Interlayer alignment holds a pivotal role for layered materials in tailoring their physical properties and chemical activities. Herein, we designed and synthesized a D2h-symmetric pyrene-derived monomer with four methyl substituents adjacent to the two nitrogen atoms embedded at the 2,7-positions of its molecular periphery. It smoothly underwent Knoevenagel condensation with linear diformylarenes to form a series of novel two-dimensional (2D) covalent organic frameworks (COFs), whose individual layers are reticulated by vinylene linking of diazapyrene vertices with arene nodes, then vertically aligned in an eclipsed or inclined stacking mode through the synergistic impacts of the twisted conformation interlocking, dipole-dipole, and π-π interactions of the building blocks. Their highly crystalline structures with large domain sizes of up to around 0.4 μm were considerably confirmed by high-resolution low-dose transmission electron microscopy imaging, powder X-ray diffraction patterns, and theoretical simulations. Correspondingly, such kinds of COFs exhibit exceptional properties, including high specific surface areas close to theoretical values, strong light-harvesting extended to the near-infrared-II, and outstanding photogenerated charge dynamics, allowing for high-performance photothermal conversion and catalysis of multiple organic transformations upon near-infrared light stimulation. These findings demonstrate that the crystal growth and properties of 2D COFs can be promoted by subtly tuning interlayer stacking via building-block design.

Two vinylene-linked covalent organic frameworks, featuring hexagonal and orthorhombic topologies, respectively, exhibit fully pyridine-patterned iso-π-conjugation, enabling the photocatalytic synthesis of benzothiazoles with similar yields.

Precisely arranging organic π-conjugated macrocyclic units to long-range-ordered arrays might not only diversify the geometric and topological structures, but also bring out exceptional semiconducting properties. Herein, upon Knoevenagel condensation of angular ditopic phenanthroline and tetratopic biphenyl or bipyridinyl derivatives, we synthesized new types of 1D fully sp2 carbon-linked covalent organic frameworks (COFs). Powder X-ray diffraction patterns and nitrogen adsorption/desorption isotherms revealed the repeated vinylene-linked macrocycles interconnected by carbon-carbon single bonds, which further assembled to long-range ordered alignments along the in-plane and vertical directions. Such unique 1D COF motifs are the congeners of the crystalline assemblies of linear conjugated polymacrocycles, favorable for dispersion and active site exposure. The π-delocalization of these COFs can be efficiently modulated by the macrocycle moieties with the cross- or linear-conjugation mode, then affecting their electron coupling and exciton dynamics. With the phenanthroline nitrogen atoms in the macrocyclic backbones serving as catalytic active sites, they exhibited photocatalytic reduction of CO2 to CO in a generation rate of 3535.9 µmol.g-1.h-1, and up to 19678.3 µmol.g-1.h-1 upon loading cobalt (II) cation. Both values are among the highest values of the organic or organic-inorganic hybrid photocatalysts to date.

In nature, photocatalytic reduction of carbon dioxide is a critical process for maintaining the global carbon cycle, which is initiated by the enzymes consisting of chromophoric organic macrocycles in the presence of water. It is extremely desirable to develop an artificial organic photosynthetic system for the efficient reduction of CO2 to syngas for addressing the energy crisis and achieving the strategic environmental goal of carbon neutrality. In this work, we synthesized a series of vinylene-linked covalent organic frameworks (COFs) by Knoevenagel condensation of tetra-methylbipyrimidine as a tetratopic monomer with ditopic linear aromatic dialdehydes. The resultant COFs were crystallized in orthorhombic lattices with eclipsed AA stacking modes. Such tetravinylbipyrimidine-containing frameworks possess π-extended conjugation and highly dense accessible coordination sites, leading to substantially tunable semiconducting properties. Through simple post-functionalization, these COFs were coordinated with rhenium mono-cation with high utilization rates (up to ∼97%) of bipyrimidine units. The resultant rhenium-modified COFs enable efficient photocatalytic CO2 reduction to CO in water without any additional sacrificial-agent. The CO generation reached a rate of up to 234.4 µmol·g- 1·h- 1 with high selectivity of 100%, which is among the highest values so far for organic porous materials. Such results seem align more closely with environmental sustainability principles.

Dynamic covalent chemistry (DCC) is a type of reversible chemical reactions under the control of thermodynamics. The reversibility of DCC allows the exchange of reaction components to form thermodynamically stable products. This kind of reaction has been widely incorporated in various research directions, holding an important significance in guiding emerging fields, such as two-dimensional macrocycles, two-dimensional materials and three-dimensional molecular cages. Of them, covalent organic frameworks (COFs), as a class of high crystalline porous conjugated polymers linked by dynamic covalent bonds exhibit huge potential application in various fields, such as gas separation, catalysis, sensing, biomedicines, and electronic devices due to their long-range ordered structures, regular pore distribution, high specific surface areas, and excellent molecular material designability. Vinylene-linked COFs feature high chemical stability and outstanding π-electron delocalization, extremely desired for the development of high-performance semiconducting catalysts and device. However, given that the formation reaction of carbon-carbon double bond only exhibited much poorer reversibility than those of the traditional dynamic covalent bonds, it still a big challenge to well-control the preparation of high-quality vinylene-linked COFs. In this review article, we intend to summarize the synthetic strategy approach to 2D vinylene-linked COFs on the basis of the rational design of the key monomers and the optimized reaction conditions for efficiently promoting Knoevenagel/aldol condensation. Then, we exemplified several applications arising from the unique characters of such kinds of COFs. Eventually, the challenges and opportunities of vinylene-linked COFs were also foreseen.

Precisely arranging organic π-conjugated macrocyclic units to long range-ordered arrays might not only diversify the geometric and topological structures, but also bring out exceptional semiconducting properties. Herein, upon Knoevenagel condensation of angular ditopic phenanthroline and tetratopic biphenyl or bipyridinyl derivatives, we synthesized new types of one-dimensional (1D) fully sp2 carbon-linked covalent organic frameworks (COFs). Powder X-ray diffraction patterns and nitrogen adsorption/desorption isotherms revealed the repeated vinylene-linked macrocycles interconnected by carbon-carbon single bonds, which further assembled to long-range ordered alignments along the in-plane and vertical directions. Such unique 1D COF motifs are the congeners of the crystalline assemblies of linear conjugated polymacrocycles, favorable for dispersion and active site exposure. The πdelocalization of these COFs can be efficiently modulated by the macrocycle moieties with the cross- or linear-conjugation mode, then affecting their electron coupling and exciton dynamics. With the phenanthroline nitrogen atoms in the macrocyclic backbones serving as catalytic active sites, they exhibited photocatalytic reduction of CO2 to CO in a generation rate of 3535.9 umol.g-1.h-1, and up to 19678.3 umol.g-1.h-1 upon loading cobalt (II) cation. Both values are among the highest values of the organic or organic-inorganic hybrid photocatalysts to date.

ABSTRACT Covalent organic frameworks (COFs) offer significant potential for solar energy conversion, but their sluggish intrinsic charge‐transfer kinetics inherently restrict the activation of stable CO 2 . Herein, we developed a new electron‐deficient monomer 6,6′‐dimethyl‐3,3′‐bipyridazine (DPz), which can undergo Knoevenagel condensation with triformyl polyphenylenes to construct a new type of π‐conjugated COFs. Their in‐plane backbones are patterned with a repeated donor‐π‐acceptor–acceptor‐π‐donor (D‐π‐A–A‐π‐D) moiety by vinylene‐linking of a bipyridazine core with two (bi‐)phenyl terminals, which are vertically packed into a hexagonal lattice in an AA‐stacking mode, yielding high specific surface areas and well‐defined nanochannels. The quadrupolar structure strengthened by bipyridazine as the dual acceptors, endowed these COFs with exceptional semiconducting performance. In particular, analysis of femtosecond transient absorption (fs‐TA) spectra revealed outstanding intramolecular charge transfer. Meanwhile, the substantial 1,2‐diazine units might dominate either the highest occupied molecular orbital or lowest unoccupied molecular orbital energy levels of these COFs, thereby promoting hybrid orbital‐coupled electron transfer, as also evaluated by theoretical calculations. Accordingly, the neat as‐prepared COFs exhibit promising photoinduced charge‐transfer dynamics. Using [Ru(bpy) 3 ]Cl 2 as a photosensitizer, the system achieved CO production rates of up to 1594 µmol g − 1 h − 1 , with a selectivity of more than 97%, among the highest values for all COF‐based photocatalysts reported to date.

The layer stacking of two-dimensional (2D) vinylene-linked covalent organic frameworks can create different topologies and some unexpected properties but is still less explored rather than well-tuned. Here, trimethyl triazacoronene was newly developed as a tritopic monomer. Three pyridine nitrogen atoms evenly embedded at its molecular periphery endow it with not only a noncentrosymmetrically dense-sparse alternating distribution of electron cloud but also a strong electron-deficient character. It enables smooth Knoevenagel condensation with 1,4-phenyl- or 4,4'-diphenyl dialdehyde in the presence of benzoic acid to form two 2D COFs. One of them comprising phenyl nodes shows the less steric interactions between vinylene linkages with the aromatic units in each layer, where all building blocks tend to show an in-plane arrangement under the π-conjugated effect, and the layers could be periodically offset and stacked in a staggered AB mode upon the through-space polar interactions between the interlayer triazacoronene vertexes. For the other COF, its biphenyl nodes favorably adopt a twisted conformation, which could exert an interlocked effect for constraining the slip offset of the layers and result in an eclipsed AA assembly upon the interlayer π-π stacking interaction. These assemblies were confirmed by well-defined powder X-ray diffraction patterns and low-dose imaging in transmission electron microscopy. Moreover, the photophysical properties and photocatalytic activities of as-prepared COFs were fully investigated, which are highly in correlation with their in-plane and stacking structures. These findings provided an efficient strategy for fine-modulating the interlayer alignments of 2D materials with improved properties/functions.

Developing high-sensitivity hydrogen peroxide (H2O2) sensors is crucial. Metal organic frameworks (MOFs) are considered one of the ideal materials for developing H2O2 sensors for their adjustable pore size and diverse topological structures. In this work, solvothermal synthesis is utilized CQD@Mn-MOF using carbon quantum dots (CQDs) and two-dimensional Mn-MOF ([Mn(Tib)(H2O)3]center dot(TPA)center dot 3H2O, Tib = 1,3,5-triamidazolylbenzene, TPA = terephthalic acid) as precursors. Interestingly, CQD@Mn-MOF as an electrochemical sensor can effectively detect H2O2 with a lower detection limit of 14.7 mu M, and higher sensitivity (approximately 5 times that of pure MnMOF). CQD@Mn-MOF sensor is capable of detecting H2O2 with high selectivity in the presence of other interfering agents such as proline, ascorbic acid, glucose, and various metal salts. In addition, CQD@Mn-MOF electrochemical sensor has been used to effectively determine the H2O2 content in actual beverages such as fruit juice and beer. The sensing mechanism has been reasonably analyzed that the MnO2 produced by Mn2+ + H2O2 = MnO2 + 2H+ reaction acts as a specific catalyst for H2O2 decomposition reaction (MnO2 + H2O2 + 2H+ = Mn2+ + O2 + 2H2O). This sensing mechanism further ensures the high selectivity of the sensor for H2O2. Significantly, the introduction of CQD not only improves the conductivity of Mn-MOF, but also can provide more active sites in the catalytic reaction, improve the contact area and reaction rate of the reaction, and improve the catalytic performance of Mn-MOF, further improve the sensitivity.

Covalent organic frameworks(COFs)with po-lar linkages have been employed as metal-free catalysts for the oxygen reduction reaction(ORR).However,it is still a big challenge to precisely design or locate the catalytic sites for such kinds of COFs because their polar linkages always make some catalytic activity.In addition,the polar linkages are fa-cile to bind with O2 and oxygen-contained intermediates in the catalytic process,severely weakening the long-term stability of these COFs.In this work,we demonstrated the single metal-free catalytic sites based on the pyridine-cored COFs with nonpolar linkages(C=C bonds)to catalyze the ORR.The nonpolar linkages excluded their potential roles as catalytic sites and also circumvented the possible decomposition in the process of catalysis.By modulating the pyridine N with posi-tive charges,the catalytic performance can be previously im-proved,because of the enhanced Lewis acidity of the carbon atoms next to the pyridine N,and thus favorable for the electrons transfer to the catalytic sites.The newly-synthesized charged COF showed high activity of a half-wave potential of 0.74 V with a mass activity of 4.34 A g-1,which was 50 mV more positive and 1.63 times higher than those of the neutral COF.And the nonpolar linkages made the COFs display better long-term stability than other metal-free COFs.The theore-tical calculation revealed that the ionization of pyridine pro-moted the formation of the intermediate OOH*,and thus improved the catalytic activity.This work gives us a new in-sight into designing single sites based on COFs.

Assembling various organic building blocks through carbon-carbon double-bond linkages is highly efficient for constructing high-performance organic semiconductors. Microporous/nanoporous structures can provide robust mass collection accommodation and reactive reaction sites. Here, we report the synthesis of a series of vinylene-linked conjugated porous polymers by Knoevenagel condensation of a tetratopic monomer tetramethyl-2,2 '-bipyridine with different ditopic monomers. The presence of the 2,2 '-bipyridine building blocks created pi-extended conjugation polymeric frameworks, substantial n-type semiconducting properties and coplanar conformation. These frameworks also exhibit strong electron-deficient characters and finely tuned energy levels. Upon visible light irradiation, they exhibited the highest activity of hydrogen peroxide generation up to 1413 mu mol h(-1) g(-1) in pure water. Their excellent recycling and reusability suggest their potential applications in green chemical transformation. (c) 2025 Society of Chemical Industry.

Obesity is one of the major global public health concerns. Purple potatoes exhibit anti-obesity properties attributable to their content of abundant polyphenols and amylose. However, the anti-obesity effects and underlying mechanisms of purple potato-based staple foods in vivo remain to be fully elucidated. Here, the anti-obesity effects and underlying mechanism of fermented purple potato dough (FD) were investigated in high-fat diet (HFD)-induced obese mice. The results showed that FD could reduce the body weight gain and improve the glucose tolerance and insulin resistance in HFD-induced obesity mice. FD effectively reduced the total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels, and this reduction was accompanied by improved lipid homeostasis in hepatic and epididymal adipose tissues. Supplementation with FD effectively modified the gut microbiota to facilitate a protective effect in the colon, such as increasing the abundance of genera Colidextribacter, unidentified_Lachnospiraceae, Blautia, Ligilactobacillus, and Oscillibacter, and decreasing the abundance of genera Dubosiella and Faecalibaculum. Meanwhile, FD remarkably modulated the metabolites involved in glycerophospholipid metabolism, including elevated PE-NMe (15 : 0/22 : 0) and PE-NMe (15 : 0/22 : 6(4Z,7Z,10Z,13Z,16Z,19Z)), thus further improving dyslipidemia. These findings elucidated that FD could be used as a promising foodstuff in a dietary strategy for alleviating obesity by regulating specific gut microbiota and fecal metabolites.

sp2-nitrogen atom holds a promising role either in promoting the construction of covalent organic frameworks (COFs) or tailoring their properties and functions. Herein, starting from 3,6-dimethylpyridazine as the linear ditopic monomer embedded with two adjacent sp2-nitrogen atoms, we successfully built up two novel vinylene-linked COFs upon Knoevenagel condensation with triformyl substituted aromatic derivatives. The finely-resolved powder X-ray diffraction (PXRD) patterns demonstrated their high crystalline structures with a hexagonal lattice in AA mode stacking along vertical direction. The resultant one-dimensional channels possess fruitful strong hydrogen-bond accepting sites arising from the decorated cis-azo units with two pair of the fully exposed lone pair electrons. In combination with their finely tailored micro-/nano-pore sizes, high surface areas and stable nonpolar vinylene linkages, as-prepared COFs enable exceptionally stepwise water harvesting from air, as shown by their water sorption isotherms consisting of successive steep water uptake steps even starting from a very low humidity (~10%), and reaching the largest water uptake capacity up to 1.26 g/g at P/PSTA = 0.95 (25 °C), representing the record values among the reported COF materials so far. Dynamic vapor sorption measurements confidently revealed the fast kinetics of such kinds of COFs, even in the cluster formation process. Water uptake and release cycling test manifested their outstanding hydrolytic stability, durability and adsorption-desorption retention ability.

Osteoporosis (OP) is the most common bone metabolic disorder worldwide, markedly compromising patients' quality of life and imposing a substantial healthcare burden. However, current clinical treatments for OP are not able to provide satisfactory therapeutic outcomes, particularly in the presence of complex inflammatory conditions. The integration of noninvasive physical therapy and bionanotechnology has shown great promise in modulating cellular functions and optimizing the bone microenvironment. In this study, we demonstrated that electromagnetized gold nanoparticles (AuNPs) exhibited excellent biocompatibility at the cellular, vascular, and major organ levels. These electromagnetized AuNPs significantly enhanced the biological behaviors of osteoblasts, including proliferation, migration, colony formation, and osteogenic differentiation. Remarkably, RNA sequencing analysis revealed that electromagnetized AuNPs significantly activated the mitochondrial oxidative phosphorylation pathway while suppressing the interleukin-17 pro-inflammatory signaling pathway. Additionally, electromagnetized AuNPs stabilized mitochondrial membrane potential and boosted adenosine triphosphate (ATP) production while reducing cell apoptosis and oxidative stress, thereby promoting osteogenic differentiation under inflammatory conditions. Furthermore, in a mouse model of inflammation-induced OP, the electromagnetized AuNPs effectively restored bone mass and improved trabecular architecture. Collectively, our findings provide a proof-of-concept that electromagnetized AuNPs enhance osteogenesis by promoting osteogenic differentiation and optimizing the bone microenvironment, highlighting their potential as a promising therapeutic strategy for OP.

Formalin-fixed tissues possess irreplaceable value as a source of DNA for identification, especially when fresh samples are unavailable. Nonetheless, extracting and amplifying DNA from these tissues is challenging, primarily due to formaldehyde-induced cross-linking and nucleic acid fragmentation. In this study, two pre-extraction treatments, gradual dehydration using ethanol and pre-digestion heat treatments, and three DNA extraction methods, the Chelex-100 method, TIANamp FFPE DNA Kit, and ML Ultra-micro DNA extraction kit, were utilized to optimize DNA extraction from different tissues, which were fixed in 4

Vinyl units intrinsically featuring less steric, nonpolarity, and unsaturated character, are well-known π-bridge used in the synthesis of high-performance semiconducting materials. Two-dimensional (2D) vinylene-linked covalent organic frameworks (COFs) represent a promising class of π-conjugated structures, however, the range of available monomers for the reversible formation of carbon-carbon double bonds remains limited. In this study, a new class of 2D vinylene-linked COFs were synthesized using dimethyldiketopyrrolopyrrole (DM-DPP) as the key monomer. The strong electron deficiency of diketopyrrolopyrrole (DPP) makes its methyl substituents readily activated upon the cocatalysis of L-proline and 4-dimethylaminopyridine in aqueous solution to conduct dynamic condensation with tritopic aromatic aldehydes. The resulting COFs crystallized in an eclipsed AA stacking arrangement and featured abundant, regular nanochannels. Their robust vinyl DPP-linking mode enhanced donor-π-acceptor conjugation and promoted π-stacked alignment along the vertical direction. Consequently, the synthesized COFs exhibited band gaps as narrow as 1.02 eV and demonstrated excellent light-harvesting capability across the visible to near-infrared I (NIR-I) regions. Furthermore, the COFs could be converted into free-standing thin pellets through simple pressure casting, and show excellent photothermal response and cycling stability under different light sources.

In this study, we successfully developed two novel vinylene-linked covalent organic frameworks (COFs) using 2-connected 3,6-dimethylpyridazine through Knoevenagel condensation. These COFs featured finely tailored micro-/nano-scale pore sizes, high surface areas and stable non-polar vinylene linkages. Finely resolved powder X-ray diffraction patterns demonstrated highly crystalline structures with a hexagonal lattice in the AA layer stacking. The resulting one-dimensional channels possess strong hydrogen-bond accepting sites arising from the decorated cis -azo/azine units with two pairs of fully exposed lone pair electrons, endowing the as-prepared COFs with exceptional water absorption properties. The g-DZPH-COF exhibited successive steep water uptake steps starting from low relative pressures ( P / P STA =0.1), with the remarkable water uptake capacity of 0.26 g/g at P / P STA =0.2 (25 °C), which is the optimal value recorded among the reported COFs. Dynamic vapour sorption measurements revealed the fast kinetics of these COFs, even in the cluster formation process. Water uptake and release cycling tests demonstrated their outstanding hydrolytic stability, durability, and adsorption–desorption retention ability.

Polycyclic aromatic hydrocarbons (PAHs) hold the predominant role either as individual molecules or building blocks in the field of organic semiconductors or nanocarbons. Connecting PAHs via sp2-carbon bridges to form high-crystalline π-extended structures are highly desired not only for enlarging the regimes of two-dimensional materials but also for achieving exceptional properties/functions. In this work, we developed 5,10-dimethyl-4,9-diazapyrene as a key monomer, whose two methyl groups at the positions adjacent to nitrogen atoms, can helpfully increase the solubility, and serve as the active connection sites. In the presence of organic acids, this monomer enables smoothly conducting Knoevenagel condensation to form two vinylene-linked PAH-cored COFs, which show high-crystalline honeycomb structures with large surface areas up to 1238 m2 g−1. Owing to the direct connection mode of PAH building blocks with vinylene, the as-prepared COFs possess spatially extended π-conjugation and substantial semiconducting properties. Consequently, their visible-light photocatalysis with exceptional activity and durability was manifested to generate H2O2 up to 3820 µmol g-1 h-1 in pure water, and 17080 µmol g-1 h-1 under benzyl alcohol as a hole sacrificial agent.

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. The resulting COFs show high-quality periodic mesoporous structures with high surface areas. Embedding heteroatoms into the backbones enables significantly improving their crystallinity, and finely tailoring their semiconducting structures. Upon visible light stimulation, one of the as-prepared COFs with donor-π-acceptor structure could deliver a nearly seven-fold increase in the catalytic activity of hydrogen generation as compared with the other two. Meanwhile, in combination with high crystallinity and the matched conduction band energy level, such kind of COFs can be able to selectively generate singlet oxygen and superoxide radicals in a high ratio of up to 30 : 1, allowing for catalyzing aerobic thioanisole oxidation in distinctly tunable activities through the substituent electronic effect of the substrates.

Fully sp 2 -carbon connected polymeric frameworks with conformationally tuned flexibilities, rich redox sites, and porous structures, were constructed, and fabricated with carbon nanotubes to film-like electrodes for high-performance electrochemical lithium-ion storage.