Tài liệu miễn phí Hoá học
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Synthesis and antioxidant, aggregation, and electronic properties of 6-tert-butyl-1,4-benzodioxine substituted phthalocyanines
As a starting material, 7-tert-butyldibenzo [b,e] [1,4] dioxine-2,3-dicarbonitrile was prepared by the reaction of 4-tert-butylcatechol with 4,5-dichlorophthalonitrile. Metallophthalocyanine complexes (4–7) were obtained by cyclotetramerization of 7-tert-butyldibenzo [b,e] [1,4] dioxine-2,3-dicarbonitrile. All compounds were characterized by elemental analysis and other spectroscopic methods (IR, UV/Vis, and 1 H NMR). Phthalocyanine compounds remained nonaggregated in tetrahydrofuran at the studied concentration ranges. Metallophthalocyanines (4–7) were tested for their antioxidant activities.
4/3/2023 10:06:12 PM +00:00
Adsorption of anionic and cationic dyes on biochars, produced by hydrothermal carbonization of waste biomass: Effect of surface functionalization and ionic strength
In this work, surface-functionalization agents and various salts as auxiliaries were used to improve the adsorption capacity of biochars produced via hydrothermal carbonization of glucose, cellulose, and hazelnut shell. The effect of surface functionalization with different acids and bases as well as neutral salts on the adsorption of methylene blue and methyl orange was investigated using Boehm titration, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy techniques. Surface functionalization of biochars leads to an increase in the number of oxygen-containing functional groups on the surface, thus increasing the adsorption capacity.
4/3/2023 10:05:55 PM +00:00
Synthesis of benzaldehyde by Swern oxidation of benzyl alcohol in a continuous flow microreactor system
Preparation of benzaldehyde by Swern oxidation of benzyl alcohol was carried out in a continuous flow microreactor system. Dimethyl sulfoxide (Me2SO) was used as oxidizing agent and oxalyl chloride or p-toluenesulfonyl (p-TsCl) chloride was used as the activating agent. Benzyl alcohol was oxidized to benzaldehyde by the Me2SO activating agent mixture in the continuous flow microreactor system. The optimized reaction conditions of the Swern oxidation were as follows: oxalyl chloride was used as the activating agent; the mole ratio of Me2SO, oxalyl chloride, and benzyl alcohol was 4:2:1.
4/3/2023 10:05:46 PM +00:00
One-pot synthesis of new N -(1-methylpyridin-4(1H)-ylidene)amine ligands for palladium-catalyzed Heck coupling reaction
A series of new derivatives of N-(1-methylpyridin-4(1H)-ylidene)amines, [L1]–[L5], were synthesized and characterized by FTIR, NMR, MS, and XRD analysis. These targeted compounds were synthesized by the melt reaction between N-methylated-4-chloropyridinium triflate and corresponding amines (1-naphthyl amine, o-ansidine, 2-nitroaniline, p-ansidine, and cyclohexyl amine) followed by the addition of sodium hydride in dichloromethane in the same pot. These highly electron-donating N-(1-methylpyridin-4(1H)-ylidene)amine ligands considerably improve the catalytic activity of palladium acetate towards Heck–Mizoroki carbon–carbon cross-coupling reactions.
4/3/2023 10:05:40 PM +00:00
Organic modification of montmorillonite and effect of catalytic selectivity on the dimerization of unsaturated fatty acid
This study describes the selective synthesis of C36 -dimer fatty acids, by reacting unsaturated fatty acid at 533 K for 6 h in the presence of montmorillonite and lithium chloride as the catalyst and cocatalyst, respectively. The catalytic performance of different montmorillonite and organic modified montmorillonite catalysts was investigated in the dimerization of technical grade unsaturated fatty acid, and the influence of the catalyst structure and composition on the catalytic performance was analyzed.
4/3/2023 10:05:28 PM +00:00
Simultaneous determination of azithromycin and levofloxacin in pharmaceuticals by charge transfer complexation with alizarin red S using an absorption-factor
A new approach based on a selective charge transfer reaction with alizarin red S is described for the simultaneous determination of azithromycin and levofloxacin in their binary mixtures using an absorption-factor spectrophotometric method. Native absorbance was used for the determination for levofloxacin, while a charge transfer complexation of alizarin red S served as the basis for the quantitation of azithromycin. The reaction of azithromycin with alizarin red S was possible in methanol under neutral conditions within 15 min at 25◦C. The conditions were suitably optimized for selective complexation of azithromycin with minimal interference from levofloxacin.
4/3/2023 10:05:15 PM +00:00
Facile synthesis of heteroaryl substituted γ-lactams from nitrovinyl arenes
Aliphatic nitroalkanes with different functional groups were synthesized from the Michael addition reactions of active methylene compounds 2 and nitrovinyl arenes 1 in high yields. The synthesized Michael adducts were subjected to intramolecular cyclization to give heteroaryl substituted γ -lactams in good to high yields under mild reaction conditions.
4/3/2023 10:05:07 PM +00:00
Synthesis and some optical results of long chain substituted phthalocyanines
Four metallo (zinc, copper, vanadyl, and indium) phthalocyanine derivatives bearing four aliphatic (hexylthio) groups were prepared from corresponding phthalonitrile compounds. The metallophthalocyanines were characterized with ultraviolet–visible spectroscopy (UV-Vis), proton nuclear magnetic resonance (1H NMR), Fourier transform-infrared spectroscopy (FT-IR), and mass and elemental analyses techniques. Aggregation properties of metallophthalocyanines in solution were studied in varied concentration ranges. Thin films of metallophthalocyanines were obtained by spin coating technique. Optical measurements showed that transmittance values of metallophthalocyanine thin films obviously changed with respect to the metal ion in the phthalocyanines.
4/3/2023 10:04:59 PM +00:00
Hybrid organic molecules as antiinflammatory agents; a review of structural features and biological activity
Nonsteroidal antiinflammatory drugs (NSAIDs) are widely used for the treatment of pain and inflammation. Some undesirable effects are linked with NSAIDs such as the gastrointestinal tract (GIT) toxicity and cardiovascular disturbances. At present the preparation of a hybrid molecular technique is being used to produce new analgesic and antiinflammatory molecules. Attachment of NSAIDs with nitric oxide and hydrogen sulfide releasing molecules produced some gastroprotective agents with improved analgesic and antiinflammatory activities. Combination of NSAIDs with different biologically active 5-membered, 6-membered, and condensed heterocyclic rings has also led to the formation of some potent molecules.
4/3/2023 10:04:50 PM +00:00
A simple and effective method for determination of the antithyroid drug carbimazole using ruthenium trichloride
An accurate, precise, and simple spectrophotometric method is proposed for the determination of the antithyroid drug carbimazole using ruthenium(III) chloride. This method is based on the formation at room temperature of a stable yellow-colored complex with λmax 370 nm. The method has a Beer’s law range of 7.81 to 1.95 × 10 2 µg mL−1, molar absorptivity coefficient ε = 1.519 × 103 L mol−1 cm−1, and correlation coefficient of 0.997. The metal:ligand (M:L) ratio of the complex was confirmed by the mole ratio and Job’s method of continuous variation, suggesting a 1:2 stoichiometry.
4/3/2023 10:04:31 PM +00:00
Spectrophotometric detection of rhodamine B in tap water, lipstick, rouge, and nail polish samples after supramolecular solvent microextraction
A simple and sensitive supramolecular solvent-based dispersive liquid–liquid microextraction method was described for the separation/preconcentration and spectrophotometric detection of rhodamine B. The microextraction method, which was realized at ambient temperature for the detection of rhodamine B, was carried out by using supramolecular solvents such as tetrahydrofuran and decanoic acid. The method was based on analyses of rhodamine B by using UV-Vis spectrophotometry at 558 nm. The influences of some parameters such as pH, sample volume, eluent solutions, centrifugation time, and ultrasonic bath time were optimized. The effects of various matrix ions were also investigated.
4/3/2023 10:04:24 PM +00:00
Adsorption of copper ions and alizarin red S from aqueous solutions onto a polymeric nanocomposite in single and binary systems
Adsorption of Cu(II) ions and alizarin red S (ARS) has been studied using beads of chitosan (CS) and a chitosan/ZnO nanorod composite (CS-ZnO) in single and binary systems. The beads were synthesized and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. Factors affecting adsorption of Cu(II) ions and ARS such as pH and initial concentrations as well as adsorption kinetics, isotherms, thermodynamics, reusability, and competitive adsorption in binary systems were studied.
4/3/2023 10:04:11 PM +00:00
Ultrasound-assisted surfactant/ionic liquid aqueous two-phase system extraction prior to high performance liquid chromatography for the determination of tetracyclines in milk and honey samples
In this work, an ultrasonic-assisted surfactant/ionic liquid aqueous two-phase system (ATPS) extraction method was developed to extract six tetracycline antibiotics from food samples before their chromatographic determination using high performance liquid chromatography. The ATPS was formed with 1-allyl-3-methyl-imidazolium bromide, Triton X-100, and dipotassium hydrogen phosphate. The parameters including type and amount of surfactant, ionic liquid and salt, pH of sample solution, and sonication time were optimized.
4/3/2023 10:04:03 PM +00:00
A promising materials approach to combatting renal hyperphosphatemia: Fe(II)-montmorillonites
The objective of the current effort was to determine the efficacy of Fe(II)-montmorillonite (Fe(II)-MMT) as an adjuvant for specific targeted adsorption of phosphate. Specifically, Fe(II)-MMT was studied to combat hyperphosphatemia and anemia arising from chronic renal failure. The adsorption of phosphate over time, pH, and initial concentration was studied. The systems were characterized by X-ray diffraction (XRD), Raman, and zeta potential. The experimental results demonstrated the adsorption time was set to 140 min to achieve maximum adsorption efficiency. It was thus found that the maximum adsorption was at pH 3.0.
4/3/2023 10:03:52 PM +00:00
Naked eye and smartphone applicable detection of toxic mercury ions using fluorescent carbon nanodots
Chitosan passivated carbon nanodots (C-Dots CHIT) were synthesized from expired molasses via a simple and green thermal synthesis procedure. As-synthesized C-Dots were nitrogen-doped (NC-Dots CHIT) by posttreatment with liquid ammonia and used as nanoprobes for fluorometric detection of mercury ions (Hg(II) aq.). Fluorescence response of NC-Dots CHIT in the presence of mercury was evaluated and compared with that of the polyethylene glycol passivated C-Dots P EG . This sensing strategy using NC-Dots CHIT displayed a wide linear working range from 1.25 µg/mL to 43.54 µg/mL with a detection limit of 1.41 µg/mL. The fluorescence of C-Dots P EG did not show any significant change upon mercury addition.
4/3/2023 10:03:39 PM +00:00
Investigation of the photophysical and photochemical behavior of substituted zinc phthalocyanines and their water-soluble quaternized derivatives
New nonperipherally and peripherally tetrasubstituted zinc(II) phthalocyanine complexes containing 1- benzylpiperidin-4-ol groups and their quaternized derivatives are reported in this work. These complexes were characterized successfully and their photophysical and photochemical properties were studied. These properties were determined in dimethylsulfoxide for all studied complexes and in water and water + Triton X-100 solutions for ionic Zn(II) phthalocyanines. All studied zinc(II) phthalocyanine complexes generated high singlet oxygen, especially in dimethylsulfoxide, and these properties make them potential photosensitizers for use in the photodynamic therapy of cancer.
4/3/2023 10:03:26 PM +00:00
Impurity profiling of morphine by liquid chromatography-heated electrospray ionization mass spectrometry (LC-HESI-MS)
Separation of morphine and its impurities (related substances specified in relevant European Pharmacopoeia monographs, as well as the other naturally occurring coextracted alkaloids) was obtained within a close retention window on a reverse phase HPLC column, eluted with optimized gradient, consisting of methanol and 5 mM ammonium formate, adjusted to pH 10.2. Systematic optimization of the chromatographic conditions was carried out using design of experiments. According to their mass spectra, known and specified impurities were identified and tentative structures for unknown impurities were proposed.
4/3/2023 10:03:17 PM +00:00
Separation and recovery of gallium(III) ions from aqueous phase by liquid–liquid extraction using a novel extractant, Cyphos IL 101
The present study describes the extraction behavior of gallium(III) using a novel ionic liquid trihexyl(tetradecyl) phosphonium chloride (Cyphos IL 101) diluted with kerosene from acidic chloride medium. The extraction of gallium was found to depend on the hydrochloric acid concentration and quantitative extraction of gallium took place at 2.0 mol/L HCl concentration. The nature of the extracted complex in the organic phase was determined using Job’s method and proposed to be [R3R′PGaCl4]. The loading capacity of 5.0×10−3 mol/L Cyphos IL 101 was determined to be 320.0 mg/L. Two stages of stripping were required for complete removal of gallium from the loaded organic phase using 0.1 mol/L HCl.
4/3/2023 10:03:08 PM +00:00
Synthesis of novel 5-substituted phenyl-3-(p-isopropylphenyl)-1-phenylformazan and their biological activities
Novel 1-substituted 3-(p-isopropylphenyl)-5-phenylformazans (3a–g) were synthesized and characterized by elemental analysis, 1H NMR, and FT-IR techniques and UV-visible spectroscopy. Antiproliferative activities of 3a–g against HeLa and C6 cells were determined using the BrdU cell proliferation ELISA assay. 5-Florouracil was used as the positive control. The effects of substituents (–H, –CH3, and –I) and their positions (ortho, meta, and para) on the antiproliferative activities were evaluated. The results of the assay indicate that I substituent exhibited higher activity against the cells at the meta and para positions than –CH3 and –H substituents. 3a–g exhibited both high antiproliferative activities against C6 cells and noncytotoxicity. 3a–g may be anticancer drug candidates.
4/3/2023 10:03:00 PM +00:00
Synthesis of PdS/ZnS–CdS-type photocatalysts using ZnS as sulphide source
: In this work, a new method for the growth of large CdS crystals into PdS/ZnS–CdS-type photocatalysts is presented. In order to accomplish this, in the first stage zinc sulphide was synthesised and hydrothermally crystallised. In the second stage, after PdS decoration, the recrystallised zinc sulphide was utilised as sulphur source for the synthesis of PdS/ZnS–CdS-type photocatalysts. The photocatalysts were characterised by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, and diffuse reflectance spectroscopy. In the third stage magnetic polymer supports were manufactured and loaded with photocatalyst.
4/3/2023 10:02:43 PM +00:00
Investigation of photoinduced polymerization of doxycycline-imprinted hydrogels: Effect of template on initiator reactivity, conversion, and reaction rate
Photopolymerization kinetics of doxycycline hyclate (DOX)-imprinted hydrogels were monitored by real-time Fourier transform infrared spectroscopy and differential photocalorimetry. 2-Hydroxyethyl methacrylate-based hydrogels were synthesized by using ethylene glycol dimethacrylate as a cross-linker, acrylic acid (AA) as a functional monomer, and 2,2-dimethyl-2-hydroxy acetophenone as a photoinitiator. For imprinting DOX in hydrogels, the molar ratio of template to functional monomer (DOX:AA) was chosen as 1:8 and 1:16. The polymerization was achieved at two different initiator concentrations.
4/3/2023 10:02:27 PM +00:00
Methanolysis of Jatropha curcas oil using K2CO3/CaO as a solid base catalyst
Biodiesel, fatty acid methyl ester produced by the transesterification of vegetable oil with methanol, is a promising alternative to petroleum-based diesel fuel. In the present study, the methanolysis of high free fatty acid (FFA) Jatropha curcas oil in a transesterification reaction using K2CO3/CaO solid base catalyst was studied. The various reaction parameters in the transesterification reaction were also discussed. The catalyst was characterized by means of Fourier transform infrared, X-ray diffraction, temperature programmed desorption of CO2, scanning electron microscopy, particle size analyzer, true density, and surface area analyzer.
4/3/2023 10:02:13 PM +00:00
Cyclic voltammetry behavior of tamoxifen in different electrolytes, electrochemical characterization, and its measurement by differential pulse anodic voltammetry
Cyclic voltammetry (CV) was performed on tamoxifen (tam) using different electrodes and in various acidic electrolytes containing 10% v v−1 methanol (MeOH). Tam oxidation was found to be most favorable using 0.1 mol L−1 H2SO4. To investigate the mechanism, we performed chronoamperometry, CV at different scan rates, differential pulse anodic voltammetry (DPAV), and electrochemical impedance spectroscopy on tam-covered glassy carbon electrodes (GCEs). The electrode area, diffusion coefficient, and surface concentration (Γ) of tam were calculated to be 0.062 cm2, 3.65 × 10−6 cm2 s−1 , and 3.2 × 10 −10 mol cm−2 respectively. Then the effects of different parameters on the DPAV were optimized. The best conditions were 2.5% v v−1 cMeOH, 0.1 mol L−1 H2SO4 , deposition potential 0.4 V, deposition time 30 s, and GCE rotating rate 400 rpm.
4/3/2023 10:02:03 PM +00:00
Understanding of phenolic compound retention mechanisms on PES-UF membrane
Ultrafiltration (UF) is investigated as a possible alternative to remove organic compounds from aqueous synthetic solution. This paper presents a comprehensive study towards a better understanding of phenolic compound retention mechanisms during UF processes. Thus, removal of phenol and resorcinol was studied using a polyethersulfone ultrafiltration (PES-UF) membrane. The influence of main operating conditions (feed concentration, transmembrane pressure, and pH) on the retention was evaluated. Membrane–solute interactions were found to play an important role during the process, suggesting the adsorption of the target compounds on the PES-UF membrane.
4/3/2023 10:01:55 PM +00:00
Investigation of photochemical and photophysical properties of novel silicon(IV) phthalocyanines and their µ-oxo dimers
The synthesis and characterization of novel tetraalkylthio (SC6H13 or SC12H25) substituted µ-oxo silicon(IV) phthalocyanines (3a and 3b) and their µ-oxo derivatives (4a and 4b) were described in this study. These silicon(IV) phthalocyanines were characterized using different spectroscopic techniques such as UV-Vis, 1H NMR, FTIR, and mass and elemental analysis, as well. Furthermore, the photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation) properties of the newly synthesized silicon(IV) phthalocyanines (3a, 3b, 4a, and 4b) were investigated in dimethylformamide solution.
4/3/2023 10:01:43 PM +00:00
The multiple effects of organoclay and solvent evaporation on hydrophobicity of composite surfaces
A superhydrophobic high-density polyethylene (HDPE)/organoclay composite material with a water-static contact angle of ∼162◦ and low hysteresis (7◦) was prepared by a simple solution-intercalation technique. This onestep method consists of the insertion of organoclay, produced through cation exchange with cetyltrimethylammonium bromide (CTAB), in the polymer matrix at 120◦C in xylene. In this process, evaporation of the solvent and organoclay amount are key factors for the achievement of superhydrophobicity. We characterized composite material with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and contact angle measurements.
4/3/2023 10:01:30 PM +00:00
Catalytic application of 1,3,5-triazine-pentaethylenehexamine polymer-supported palladium nanoparticles in the convenient reduction of nitroarenes with sodium borohydride or hydrazine
The catalytic activity of 1,3,5-triazine-pentaethylenehexamine (TAPEHA) polymer-supported Pd nanoparticles was investigated in the reduction of nitro arenes to the corresponding amines by NaBH4 or N2H4.HO. Optimized reaction conditions for both systems were successfully tested on 20 nitroarenes with different characteristics. Considerably high yields (80%–98% in NaBH4 and 85%–98% in N2H4) were obtained in a short time and at ambient temperature. In addition to these methods being selective against other reducible functionalities such as –CN, –Br, –Cl, and –I, the catalyst can be recovered easily and reused more than ten times.
4/3/2023 10:01:22 PM +00:00
Palladium nanoparticles entrapped in melamine-formaldehyde resin microparticles for Mizoroki–Heck reactions
Melamine-formaldehyde resin (MFR) microparticles with average diameters of 1.06 µm were synthesized with PEG-20000 as the particle-forming agent. Palladium nanoparticles were entrapped in and adsorbed on the MFR microparticles, consecutively. Scanning electron microscopy (SEM) was used to characterize the morphologies of MFR microparticles. X-ray diffraction (XRD) and transition electron microscopy (TEM) showed that the palladium nanoparticles entrapped in the MFR microparticles dispersed much more homogeneously than those adsorbed on the MFR microparticles.
4/3/2023 10:01:14 PM +00:00
Adsorption of Cu(II) on three adsorbents, Fe3O4/Ni/NixB nanocomposite, carob (Ceratonia siliqua), and grape seeds: A comparative study
A novel adsorbent Fe3O4/Ni/NixB nanocomposite was synthesized and used for the adsorption of copper. Moreover, natural adsorbents carob and grape seeds were used for this purpose. The surfaces and the elemental compositions of the adsorbents were characterized by SEM-EDX. The zero point charges of pH of Fe3O4/Ni/NixB nanocomposite, carob, and grape seeds were found as 8.4, 6.0, and 5.6, respectively. The Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models were used for the identification of the mechanism of the adsorption. The adsorptions of Cu(II) on the three adsorbents were well fitted to the Langmuir isotherm.
4/3/2023 10:00:56 PM +00:00
Removal of Pb(II) and Cd(II) from aqueous solution using alkaline-modified pumice stone powder (PSP): Equilibrium, kinetic, and thermodynamic studies
Adsorption processes of Cd(II) and Pb(II) from aqueous solutions onto pumice stone powder (PSP) were investigated in batch mode. The influences of solution pH, contact time, adsorbent dosage, initial metal (M) concentration, and temperature on adsorption process were investigated. The kinetic and isotherm data were analysed using different model equations. The adsorption process was consistent with the Langmuir model for both metal ions with high R2 and low χ2 values for both Pb(II) and Cd(II). The maximum monolayer adsorption capacities were 28.09 and 27.17 mg g−1 for Pb(II) and for Cd(II), respectively.
4/3/2023 10:00:49 PM +00:00