Covalent organic frameworks (COF) possess a robust and porous crystalline structure, making them an appealing candidate for energy storage. Herein, we report an exfoliated polyimide COF composite ...(P‐COF@SWCNT) prepared by an in situ condensation of anhydride and amine on the single‐walled carbon nanotubes as advanced anode for potassium‐ion batteries (PIBs). Numerous active sites exposed on the exfoliated frameworks and the various open pathways promote the highly efficient ion diffusion in the P‐COF@SWCNT while preventing irreversible dissolution in the electrolyte. During the charging/discharging process, K+ is engaged in the carbonyls of imide group and naphthalene rings through the enolization and π‐K+ effect, which is demonstrated by the DFT calculation and XPS, ex‐situ FTIR, Raman. As a result, the prepared P‐COF@SWCNT anode enables an incredibly high reversible specific capacity of 438 mA h g−1 at 0.05 A g−1 and extended stability. The structural advantage of P‐COF@SWCNT enables more insights into the design and versatility of COF as an electrode.
We prepare a polyimide covalent organic framework composite anode by effective in‐situ condensation of anhydride and amine on the surface of single‐walled carbon nanotubes. The construction of the conductive network accelerates the transport of electron. Dual electroactive sites in the framework, carbonyls and aromatic naphthalene rings, could store more potassium ions by the enolization and π‐K+ effect.
Organocatalysis has proven to be one of the most rapidly developing and competitive research areas in asymmetric catalysis since 2000, and has become a third branch besides biocatalysis and ...transition metal catalysis. In this feature article, recent progress from our research group on asymmetric organocatalysis, focusing on fine-tunable amine-thiourea catalysis, is described. Design of novel bifunctional amine-thiourea organocatalysts based upon the synergistic activation strategy
via
multiple hydrogen bonds and their applications in asymmetric C-C, C-N, and C-S bond-forming reactions under mild conditions are discussed in detail. The most attractive feature of the newly designed fine-tunable amine-thiourea catalysts is the incorporation of multiple hydrogen bonding donors and stereogenic centers.
Recent progress in asymmetric organocatalysis, focusing on fine-tunable amine-thiourea catalysis, is described. Design of novel bifunctional amine-thiourea organocatalysts bearing multiple hydrogen-bonding donors and their applications in asymmetric C-C, C-N, and C-S bond-forming reactions under mild conditions are discussed.
Spirocyclic pyrrolidines are structural motifs frequently found in a wide variety of natural products, pharmaceuticals and biologically significant compounds. In the past few years, catalytic ...asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides have shown to be one of the most straightforward methods for the stereoselective preparation of diverse biologically important spiropyrrolidine heterocycles in high yields with excellent enantioselectivities under mild reaction conditions. In this review, we will discuss the recent major developments in the catalytic enantioselective synthesis of chiral spiropyrrolidine derivatives since 2009.
In this review, recent progress on the catalytic enantioselective synthesis of chiral spiropyrrolidine derivatives
via
1,3-dipolar cycloaddition of azomethine ylides has been discussed.
The plant immune system is fundamental for plant survival in natural ecosystems and for productivity in crop fields. Substantial evidence supports the prevailing notion that plants possess a ...two-tiered innate immune system, called pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). PTI is triggered by microbial patterns via cell surface-localized pattern-recognition receptors (PRRs), whereas ETI is activated by pathogen effector proteins via predominantly intracellularly localized receptors called nucleotide-binding, leucine-rich repeat receptors (NLRs)
. PTI and ETI are initiated by distinct activation mechanisms and involve different early signalling cascades
. Here we show that Arabidopsis PRR and PRR co-receptor mutants-fls2 efr cerk1 and bak1 bkk1 cerk1 triple mutants-are markedly impaired in ETI responses when challenged with incompatible Pseudomonas syrinage bacteria. We further show that the production of reactive oxygen species by the NADPH oxidase RBOHD is a critical early signalling event connecting PRR- and NLR-mediated immunity, and that the receptor-like cytoplasmic kinase BIK1 is necessary for full activation of RBOHD, gene expression and bacterial resistance during ETI. Moreover, NLR signalling rapidly augments the transcript and/or protein levels of key PTI components. Our study supports a revised model in which potentiation of PTI is an indispensable component of ETI during bacterial infection. This revised model conceptually unites two major immune signalling cascades in plants and mechanistically explains some of the long-observed similarities in downstream defence outputs between PTI and ETI.
In this paper, an iterative algorithm is introduced to solve the split common fixed point problem for asymptotically nonexpansive mappings in Hilbert spaces. The iterative algorithm presented in this ...paper is shown to possess strong convergence for the split common fixed point problem of asymptotically nonexpansive mappings although the mappings do not have semi-compactness. Our results improve and develop previous methods for solving the split common fixed point problem. MSC: 47H09, 47J25.
The aboveground parts of terrestrial plants, collectively called the phyllosphere, have a key role in the global balance of atmospheric carbon dioxide and oxygen. The phyllosphere represents one of ...the most abundant habitats for microbiota colonization. Whether and how plants control phyllosphere microbiota to ensure plant health is not well understood. Here we show that the Arabidopsis quadruple mutant (min7 fls2 efr cerk1; hereafter, mfec)
, simultaneously defective in pattern-triggered immunity and the MIN7 vesicle-trafficking pathway, or a constitutively activated cell death1 (cad1) mutant, carrying a S205F mutation in a membrane-attack-complex/perforin (MACPF)-domain protein, harbour altered endophytic phyllosphere microbiota and display leaf-tissue damage associated with dysbiosis. The Shannon diversity index and the relative abundance of Firmicutes were markedly reduced, whereas Proteobacteria were enriched in the mfec and cad1
mutants, bearing cross-kingdom resemblance to some aspects of the dysbiosis that occurs in human inflammatory bowel disease. Bacterial community transplantation experiments demonstrated a causal role of a properly assembled leaf bacterial community in phyllosphere health. Pattern-triggered immune signalling, MIN7 and CAD1 are found in major land plant lineages and are probably key components of a genetic network through which terrestrial plants control the level and nurture the diversity of endophytic phyllosphere microbiota for survival and health in a microorganism-rich environment.
Metals play vital roles in nutrients and medicines and provide chemical functionalities that are not accessible to purely organic compounds. At least 10 metals are essential for human life and about ...46 other non-essential metals (including radionuclides) are also used in drug therapies and diagnostic agents. These include platinum drugs (in 50% of cancer chemotherapies), lithium (bipolar disorders), silver (antimicrobials), and bismuth (broad-spectrum antibiotics). While the quest for novel and better drugs is now as urgent as ever, drug discovery and development pipelines established for organic drugs and based on target identification and high-throughput screening of compound libraries are less effective when applied to metallodrugs. Metallodrugs are often prodrugs which undergo activation by ligand substitution or redox reactions, and are multi-targeting, all of which need to be considered when establishing structure-activity relationships. We focus on early-stage
in vitro
drug discovery, highlighting the challenges of evaluating anticancer, antimicrobial and antiviral metallo-pharmacophores in cultured cells, and identifying their targets. We highlight advances in the application of metal-specific techniques that can assist the preclinical development, including synchrotron X-ray spectro(micro)scopy, luminescence, and mass spectrometry-based methods, combined with proteomic and genomic (metallomic) approaches. A deeper understanding of the behavior of metals and metallodrugs in biological systems is not only key to the design of novel agents with unique mechanisms of action, but also to new understanding of clinically-established drugs.
The vital roles of metals in nutrients and medicines are not accessible to purely organic compounds.
It′s just a phase: The title reaction sequence of para‐quinone methides (p‐QMs) has been developed with malonates under phase‐transfer catalysis. The reaction also offers an alternative route to ...asymmetric construction of diarylmethine stereocenters in excellent enantioselectivities and high yields.
A carbene-catalyzed reductive coupling reaction of carboxylic esters and substituted Hantzsch esters is disclosed. Key steps of this reaction include one-electron reduction of a carbene ...catalyst-bound acyl azolium intermediate to generate the corresponding radical intermediate for subsequent alkylation reactions. The reaction is promoted by irradiation with visible light without the involvement of transition-metal photocatalysts. Mechanistic studies suggest that direct photoexcitation of the in situ formed acyl azolium intermediate is likely responsible for this light-induced one-electron-reduction process. Photoexcitation converts the acyl azolium intermediate to a single-electron oxidant, enabling single-electron oxidation of Hantzsch esters to generate radical intermediates. Our reactions work well for a broad range of aryl carboxylic ester and Hantzsch ester substrates. Sophisticated structures, including those present in medicines, can be incorporated into ketone molecules using our approach via very mild conditions that tolerate various functional groups.
The controllable modulation of the response mode is highly attractive for the construction of photoelectrochemical (PEC) sensors with improved sensitivity and anti-interference ability in complex ...real samples matrix. Here, we present a charming proof-of-concept ratiometric PEC aptasensor of enrofloxacin (ENR) analysis via the controllable signal transduction. Different with the traditional sensing mechanism, this ratiometric PEC aptasensor integrates the anodic PEC signal induced by PtCuCo nanozyme-catalyzed precipitation reaction and the polarity-switching cathodic PEC response mediated by Cu2O nanocubes on S-scheme FeCdS@FeIn2S4 heterostructure. Taking advantages of the photocurrent-polarity-switching signal response model and the superior performance of the photoactive substrate material, the proposed ratiometric PEC aptasensor displays a good detection linear range for ENR analysis from 0.01 pg mL−1 to 10 ng mL−1, with a detection limit of 3.3 fg mL−1. This study provides a general platform for detecting interested trace analytes in real samples and expands the diversity of sensing strategy design.
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