RESUMO
The synthesis of ketones has been a long focus of chemistry research, on account of its unique reactivity. Herein, we report a simple light-driven photocatalyst-free synthesis of ß, δ-functionalized ketones from aldehydes, using inexpensive and commercially abundant feedstock chemicals. This reaction is enabled by the direct acyl radical generation via hydrogen atom transfer and the subsequent radical addition process, avoiding the need for prefunctionalized substrates and organometallic reagent.
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As novel and efficient difluoromethyl building blocks, difluoroacetohydrazonoyl bromides have been synthesized for the first time. The synthetic utility of this reagent for the construction of difluoromethyl organic compounds is demonstrated by their effective regioselective [3 + 2] cycloaddition reactions with ynones, alkynoates, and ynamides. The reactions provide a novel and efficient protocol to access difluoromethyl-substituted pyrazoles in good to excellent yields.
RESUMO
Carbonyl compounds are widely found in various pharmaceutical intermediates and synthetic precursors. Herein we report a simple light-driven three-component aryl halide process for synthesizing a variety of carbonylation products, utilizing Co2(CO)8 as an abundant solid carbonyl source, in good to excellent yields. The products can easily be subjected to further functionalization in synthesis. Mechanism studies indicated that this reaction is enabled by aryl radical generation and the subsequent CO insertion, alkene insertion, and protonation process.
RESUMO
Metal-organic frameworks (MOFs) with fit ligands and metals can be integrated into electrochemical biosensors for the detection of various biomolecules. In this study, we have synthesized novel magnetic MOF composites as electrocatalysts and constructed a novel biosensor for electrochemical detection of dopamine. The composites named Fe3O4@ZIF-8@AuNPs-COOH are synthesized through layer-by-layer assembly. They exhibit excellent stability and cooperative catalytic activity. In addition, green recycling is readily achieved through magnetizing/demagnetizing the electrode. The large specific surface area and ordered porous structures of the magnetic MOFs ensure good dispersion of gold nanoparticles, while the carboxyl group efficiently shields other redox-active interfering substances. The proposed electrochemical biosensor accomplishes the sensitive detection of dopamine in human serums and living cells. This study broadens the application of MOFs in electrochemical biosensing, validates the feasibility of biosensors for in vivo analysis, and provides new insights into green sensing.
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Nanoplastics, as emerging contaminants are being released into aquatic environments with their increasing applications, and induce potential hazards to aquatic ecosystem. In this work, we investigated the removal process of polystyrene nanoparticles (PS NPs) by Eichhornia crassipes and the related photosynthetic responses of E. crassipes. Results showed that both sizes of PS NPs (20 and 200 nm) with 50 mg/L induced the prominent damage on the root epidermis after 48 h exposure, and smaller size PS NPs caused the greater damage. PS NPs has been entered the roots of E. crassipes and migrated from the epidermis, cortex, to vascular system by using confocal laser scanning microscopy observation. Scanning electron microscope images confirmed the distribution of PS NPs (200 nm) in the roots. The crack at sites of primary-lateral root junction was an important way for the uptake of PS NPs, which destroyed the defense of Casparian strip, and promoted the migration of PS NPs into the vascular system. PS NPs entered the submerged leaves by stomata and the intercellular spaces of lower epidermis. Moreover, PS NPs in the plants showed significant inhibition on net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate. This study concluded the absorption and migration processes of PS NPs by E. crassipes, and the negative effects on photosynthesis, which will be useful for guiding the floating plants application for PS NPs removal in aqueous environment and ecological improvement.
Assuntos
Eichhornia , Nanopartículas , Poluentes Químicos da Água , Poliestirenos , Microplásticos , Ecossistema , Nanopartículas/toxicidade , Fotossíntese , Plantas , Poluentes Químicos da Água/análiseRESUMO
A simple naphthalene based fluorescent probe was first time reported as dual sensing of 2,4,6-trinitrotolune (TNT) and 2,4,6-trinitrophenol (TNP) by distinguishable changes in both solution color change and fluorescence within same sample without any mask agent. Upon addition of TNT and TNP, the strong emission quenching at 412nm and a new emission band at 530nm was observed, respectively. In addition, the sensing mechanism was evaluated by DFT calculations by Gaussian 09 software.