Tài liệu miễn phí Hoá học
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Phosphorus-nitrogen compounds (Part 51): The relationship between spectroscopic and crystallographic data of mono- and di-spirocyclophosphazene derivatives with 4-fluoro/nitrophenylmethyl pendant arm/arms
A great wealth of structural information about phosphazenes can be gleaned from the combined spectroscopic and crystallographic data. When data from 31P NMR spectroscopy and X-ray crystallography are put together like pieces in a puzzle, a number of correlations can be obtained for phosphazene derivatives. A systematic study concerning the correlations among the structural parameters (e.g., 31P NMR data, endocyclic/exocyclic NPN bond angles and bond lengths) revealed some characteristics of mono- and di-spirocyclophosphazene derivatives bearing 4- fluoro/nitrophenylmethyl pendant arm/arms.
4/3/2023 11:09:16 PM +00:00
Phosphorus-nitrogen compounds- (Part 50): Correlations between structural parameters for cylophosphazene derivatives containing ferrocenyl pendant arm(s)
The results of a systematic study of spiro-cyclotri/tetraphosphazenes with ferrocenyl pendant arm on the basis of correlation between structural parameters were presented. The main parameters were obtained from Xray crystallography and 31P NMR results in order to investigate the relationship between the δPspiro shift values and endocyclic and exocyclic NPN bond angles, and electron density transfer parameters. Structural parameters derived from 11 types of the ferrocenyl cyclophosphazene derivatives with 5- to 7-membered spiro-rings introduced to the literature from our research group were studied and compared with each other.
4/3/2023 11:08:56 PM +00:00
Arene diazonium saccharin intermediates: a greener and cost-effective alternative method for the preparation of aryl iodide
In the current protocol, the arene diazonium saccharin derivatives were initially produced from various substituted aromatic amines; subsequently, these intermediates were treated with a greener organic iodide for the preparation of the aryl iodide. We tried to choose low-cost, commercially available, biodegradable, recoverable, ecofriendly, and safe reagents and solvents. The arene diazonium saccharin intermediates could be stored in the liquid phase into a refrigerator for a long time with no significant loss activity.
4/3/2023 11:08:48 PM +00:00
Design of an amphiphilic hyperbranched core/shell-type polymeric nanocarrier platform for drug delivery
Monodisperse HPAE-PCL- b - MPEG nanoparticles with dimensions of
4/3/2023 11:08:26 PM +00:00
Combined computational and experimental studies on cysteine-sulfadiazine adduct formation
In addition to experimental studies, a computational approach was carried out to study the geometrical parameters, electron densities, and UV-Vis absorption spectra of sulfadiazine and SDCYS adduct in water. Calculated (B3LYP/6-311++G(d,p) level) and experimental UV-Vis absorption spectra of the compounds were found to be in good agreement in water. The computational study suggests that cysteine bound to the C(5) on the pyrimidine ring via SH-group nucleophilic attack. Computational results reveal that sulfadiazine and its derivatives effectively bind cysteine and may lead to new molecules/drugs to target cysteine.
4/3/2023 11:08:17 PM +00:00
Investigation of the effect of PAn and PAn/ZnO photocatalysts on 100% degradation of Congo red under UV visible light irradiation and lightless environment
PAn (polyaniline) and PAn/ZnO photocatalysts were synthesized using chemical polymerization of aniline. The structure characterization of the synthesized samples was analysed by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis spectroscopy measurements, and thermal gravimetric analysis (TGA). The photocatalytic activities of PAn and PAn/ZnO (0.1g/100ml) on the degradation of the Congo red (CR) dye were studied under the UV visible light irradiation and the lightless environment and the efficiency of catalysts have been explained in details.
4/3/2023 11:08:01 PM +00:00
Fabrication and biocompatibility assessment of polypyrrole/cobalt(II) metal-organic frameworks nanocomposites
The biocompatibility of nanocomposites was assessed by haemolytic, cytotoxic, and quantitative reverse transcription PCR (qRT-PCR) assays. FT-IR and PXRD results revealed that nanocomposites consisted of pure MOFs and PPy. Moreover, SEM results indicated their spherical morphology along with an average diameter of 190 nm. (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed a concentration, and percentagedependent cytotoxic effect of the nanocomposites on some cell lines including 3T3 fibroblasts, MCF-7, and J774.A1 macrophages. Haematological toxicity of PPy/x%Co-MOF composites was less than 7% in most concentrations. Furthermore, PPy/x%Co-MOF composites did not show any significant effect on the expression of cyclooxygenase−2(COX-2) and inducible nitric oxide synthase(iNOS) genes.
4/3/2023 11:07:12 PM +00:00
Development of a biosensor platform based on ITO sheets modified with 3-glycidoxypropyltrimethoxysilane for early detection of TRAP1
The aim of this research was to design an electrochemical immunosensor for determination of tumour necrosis factor receptor-associated protein-1(TRAP1) antigen, a heat shock protein linked to tumour necrosis factor. The indium-tin oxide covered polyethylene terephthalate (ITO-PET) electrode surface was cleaned and was prepared for the introduction of hydroxyl groups on its surface by using NH4 OH/H2 O2 /H2 O. As a silanization agent for covalent attachment of anti-TRAP1 on the surface of the ITO working electrode, 3-glycidoxypropyltrimethoxysilane (3-GOPS) was used. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the immobilization steps.
4/3/2023 11:06:55 PM +00:00
Preparation and catalytic evaluation of Au/γ-Al2O3 nanoparticles for the conversion of 4-nitrophenol to 4-aminophenol by spectrophotometric method
A set of catalysts having gold nanoparticles deposited on γ-Al2O3 (Au/γ-Al2O3) with lowest effective amount of gold content were prepared by successive impregnation and hydrogen reduction method. The structural features of prepared catalysts were analysed by X-ray diffraction (XRD), N2 physisorption, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR). The catalytic activity was evaluated for the reduction of an organic pollutant 4-nitrophenol (4NP) to 4-aminophenol (4AP) by spectrophotometric analysis. Supported catalyst presented excellent catalytic ability to convert 4NP to 4AP in the presence of sodium borohydride (SBH) due to synergistic effect of Au NPs and mesoporous γ-Al2O3 support.
4/3/2023 11:06:39 PM +00:00
Sensitive determination of hydrogen peroxide in real water samples by high spin peroxo complex
In this paper, a fast, cheap, simple, sensitive and selective spectrophotometric method based on high spin peroxo-Fe(III)-EDTA complex in the alkaline medium was developed for the determination of hydrogen peroxide (H2O2) in real water samples. The purple-coloured complex with a maximum absorbance at a wavelength of 525 nm was formed. Various parameters such as type of stabilizer reagent and its concentration, reaction time, Fe(III), EDTA and NH3 concentration were optimized. The method was confirmed with the Beer’s law with a molar absorption coefficient of 267.36 L mol−1cm −1 in the 8.3×10−6 –4.08×10−3 mol/L concentration range.
4/3/2023 11:06:31 PM +00:00
Preparation and characterization of form-stable phase change material/end-of-life tires composites for thermal energy storage
The management of end-of-life tires (ELT) waste gains importance in aspect of possible environmental and economic issues so the waste recycling becomes unavoidable. This study describes the fabrication and characterization of a new phase changing material (PCM)/ELT microcomposites that could be used in thermal energy storage. Paraffin together with the 4 fatty acids and ELT rubber powder are used as PCMs and as the supporting material, respectively. Paraffin/ELT composites are fabricated, as well, by the vacuum impregnation method in order to investigate the effect of the preparation method.
4/3/2023 11:06:17 PM +00:00
The single nucleotide β -arrestin2 variant, A248T, resembles dynamical properties of activated arrestin
β -arrestins are responsible for termination of G protein-coupled receptor (GPCR)-mediated signaling. Association of single nucleotide variants with onset of crucial diseases has made this protein family hot targets in the field of GPCR-mediated pharmacology. However, impact of these mutations on function of these variants has remained elusive. In this study, structural and dynamical properties of one of β -arrestin2 (arrestin 3) variants, A248T, which has been identified in some cancer tissue samples, were investigated via molecular dynamics simulations. The results showed that the variant underwent structural rearrangements which are seen in crystal structures of active arrestin.
4/3/2023 11:05:54 PM +00:00
Effect of various g-C3N4 precursors on the catalytic performance of alkylorganotin-based catalysts in acetylene hydrochlorination
A series of alkylorganotin-based catalysts (Sn-g-C3N4/AC) was prepared by wet impregnation in ethanol using different g-C3N4 precursors and alkylorganotin compounds. The structure, texture, surface composition, and adsorption properties of the as-prepared catalysts were extensively characterized. Then, the obtained samples were evaluated for their catalytic performance in hydrochlorination of acetylene. The results provided by the X-ray photoelectron spectroscopy, acetylene temperature-programmed desorption, and HCl adsorption confirmed the nature of the active sites (i.e.Sn-Nx) involved in the reactant adsorption, and hence in the improved catalytic performance.
4/3/2023 11:05:37 PM +00:00
A comparative study of silver electrodeposition from pyrophosphate-cyanide and high concentration cyanide electrolytes in the presence of brighteners
A study of the electrodeposition of silver from 2 different types of electrolytes; (1) neutral pyrophosphatecyanide electrolyte and (2) alkaline high concentrated cyanide electrolyte in the presence of a variety of additives such as 2-mercaptobenzothiazole, potassium selenocyanate, and potassium antimony tartrate was performed. Influence of additives and cyanide concentration on microstructure and kinetics of the cathodic processes were studied. A brightener couple, 2-mercaptobenzothiazole and potassium antimony tartrate, were combined within this investigation and detected to be highly effective for silver electrodeposition. The rapid increase in current density at the same potential interval related to grain refinement effect of potassium antimony tartrate was shown.
4/3/2023 11:05:16 PM +00:00
Hydrotalcite framework stabilized ruthenium nanoparticles (Ru/HTaL): Efficient heterogeneous catalyst for the methanolysis of ammonia-borane
Ruthenium nanoparticles stabilized by a hydrotalcite framework (Ru/HTaL) were prepared by following a 2-step procedure comprising a wet-impregnation of ruthenium(III) chloride precatalyst on the surface of HTaL followed by an ammonia-borane (NH3 BH3) reduction of precatalyst on the HTaL surface all at room temperature. The characterization of Ru/HTaL was done by using various spectroscopic and visualization methods including ICP-OES, P-XRD, FTIR, 11 B NMR, XPS, BFTEM, and HRTEM. The sum of the results gained from these analyses has revealed the formation of well-dispersed and highly crystalline ruthenium nanoparticles with a mean diameter of 1.27 ±0.8 nm on HTaL surface.
4/3/2023 11:05:03 PM +00:00
GC-MS analysis of the methanolic extracts of Smilax china and Salix alba and their antioxidant activity
Smilax china L. (family Smilacaceae) and Salix alba L. (family Salicaceae) are plants that have been traditionally used to treat various ailments in Indian and Chinese medicine. A quantitative estimation of the methanolic extracts of these plants was performed by GC-MS analysis to obtain insight into its phytoconstituents responsible for therapeutic action. The antioxidant potential of the methanol extracts of Smilax china (MESC) and Salix alba (MESA) were assessed with DPPH by using a UV spectrophotometer at a wavelength of 517 nm.
4/3/2023 11:04:53 PM +00:00
Proline-based organocatalyst-mediated asymmetric aldol reaction of acetone with substituted aromatic aldehydes: An experimental and theoretical study
This work involves a facile synthesis of three (S)-proline-based organocatalysts with C2 symmetry and their effects in enantioselective aldol reaction of acetone with substituted aromatic aldehydes. Moderate enantioselectivities (up to 61% ee) were obtained depending on the nature of the substituents on the aryl ring. Computational calculations at HF/6-31 + G(d) level were employed to underline the enantioselectivity imposed by all the organocatalysts. Higher calculations at B3LYP/6-311 ++ G(d,p) scrf=(solvent=dichloromethane)//B3LYP/6-31 + G(d) levels of theory were also performed for the aldol reaction of acetone with benzaldehyde and 4-nitrobenzaldehyde catalyzed by 1.
4/3/2023 11:04:29 PM +00:00
Bioreduction: The biological activity, characterization, and synthesis of silver nanoparticles
Today, nanoparticles are effectively used in different areas. Initially, physical and chemical methods were used in the synthesis of nanoparticles. Biosynthesis (green synthesis) has emerged as an alternative to overcome the toxic effects of chemically synthesized nanoparticles. In this study, green synthesis of silver nanoparticles (AgNPs) with the leaf extract of Anthurium andraeanum was performed. UV-Vis spectrophotometry, scanning transmission electron microscopy, and XRD were applied to characterize the biosynthesized nanoparticles. As a result of the characterization, the spectra showed that a spectrum at a wavelength of about 419 nm and a spherical size of 38 nm nanoparticles was formed.
4/3/2023 11:04:12 PM +00:00
Multiwall carbon nanotube-supported molybdenum catalysts for ammonia decomposition reaction under microwave effect
In this study, microwave-assisted ammonia decomposition reaction was investigated over molybdenum incorporated catalysts. Due to the selective, volumetric, and noncontact heating properties of the microwave system, higher conversion values could be achieved at relatively lower reaction temperatures, which is important for on-site COx-free hydrogen production. Multiwall carbon nanotube-supported molybdenum catalysts were prepared following the impregnation procedure with different metal loading (3.5%–12.5% wt%), and inductively coupled plasma, nitrogen physisorption, X-ray diffraction, and transmission electron microscopic techniques were employed to characterize the fresh and used samples.
4/3/2023 11:03:57 PM +00:00
Synthesis of metallo-supramolecular materials based on terpyridine functionalized double-decker silsesquioxane with improved complexation efficiency
Silsesquioxane-based transition-metal complexes have come to the forefront due to the ability of silsesquioxane to control nanostructures and properties. However, some difficulties in complete complexation and purification limit the widespread use of transition-metal-based supramolecular coordination complexes comprising silsesquioxane. Herein, 2 different approaches have been proposed for the synthesis of metallo-supramolecular materials on the basis of ruthenium(II)-terpyridine functional double-layer silsesquioxane (DDSQ) (Tpy/Ru-DDSQ) (Routes 1 and 2). In Route 1, complexation was followed by functionalization of DDSQ with the ligand, whereas in Route 2, complexation was performed before the ligand was inserted into the DDSQ.
4/3/2023 11:03:42 PM +00:00
BET, FTIR, and RAMAN characterizations of activated carbon from waste oil fly ash
Activated carbon (AC), a porous material with high pore volume, attracts increasing attention owing to its potential applications in several fields. The development of a porous structure in AC marginally relies on both the treatment methods and the type of precursor. Thus far, both renewable and nonrenewable precursor sources have been used to synthesize AC with high surface area and pore volume. This study presents the synthesis of AC via physicochemical treatment of waste oil fly ash (OFA), a waste material produced from power plants. The aim was to produce AC by adding surface pores and surface functional groups to the basal plane of OFA. Toward this objective, OFA was first chemically leached/activated with various combinations of H2SO4 and H3PO4, and then physically activated with CO2 at 900°C.
4/3/2023 11:03:33 PM +00:00
Selective modifications at the different positions of cyclodextrins: A review of strategies
Cyclodextrins (CDs) are natural, nontoxic, and biodegradable macrocyclic oligosaccharides. As supramolecular hosts, CDs have numerous applications in many aspects. However, nonsubstituted CDs have the disadvantages of solubility, unspecific recognition sites, and weak interactions with guest molecules. Therefore, new CD-based derivatives are successfully designed, synthesized, and widely used in various fields. This contribution outlines the research progress in CD derivatives. In particular, this review emphasizes the synthesis and application of CDs modified through functionalization in definite positions, random substitution, and reconstruction of the skeleton. At the end of this review, a summary and future directions are presented.
4/3/2023 11:03:23 PM +00:00
Choline derivatives immobilized on silica to catalyze transesterification reaction for production of glycerophosphocholine
Choline derivatives were covalently immobilized on the surface of γ-aminated silica. The obtained immobilized choline derivative was then successfully used for a transesterification reaction to produce glycerophosphocholine (GPC). Fourier transform infrared analysis and thermogravimetric analysis/differential thermal gravimetry indicated that the surface of the γ-aminated silica was covered by choline derivatives and the highest immobilization amount reached 1.1 mmol/g under optimal conditions. More importantly, the highest yield of GPC reached 97.9% during transesterification.
4/3/2023 11:03:14 PM +00:00
Synthesis, spectroscopic studies, and antioxidant activities of novel thio/carbohydrazones and bis-isatin derivatives from terephthalaldehyde
New bis(isatins-thio/carbohydrazones) based on Schiff bases were prepared from terephthalaldehyde biscarbohydrazone and 5-substituted isatins in the presence of a drop of sulfuric acid under reflux in ethanol. Terephthalaldehyde bis(thio/carbohydrazone) was synthesized by the reaction of (thio)/carbohydrazide and terephthalaldehyde in the presence of a few drops of acetic acid under reflux in ethanol. The structures of these synthesized compounds were determined using IR, 1H NMR, and 13C NMR spectroscopy and elemental analysis.
4/3/2023 11:03:00 PM +00:00
Development of thermoplastic polyurethane/polyaniline-doped membranes for the separation of glycine through electrodialysis
Recently, membrane-based separation processes, particularly electrodialysis, have attracted attention for the separation and purification of organic and amino acids from animal feedstock waste. In this study, cation exchange membranes were synthesized by making a composite of thermoplastic polyurethane and polyaniline (PANI) via the doping of various aromatic sulfonic acids, such as β-naphthol sulfonic acid and phenol sulfonic acid. The PANI was prepared using a standard method, which was further used in the composite blending at varying concentrations of 10%–20%. The impact of the concentration of PANI and the nature of the dopant on the membrane characteristics were comparatively studied.
4/3/2023 11:02:34 PM +00:00
Effect of surfactant types on particle size and morphology of flame-retardant zinc borate powder
In this study, nano zinc borate powder was synthesized by a wet chemical method and the effects of nonionic, anionic, and cationic surfactants on the particle size and morphology of the zinc borate particles were investigated. Chemical purity and physical structures of the synthesized zinc borate powder were analyzed by XRD, FTIR, TG-DTA, TEM, and Zetasizer. The analysis results showed that the zinc borate powder had a chemical formula of 2ZnO·3B2O3·7H2O. TEM and Zetasizer results indicated that the nano zinc borate powder, which had nanoscale particle size distribution with needle- and flake-like structures, was synthesized using nonionic, anionic, and cationic surfactants.
4/3/2023 11:02:25 PM +00:00
Synthesis, cytotoxic assessment, and molecular docking studies of 2,6-diaryl-substituted pyridine and 3,4- dihydropyrimidine-2(1H)-one scaffolds
Cancer is one of the main global health problems. In order to develop novel antitumor agents, we synthesized 3,4-dihydropyrimidine-2(1H)-one (DHPM) and 2,6-diaryl-substituted pyridine derivatives as potential antitumor structures and evaluated their cytotoxic effects against several cancer cell lines. An easy and convenient method is reported for the synthesis of these derivatives, employing cobalt ferrite (CoFe 2 O4 @SiO2 -SO3 H) magnetic nanoparticles under microwave irradiation and solvent-free conditions. The structural characteristics of the prepared nanocatalyst were investigated by FTIR, XRD, SEM, and TGA techniques. In vitro cytotoxic effects of the synthesized products were assessed against the human breast adenocarcinoma cell line (MCF-7), gastric adenocarcinoma (AGS), and human embryonic kidney (HEK293) cells via MTT assay.
4/3/2023 11:02:14 PM +00:00
Blue dye degradation in an aqueous medium by a combined photocatalytic and bacterial biodegradation process
This paper aimed at implementing a treatment system for polluted water with textile dyes, starting with a photocatalytic decomposition process using sunlight as a source of energy and continuing with a bacterial biodegradation process, in order to reach degradation percentages higher than those obtained using only one of the processes mentioned above. When water treatment with the dye in the combined system was over, an acute ecotoxicity test was performed to make sure that toxic metabolites were not produced due to biodegradation. Solophenyl Blue azoic dye, and Erionyl Blue and Terasil Blue anthraquinone dye-colored solutions were treated with the Pd/Al80Ce10Zr10 catalyst in a solar collector for the photocatalytic process.
4/3/2023 11:02:05 PM +00:00
Ranolazine-functionalized CuO NPs: Efficient homogeneous and heterogeneous catalysts for reduction of 4-nitrophenol
In the present study copper oxide nanoparticles (CuO NPs) were synthesized using a hydrothermal method with ranolazine as a shape-directing agent. Ranolazine-functionalized CuO NPs were characterized by various analytical techniques such as scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The SEM pattern confirmed the morphology of ranolazine-functionalized CuO NPs with well-defined rice-like structures. FTIR spectroscopy confirmed the interaction between CuO NPs and ranolazine. The XRD analysis indicated that the structure of ranolazine-functionalized CuO NPs was monoclinic crystalline and the size ranged between 9 and 18 nm with an average particle size of 12 nm. The smaller size range of CuO NPs gave a large surface area that enhanced the efficiency of these catalysts employed for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the H2O system.
4/3/2023 11:01:51 PM +00:00
SO2 sorption properties of fly ash zeolites
In the presented study, the sulfur dioxide sorption properties of fly ash zeolite X were investigated. Sorption tests were performed on fly ash zeolite samples that were not prepared specially for sorption, in addition to dried samples and samples in the presence of water vapor. The samples saturated with water vapor showed the highest sorption capacity. The sorption capacity of the samples additionally dried prior to the sorption experiment was higher than that of the samples that were not specially prepared for the sorption test. Regeneration tests indicated relatively good regeneration properties. The obtained results were described with the use of Langmuir, Sips, and Dubinin–Astakhov models, with the Dubinin–Astakhov model providing the best fit.
4/3/2023 11:01:37 PM +00:00