Recent Progress in Polymer Waste‐Derived Porous Carbon for Supercapacitors

Posted on 20 September 2023 by

In this paper, the PWCM electrode prepared from polymer wastes in recent years was reviewed, and the effect of different preparation methods on the electrode performance was compared.

Abstract

Due to the high power density, fast charging speed, and long cycling stability, supercapacitors have been developed rapidly in the area of electrical energy storage devices in the past decades. During the application of supercapacitors, it was found that the properties of the electrode material can greatly affect the supercapacitor performance. Recently, electrode materials based on polymer waste-derived carbon materials (PWCM) have attracted much attention because of the low preparation cost, good electrode performance, and great benefits for environmental protection. This review aims to describe the recent research development and summarize the investigation state in the field of the PWCM electrodes prepared from polyethylene, polypropylene, polyethylene terephthalate, polystyrene, etc. The preparation method and the electrode performance of the PWCM electrodes are compared. The relationship among the preparation methods, material structure, and electrochemical performance of the PWCM electrodes was explored. Furthermore, the prospects for the application of the PWCMs were provided.

Construction of the Bioconjugate Py‐Macrodipa‐PSMA and Its In Vivo Investigations with Large 132/135La3+ and Small 47Sc3+ Radiometal Ions

Posted on 20 September 2023 by

To harness radiometals in clinical settings, a chelator forming a stable complex with the metal of interest and targets the desired pathological site is needed. Toward this goal, we previously reported a unique set of chelators that can stably bind to both large and small metal ions, via a conformational switch. Within this chelator class, py-macrodipa is particularly promising based on its ability to stably bind several medicinally valuable radiometals including large 132/135La3+, 213Bi3+, and small 44Sc3+. We report a 10-step organic synthesis of its bifunctional analogue py-macrodipa-NCS, which contains an amine-reactive –NCS group that is amenable for bioconjugation reactions to targeting vectors. The hydrolytic stability of py-macordipa-NCS was assessed, revealing a half-life of 6.0 d in pH 9.0 aqueous buffer. This bifunctional chelator was then conjugated to a prostate-specific membrane antigen (PSMA)-binding moiety, yielding the bioconjugate py-macrodipa-PSMA, which was subsequently radiolabeled with large 132/135La3+ and small 47Sc3+, revealing efficient and quantitative complex formation. The resulting radiocomplexes were injected into mice bearing both PSMA-expressing and PSMA-non-expressing tumor xenografts to determine their biodistribution patterns, revealing delivery of both 132/135La3+ and 47Sc3+ to PSMA+ tumor sites. Urine analysis, however, revealed partial radiometal dissociation, suggesting that py-macrodipa-PSMA needs further structural optimization.

Copper‐Catalyzed Highly Stereoselective Hydrodifluoroallylation of Cyclopropenes and Alkenyl Boronates with 3,3‐Difluoroallyl Sulfonium Salts

Posted on 20 September 2023 by nXing Gao, nXiaoxiao Ren, nWei Deng, nXingang Zhangn

A copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts (DFASs) has been developed. The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions. The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products.

Comprehensive Summary

Despite the paramount applications of organofluorine compounds in life and materials sciences, efficient strategies for stereoselectively constructing the C(sp³)-CF₂R bond at the stereogenic center remain limited. Here, we report a copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts (DFASs). The use of DFASs overcomes the previous challenge of suppressing the reduction of fluoroalkylating reagents with M-H species. The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions. Using chiral phosphine ligand could provide gem-difluoroallyl borylalkanes with high enantioselectivities, paving a new way for the catalytic asymmetric fluoroalkylation with ubiquitous alkenes. The advantages of this protocol are synthetic convenience, high functional group tolerance, and the synthetic versatility of the resulting gem-difluoroallyl cyclopropanes and borylalkanes. The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products and the rapid synthesis of bioactive molecule analogs.

DFT Calculations and Synthesis Reveal: Key Intermediates, Omitted Mechanisms, and Unsymmetrical Bimane Products

Posted on 20 September 2023 by

We studied the mechanism behind the formation of fluorescent syn-bimane. This work combines theoretical and experimental approaches. Our computational study supports Kosower's mechanism while introducing a crucial diaziridine intermediate. Our results suggest the rate-limiting step is the formation of a diazoketene. The reaction of 4,5-dimethyl-2,3-diazacyclopentadienone with diphenylcyclopropenone produced the unexpected unsymmetrical anti-(Me,Me)(Ph,Ph)bimane.

Abstract

Theoretical and experimental mixed approaches are complementary and valuable. Our DFT calculations support the mechanism suggested by Kosower, adding to it a key diaziridine intermediate that determines the relative product distribution of this reaction. Our results are consistent with the formation of the diazoketene intermediate as the rate-limiting step. Based on curve fittings, first or second-order kinetics cannot be ruled out. This may indicate that more than one mechanism is simultaneously at play in this transformation. This unexpected outcome led us to study an alternative cyclopropenone intermediate. Although cyclopropenone is not likely to be formed under thermal conditions, adding it to the reaction mixture results in bimane structures. The most staggering finding from this investigation was the unanticipated generation of the unsymmetrical anti-(Me,Me)(Ph,Ph)bimane. The optimization of this route towards unsymmetrical bimanes will require additional investigation.

Meta‐Ortho Effect on the Excited State Pathways of Chloroanilines

Posted on 20 September 2023 by

Computational chemistry allows to elucidate the observed selectivity in the photochemistry of chloroanilines. A meta-ortho effect of the substituents favours the population of the prefulvenic conical intersection which leads to rapid deactivation of the m- and o-isomers of chloroaniline, while the para derivative lives long enough to emit and populate the reactive triplet state which leads to C−Cl dissociation.

Abstract

Direct excitation of aromatic compounds grants access to high-energy intermediates that can be utilised in organic synthesis. Understanding and predicting the substituent effects at the excited state for aromatic molecules remains challenging for the synthetic photochemist. In this work, we present an experimental and computational investigation of the excited state of the isomeric chloroanilines, which promptly react by losing the chloride when the amino group is in para position, but are non-reactive and non-emissive in the meta and ortho isomers. XMS-CASPT2//CASSCF computations explain this apparent contradiction of the meta-ortho selectivity rule of Zimmerman, which originates from the substituent effects lowering to a different extent the barrier to populate the prefulvenic conical intersection that deactivates non-radiatively the singlet excited state of the chloroanilines.

Three Component Synthesis of 4‐Aryl‐2‐aminothiazoles under Transition‐Metal Free Conditions

Posted on 20 September 2023 by nXi Cheng, nDa‐Bin Qin, nZhi‐Bing Dongn

An efficient three-component synthesis of disubstituted 4-aryl-2-aminothiazoles was reported. The protocol features transition-metal free, short reaction time, easily available starting materials, good yields and broad substrates scope, showing potential synthetic value for the synthesis of a variety of biological or pharmaceutical active compounds.

Abstract

An efficient three-component synthesis of 4-aryl-2-aminothiazoles was reported. Phenyl-thioureas reacted with 2-bromoacetophenones to form 4-aryl-2-aminothiazoles through cyclization, and the subsequent C−N bonding with benzyl/allyl bromides gave the desired disubstituted thiazoles smoothly. The protocol features transition-metal free, short reaction time, easily available starting materials, good yields and broad substrate scope, showing potential synthetic value for the synthesis of a variety of biologically or pharmaceutically active compounds.

Practical Synthesis of Pharmaceutically Relevant Pyrroles from α,β‐Unsaturated Aldehydes and Phenacyl Azides

Posted on 20 September 2023 by nLodsna Borkotoky, nRam Awatar Mauryan

A method for the synthesis of 2-aroyl-5-aryl-pyrroles using phenacyl azide and α,β-unsaturated aldehyde at room temperature has been developed. High yield, atom economy and requirement of economic substrates, reagents and organocatalyst as well as non-involvement of cryogenic or very high temperature and inert or anhydrous conditions make this protocol a sustainable synthetic approach towards the synthesis of 2-aroyl-5-aroyl-pyrroles.

Abstract

Structurally diverse pyrroles were synthesized by direct coupling of α, β-unsaturated aldehydes and phenacyl azides. The scope of the synthetic method was successfully demonstrated by synthesizing 28 different phenyl(5-phenyl-1H-pyrrol-2-yl)methanones in high yields (87–95 %). Derivatization of a few synthesized pyrroles was demonstrated which shows the potential application of the developed protocol in new functional materials. To get a mechanistic insight of the reaction, a typical reaction was performed in a deuterated solvent and the progress of the reaction was monitored by recording its ¹H NMR at regular time intervals.

Ring Transformation of α‐Amino‐β‐oxoesters to δ‐Butyrolactams

Posted on 20 September 2023 by nDaniel Krieger, nJens Christoffersn

Lactams by Ring Transformation: δ-Butyrolactams with an exocyclic ester moiety in the δ-position were accessed by reduction of cyclic α-azido-β-oxocyclopentane carboxylates with Zn−AcOH. The ring transformation proceeded readily under the conditions of the reduction which is an unprecedented process.

Abstract

δ-Butyrolactams with an exocyclic ester moiety in the δ-position were accessed by reduction of 1-azido-2-cyclopentanone carboxylates with PBu₃ or Zn−AcOH. The ring transformation proceeded readily under the conditions of this reduction which is an unprecedented process. Primary amines formed by catalytic hydrogenation of α-azido-β-oxoesters with larger ring sizes or with benzannulation do not show this rearrangement under the conditions of the azide reduction. In these cases, the ring transformation to respective lactams was achieved by treatment of the α-amino-β-oxoesters with a stoichiometric amount of lithium diisopropylamide.

Exploring the Therapeutic Properties of Alga‐Based Silver Nanoparticles: Anticancer, Antibacterial, and Free Radical Scavenging Capabilities

Posted on 20 September 2023 by

Abstract

The current study was designed to evaluate the antioxidant, anticancer and antimicrobial activities of silver nanoparticles (AgNPs) biosynthesized by Spirulina platensis extract. The biosynthesized silver nanoparticles were characterized using Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The antioxidant activity of the biosynthesized AgNPs were determined via DPPH radical scavenging assay while its anticancer activity was determined using the MTT assay. The antimicrobial activity of the biosynthesized AgNPs were analyzed by disc diffusion method. Spirulina platensis acts as a reducing and capping agent. The efficacy of silver nanoparticles (AgNPs) in inhibiting the growth of Gram-negative bacteria, specifically Acetobacter, Klebsiella, Proteus vulgaris, and Pseudomonas aeruginosa, was assessed by the utilisation of the diffusion method. The study aimed to evaluate the efficacy of biosynthesized silver nanoparticles (AgNPs) against many strains of Pseudomonas aeruginosa bacteria. The findings of the study revealed that when administered in doses of 50 μl, 75 μl, and 100 μl, the largest observed zone of inhibition corresponded to measurements of 10.5 mm, 14 mm, and 16 mm, respectively. A zone of inhibition with dimensions of 8 mm, 10.5 mm, and 12 mm was detected during testing against Acetobacter at concentrations of 50 μl, 75 μl, and 100 μl, respectively. The findings also indicate that there is a positive correlation between the concentration of AgNP and the DPPH scavenging ability of silver nanoparticles. The percentage of inhibition observed at concentrations of 500 μg/ml, 400 μg/ml, 300 μg/ml, 200 μg/ml, and 100 μg/ml were recorded as 80±1.98, 61±1.98, 52±1.5, 42±1.99, and 36±1.97, respectively. In addition, it was observed that the silver nanoparticles exhibited the greatest antioxidant activity at a concentration of 500 g/ml, with a measured value of 80.89±1.99. The IC-50 values, representing the inhibitory concentration required to achieve 50 % inhibition, were found to be 8.16, 19.15, 30.14, 41.13, and 63.11 at inhibition levels of 36±1.97, 42±1.99, 52±1.5, 61±1.98, and 80±1.98, respectively.

Structurally Diverse Sesquiterpenoids with NO Production and α‐Glucosidase Inhibitory Activities from the Fruits of Schisandra chinensis

Posted on 20 September 2023 by

Abstract

Chemical fractionation of the AcOEt partition, generated from the EtOH extract of the fruits of Schisandra chinensis, afforded a series of sesquiterpenyl constituents including two new cadinanes, a new eudesmane, two new widdranes (a handling artefact and a new natural product), a new bisabolane and two new natural cuparane enantiomers, along with 15 known structurally related analogs. Structures of the new compounds were unambiguously characterized by interpretation of detailed spectroscopic data including ESI-MS and 1D/2D NMR, with their absolute configurations being established by electronic circular dichroism (ECD) calculation and induced ECD experiment. The inhibitory effects of all the isolates against α-glucosidase and lipopolysaccharide (LPS) induced nitric oxide (NO) production in murine RAW264.7 macrophages, as well as their antibacterial and cytotoxic potential, were evaluated, with selective compounds showing moderate α-glucosidase and NO inhibitory activity. Notably, canangaterpene III exhibited the most significant NO inhibitory effect with an IC₅₀ value of 31.50±1.49 μM.