Tài liệu miễn phí Hoá học
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The role of some metal ions in enhancement of photocatalytic activity of Fe2O3–V2O5 binary oxide
Fe2O3 -V2O5 mixed oxides were synthesized with solid-state dispersion (SSD) and coprecipitation methods. In addition, transition metal oxides such as CuO, NiO, and Co3O4 were successfully loaded on the synthesized catalyst (Fe2O3 -V2O5) using the SSD method. The composite catalysts were inspected for their photocatalytic activities in degrading 2,4-dichlorophenol under UV light enforcement. The produced samples were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy, photoluminescence, and the Brunauer–Emmett– Teller method.ry oxide
4/3/2023 11:34:46 PM +00:00
Reusability and regeneration of solid catalysts used in ultrasound assisted biodiesel production
Reusability of two heterogeneous catalysts in ultrasound (US) assisted biodiesel production was investigated in comparison to each other. An ultrasound (US) generator (200 W, 20 kHz) equipped with a horn type probe (19 mm) was used. Regeneration experiments were planned according to second order central composite design (CCD) method. After the eighth use of the catalysts, biodiesel yield decreased from 99.1% to 90.4% for calcined calcite (CaO) and from 98.8% to 89.8% for calcined dolomite (CaO.MgO). Furthermore, regeneration of spent catalysts by calcination was investigated; optimum temperature and time were found as 750 °C and 90 min, lower than fresh catalyst preparation conditions.
4/3/2023 11:34:33 PM +00:00
Efficiency enhancement with chloride to iodide ion exchange of benzimidazolium salt as
The new benzimidazolium derivative (SM-1) salt with ion exchange from the (SM-0)was fabricated and characterized by protonnuclear magnetic resonance (1 H-NMR), carbon-nuclear magnetic resonance (13C-NMR), Fourier-transform infrared spectroscopy (FTIR), electrospray ionization (EIS-MS), thermal analysis (TG), cyclic voltammetry (CV), and ultraviolet-visible spectroscopy (UV-vis), for electrolytes (liquid or dried) in the DSSC charge transportation mechanism. Also, the influence of ion exchange from chloride to iodine in the synthesized electrolytes, compared to other electrolytes (conventional or commercial), was investigated about DSSC performance efficiency.
4/3/2023 11:34:19 PM +00:00
Electrophoretic deposition and characterization of self-doped SrTiO3 thin films
Herein, titanium (Ti3+) self-doped strontium titanate (SrTiO3), so-called blue SrTiO3, with a bandgap of 2.6 eV and favorable photocatalytic characteristics was fabricated through a facile and effective method. For electrochemical investigations, the electrophoretic deposition was applied to produce SrTiO3 thin films on (fluorine-doped tin oxide) FTO conductive substrates. The electrophoretic voltage of 20V and a process duration of 10 min were optimized to reach transparent and uniform coatings on FTO. The blue SrTiO3 reveals lower resistance (charge transfer resistance of 6.38 Ωcm−2) and higher electron mobility (current density value of 0.25 mAcm−2) compared to a pure SrTiO3 electrode. These findings may provide new insights for developing high-performance visible light photocatalysts.
4/3/2023 11:34:06 PM +00:00
Toxicity remission of PAEs on multireceptors after molecular modification through a 3D-QSAR pharmacophore model coupled with a gray interconnect degree method
In the proposed model, the gray interconnect degree method was employed to process the acute toxicity values of phthalate acid esters (PAEs) to green algae, daphnia, mysid, and fish (predicted by EPI Suite software) and to obtain the comprehensive characterization value of the multireceptor toxicity effect (MTE) of PAEs. The 3D-QSAR pharmacophore model indicated that hydrophobic groups significantly affected the MTE of PAEs. Based on this, 16 PAEs derivative molecules with significantly decreased comprehensive characterization value (more than 10%) of the toxic effects of multireceptors were designed. Among them, 13 PAEs derivative molecules reduced the toxicity values (predicted by the EPI Suite software) of four receptor organisms to varying degrees.
4/3/2023 11:33:58 PM +00:00
Enhanced ethanol sensing properties of WO3 modified TiO2 nanorods
Pristine and WO3 decorated TiO2 nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO2 NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO2 NRs and thermally oxidised to obtain WO3 nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures.
4/3/2023 11:33:47 PM +00:00
Formation and characterization of mechanochemically generated free lignin radicals from olive seeds
In this study, formation and quantification of mechanochemically generated free radicals of lignin were evaluated after the extraction of lignin from olive seeds and detailed lignin characterization was performed. Lignin was extracted from crushed olive seeds as an insoluble solid using Klason method. Isolated lignin was mechanochemically grinded under cryo conditions using Cryomill and particlesizes were determined by using Zeta Sizer, structural changes were followed by XRD and FTIR-ATR; thermal stabilities were tracked by TGA and DSC.
4/3/2023 11:33:26 PM +00:00
Treatment of industrial contaminants with zero-valent iron- and zero-valent aluminiumactivated persulfate: A case study with 3,5-dichlorophenol and 2,4-dichloroaniline
Zero-valent iron (ZVI)- and zero-valent aluminium (ZVA)-activated persulfate (PS) oxidation procedure was applied to remove the industrial pollutants 3,5-dichlorophenol (3,5-DCP; 12.27 µM) and 2,4-dichloroaniline (2,4-DCA; 12.34 µM) from aqueous solutions. The effects of PS concentration and pH were investigated to optimize heterogeneous treatment systems. Negligible removals were obtained for both pollutants by individual applications of nanoparticles (1 g/L) and PS (1.00 mM). PS activation with ZVI resulted in 59% (1.00 mM PS; 1 g/L ZVI; pH 5.0; 120 min) and 100% (0.75 mM PS; 1 g/L ZVI; pH 5.0; 80 min) 3,5-DCP and 2,4-DCA removals, respectively.
4/3/2023 11:33:15 PM +00:00
4,4’-trimethylenedipiperidine as a nitrogen heterocycle solvent and/or catalyst: Liquid phase tandem Knoevenagel–Michael condensation
Liquid phase tandem Knoevenagel–Michael condensation of various aromatic and heteroaromatic aldehydes with barbituric acid or 2-thiobarbituric acid and malononitrile was studied in a one-pot three-component reaction. For the first time, TMDP was employed as a safe and efficient solvent and/or catalyst in the liquid and aqueous ethanol medium, respectively, for the practical and eco-friendly Knoevenagel–Michael condensation. The reactions were carried out by using greener procedures, including a) the use of TMDP as an N-heterocycle organocatalyst in a green medium including water and ethanol (1:1 v/v) at reflux temperature, and b) the use of TMDP as a dual solvent-catalyst at 65 °C in the absence of any solvent.
4/3/2023 11:33:03 PM +00:00
Size-controllable carbon spheres doped Ni (II) for enhancing the catalytic oxidation of methanol
The results of cyclic voltammetry and chronoamperometry showed that the electrocatalytic activity and stability of Ni(II)/CSs were higher than that of unloaded NiAc under alkaline environment. When the nickel content was 5 wt.%, the peak oxidation current density of methanol on Ni(II)/CSs electrocatalyst reached the maximum of 34.54 mA/cm2 , which was about 1.8 times that of unloaded NiAc. These results indicate that Ni(II)/CSs has potential applications in the electrocatalytic oxidation of methanol.
4/3/2023 11:32:39 PM +00:00
CO2 hydrogenation to methanol and dimethyl ether at atmospheric pressure using Cu-Ho-Ga/γ–Al2O3 and Cu-Ho-Ga/ZSM-5: Experimental study and thermodynamic analysis
CO2 valorization through chemical reactions attracts significant attention due to the mitigation of greenhouse gas effects. This article covers the catalytic hydrogenation of CO2 to methanol and dimethyl ether using Cu-Ho-Ga containing ZSM-5 and g-Al2O3 at atmospheric pressure and at temperatures of 210°C and 260°C using a CO2:H2 feed ratio of 1:3 and 1:9. In addition, the thermodynamic limitations of methanol and DME formation from CO2 was investigated at a temperature range of 100–400°C.
4/3/2023 11:32:28 PM +00:00
Microwave assisted, sequential two-step, one-pot synthesis of novel imidazo[1,2-a] pyrimidine containing tri/tetrasubstituted imidazole derivatives
A series of novel imidazo[1,2-a]pyrimidine containing tri/tetrasubstituted imidazole derivatives (1-10) has been synthesized via sequential two-step, one-pot, multicomponent reaction using imidazo[1,2-a]pyrimidine-2-carbaldehyde, benzil, primary amines, and ammonium acetate catalyzed by p-toluenesulfonic acid under microwave-assisted conditions. The results showed that target compounds can be obtained from a wide range of primary amines bearing different functional groups with moderate to good yields (46%-80%) under optimum reaction conditions.
4/3/2023 11:32:14 PM +00:00
Vortex-assisted magnetic solid phase extraction of Pb and Cu in some herb samples on magnetic multiwalled carbon nanotubes
This study is the development of a new solid phase extraction method based on using magnetic multiwalled carbon nanotubes impregnated with 1-(2-pyridylazo)2-naphthol (PAN) for separation, preconcentration, and flame atomic absorption spectrometric determination of Pb(II) and Cu(II). Optimization of the method was done by investigating pH effect, amount of magnetic multiwalled carbon nanotubes impregnated with PAN, eluent type and volume, matrix effects, and volume of the sample. The optimum adsorbent amount was found to be 75 mg and the optimum pH value was found as 5.5. The detection limits were 16.6 μg L-1 for Pb(II) and 18.9 μg L-1 for Cu(II).
4/3/2023 11:32:06 PM +00:00
New chlorogenic acid derivatives and triterpenoids from Scorzonera aucheriana
Chromatographic separation of n-hexane and ethyl acetate fraction of a crude methanol extract obtained from aerial parts of the Scorzonera aucheriana DC collected from Sivas province of Turkey yielded nine natural compounds; two new 3-caffeoyl-quinic acid analogs (1-2), one new taraxasterol oleate (3), and six known triterpenoids taraxasterol (4), taraxasterol acetate (5), ptiloepoxide (6), lupeol (7), lupeol acetate (8), and β-sitosterol (9) were characterized. The structures of the isolated compounds were elucidated on the basis of NMR (1H, 13C, COSY, HMBC, HSQC, and TOCSY), UV, FT-IR and LC-Q-TOF-MS spectrometric data.
4/3/2023 11:31:59 PM +00:00
Cytotoxic and apoptotic potential of some coumarin and 2-amino-3-carbonitrile selenophene derivatives in prostate cancer
3-acetyl coumarin derivatives (1a-d) are formed as a result of condensation of salicylaldehyde derivatives and ethyl acetoacetate and were converted into coumarin-selenophene hybrid compounds (2a-d) in the basic medium by modified Gewald reaction in the presence of malononitrile and selenium. Products are characterized by nuclear magnetic resonance (NMR). The prepared compounds are screened for their anticancer activity against DU-145 cell line. In addition, selected target compounds are evaluated for apoptosis and oxidative stress on DU-145 (prostate carcinoma) cell lines.
4/3/2023 11:31:51 PM +00:00
Fabrication of silane-modified magnetic nano sorbent for enhanced ultrasonic wave driven removal of methylene blue from aqueous media: Isotherms, kinetics, and thermodynamic mechanistic studies
In this study, we report a simple and economic one-pot synthesis of magnetite (Fe3O4) nanostructure and its modification with tetraethyl orthosilicate by coprecipitation method. The synthesized (Fe3O4@SiO2 ) nano sorbent was applied for enhanced adsorptive removal of methylene blue by ultrasonic wave driven batch experiments. After successful synthesis, the nanostructure was characterized for their physical structure by FT-IR, VSM, TEM, and XRD. For the maximum adsorptive performance of nano sorbent, various parameters were optimized, such as dose, pH, time, concentration, and temperature.
4/3/2023 11:31:42 PM +00:00
Sensitive determination of hydrazine using poly(phenolphthalein), Au nanoparticles and multiwalled carbon nanotubes modified glassy carbon electrode
This study reports a detailed analysis of an electrode material containing poly(phenolphthalein), carbon nanotubes and gold nanoparticles which shows superior catalytic effect towards to hydrazine oxidation in Britton–Robinson buffer (pH 10.0). Glassy carbon electrode was modified by electropolymerization of phenolphthalein (PP) monomer (poly(PP)/GCE) and the multiwalled carbon nanotubes (MWCNTs) was dropped on the surface. This modified surface was electrodeposited with gold nanoparticles (AuNPs/CNT/poly(PP)/GCE). The fabricated electrode was analysed the determination of hydrazine using cyclic voltammetry, linear sweep voltammetry and amperometry.
4/3/2023 11:31:30 PM +00:00
Heavy metal removal with magnetic coffee grain
The presence of heavy metals in environmental waters having an important place in the industrial waste is a major threat to viability. Heavy metals are transported to humans through the ecological cycle, damaging many tissues and organs. In recent years, agricultural and food waste can be used to remove heavy metals. At the present study, magnetically modified coffee grains which are alternative to conventional particle systems were prepared and heavy metal removal performances were investigated. The coffee grains used were magnetically modified by contact with water-based magnetic fluid.
4/3/2023 11:31:22 PM +00:00
Novel nonperipheral octa-3-hydroxypropylthio substituted metallo-phthalocyanines: Synthesis, characterization, and investigation of their electrochemical, photochemical and computational properties
The current study describes the synthesis, electrochemical, computational, and photochemical properties of octa (3-hydroxypropylthio) substituted cobalt (II) (4), copper (II) (5), nickel (II) (6) and zinc(II) (7) phthalocyanine derivatives. These novel compounds were characterized by elemental analysis, 1H, 13C NMR, FT-IR, UV-Vis, and MS. The redox behaviors of these metallophthalocyanines were investigated by the cyclic voltammetric method. The optimized molecular structure and gauge-including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of these phthalocyanines in the ground state had been calculated by using B3LYP/6–31G(d,p) basis set.
4/3/2023 11:31:02 PM +00:00
The application of qNMR for the determination of rosuvastatin in tablet form
: In this study, quantative nuclear magnetic resonance (qNMR) method was used to determine the content of rosuvastatin in tablet. Linearity, range, limit of detection (LOD), limit of quantification (LOQ), accuracy, and precision were determined in validation study of rosuvastatin. Furthermore, validation study of rosuvastatin was performed with high performance liquid chromatography (HPLC). Uncertainties of qNMR and HPLC methods were determined using per EURACHEM/CITAC Guide CG 4 (3th edition), quantifying uncertainty in analytical measurement. qNMR and HPLC methods were linear in the ranges of 0.10 - 5.00 mg/mL and 0.001 - 0.0995 mg/mL, respectively and these lineraties indicate very good linearity performance with regression coefficients (R2 value) above > 0.99.
4/3/2023 11:30:52 PM +00:00
Theoretical investigation of the interaction between the metal phthalocyanine [MPc]a (M = Sc, Ti, and V; a = –1, 0, and +1) complexes and formaldehyde
Formaldehyde (FA, CH2 O) is one of the toxic volatile organic compounds that cause harmful effects on the human body. In this work, the interaction of FA gas with metal phthalocyanine (MPc) molecules was studied by employing density functional theory calculations. A variety of [MPc]a (M = Sc, Ti, and V; a = –1, 0, and +1) complexes were studied, and the electronic properties, interaction energies, and charge transfer properties of all of the studied molecules were systematically discussed. Among the studied complexes, the Sc and Ti phthalocyanines were more reactive toward the adsorption of FA gas.
4/3/2023 11:30:44 PM +00:00
A new electrochemical impedance biosensor based on aromatic thiol for alpha-1 antitrypsin determination
Alpha-1 antitrypsin (A1AT) is one of the acute phase proteins which are synthesized in the liver. A1AT inhibits the activity of many proteases, but its main task is to protect the lungs from the attack of neutrophil elastase. In an autosomal hereditary disease known as alpha-1 antitrypsin deficiency, the A1AT level in blood serum decreases, increasing the risk of developing emphysema, liver apoptosis, and liver cancer. Thus, the detection of A1AT concentration in blood serum is very important. In this study, an impedimetric biosensor was developed, forming an SAM (self-assembled monolayer) with 4-mercaptophenylacetic acid (4MPA) on the surface of the gold electrode.
4/3/2023 11:30:29 PM +00:00
Investigation of Olea ferruginea Roylebark extracts for potential in vitro antidiabetic and anticancer effects
This study was conducted to investigate the physicochemical, phytochemical, in vitro antidiabetic and anticancer potential of Olea ferruginea R bark. After extraction using Soxhlet, in vitro antidiabetic and cytotoxic activity on human hepatocellular carcinoma (HepG2) cells was assessed by nonenzymatic glycosylation of hemoglobin assay, alpha-amylase inhibition assay, glucose uptake by yeast cells, and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay, respectively, and gene expression via real-time polymerase chain reaction. Primary and secondary metabolites were present in the extractants; polyphenols (35.61 ± 0.03) and flavonoids (64.33 ± 0.35) in the chloroform; and polysaccharides in the ethanol (268.75 ± 0.34), and glycosaponins (78.01 ± 0.07) in the methanol.
4/3/2023 11:30:15 PM +00:00
Spectrophotometric analysis of stability of gold nanoparticles during catalytic reduction of 4-nitrophenol
Spectrophotometric monitoring of 4-nitrophenol (4-NP) reduction by sodium borohydride (NaBH4 ) using gold nanoparticles (GNPs) as a catalyst has been extensively studied, but the stability of GNPs in terms of change in the surface plasmon resonance (SPR) at different temperatures has not been explored. In the present investigation, our aim was to evaluate the SPR stability of GNPs as a catalyst during the reduction of 4-NP at different elevated temperatures (i.e. 30–60 °C) and sodium borohydride concentrations. Sensitivity of this degradation process toward concentration of GNPs at a range of temperatures is also evaluated.
4/3/2023 11:30:08 PM +00:00
Synthesis and characterization of novel 4-benzyloxyphenyl 4-[4-(n-dodecyloxy) benzoyloxy]benzoate liquid crystal
Liquid crystal (LC) compound 4-Benzyloxyphenyl 4-[4-(n-dodecyloxy)benzoyloxy]benzoate (BDBB) was prepared and characterized. Inverse gas chromatography (IGC) was to be a beneficial analysis method for the research of thermodynamic characteristics of the new LC. Acetate and alcohol isomers were used to examine LC selectivity via the IGC technique at temperatures between 333.2 K and 483.2 K. The retention diagrams of n-heptane, n-octane, n-nonane, n-decane, undecane, dodecane, tridecane, n-butyl acetate, isobutyl acetate, ethyl acetate, n-propylbenzene, isopropylbenzene, ethylbenzene, chlorobenzene, and toluene on BDBB were plotted with temperatures of 483.2–493.2 K. Flory–Huggins interaction parameter and weight fraction activity coefficient at infinite dilution were researched for BDBB.
4/3/2023 11:29:55 PM +00:00
First determination of some phenolic compounds and antimicrobial activities of Geranium ibericum subsp. jubatum: A plant endemic to Turkey
This paper includes the results of the first study about the phenolic characteristics and antimicrobial analyses of Geranium ibericum subsp. jubatum species found in Turkey. In the present work, the phenolic contents of different parts of the G. ibericum (flower, root, leaf) were determined with high-performance liquid chromatography (HPLC)–DAD (diode-array detector) and liquid chromatography (LC)–MS/MS (mass spectrometry). The following phenolic compounds were investigated: catechin, protocatechuic acid, gallic acid, ellagic acid, chlorogenic acid, 4-hydroxybenzaldehyde, p-coumaric acid, rutin, naringenin, kaempferol.
4/3/2023 11:29:46 PM +00:00
In situ preparation of hetero-polymers/clay nanocomposites by CUAAC click chemistry
A series of polymer/clay nanocomposites containing mechanistically two different polymers, poly(ethylene glycol) (PEG) and poly(epsilon caprolactone) (PCL), were prepared by simultaneous copper(I)-catalyzed alkyne-azide cycloaddition click reactions. Both clickable polymers, PEG-Alkyne and PCL-Alkyne, were simultaneously clicked on to azide-functional montmorillonite (MMT-N3) nanoclay to get corresponding PEG-PCL/MMT nanocomposites. The chemical structures of the resulting nanocomposites were verified by following azide and silicone-oxygen bands using FT-IR and characteristic bands of PEG and PCL segments using 1H-NMR spectroscopy.
4/3/2023 11:29:36 PM +00:00
Synthesis of 7,12-bis(4-(di(1H-pyrrol-2-yl)methyl)phenyl)benzo[k]fluoranthene from a new dialdehyde as a novel fluorometric bis-Dipyrromethane derivative
Dipyrromethanes are useful mediator structures which can be used as a part of other molecules such as bis-porphyrins and their derivations. Various methods have been developed for their synthesis. This study presents the synthesis of a new bisdipyrromethane, 7,12-bis(4-(di(1H-pyrrol-2-yl)methyl)phenyl)benzo[k]fluoranthene, using the Lewis acid catalyzed reaction between a new dialdehyde and pyrrole at room temperature. The UV spectroscopic and fluorometric properties of the final product and precursors were determined. The newly synthesized product with desirable UV spectroscopic and fluorometric properties has the potential to be applied as a part of bisporphyrins or it can be used for other purposes in future studies.
4/3/2023 11:29:23 PM +00:00
Validation of HPLC method for the determination of chemical and radiochemical purity of a 68Ga-labelled EuK-Sub-kf-(3-iodo-y-) DOTAGA
The prostate-specific membrane antigen (PSMA) represents an ideal biomarker for molecular imaging. Various PSMAtargeted radioligands are available for prostate cancer imaging. In this study, labeling of PSMA I&T with 68Ga, as well as validation of the radiochemical purity of the synthesis product by reverse phase radio high-performance liquid chromatography (HPLC) method are intended. Since the standard procedure for the quality control (QC) was not available, definition of chemical and radiochemical purity of 68Ga-PSMA I&T was carried out according to the Q2 (R1) ICH guideline.
4/3/2023 11:29:16 PM +00:00
Synthesis of nonperipherally tetra-[5-(diethylamino)-2-formylphenoxy] substituted metallophthalocyanines and their electrochemistry
3-[5-(diethylamino)-2-formylphenoxy]phthalonitrile (n-TY-CN), metallophthalocyanines n-TY-Co, n-TY-Cu, and n-TY-Mn bearing [5-(diethylamino)-2-formylphenoxy] groups at nonperipheral positions were prepared for the first time. These compounds were characterized with IR, NMR (only for n-TY-CN), mass and UV-vis (except n-TY-CN) spectroscopy. Voltammetric characterizations of n-TY-Co, n-TY-Cu, and n-TY-Mn revealed that while n-TY-Co, n-TY-Cu, and n-TY-Mn showed characteristic Pc ring and/or metal-based reduction reaction, n-TY-Co, n-TY-Cu, and n-TY-Mn were coated on the working electrode during the oxidation processes owing to the cationic electropolymerizations of the [5-(diethylamino)-2-formylphenoxy] substituents.
4/3/2023 11:29:06 PM +00:00