Trauma and tumor removal usually cause bone defects; in addition, the related postoperative infection also shall be carefully considered clinically. In this study, polylactic acid (PLLA) composite fibers containing Cerium oxide (CeO2) are first prepared by electrospinning technology. Then, the PLLA/CeO2@PDA/Ag composite materials are successfully prepared by reducing silver ion (Ag+) to nano-silver (AgNPs) coating in situ and binding AgNPs to the materials surface by mussel structure liked polydopamine (PDA). In the materials, Ag+ can be slowly released in simulated body fluids. Based on the photothermal performance of AgNPs, the photothermal conversion efficiency of the materials is 21%, under NIR 808 nm illumination. The effective photothermal conversion can help materials fighting with E. coli and S. aureus in 3 h, with an antibacterial rate of 100%. Additionally, the sustained Ag+ release contributes to the antibacterial in long term. Meanwhile, the materials can mimic the bio-behavior of superoxide dismutase and catalase in decreasing the singlet oxygen level and removing the excess reactive oxygen species. Furthermore, the materials are beneficial for cell proliferation and osteogenic differentiation in vitro. In this study, a promising bone-regenerated material with high photothermal conversion efficiency and antibacterial and anti-oxidation properties, is successfully constructed.
BACKGROUND: Succinate dehydrogenase inhibitors (SDHIs) are the fastest growing agricultural fungicides at present, but their rapidly growing resistance is a serious problem for their application. Previously, we screened out a fungicidal lead compound CBUA-TPP (1) through triphenylphosphonium (TPP)-driven mitochondrial-targeting strategy. The targeting led to the rapid accumulation of 1 in mitochondria and the saturation inhibition of complex II in a short time, resulting in electron leakage and the explosion of reactive oxygen species (ROS). However, the contribution of biphenyl-2-amines to the activity of these compounds and their structure-activity relationship are still unknown. RESULTS: Two series of CBUA-TPP (1) analogues (series 2 and 3) were designed and synthesized. The bioassay results indicated that series 2 compounds generally showed much higher fungicidal activities than series 3, suggesting the crucial contribution of the biarylamine module in these targeted molecules and the pyridinyl substitution of phenyl is unfavorable to their activities. Interestingly, these two series of compounds displayed almost opposite substituent effects. Several compounds showed excellent fungicidal activities in vitro, among which compound 2-1 exhibited excellent field control efficacy on potato late blight. CONCLUSION: By optimizing the lead compound, the contribution of biarylamine in CBUA-TPP (1) analogs to the fungicidal activity is clarified. Several compounds, represented by 2-1, have great potential as fungicide candidates. They exhibit high and broad-spectrum fungicidal activities and are highly effective against common pathogenic fungi infecting vegetables and fruits both in vitro and field control. It not only provided a new choice for controlling these diseases, but its low resistance tendency also provided a better scheme for resistance management. © 2023 Society of Chemical Industry.
Ascomycota , Fungicides, Industrial , Fungicides, Industrial/pharmacology , Fungicides, Industrial/chemistry , Amides/pharmacology , Structure-Activity Relationship
Metal-organic frameworks (MOFs) can respond to light in a number of interesting ways. Photochromism is observed when a structural change to the framework is induced by the absorption of light, which results in a color change. In this work, we show that introducing quinoxaline ligands to MUF-7 and MUF-77 (MUF = Massey University Framework) produces photochromic MOFs that change color from yellow to red upon the absorption of 405 nm light. This photochromism is observed only when the quinoxaline units are incorporated into the framework and not for the standalone ligands in the solid state. Electron paramagnetic resonance (EPR) spectroscopy shows that organic radicals form upon irradiation of the MOFs. The EPR signal intensities and longevity depend on the precise structural details of the ligand and framework. The photogenerated radicals are stable for long periods in the dark but can be switched back to the diamagnetic state by exposure to visible light. Single-crystal X-ray diffraction analysis reveals bond length changes upon irradiation that are consistent with electron transfer. The multicomponent nature of these frameworks allows the photochromism to emerge by allowing through-space electron transfer, precisely positioning the framework building blocks, and tolerating functional group modifications to the ligands.
The guest adsorption phenomena in multicomponent metal-organic frameworks (MOFs) are intricate due to their structural complexities. In this work, we studied two members of the isostructural series of MUF-77 frameworks that consist of long or short alkyl groups. The adsorption of methanol, N,N-dimethylaniline (DMA) and acridine orange (AO) in two structures of MUF-77 has been investigated. 2H solid-state nuclear magnetic resonance (SSNMR) and two-dimensional 1H-13C NMR spectroscopy were used to probe the dynamics of various compartments of MUF-77. Through the analyses of dynamic behavior by SSNMR and molecular dynamics simulations, we elucidate the spatial distribution of guest molecules are nonuniform around different chemical components, in different pore structures, and across different parts of MOF lattice. In addition, we reveal that the framework flexibility of MUF-77 with short alkyl groups is reduced upon guest adsorption yet the framework flexibility of MUF-77 with long alkyl groups increases upon loading with methanol.
The development of efficient and abundant transition metal bifunctional electrocatalysts is crucial in sustainable energy utilization. Copper-cobalt bimetallic composites exhibit excellent electrochemical performance but the agglomeration of nanoparticles and phase separation cannot be avoided in high temperature pyrolysis. Herein, Cu(ii) ions are introduced into Co-based zeolitic imidazolate frameworks (ZIF-67) by a polymer-coating method to synthesize copper-cobalt bimetallic composite phosphides (CuCoP). After further pyrolysis and phosphidation, the uniform CuCoP nanoparticles are embedded into N-doped carbon frameworks (CuCoP-NC) derived from organic ligands. CuCoP-NC possesses unique hollow structure, rich pores in the carbon framework and large specific surface areas. At an optimal carbonization temperature of 700 °C, CuCoP-NC-700 exhibits admirable electrocatalytic performance such as high onset potentials (0.978 V vs. reversible hydrogen potential (RHE) in alkaline media and 0.801 V vs. RHE in acidic media), large limiting current densities, long-term stability and eximious resistance to methanol poisoning towards the oxygen reduction reaction (ORR) in both alkaline and acidic media and a low overpotential of 337 mV at 10 mA cm-2 towards the oxygen evolution reaction (OER). Moreover, CuCoP-NC-700 is assembled into a Zn-air battery and presents a higher power density (116.5 mW cm-2) and stability compared to Pt/C.
Controlling chemical reactions in porous heterogeneous catalysts is a tremendous challenge because of the difficulty in producing uniform active sites that can be tuned with precision. However, analogous to enzymes, when a catalytic pocket provides complementary close contacts and favorable intermolecular interactions with the reaction participants, the reaction efficiency and selectivity may be tuned. Here, we report an isoreticular family of catalysts based on the multicomponent metal-organic framework MUF-77. The microenvironment around the site of catalysis was successfully programmed by introducing functional groups (modulators) to the organic linkers at sites remote from the catalytic unit. The framework catalysts produced in this way exhibit several unique features, including the simultaneous enhancement of both reactivity and stereochemical selectivity in aldol reactions, the ability to catalyze Henry reactions that cannot be accomplished by homogeneous analogs, and discrimination between different reaction pathways (Henry versus aldol) that compete for a common substrate.
Metal-organic frameworks (MOFs) exhibit a broad range of luminescence characteristics due to the vast array of metal ions and organic linkers available as building blocks. Systematic control over the emissive output of MOFs is highly sought after. Methods for tuning emission profiles are emerging based largely on luminescent metal ions and the encapsulation of emissive guests. Herein, we show how the functionalization of the organic linkers of a series of multicomponent MUF-77 (MUF = Massey University Framework) materials can methodically tune their spectral output. This was quantified by chromaticity diagrams. White-light emission was obtained by combining the photophysical characteristics of the three distinct organic fluorophores present in these materials. Our results also show that both (i) energy transfer interactions between the organic components and (ii) noncovalent interactions with guests can also be harnessed to tune the emission. These results establish multicomponent metal-organic frameworks as fluorescent materials with unique spectral characteristics.
Systematically tuning the spatial environment around the active sites of synthetic catalysts is a difficult challenge. Here, we show how this can be accomplished in the pores of multicomponent metal-organic frameworks. This relies on embedding a catalytic unit in a pore of the MUF-77 framework and then tuning its environment by introducing different functional groups to the surrounding linkers. This approach benefits from the structural regularity of MUF-77, which places each component in a precise location to circumvent disorder. Prolinyl groups, which are catalytically competent toward asymmetric aldol reactions, were selected as the catalytic unit. Since every prolinyl group is positioned in an identical environment, correlations between the pore architecture and the activity of these single-site catalysts can be elucidated. Systematic engineering of the pore structure, which is achieved by installing modulator groups on the framework linkers, impacts on the reaction rate and the enantiomeric excess of the aldol products. Furthermore, the spatial environment around the proline catalyst can override its innate stereochemical preference to dictate the preferred enantiomer of the reaction product. These results offer a new way to design three-dimensional active site environments for synthetic catalysts.
The topology of a covalent organic framework (COF) is generally believed to be dictated by the symmetries of the monomers used for the condensation reaction. In this context, the use of monomers with different symmetries is usually required to afford COFs with different topologies. Herein, we report a conceptual strategy to regulate the topology of 2D COFs by introducing alkyl substituents into the skeleton of a parent monomer. The resulting monomers, sharing the same C2 symmetry, were assembled with a D2h symmetric tetraamine to generate a dual-pore COF or single-pore COFs, depending on the sizes of the substituents, which were evidenced using PXRD studies and pore size distribution analyses. These results demonstrate that the substituent is able to exert a significant influence on the topology of COFs, which is crucial for their application.
Critical flicker fusion thresholds (CFFTs) describe when quick amplitude modulations of a light source become undetectable as the frequency of the modulation increases and are thought to underlie a number of visual processing skills, including reading. Here, we compare the impact of two vision-training approaches, one involving contrast sensitivity training and the other directional dot-motion training, compared to an active control group trained on Sudoku. The three training paradigms were compared on their effectiveness for altering CFFT. Directional dot-motion and contrast sensitivity training resulted in significant improvement in CFFT, while the Sudoku group did not yield significant improvement. This finding indicates that dot-motion and contrast sensitivity training similarly transfer to effect changes in CFFT. The results, combined with prior research linking CFFT to high-order cognitive processes such as reading ability, and studies showing positive impact of both dot-motion and contrast sensitivity training in reading, provide a possible mechanistic link of how these different training approaches impact reading abilities.
A two-dimensional (2D) supramolecular organic framework (SOF) has been constructed through the co-assembly of a triphenylamine-based building block and cucurbit[8]uril (CB[8]). Fluorescence turn-on of the non-emissive building block was observed upon the formation of the 2D SOF, which displayed highly selective and sensitive recognition of picric acid over a variety of nitroaromatics.
It is very important to create novel topologies and improve structural complexity for covalent organic frameworks (COFs) that might lead to unprecedented properties and applications. Despite the progress achieved over the past decade, the structural diversity and complexity of COFs are quite limited. In this Communication, we report the construction of COFs bearing three different kinds of pores through the heterostructural mixed linker strategy involving the condensation of a D2h-symmetric tetraamine and two C2-symmetric dialdehydes of different lengths. The complicated structures of the triple-pore COFs have been confirmed by powder X-ray diffraction and pore size distribution analyses.
Two chiral (A)6B-typed supramolecular cages were constructed from hydrogen-bonded C6 -symmetric zinc porphyrin hexamers and chiral C3-symmetric pyridyl hexadentates with a core of 1,3,5-triphenylbenzene. Circular dichroism and molecular simulations revealed that the symmetry of the supramolecular cages switched from pseudo-C3v to C3 with the rotational confinement of the biphenyl backbones at low temperatures, which generated conformationally chiral transfer and amplification. This unique phenomenon suggests a new strategy to develop smart materials with high sensitivity and excellent reversibility.
A triptycene-based microporous organic polymer (MOP) in which 2,6-bis(benzimidazol-2-yl)pyridine (bbp) is incorporated as linkage and coordination site is designed and synthesized. Pd(II) ions are further immobilized in this MOP through the coordination interactions between Pd(II) ion and nitrogen atoms of bbp. The resulting material shows high stability and exhibits excellent heterogeneously catalytic activity for the Suzuki-Miyaura cross-coupling reaction. Its high efficiency can be maintained after being reused for a number of cycles.
Anthracenes/chemistry , Polymers/chemistry , Catalysis , Ligands , Palladium/chemistry , Photoelectron Spectroscopy , Polymers/chemical synthesis , Porosity
Self-assembly has emerged as a powerful approach to generating complex supramolecular architectures. Despite there being many crystalline frameworks reported in the solid state, the construction of highly soluble periodic supramolecular networks in a three-dimensional space is still a challenge. Here we demonstrate that the encapsulation motif, which involves the dimerization of two aromatic units within cucurbit[8]uril, can be used to direct the co-assembly of a tetratopic molecular block and cucurbit[8]uril into a periodic three-dimensional supramolecular organic framework in water. The periodicity of the supramolecular organic framework is supported by solution-phase small-angle X-ray-scattering and diffraction experiments. Upon evaporating the solvent, the periodicity of the framework is maintained in porous microcrystals. As a supramolecular 'ion sponge', the framework can absorb different kinds of anionic guests, including drugs, in both water and microcrystals, and drugs absorbed in microcrystals can be released to water with selectivity.
Covalent organic frameworks (COFs) are crystalline porous materials bearing microporous or mesoporous pores. The type and size of pores play crucial roles in regulating the properties of COFs. In this work, a novel COF, which bears two different kinds of ordered pores with controllable sizes: one within microporous range (7.1 Å) and the other in mesoporous range (26.9 Å), has been constructed via one-step synthesis. The structure of the dual-pore COF was confirmed by PXRD investigation, nitrogen adsorption-desorption study, and theoretical calculations.
Two new types of supramolecular polymers have been constructed via the self-assembly of rigid rod-like monomers and cucurbit[8]uril (CB[8]) in water. These supramolecular polymers possessed rigid backbones and further aggregated into stick-like bunched fibres.
The construction of supramolecular systems in aqueous media is still a great challenge owing to the limited sources of building blocks. In this study, a series of 4-aryl-N-methylpyridinium derivatives have been synthesized. They formed very stable host-guest (1:2) complexes with CB[8] in water (binding constants up to 10(14) M(-2)) with the two guest molecules arranged in a head-to-tail manner and the complexes showed high thermostability, which was revealed by (1) Hâ NMR and UV/Vis spectroscopic studies, ITC, and crystallographic analysis.
