial solid-electrolyte interphase (SEI) layer in Li anode, such as 2D covalent organic frameworks (COFs), is an effective strategy to restrain the formation of Li dendrites and improve cycling performance. However, the exploration of 3D COFs as protecting layers is rarely reported, because of the preconception that the interconnect pores in 3D COFs eventually cause Li dendrites in disordered direction.

Modulating Skeletons of Covalent Organic Framework for High-Efficiency Gold Recovery.

Covalent organic frameworks (COFs) have attracted considerable attention as adsorbents for capturing and separating gold from electronic wastes. To enhance the binding capture efficiency, constructing hydrogen-bond nanotraps along the pore walls was one of the most widely adopted approaches. However, the development of absorbing skeletons was ignored due to the weak binding ability of the gold salts (Au).

Hexatopic Vertex-Directed Approach to Vinylene-Linked Covalent Organic Frameworks with Heteroporous Topologies.

A -symmetric hexatopic monomer was first prepared by attaching the three-fold ditopic moiety 2,6-dimethylpyridine to the -positions of a phenyl ring. It was further condensed at its six pyridylmethyl carbons with linear ditopic aromatic dialdehydes, resulting in two vinylene-linked COFs with heteroporous topologies, as revealed by powder X-ray diffraction (PXRD), nitrogen sorption, and pore-size distribution analyses, as well as transmission electron microscopy (TEM) image. The linear- and cross-conjugations, respectively, arising from the 2,6-linked pyridines and -linked phenylenes in the hexatopic nodes rendered the resultant COFs with well-patterned π-delocalization, allowing for efficiently catalyzing the bromination of aromatic derivatives with the pore-size-dependent conversion yields and regioselectivity under the irradiation of green light.

3D network with channel excitation and knowledge distillation for action recognition.

Modern action recognition techniques frequently employ two networks: the spatial stream, which accepts input from RGB frames, and the temporal stream, which accepts input from optical flow. Recent researches use 3D convolutional neural networks that employ spatiotemporal filters on both streams. Although mixing flow with RGB enhances performance, correct optical flow computation is expensive and adds delay to action recognition.

2,4,6-Trimethylpyridine-Derived Vinylene-Linked Covalent Organic Frameworks for Confined Catalytic Esterification.

Knoevenagel condensation is a powerful tool for the construction of vinylene-linked covalent organic frameworks. Herein, we established a concise approach to vinylene-linked COFs by Knoevenagel condensation at the multi-methyl groups of a pyridine ring through in situ formation of an N-acyl pyridinium cation in the presence of various acylating reagents. Following this strategy, two vinylene-linked COFs were constructed using 2,4,6-trimethylpyridine and multi-aldehyde-substituted aromatic derivatives as monomers.

Differential Effects of Toll-Like Receptor Signaling on the Activation of Immune Responses in the Upper Respiratory Tract.

Vaccination through the upper respiratory tract (URT) is highly effective for the prevention of respiratory infectious diseases. Toll-like receptor (TLR)-based adjuvants are immunostimulatory and considered potential adjuvant candidates. However, the patterns of immune response to different TLRs at the URT have not been revealed.

Synthesis of Vinylene-Linked Covalent Organic Frameworks by Monomer Self-Catalyzed Activation of Knoevenagel Condensation.

Reticular chemistry based on thermodynamically controlled linking modes and numerous organic building blocks has constituted versatile crystalline frameworks in molecular-level precision. However, vinylene-linked covalent organic frameworks (COFs) are still quite far from flexible tailoring in either their structures or topologies, due to the lack of monomers with sufficient activities. Herein, we establish a strategy to synthesize vinylene-linked COFs via Knoevenagel condensation between a tetratopic monomer 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) and linear aromatic dialdehydes in a mixed solvent of benzoic anhydride and benzoic acid.

Immunity to Sda1 Protects against Infection by Sda1 and Sda1 Serotypes of Group A .

Group A (GAS) causes a variety of diseases globally. The DNases in GAS promote GAS evasion of neutrophil killing by degrading neutrophil extracellular traps (NETs). Sda1 is a prophage-encoded DNase associated with virulent GAS strains.

Heteroatom-Embedded Approach to Vinylene-Linked Covalent Organic Frameworks with Isoelectronic Structures for Photoredox Catalysis.

Embedding heteroatoms into the main backbones of polymeric materials has become an efficient tool for tailoring their structures and improving their properties. However, owing to comparatively harsh heteroatom-doping conditions, this has rarely been explored in covalent organic frameworks (COFs). Herein, upon aldol condensation of a trimethyl-substituted pyrylium salt with a tritopic aromatic aldehyde, a two-dimensional oxonium-embedded COF with vinylene linkages was achieved, which was further converted to a neutral pyridine-cored COF by in situ replacement of oxonium ions with nitrogen atoms under ammonia treatment.

Synthesis of Ionic Vinylene-Linked Covalent Organic Frameworks through Quaternization-Activated Knoevenagel Condensation.

We developed a simple approach to synthesizing ionic vinylene-linked two-dimensional covalent organic frameworks (COFs) through a quaternization-promoted Knoevenagel condensation at three aromatic methyl carbon atoms of N-ethyl-2,4,6-trimethylpyridinium halide with multitopic aromatic aldehyde derivatives. The resultant COFs exhibited a honeycomb-like structure with high crystallinity and surface areas as large as 1343 m  g . The regular shape-persistent nanochannels and the positively charged polymeric frameworks allowed the COFs to be uniformly composited with linear polyethylene oxide and lithium salt, displaying ionic conductivity as high as 2.

Trimethyltriazine-derived olefin-linked covalent organic framework with ultralong nanofibers.

Two-dimensional (2D) olefin-linked covalent organic frameworks (COFs) with excellent π-electron communication and high stability are emerging as promising crystalline polymeric materials. However, because of the limited species of COFs, their characteristics, processability and potential applications have not been completely understood and explored. In this work, we prepared two novel olefin-linked 2D COFs through Knoevenagel condensation of 2,4,6-trimethyl-1,3,5-triazine with tritopic triazine-cored aldehydes.

Ordered Bicontinuous Mesoporous Polymeric Semiconductor Photocatalyst.

Owning triply periodic minimal surfaces and three-dimensional (3D) interconnected pores, bicontinuous porous materials have drawn enormous attention due to their great academic interest and potential applications in many fields including energy and catalysis. However, their synthesis has remained a great challenge. Here, we demonstrate the synthesis of a bicontinuous porous organic semiconductor photocatalyst, which involves the preparation of SiO with a shifted double diamond (DD) structure through solvent evaporation-induced self-assembly of a polystyrene--poly(ethylene oxide) diblock copolymer and tetraethyl orthosilicate, followed by SiO-templated self-condensation of melamine monomers in a vacuum.

Vinylene-Linked Covalent Organic Frameworks (COFs) with Symmetry-Tuned Polarity and Photocatalytic Activity.

The polarity of a semiconducting molecule affects its intrinsic photophysical properties, which can be tuned by varying the molecular geometry. Herein, we developed a D -symmetric tricyanomesitylene as a new monomer which could be reticulated into a vinylene-linked covalent organic framework (g-C N -COF) via Knoevenagel condensation with another D -symmetric monomer 2,4,6-tris(4'-formyl-biphenyl-4-yl)-1,3,5-triazine. Replacing tricyanomesitylene with a C -symmetric 3,5-dicyano-2,4,6-trimethylpyridine gave a less-symmetric vinylene-linked COF (g-C N -COF).

Vinylene-Bridged Two-Dimensional Covalent Organic Frameworks via Knoevenagel Condensation of Tricyanomesitylene.

Vinylene-bridged covalent organic frameworks (COFs) have shown great potential for advanced applications because of their high chemical stability and intriguing semiconducting properties. Exploring new functional monomers available for the reticulation of vinylene-bridged COFs and establishing effective reaction conditions are extremely desired for enlarging the realm of this kind of material. In this work, a series of vinylene-bridged two-dimensional (2D) COFs are synthesized by Knoevenagel condensation of tricyanomesitylene with ditopic or tritopic aromatic aldehydes.

Long-lasting protective immunity against H7N9 infection is induced by intramuscular or CpG-adjuvanted intranasal immunization with the split H7N9 vaccine.

There is an urgent need for efficient vaccines against the highly pathogenic avian influenza A viral strain H7N9. The duration and intensity of the immune response to H7N9 critically impacts the epidemiology of influenza viral infection at the population level. However, the insufficient immunogenicity of H7N9 raises concerns about vaccine efficacy.

A Multicomponent Vaccine Provides Immunity against Local and Systemic Infections by Group A Streptococcus across Serotypes.

Group A streptococcus (GAS) species are responsible for a broad spectrum of human diseases, ranging from superficial to invasive infections, and are associated with autoimmune disorders. There is no commercial vaccine against GAS. The clinical manifestations of GAS infection may be attributable to the large repertoire of virulence factors used selectively in different types of GAS disease.