Tài liệu miễn phí Hoá học
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A flame retardant-hardener for epoxy resins: Synthesis, structural, and DFT studies of the [Cu(H2NC2H4NH2)2(H2O)Cl]Cl complex
The aqua-bis(ethylenediamine)-chloro-copper(II) chloride complex, [Cu(en)2(H2O)(Cl)]Cl (1), was synthesized by direct interaction of CuCl2 ×2H2O with pepa (pepa is a polyethylenepolyamine containing ethylenediamine (en)). The crystalline complex 1 was characterized by IR spectra and structurally studied. Crystals of this complex consist of the [Cu(en)2(H2O)(Cl)]+ discrete cations, whose Cu2+ ion is chelated by two en molecules. The Cu(II) coordination polyhedron has the shape of an elongated square bipyramid, in which four nitrogen atoms of the –NH2 groups of en molecules form the base of this bipyramid, and the oxygen atom of the water molecule and Cl– are in its apical positions.
4/5/2023 5:51:10 AM +00:00
The removal of chromium (VI) from tannery waste using Spirulina sp. immobilized silica gel
The use of microalgae biomass is an alternative solution to the problem of environmental pollution due to heavy metals, one of which is Cr metal in leather tanning liquid waste. However, the ability of biomass to adsorb heavy metals has limitations. Therefore, the algal biomass is immobilized with silica gel in order to obtain a stable structure. This research aims to study the absorption efficiency of Cr (VI) metal by the biomass of Spirulina sp. which is immobilized with silica gel from the tannery liquid waste. The preparation stages in this study were adsorbent preparation, immobilization of biomass with silica gel, and preparation of tannery liquid waste.
4/5/2023 5:51:03 AM +00:00
Synthesis, characterization, COX1/2 inhibition and molecular modeling studies on novel 2-thio-diarylimidazoles
Heterocyclic compounds with diaryl substituents have been a milestone approach for selective cyclooxygenase 2 (COX 2) inhibition by bioisosteric replacements and modifications. It is also known that thiazole derivatives have different pharmacological activities. In this study, nine novel 2-[(1,5-diphenyl-1H-imidazole-2-yl)thio]-N-(thiazole-2-yl)acetamide derivatives (Compound 1-9) were synthesized via the reaction of 1,5-disubstitued phenyl-imidazole-2-thiole and N-thiazole acetamide. The inhibitory effects of COX-1 and COX-2 enzymes were tested for the synthesized compounds
4/5/2023 5:50:51 AM +00:00
The hydrothermal synthesis of blue-emitting boron-doped CQDs and its application for improving the photovoltaic parameters of organic solar cell
In this work, boron-doped CQDs (B-CQDs) were synthesized by using boric acid, urea, and citric acid via hydrothermal method to use as a novel additive material for poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) based organic solar cells. The OSCs with an inverted device structure were fabricated on titanium dioxide (TiO2 ) thin film. It was showed the crystallinity, morphological and optical properties of P3HT:PCBM films improved after B-CQDs additive. The best performance was obtained to be a 39.65% of FF, a 546 mV of Voc, an 8.606 mA cm–2 of Jsc after 3 vol.% B-CQDs addition in P3HT:PCBM blend.
4/5/2023 5:50:35 AM +00:00
Puerarin-coated gold nanoparticles (PUE-AuNPs) synthesized via green synthetic route: a new colorimetric probe for the detection of ciprofloxacin
Puerarin-coated gold nanoparticles (PUE-AuNPs) synthesized via green synthetic route, a new colorimetric sensor, efficiently detected the ciprofloxacin (CP) in tap water and cow milk samples. The PUE-AuNPs were characterized by UV-visible, FTIR, AFM, and DLS techniques and were found to be spherical with an average size of approximately 19–20 nm. FTIR spectrum confirms that functional groups such as –OH, -C=O, -CO and –C=C were responsible for the reduction of gold (III) chloride trihydrate. These functional groups acted as capping agents to form AuNPs. The PUE-AuNPs sensor was proved to be selective and sensitive for the detection of CP through colorimetric method within the concentration of 1 to 1000 µM and the limit of detection was 51 µM. This colorimetric sensor is simple, cost-effective, and selective towards CP detection in environmental (tap water and milk) samples.
4/5/2023 5:50:26 AM +00:00
Microwave irradiated synthesis of Schiff bases of 4-(arylideneamino)-5-alkyl-2,4- dihydro-1,2,4-triazole-3-thione containing 1,2,4-triazole segment
Novel compounds based on the 1,2,4-triazole skeleton were synthesized. A class of 4-amino-5-alkyl-4H-1,2,4-triazole-3- thione created by reaction of thiocarbohydrazide with long-chain aliphatic carboxylic acids, and then the Schiff bases were obtained in the media of heat and microwave waves, in the presence and the absence of a catalyst. Their chemical structures were assayed by elemental analysis, also device spectroscopic methods.
4/5/2023 5:50:12 AM +00:00
Study of the effectiveness of a presoaking process for reducing the additives migration from babies toys
This research aims to study a process of steeping in the n-heptane, used for reducing the migration of additives contained initially in toys for babies plasticized with di-octylphtalate (DOP) based on poly (vinyl chloride) (PVC) and stabilized with epoxidized sunflower oil (ESO). Two formulations were carried out at different levels of DOP plasticizers (15% and 45%). The migration tests were conducted in the synthetic saliva in the absence and in the presence of α-amylase with or without agitation at 37° C for 1, 3, and 6 h. The migration phenomenon was studied on the basis of preliminary studies based on the mass variation of the two formulations and where the physicochemical technical analysis: Fourier-transform infrared spectroscopy (FTIR) and gas chromatography coupled with gas chromatographymass spectrometry (GC-MS) were performed.
4/5/2023 5:50:05 AM +00:00
Novel surfactant stabilized PLGA cisplatin nanoparticles for drug delivery applications
In the current study, cisplatin loaded (Poly(lactic-co-glycolicacid)) (PLGA) stabilized with 4-phenylphenacylbromide based surfactants nanoparticles were developed for drug delivery applications. For the course of this study four new 4-phenylphenacylbromide based compounds abbreviated as PA(C2 )3 , PA(C8 )3 , PAC16 and PAC18 have been synthesized by the reaction of 4-phenylphenacylbromide with various long chain amines. The new surfactants were characterized with 1 H and 13C NMR and FTIR spectroscopy. The critical micelle concentration (CMC) of newly synthesized surfactants are in the range of 0.024–0.091 mM.
4/5/2023 5:49:58 AM +00:00
Determination of characterization, antibacterial and drug release properties of POSSbased film synthesized with sol-gel technique
In the study, antibacterial film synthesis was aimed using sol-gel technique from POSS structure with various functional groups. For this purpose, antibacterial properties have been acquired by metronidazole to the films to be synthesized. The films obtained were coated on glass surface samples by dip coating method. Antibacterial activities of surface coated glass samples were observed in E.coli and S. aureus bacteria. Metronidazole release studies in the film samples were followed by UV spectrophotometer. It was observed that drug release reached 68.90% at the end of the 24th h. As a result, it is thought that the synthesized film will be a good candidate especially for biomedical surface coating areas.
4/5/2023 5:49:34 AM +00:00
Structural, surface morphological, optical and electrical properties of InxSey thin films, an absorber layer for photovoltaic cells fabricated by M-CBD method using different variables
Mixed-phased Inx Sey thin film containing InSe, In2 Se3 and In6 Se7 phases was prepared by M-CBD method and characterized by X-ray diffraction, AFM, optical spectroscopy and J-V measurements. Structural, optical and electrical conductance properties were modified by annealing the films at different temperatures. Optical and morphological properties were also investigated dependently on temperature and concentration of cationic precursor solution. It has been observed with annealing that, the compositions of the phases changed, particle sizes increased, energy band gaps decreased and electrical conductivity increased.
4/5/2023 5:49:27 AM +00:00
Antiinflammatory photodynamic therapy potential of polyoxyethylene-substituted perylene diimide, nitrocatechol, and azo dye
Photodynamic therapy (PDT) applications enable light-controlled activation of drug candidates instead of their constitutive activities to prevent undesired side effects associated with their constant activities. A specific wavelength of light is utilized to enable electron mobility in the chemical structure, which results in differential activities that may alter cell viability and cellular functions. Canonical photodynamic therapy applications mostly focus on cytotoxicity-based antimicrobial and anticancer properties of the PDT agents. In this study, we focused on subtoxic concentrations of three different molecules containing polyoxyethylene group and examined their antiinflammatory activities on stimulated mammalian macrophages. Stimulated macrophages produce proinflammatory cytokines TNF and IL6.
4/5/2023 5:49:19 AM +00:00
Green dehydrogenation of dimethylamine borane catalyzed by cheaply copper(0) nanocatalysts without any stabilizer at nearly room temperature
In this work, the findings of the work on the green dehydrogenation behavior of molten dimethylamine borane (DMAB) catalyzed by the precatalyst copper(II) acetylacetonate (Cu(acac)2) in solvent-free medium (green) at near room temperature (nRT, 30.0+0.1°C) were reported. Herein, a complete study has been presented, which includes the following steps: (i) synthesis and catalytic activity of Cu(0) NCats in solvent-free medium, (ii) determination of activation energy for Cu(0) NCats catalyzed green dehydrogenation of DMAB, (iii) demonstration of catalytic lifetime of Cu(0) NCats, (iv) test of isolability and reusability of Cu(0) NCats, (v) poisoning experiments using carbon disulfide on a per-active-copper-atom basis, (vii) characterization of Cu(0) NCats by UV–vis, XRD, XPS and TEM/HRTEM/TEM-EDX spectroscopies.
4/5/2023 5:49:11 AM +00:00
One-pot synthesis of graphene hydrogel-anchored cobalt-copper nanoparticles and their catalysis in hydrogen generation from ammonia borane
We reported a facile one-pot synthesis of bimetallic CoCu nanoparticles (NPs) anchored on graphene hydrogel (GH-CoCu) as catalysts in hydrogen generation from the hydrolysis of ammonia borane (HAB). The presented novel one-pot method composed of the reduction of the mixture of graphene oxide, cobalt(II), and copper(II) acetate tetrahydrates by aqueous ethylene glycol solution in a teflon-coated stainless-steel reactor at 180 °C. The structure of the yielded GH-CoCu nanocatalysts was characterized by TEM, SEM, XRD, XPS, and ICP-MS. This is the first example of both the synthesis of bimetallic CoCu NPs anchored on GH and the testing of a hydrothermally prepared noble metal-free GH-bimetallic nanocomposites as catalysts for the HAB.
4/5/2023 5:49:04 AM +00:00
Cyclodextrin-active natural compounds in food applications: a review of antibacterial activity
Many natural compounds have excellent activity against different bacteria. However, their food use to inhibit the bacteria is often limited by poor water solubility, or instability to light, heat, oxygen, and other environmental factors. Cyclodextrin combines with these natural compounds could not only overcome these shortcomings, but also increase the antibacterial ability of active compounds. This review focuses on the following aspects of active natural compounds in cyclodextrin-based food: the preparation, food applications, and their possible antibacterial mechanisms of different systems.
4/5/2023 5:48:55 AM +00:00
Study on potential applications and toxicity analysis of green synthesized nanoparticles
Nanomaterials have garnered the significant interest of scientists owing to their technological as well as medical applications. In particular, metal and metal oxide nanoparticles have gained prominence because of their enhanced performance as compared to their bulk counterparts. Metal-supported nanomaterials are anticipated to make major contributions to solving today’s most challenging issues, like energy harvesting and environmental remediation. The incorporation of nanoparticles into sensors has significantly enhanced their precision and selectivity. With the advent of green chemistry, green synthetic techniques have been prioritized for the synthesis of single and multicomponent nanomaterials.
4/5/2023 5:48:48 AM +00:00
Glucosamine derived hydrothermal carbon electrodes for aqueous electrolyte energy storage systems
Nitrogen-doped porous hard carbons are synthesized by hydrothermal carbonization method (HTC) using glucosamine as biosource and treated at different carbonization temperatures in nitrogen environment (500, 750, 1000°C). The electrochemical performances of hard carbons electrode materials for aqueous electrolyte sodium ion batteries are examined to observe the effect of two different voltage ranges (–0.8-0.0) V and (0.0-0.8) V in 1.0 M Na2SO4 aqueous electrolyte. The best electrochemical performances are acquired for the 1000 °C treated glucosamine (GA-1000) porous carbon sample that provides ~96 F/g capacitance value in the negative voltage range (between –0.8 and 0.0) V. The sodium diffusion coefficient of the GA-1000 carbon calculated by electrochemical impedance measurements is found to be 1.5 × 10–14 cm2/s.storage systems
4/5/2023 5:48:40 AM +00:00
Supramolecular solvents: a review of a modern innovation in liquid-phase microextraction technique
Supramolecular solvents (SUPRASs) have rapidly gained more attention as a potential substitute to organic solvents in the sample preparation and preconcentration process. The essential properties of SUPRAS solvents (e.g., multiple binding sites, different polarity microenvironments, the opportunity to tailor their properties, etc.) these qualities offer numerous opportunities to advance innovative sample preparation and pretreatment platforms compared to the traditional solvents. Among these qualities, certain importance is placed on theoretical and practical knowledge. That has assisted in making significant developments in SUPRAS that advance our understanding of the processes behind SUPRA’S formation.
4/5/2023 5:48:32 AM +00:00
A biochar-modified carbon paste electrode
The present work examıned the use of biochar derived from tea waste as a novel electrode material. For the fabrication of the biochar electrode, suitable amounts of biochar and graphite were mixed with mineral oil for the first time. The electrochemical performance of the biochar-modified carbon paste electrode (BCPE) was measured by various cyclic voltammetric reactions for several redox systems. The factors affecting the electrode kinetics of BCPE surfaces were examined and optimized. The BCPE was applied as transducer in a glucose biosensor. The results reflect the effective properties of composite electrodes and the electrochemical properties of biochar showing that the BCPE could be used for various electrochemical applications.
4/5/2023 5:48:18 AM +00:00
Synthesis of Na-, Fe-, and Co-promoted TiO2/multiwalled carbon nanotube composites and their use as a photocatalyst
The use of multiwalled carbon nanotubes (CNTs) in sol-gel synthesized titanium dioxide (TiO2) photocatalysts as templates was systematically studied. CNTs have high oxidative thermal stability and the controlled removal of CNTs can be achieved at lower temperatures under air flow by the use of Na, Fe, and Co as a catalyst. These catalysts helped to reduce the oxidation temperature of CNTs; thus anatase phase was achieved without significant sintering. The use of a promoter, heat treatment, and various heat treatment atmospheres was effective in specific surface area, crystallinity, and photocatalytic activity against methylene blue (MB) degradation.
4/5/2023 5:48:04 AM +00:00
Microwave-enhanced Fenton-like degradation by surface-modified metal–organic frameworks as a promising method for removal of dye from aqueous samples
In the current research, the sulfonated metal–organic framework loaded on iron oxide nanoparticles, Fe3O4@MIL100(Fe)-OSO3H, has been synthesized and utilized as a Fenton-like catalyst for the decolorization of aqueous solutions containing methyl orange (MO) dye as a model organic pollutant. The morphology and structure of the catalyst were characterized by X-ray powder diffraction, transmission electron microscopy, Brunauer–Emmett–Teller analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The effects of various parameters on MO degradation were investigated and the optimum conditions for MO degradation were found to be an initial concentration of MO of 100 mg/L, initial concentration of H2O2 of 40 mg/L, pH 3.0, and microwave power of 500 W.
4/5/2023 5:47:56 AM +00:00
A rapid, eco-friendly, and reliable microplate method for determination of Cr(VI)
In the present work, the reaction of Cr(VI) with 1,5-diphenylcarbazide in microplates (enzyme-linked immunosorbent assay microtiter plate) and a subsequent determination in a plate reader at 540 nm were performed. The final volume utilized for each determination was 200 µL, and the cost and waste were reduced for hexavalent chromium [Cr(VI)] quantification. The use of microplates allowed for the analysis of a large number of samples, reducing analysis time. No statistically significant differences were observed between the results obtained in the analysis of Cr(VI) in real samples by the conventional procedure and by the proposed methodology in this work (analysis of variance, P < 0.05).
4/5/2023 5:47:47 AM +00:00
Bis(indoline-2,3-diones): versatile precursors for novel bis(spirooxindoles) incorporating 4H-chromene-3-carbonitrile and pyrano[2,3-d]pyrimidine-6-carbonitrile derivatives
Multicomponent reaction of dimedone or 1,3-dimethylbarbituric acid and malononitrile with a series of bis(indoline-2,3-diones) afforded the corresponding bis(2-amino-7,7-dimethyl-2’,5-dioxo-5,6,7,8-tetrahydrospiro[chromene4,3’-indoline]-3-carbonitrile) and bis(7’-amino-1’,3’-dimethyl-2,2’,4’-trioxo-1’,2’,3’,4’-tetrahydrospiro[indoline-3,5’-pyrano [2,3-d]pyrimidine]-6’-carbonitrile) derivatives in good to excellent yield.
4/5/2023 5:47:39 AM +00:00
Dehydration behavior and kinetics of kurnakovite under microwave irradiation
In this research, the dehydration behavior of kurnakovite was studied under microwave irradiation. The kinetic parameters of the dehydration reaction were determined using different kinetic models. Kurnakovite was characterized by the techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) before and after the dehydration process. According to the results, kurnakovite was identified as a compound with the powder diffraction file (pdf) number 00-024-0700 before the dehydration process and after the dehydration process amorphous formations were observed.
4/5/2023 5:47:32 AM +00:00
Efficient photodegradation of neutral red chloride dye in aqueous medium using graphene/cobalt–manganese oxides nanocomposite
Graphene/cobalt–manganese oxides nanocomposites were prepared from their precursor through chemical reduction where NaOH was used as a reducing agent. The obtained GNs/Co-Mn nanocomposites were used as photocatalyst for the photodegradation of Neutral Red Chloride (NRC) dye in aqueous solution under sunlight as a function of time and catalyst dosage. The morphology and photodegradation study was carried out using scanning electron microscopy (SEM) and UV-VIS spectrophotometry, respectively. The SEM image showed the presence of Co-Mn nanoparticles on the surface of GNs, which were also confirmed by energy dispersive X-ray analysis.
4/5/2023 5:47:24 AM +00:00
Fabrication of multilayer graphene oxide-reinforced high density polyethylene nanocomposites with enhanced thermal and mechanical properties via thermokinetic mixing
High density polyethylene (HDPE) was compounded with thermally exfoliated graphene oxide (TEGO) by thermokinetic mixing in a short time. High shear rates during the compounding process provided high exfoliation and proper dispersion of graphene layers in the polymer matrix. Different TEGO/polymer ratios were used to get efficient melt mixing. Structural analysis by spectroscopic techniques confirmed the exfoliation of TEGO sheets and the coverage of their surfaces by HDPE chains. Furthermore, homogeneous dispersion of graphene sheets in the matrix led to the enhancement in the mechanical and thermal properties of HPDE-based nanocomposites.
4/5/2023 5:47:16 AM +00:00
Synthesis, characterization, and antimicrobial activities of novel monosaccharide-containing Schiff base ligands
Four new chiral Schiff base ligands (3a–4a, 3b–4b) have been prepared using aminoisopropylidene derivatives of glucose and aminochloralose derivatives of mannose. The synthesized compounds 1 and 2 were characterized by nuclear magnetic resonance ( 1 H and 13 C NMR), Fourier transform infrared spectroscopy (FTIR), UV/visible spectroscopy, and elemental analysis. A total of eight Schiff base compounds (3a–6a, 3b–6b) were tested for antimicrobial activity against Escherichia coli ATCC 12228, Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae CCM 2318, Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium CCM 5445, Enterococcus faecalis ATCC 29212, Bacillus subtilis ATCC 6633, and Candida albicans ATCC 10239 and exhibited a range of activities.
4/5/2023 5:47:10 AM +00:00
Development of a sample preparation strategy for the determination of tungsten in soil samples by inductively coupled plasma mass spectrometry using a response surface methodology
An alternative rapid digestion method has been developed for the determination of tungsten (W) in soil samples using fractionation studies and response surface methodology. The digestion method using the Kjeldahl instrument was applied to samples, and soluble tungsten was determined via inductively coupled plasma mass spectrometry. Digestion parameters were selected depending on the results of fractionation studies and optimized using a four-factor and five-level central composite design.
4/5/2023 5:47:02 AM +00:00
The structure and cytotoxic activity of a new saponin: cephoside A from Cephalaria elazigensis var. purpurea
Investigation of the aerial parts of Cephalaria elazigensis var. purpurea afforded one new oleanane-type saponin, namely cephoside A (1), and five known natural compounds (2–6). Compound 2, named anemoclemoside A, which is an unusual triterpene glycoside, was identified in the family Dipsacaceae for the first time. Chemical structures of all compounds were determined on the basis of the HRESIMS and 1D and 2D NMR data. Cephoside A (1) and anemoclemoside A (2) were assessed for their cytotoxic activities against HeLa cells, having IC50 values of 495 and 135 µg/mL, respectively.
4/5/2023 5:46:50 AM +00:00
Synthesis of novel derivatives of chromenone bearing an N -carbamothioyl moiety as soybean 15-LOX inhibitors
Novel derivatives of chromenone bearing an N -carbamothioyl moiety were synthesized and evaluated for their soybean 15-LOX inhibitory activity. Synthesis of the target compounds was started from 7-hydroxy-2H-chromen-2-one. It was reacted with 1-fluoro-2(4)-nitrobenzene to obtain the corresponding nitrophenoxy-chromenone derivative. Reduction of the nitro group was achieved in the presence of Zn/NH4Cl and reaction of the latter compound with in situ prepared benzoyl isothiocyanate led to the formation of the title compounds.
4/5/2023 5:46:39 AM +00:00
Stereoselective and regioselective synthesis of N -substituted methyl 2-((azolyl)methyl)-3-arylacrylates from Baylis–Hillman acetates
N -Substituted methyl 2-((azolyl)methyl)-3-arylacrylates were synthesized stereo- and regioselectively with one-pot reaction between Baylis–Hillman acetates and a suitable acylazole in the presence of K2 CO3 as a base catalyst. The targeted N -substituted azole acrylates were efficiently obtained in good yields (39%–89%).
4/5/2023 5:46:31 AM +00:00