Single-pot Reaction Research Articles

Single-Pot Reaction of Novel Fused Indolizine Derivatives.

An unprecedented fused hexacyclic indolizine derivative generated by a single-pot reaction has been developed. This model overcomes the use of catalysts, inefficient atom economy, low yields, and limitations of lengthy steps. Density functional theory calculations reveal the reaction mechanism in which the oxygen molecule plays a crucial role in trapping the penultimate zwitterionic or biradical intermediate to generate the observed products.

Production of gluconic acid from the washed rice waste water using Au/MgO catalyst – A sustainable route

The majority of the waste produced by the food and agriculture industries is abundant in proteins, carbohydrates, and fats, which can be utilized effectively in other food products or industrial products. Especially, washed rice water (WRW) contains a significant quantity of starch that has been discarded without being utilized properly. In the present investigation, we have successfully upgraded washed rice water into the industrially important intermediate, i.e., gluconic acid, using an Au/MgO catalyst in a single pot reaction. The upgrading strategy was developed in three consecutive phases using two different model reactions: (1) glucose to gluconic acid, (2) hydrolysis of starch into glucose, followed by the oxidation reaction. The results showed that almost 60% gluconic acid was achieved at room temperature with atmospheric pressure. The present investigation highlighted that hydrolysis, followed by oxidation reaction is the most promising route for upgrading WRW to gluconic acid.

Synthesis and Characterization of a New Archimedean Rhombicuboctahedral Polyoxometalate Rb2.5[(Co(H2O)6)0.5(PW12O40)].16H2O: Probing Magnetic Characteristics and Electrochemical Water Splitting Catalysis

This study describes the synthesis, structure characterization, and magnetic/electrochemical properties of a new Rubidium salt of Cobalt-based Polyoxometalate (POM). A complex Rb2.5[(Co(H2O)6)0.5(PW12O40)].16H2O (Rb-1) was successfully synthesized in a single-pot reaction. The synthesis was done using pre-synthesized [Co2(μ-OH2)(O2CCMe3)4(HO2CCMe3)4] and tri-lacunary Keggin anion Na9[A-α-PW9O34].7H2O. The structure of Rb-1 was verified through Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray (EDX), and single-crystal X-ray crystallography. The crystal structure revealed a cubic crystal system (a, b, c = 22.5801(8) Å and α, β, γ = 90°) with a central Co (II) surrounded by six water molecules. The magnetic properties of Rb-1 were investigated via a superconducting quantum interference device (SQUID), which revealed antiferromagnetic behavior in Rb-1.Moreover, Rb-1 deposited on a Ni-foam electrode with a geometrical area of 1 × 1 cm2 functioned as an anode for efficient oxygen evolution reaction (OER) in water splitting. The Rb-1/Ni-Foam electrode showed excellent overpotential values of 207 mV at 10 mA.cm−2 and 390 mV at 100 mA.cm−2 current densities. The electrode had fast kinetics, as indicated by a low Tafel Slope of 51.76 mVdec−1 and a small charge transfer resistance (RCT) of 5.904 ohms. It exhibited remarkable stability over an 8-hour test period, emphasizing its practical value.

Simultaneous production of d-allulose and d-tagatose from lactose

The high-demand rare sugars d-tagatose and d-allulose may be produced from lactose in a combined process, though this dual conversion has not yet been demonstrated. Four enzymes from thermophilic organisms were cloned and expressed in Escherichia coli to synthesize d-tagatose and d-allulose from lactose: β-galactosidase (Geobacillus stearothermophilus), l-arabinose isomerase (G. stearothermophilus US100), d-glucose isomerase (Weizmannia coagulans) and d-allulose epimerase (Arthrobacter globiformis). A single-pot reaction mixture yielded 9.9 ± 1.5 mg mL−1d-allulose and 10.7 ± 1.1 mg mL−1d-tagatose after 24 h at 70 °C. Enzyme addition order did not have an impact on yields (p = 0.3527). Higher lactose concentrations resulted in higher d-tagatose concentrations (p ≤ 0.001) regardless of when the lactose was added, however, specific yields for d-allulose were higher without adding additional lactose during the reaction (p ≤ 0.001). These experiments demonstrate that a single pot synthesis of d-tagatose and d-allulose is feasible and with more optimization could be used in industrial applications.

Properties of APTES-Modified CNC Films.

Sulfated cellulose nanocrystals' (CNCs') facile aqueous dispersibility enables producing films, fibers, and other materials using only water as a solvent but prevents using sulfated CNCs in applications that require water immersion. We report that modifying CNCs with 3-aminopropyl-triethoxysilane (APTES) via a simple, single-pot reaction scheme dramatically improves the hydrolytic stability of CNC films. The effects of APTES modification on CNCs' properties were studied using attenuated total reflectance Fourier transform infrared spectroscopy, atomic force and optical microscopy, thermogravimetric analysis, dynamic light scattering, and ultimate analysis. Substituting a mere 12.6% of the CNCs' available hydroxyl groups with APTES dramatically increased the hydrolytic stability of shear cast films while only having minor impacts on their mechanical properties. In addition, quartz crystal microbalance with dissipation monitoring (QCMD) and multiparametric surface plasmon resonance (MP-SPR) studies showed that the CNC-APTES films also had a greater irreversible binding with carbofuran, a pesticide and emerging contaminant. These results highlight that APTES modification is a promising method for increasing the utility of sulfated CNCs in sensors, adsorbents, and other applications requiring water immersion.

Pristine 2-chloroquinoline-based-thiosemicarbazones as multitarget agents against alzheimer's disease: In vitro and in silico studies of monoamine oxidase (MAO) and cholinesterase (ChE) inhibitors

Neurodegenerative diseases can be treated more effectively with multitarget approaches. monoamine oxidases (MAOs) acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are promising agents for cognitive decline. Here, a series of novel 2-chloroquinoline-3-carbaldehyd thiosemicarbazone derivatives (3a-r) were synthesized via a single-pot reaction. In-vitro testing results showed four compound 3c, 3o, 3g and 3l having chloro, fluoro, methyl and ethyl functional groups showed high potency against MAO-A, MAO-B, AChE and BChE, with an IC50 value 0.549 ± 0.045, 0.340 ± 0.02, 0.280 ± 0.135 and 2.77 ± 0.62 µM, respectively. Compounds 3g exhibited maximum inhibitory potential against all four targeted enzymes. Density functional theory (DFT) was used to evaluate the reaction profiles of the potent derivatives. We found that compounds 3c, 3o, 3l, and 3g exhibited strong reactivity because their LUMO/HOMO energy gaps were narrow. In addition, the molecular docking studies revealed excellent docking scores, ligands were well accommodated in the active site of targeted enzymes and produced stable protein-ligand complexes. The stability of the protein-ligand complex was confirmed by molecular dynamic (MD) simulations which revealed stable and equilibrated protein-ligand complexes. While compounds 3p, 3q and 3r were less effective than the whole series against the targeted enzymes. This integrated approach enhances the findings' comprehensiveness and reliability. The finding of In-vitro and In-silico studies suggested compound 3g as a promising multi-targeted compound that can be act as a molecule for AD treatment.

An isothermal CRISPR-based diagnostic assay for Neisseria gonorrhoeae and Chlamydia trachomatis detection.

The occurrence of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) is increasing worldwide, particularly in low- and middle-income countries. In cases where most infections are asymptomatic and remain in a coinfection condition. It may cause missed detections or the severe subsequent symptoms. Accurate diagnosis and convenient screening are essential for disease control. However, molecular diagnostics for CT/NG predominantly rely on polymerase chain reaction (PCR)-based detection, which requires special devices and conditions. Here, we developed an isothermal CRISPR-based CT/NG dual-target detection system by pairing recombinase polymerase amplification (RPA) and CRISPR-Cas12a/13a detection. Multiplex RPA can amplify NG and CT simultaneously, and a single-pot reaction with the Cas12a/13a can be performed for further recognizing the amplified target, driving the cleavage of the corresponding fluorescence reporter separately; thus, the signal can be monitored in different channels. This CRISPR-based CT/NG detection system achieved analytical sensitivities of 10° copies/μL for both synthetic CT/NG dsDNA and exhibited no cross-reaction with other species. In tests on 88 clinical samples, our CRISPR-based assay showed excellent agreement with the commercial assay Roche Cobas 4800 (100% accuracy for NG, 94.32% accuracy for CT, and 97.73% accuracy for CT/NG coinfection) and showed higher positive percent agreement, negative percent agreement, and accuracy than those reported for TaqMan PCR in a previous study. In addition, the results of this CRISPR-based system could be acquired within 75 min. Our isothermal diagnostic method with promising performance provides more convenience than PCR-based methods for detection and screening.IMPORTANCEA method for Neisseria gonorrhoeae (NG)/Chlamydia trachomatis (CT) detection is developed using multiplex-recombinase polymerase amplification and Cas12a/Cas13a. This method can detect NG and CT simultaneously with high sensitivity and specificity. This method has great potential to be further developed into larger-scale screening and point-of-care testing (POCT).

Rapid Development of Cell State Identification Circuits with Poly-Transfection.

Mammalian genetic circuits have demonstrated the potential to sense and treat a wide range of disease states, but optimization of the levels of circuit components remains challenging and labor-intensive. To accelerate this process, our lab developed poly-transfection, a high-throughput extension of traditional mammalian transfection. In poly-transfection, each cell in the transfected population essentially performs a different experiment, testing the behavior of the circuit at different DNA copy numbers and allowing users to analyze a large number of stoichiometries in a single-pot reaction. So far, poly-transfections that optimize ratios of three-component circuits in a single well of cells have been demonstrated; in principle, the same method can be used for the development of even larger circuits. Poly-transfection results can be easily applied to find optimal ratios of DNA to co-transfect for transient circuits or to choose expression levels for circuit components for the generation of stable cell lines. Here, we demonstrate the use of poly-transfection to optimize a three-component circuit. The protocol begins with experimental design principles and explains how poly-transfection builds upontraditional co-transfection methods. Next, poly-transfection of cells is carried out and followed by flow cytometry a few days later. Finally, the data is analyzed by examining slices of the single-cell flow cytometry data that correspond to subsets of cells with certain component ratios. In the lab, poly-transfection has been used to optimize cell classifiers, feedback and feedforward controllers, bistable motifs, and many more. This simple but powerful method speeds up design cycles for complex genetic circuits in mammalian cells.

Cyanobacteria as cell factories for the photosynthetic production of sucrose.

Biofuels and other biologically manufactured sustainable goods are growing in popularity and demand. Carbohydrate feedstocks required for industrial fermentation processes have traditionally been supplied by plant biomass, but the large quantities required to produce replacement commodity products may prevent the long-term feasibility of this approach without alternative strategies to produce sugar feedstocks. Cyanobacteria are under consideration as potential candidates for sustainable production of carbohydrate feedstocks, with potentially lower land and water requirements relative to plants. Several cyanobacterial strains have been genetically engineered to export significant quantities of sugars, especially sucrose. Sucrose is not only naturally synthesized and accumulated by cyanobacteria as a compatible solute to tolerate high salt environments, but also an easily fermentable disaccharide used by many heterotrophic bacteria as a carbon source. In this review, we provide a comprehensive summary of the current knowledge of the endogenous cyanobacterial sucrose synthesis and degradation pathways. We also summarize genetic modifications that have been found to increase sucrose production and secretion. Finally, we consider the current state of synthetic microbial consortia that rely on sugar-secreting cyanobacterial strains, which are co-cultivated alongside heterotrophic microbes able to directly convert the sugars into higher-value compounds (e.g., polyhydroxybutyrates, 3-hydroxypropionic acid, or dyes) in a single-pot reaction. We summarize recent advances reported in such cyanobacteria/heterotroph co-cultivation strategies and provide a perspective on future developments that are likely required to realize their bioindustrial potential.

Development and clinical application of a endonuclease restriction real-time loop-mediated isothermal amplification (ERT-LAMP) assay for rapid detection of Haemophilus influenzae.

Haemophilus influenzae is a main human pathogen that results in a series of diseases in children and adults, such as pneumonia, bacteremia, and meningitis. Although there are many detection methods, they cannot meet the requirements of an early diagnosis. For the prevention and control of H. influenzae infection, quick, sensitive, and particular diagnostics are crucial. Loop-mediated isothermal amplification (LAMP) coupled with restricted endonuclease digestion and real-time fluorescence (H. influenzae-ERT-LAMP) detection was employed to diagnose H. influenzae. H. influenzae-ERT-LAMP combines LAMP amplification, restriction endonuclease cleavage, and real-time fluorescence identification into a single-pot reaction, allowing for the rapid identification of H. influenzae in 40 min. The outer membrane protein (OMP) P6 gene of H. influenzae was employed to build a sequence of H. influenzae-ERT-LAMP primers. The limit of detection (LoD) of H. influenzae-ERT-LAMP test was 40 fg of genomic DNA per reaction, and the non-H. influenzae templates did not provide positive outcomes. To investigate the applicability of H. influenzae-ERT-LAMP method in clinical sample detection, 30 sputum specimens were obtained from individuals suspected of being infected with H. influenzae. H. influenzae-ERT-LAMP outcomes were in total agreement with LAMP-LFB and PCR. The H. influenzae-ERT-LAMP assay provides rapid, accurate, and sensitive detection making it a promising screening strategy in clinical and basic lab settings.

Starch-Assisted Synthesis of Bi2S3 Nanoparticles for Enhanced Dielectric and Antibacterial Applications.

Starch [(C6H10O5) n ]-stabilized bismuth sulfide (Bi2S3) nanoparticles (NPs) were synthesized in a single-pot reaction using bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and sodium sulfide (Na2S) as precursors. Bi2S3 NPs were stable over time and a wide band gap of 2.86 eV was observed. The capping of starch on the Bi2S3 NPs prevents them from agglomeration and provides regular uniform shapes. The synthesized Bi2S3 NPs were quasispherical, and the measured average particle size was ∼11 nm. The NPs are crystalline with an orthorhombic structure as determined by powder X-ray diffraction and transmission electron microscopy. The existence and interaction of starch on the NP's surface were analyzed using circular dichroism. Impedance spectroscopy was used to measure the electronic behavior of Bi2S3 NPs at various temperatures and frequencies. The dielectric measurements on the NPs show high dielectric polarizations. Furthermore, it was observed that the synthesized Bi2S3 NPs inhibited bacterial strains (Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) and demonstrated substantial antibacterial activity.

Synergism antibacterial activity for novel synthesized Schiff base ligands and semi-thiosemicarbazones with ß-diketones and 4-aminoantipyrine

Schiff base ligands were synthesised in this work, the first is (Z)-2-((Z)-3-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)-1,3-diphenylpropylidene) hydrazine-1-carboxamide, the second is (Z)-2-((1E,5Z,6E)-5-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-dien-3-ylidene)hydrazine-1-carbothioamide. The Schiff base ligands both were synthesised using the same method (the single pot reaction), using EtOH as the reaction medium and GAA as the catalyst in fixed temperature at 70 0C and reflux for 6 hrs. The starting materials of HL1 were semicarbazide,4-aminoantipyrine and dibenzoyl methane, while the starting materials of HL2 were TSC, 4-AAP and Curcumin. The ligands proved to be bi-dentate ligands that coordinate from the azomethane groups. FT-IR, U.V-Visible, 1H and 13C- NMR, molar conductivity, and magnetic susceptibility were used to identify all the compounds produced. The metal ions used in preparing the complexes in this work were Co(II), Cu(II) and Cr(III). Schiff base and its complexes were evaluated for antibacterial activity against four bacterial strains of Gram-negative (Escherichia coli and Pseudomonas aeruginosa), Gram-positive (Staphylococcus aureus and Bacillus Subtilis) and two types of fungi (Candida albicans and Rhizopus Sporium), the results were positive for all compounds tested. Keywords: Schiff base, Curcumin, 4-aminoantipyrine

Synthesis, biological evaluation and computational investigations of S-benzyl dithiocarbamates as the cholinesterase and monoamine oxidase inhibitors

The current study was aimed to identify the selective and multi-targeted inhibitors of cholinesterase and monoamine oxidase enzymes. For this purpose, a novel class of multi-targeted compounds i.e., S-benzyl dithiocarbamates (1-30) was synthesized via a single pot reaction and the structures were characterized via NMR (1H and 13C), FT-IR and high-resolution mass spectrometry (HRMS). Moreover, the purity of the final products was determined using thin-layer chromatography (TLC). The compounds were evaluated for their inhibitory potential against cholinesterases (ChE) and monoamine oxidases (MAO). Among all derivatives, compound 5 (2-(trifluoromethyl) benzyl azepane-1-carbodithioate) depicted the maximum inhibition of AChE and BChE enzyme with an IC50 value of 4.37±0.94 and 14.9±1.11, respectively. The derivative 11, expressed maximum inhibition of MAO-A and MAO-B with an IC50 value of 1.14±0.03 and 1.01±0.16 µM, respectively. Whereas, compound 16 exhibited maximum inhibitory potential against all four targeted enzymes i.e., AChE, BChE, MAO-A and MAO-B with an IC50 value of 1.39±0.07 µg/ mL, 1.52±0.14 µg/ mL, 44.9±1.54 µM and 2.85±0.21 µM, respectively. The chemical reactivity profile of the potent derivatives were evaluated through density functional theory studies (DFT) where it was found that compound 5, 6 and 11 possessed reactive character due to narrow LUMO/HOMO energy gap. In addition, Molecular docking studies revealed excellent docking scores and produced sable protein-ligand complexes. The stability of protein-ligand complex was affirmed by molecular dynamic simulations which revealed stable and equilibrated trajectories of simulated complexes. The findings of in-vitro and in-silico studies suggested compound 16 as a promising multi-targeted compound that can be act as lead molecule for the treatment of AD.

One pot synthesis of propargylamines by three component amine-aldehyde-acetylene (A3) coupling catalyzed by neutral Ag(I) and Au(I) and cationic Pd(II) and Ni(II) complexes of a pincer N-heterocyclic carbene

The amine−aldehyde−acetylene (A3) coupling yielding propargylamines was successfully catalyzed by a series of neutral silver and gold complexes, [2,6-bis-(1-(1S)-menthyl-3-methylene-imidazol-2-ylidene)-pyridine]M2Cl2 [M = Ag (2), Au (3)], and cationic palladium and nickel complexes {[2,6-bis-(1-(1S)-menthyl-3-methylene-imidazol-2-ylidene)-pyridine]MCl}X [M = Pd, X = Cl (4), BF4 (5); M = Ni, X = Cl (6), BF4 (7)], stabilized over a new (1R)-(−)-menthyl substituted bis(imidazole) based [CcarbeneNCcarbene] type pincer ligand. The Au(I) (3), Pd(II) (4) and Ni(II) (6) complexes were conveniently synthesized by transmetallation reaction from the Ag(I) analog (2), which was obtained from the N-heterocyclic carbene ligand precursor (1) by treatment with Ag2O. The anion exchange reaction of Pd(II) (4) and Ni(II) (6) with AgBF4 yielded the corresponding Pd(II) (5) and Ni(II) (7) complexes respectively. Mass spectrometry studies suggested the formation of a catalytically active metal acetylide species namely, [NHC]M2(CCPh)Cl [M = Ag (2a), Au (3a)] and {[NHC]M(CCPh)}X [M = Pd, X = Cl (4a), BF4 (5a); M = Ni, X = Cl (6a), BF4 (7a)] (where NHC = 2,6-bis-(1-(1S)-menthyl-3-methylene-imidazol-2-ylidene)-pyridine). which mediates the formation of the propargylamine with a protonated Schiff imine salt produced in situ from an aldehyde and an amine in the single pot reaction.

Synthesis and Characterization of Dipyrrin Based fac-Re(CO)3 Containing Complexes

A single pot reaction of rhenium decacarbonyl, dipyrrinato ligand (5-(4-methylbenzoate)-dipyrromethene, L1H) and an ancillary ligand (either triphenyl phosphine or pyridine) in mesitylene medium has yielded visible light absorbing complexes 1 and 2 having a general formula [L1Re(CO)3L2] (L1 = dipyrrinato ligand; L2 = PPh3 = 1; L2 = pyridyl = 2). The complexes were characterized using IR UV-Vis, NMR and HRMS techniques. Binding of fac-Re(CO)3 to L1H has significantly red-shifted the charge transfer band at 436 nm to 488-491 nm in the complexes 1 and 2. Compound 1 is previously reported, although here we report a single step process that is different from the two-step process known in the literature.

Recent Progresses in the Multicomponent Synthesis of Dihydropyridines by Applying Sustainable Catalysts Under Green Conditions.

The synthesis of dihydropyridines, valuable molecules with diverse therapeutic properties, using eco-friendly heterogeneous catalysts as a green alternative received significant consideration. By selecting appropriate precursors, these compounds can be readily modified to induce the desired properties in the target product. This review focused on synthesising diverse dihydropyridine derivatives in single-pot reactions using magnetic, silica, and zirconium-based heterogeneous catalytic systems. The monograph describes preparation techniques for various catalyst materials in detail. It covers facile and benign magnetic, silica, zirconium-based, and ionic liquid catalysts, exhibiting significant efficacy and consistently facilitating excellent yields in short reaction times and in a cost-effective way. Most of the designated protocols employ Hantzsch reactions involving substituted aldehydes, active methylene compounds, and ammonium acetate. These reactions presumably follow Knoevenagel condensation followed by Michael addition and intra-molecular cyclisation. The multicomponent one-pot protocols using green catalysts and solvents have admirably increased the product selectivity and yields while minimising the reaction time. These sustainable catalyst materials retain their viability for several cycles reducing the expenditure are eco-friendly.

A four-component modified Biginelli reaction: A novel approach for C-2 functionalized dihydropyrimidines.

A novel four component modified Biginelli reaction for the synthesis of C-2 functionalized dihydropyrimidines has been established. The approach uses assembly of less explored acetyl acetone with aromatic aldehyde, thiourea, and dimethyl sulphate to construct a novel 5-acetyl 2-methylthio dihydropyrimidine system, which works as an efficient well-designed intermediate for generating C-2 modified Biginelli libraries with nitrogen nucleophiles. Phenyl hydrazine, semicarbazide, and aryl semicarbazides are successfully used as N-nucleophiles to generate C-2 functionalized dihydropyrimidine derivatives, which fulfil the demands of active pharmacophore. Time economy, step economy, and a single pot reaction with moderate to excellent yield are the major advantages of this novel method.

Bifunctional oxidase-peroxidase inorganic nanozyme catalytic cascade for wastewater remediation

Nanozymes are inorganic nanoparticles with enzyme-like features. Noble metals and metal oxide-based nanomaterials can present enzyme-mimicking behavior mediating catalytic reactions including oxidase-, peroxidase-, catalase-, and superoxide dismutase-like activities with important applications in environmental and biomedical grounds. Thus, in this study, it was designed and developed a novel nanosystem that exploits the oxidase-like (OD) behavior of gold nanoparticles (AuNPs, GOLDzyme) and the peroxidase-like (POD) characteristics of cobalt-doped magnetic iron oxide nanoparticles (MIONs, Co-MIONzyme) amalgamated in an inorganic-inorganic bi-nanozyme cascade for the degradation of dye pollutants. GOLDzyme and Co-MIONzyme nanomaterials were synthesized and stabilized by citrate and carboxymethylcellulose (CMC) ligands, respectively, using a green aqueous colloidal process at mild conditions. The physicochemical characterization results indicated that water-dispersible colloidal supramolecular nanostructures were effectively produced, with core-shell morphologies (i.e., inorganic nanoparticle core/organic-shell). The AuNPs (GOLDzyme) presented crystalline nanostructure, with a uniform spherical shape, zeta potential (ZP) = - 46 ± 3 mV, hydrodynamic diameter (DH) = 11 ± 3 nm. Analogously, the Co-MIONzyme stabilized by CMC ligand evidenced the formation of nanocrystalline substituted magnetite (CoxFe3−xO4) with uniform spherical morphology, average size = 7.0 ± 2 nm, ZP = - 47 ± 3 mV, DH = 46 ± 3 nm, and superparamagnetic behavior. When tested separately using a colorimetric assay based on a chromogenic molecule (3,3′,5,5′ tetramethylbenzidine, TMB), they demonstrated catalytic activity upon the injection of each specific substrate in the medium, i.e., glucose for GOLDzyme that behaved predominantly as oxidase-like nanomaterial, and H2O2 for Co-MIONzyme, which showed a peroxidase-like or catalase-like behavior. In addition, these nanozymes demonstrated pH-dependent and temperature-dependent catalytic activities. As a proof of concept, when combined into a single-pot reaction system, these bifunctional nanozymes confirmed integrated catalytic cascade as oxidase and peroxidase-like nanocatalysts towards the oxidation of TMB and the degradation of methylene blue (MB, ~18%) as the model dye pollutant. Based on the preliminary encouraging results of this research, it can be foreseen that the combination of nanozymes paves the way for the development of new nanoplatforms for prospective applications in water treatment and environmental remediation.

Catching the elusive chiral nitrogen compound

The world of chirality, or the handedness of a molecule, is dominated by controlling how atoms and functional groups are arranged around a central carbon. Until now, there hasn’t been a straightforward way for chemists to make compounds with chiral nitrogen centers, which are important in drugs and biologically active molecules. Matthew Kitching and colleagues at Durham University have found that adding a carbon fragment to an amine and binding the resulting ammonium to a common chiral compound gives chiral N compounds in high specificity, in a single-pot reaction ( Nature 2021, DOI: 10.1038/s41586-021-03735-5 ). “Most people don’t think about an amine being chiral because it rapidly interconverts,” Kitching says. The lone electron pair that gives amines their typical trigonal pyramidal shape can tunnel through the N center, flipping the molecule inside out like an umbrella in a windstorm. By treating an amine with an alkyl bromide compound, Kitching’s team

Stereoselective Installation of Five Contiguous Stereogenic Centers in a Double Aldol-Tishchenko Cascade and Evaluation of the Key Transition State through DFT Calculation.

The stereoselective formation of 5 contiguous chiral centers in a single pot reaction is demonstrated using an aldol, aldol–Tishchenko reaction of N-tert-butyl sulfinimines. One diastereoisomer (from 32 possibilities) predominates, and a series of cyclic and acyclic 3-amino-1,5-diol derivatives are synthesized in good yields (up to 80%) and excellent diastereoselectivities (up to >98:2 dr). Investigations support two reversible aldol steps, and multiple intermediates which are funnelled through a remarkably selective, irreversible, Tishchenko reduction, in a Curtin–Hammett phenomenon. DFT calculations using a disolvated (THF) model reveal the factors controlling stereoselectivity in the final irreversible Tishchenko step.