Tài liệu miễn phí Hoá học
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Synthesis and photovoltaic characterization of triarylamine-substituted quinoxaline push–pull dyes to improve the performance of dye-sensitized solar cells
Novel unsymmetrical organic sensitizers having donor, π-spacer, and anchoring groups were designed and synthesized for dye-sensitized solar cell (DSSC) application. The dyes 3-{4-[7-(4-{bis[4-(hexyl)phenyl]amino} phenyl)-11,12-dibutoxy-1,4,5,8-tetrahydrodibenzo [a,c] phenazine-2-yl]phenyl}-2-cyano acrylic acid (KD-148) and 3-{5-[7-(4-{bis[4-(hexyloxy)phenyl]amino} phenyl)-11,12-dibutoxy-1,4,5,8-tetrahydrodibenzo [a,c] phenazine-2-yl]-2-thienyl}-2- cyano acrylic acid (KD-150) were anchored onto TiO2 and tested with ionic liquid electrolyte.
4/5/2023 5:46:23 AM +00:00
Efficient multicomponent synthesis of 1,2,3-triazoles catalyzed by Cu(II) supported on PEI@Fe3O4 MNPs in a water/PEG300 system
A highly dispersible and magnetically recoverable Cu-PEI@Fe 3 O4 MNPs catalyst was prepared and successfully applied in one-pot three-component coupling of terminal alkynes, sodium azide, and alkyl bromides/chlorides in water to give 1,4-disubstituted 1,2,3-triazoles with good to excellent yields. The catalyst was fully characterized with FT-IR, TGA, TEM, SEM, VSM, EDX, cyclic voltammetry, and ICP-AES spectroscopic techniques. Furthermore, the catalyst was easily recycled by an external magnet and successfully reused six times in the reaction without significant loss of its catalytic activity and copper leaching.
4/5/2023 5:46:10 AM +00:00
Investigation of solvent effect on photophysical properties of some sulfonamides derivatives
The photophysical properties of new sulfonamides synthesized recently were investigated in different solvents. Shifts in the absorption and fluorescence spectra of both compounds (S10 and S11) occurred depending on the solvents used. Ground and excited state dipole moments of the molecules were calculated using the spectral shifts of the compounds in different solvents and polarity function of solvents, respectively. They were 1.32 and 1.46 D for S10 and 1.71 and 4.89 D for S11. These results suggested that the excited state dipole moments are greater than those in ground state for both molecules.
4/5/2023 5:46:02 AM +00:00
Activity of γ-Al2O3 -based Mn, Cu, and Co oxide nanocatalysts for selective catalytic reduction of nitric oxide with ammonia
Our studies on the selective catalytic reduction of NO (SCR-deNO) properties of M/γ-Al2O3 (M = Mn, Co, Cu) nanocatalysts are presented. All catalysts were prepared by homogeneous deposition precipitation using urea as the precursor for the precipitating agent. The SCR activity followed the order Mn/γ-Al2O3 > Cu/γ-Al2O3 > Co/γ-Al2O3. The nanocatalysts were characterized with respect to their texture (N2-BET), particle size (TEM), reducibility (H2-TPR), and acidity (NH3-TPD). The TEM analysis revealed that the metal species have superior dispersion with less agglomeration and sintering on γ-Al2O3 support.
4/5/2023 5:45:55 AM +00:00
Synthesis and in vitro anticancer evaluation of 1,4-phenylene-bis-pyrimidine-2-amine derivatives
A series of 1,4-phenylene-bis-chalcones 3a–3h were synthesized by the reaction of terephthalaldehyde with substituted arylketones in this study. The novel 1,4-phenylene-bis-pyrimidine-2-amine derivatives 5a–5h were obtained by the addition of guanidine hydrochloride to 1,4-phenylene-bis-chalcone 3a–3h in ethanolic KOH under reflux conditions. The structure of the compounds was explained by means of IR, 1H NMR, 13C NMR, and elemental analyses. The anticancer activities of 3a–3h and 5a–5h were investigated against rat brain tumor cells and human uterus carcinoma in vitro. Activity tests were performed as dose-dependent assays at eight concentrations.
4/5/2023 5:45:48 AM +00:00
Spectrophotometric determination of carmoisine after cloud point extraction using Triton X-114
Carmoisine (E122) is a synthetic azo dye that is generally used to give a red color to food products. In this work, a sensitive and simple method was developed for the determination of carmoisine based on cloud point extraction. To obtain the optimum conditions for the extraction efficiency of carmoisine, the effects of different analytical parameters such as H2 SO4 concentration, concentration of Triton X-114, and equilibrium temperature were studied. The calibration graph was linear between 0.05 and 5.0 µg/mL and the detection limit based on three times the standard deviation of the blank was 7.2 µg/L.
4/5/2023 5:45:42 AM +00:00
Syntheses and photoluminescence properties of new Zn(II) and Cd(II) coordination polymers prepared from 5-sulfoisophthalate ligand
New coordination polymers, formulated as {[Zn(µ-sipH)(µ-apim)]·3H2O}n (1) and {[Cd(µ-sip)(H2O)2(apimH)]·3H2 O}n (2) were synthesized based on the 1-(3-aminopropyl)imidazole (apim) along with 5-sulfoisophthalate (sip) ligands. The complexes were synthesized under mild hydrothermal conditions. All the complexes were characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction studies. The X-ray crystallographic studies of 1 and 2 reveal Zn(II) and Cd(II) ions are µ-bridged by dianionic sipH and trianionic sip ligands in bis(monodentate) and bis(bidentate) coordination mode, respectively, to generate 1D polymer chains.
4/5/2023 5:45:33 AM +00:00
Improvement of electrochemical and structural properties of polycarbazole by simultaneous electrodeposition of chitosan
Polycarbazole/chitosan composite materials were synthesized electrochemically at various loadings of chitosan (Chi). Their electrochemical, structural, thermal, and morphological characterizations were investigated by cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy, thermal gravimetry, and scanning electron microscopy. Further electrical conductivity was measured using a four-point probe technique. The electrochemical results showed that the electrical conductivity of the polymeric composite film was increased by increasing the amount of Chi in the electrolyte medium.
4/5/2023 5:45:22 AM +00:00
Hydrolysis of ammonia borane and hydrazine borane by poly(N -vinyl-2-pyrrolidone)-stabilized CoPd nanoparticles for chemical hydrogen storage
For the first time the synthesis of poly(N -vinyl-2-pyrrolidone)-stabilized cobalt-palladium nanoparticles by an easy method, their characterization, and their use as active catalysts for hydrogen release from hydrolysis of ammonia borane and hydrazine borane is reported here. The catalyst is prepared by simultaneous reduction of suitable cobalt and palladium ions by sodium borohydride in the presence of poly(N -vinyl-2-pyrrolidone) as a stabilizer. They are characterized by UV-Vis spectroscopy, TEM analysis, X-ray diffraction, and X-ray photoelectron spectroscopy.
4/5/2023 5:45:14 AM +00:00
Homopolymerization and synthesis of a new methacrylate monomer bearing a boron side group: characterization and determination of monomer reactivity ratios with styrene
Boron methacrylate (BAc) monomer was synthesized via an esterification reaction. Boric acid, neopentyl glycol, and 2-hydroxyethyl methacrylate (HEMA) were reacted to obtain boron-containing acrylic monomer. Characterization was achieved by FT-IR, 13 C NMR, 1 H NMR, and 11 B NMR and the results for the synthesized monomer were compared to those for HEMA. Homopolymer and copolymers with styrene (St) were synthesized via free radical polymerization. The properties of the synthesized styrene copolymers were investigated using several techniques.
4/5/2023 5:45:07 AM +00:00
Impact of surface modification of green algal biomass by phosphorylation on the removal of copper(II) ions from water
A series of batch lab-scale experiments were performed to investigate the performance of dead phosphorylated algal biomass of Spirogyra species for the bioadsorption of Cu +2 ions from aqueous solutions. FT-IR and SEM analyses were performed to characterize the phosphorylated and raw algae. The SEM analysis indicated that the phosphorus content increases by about 5 times. The isotherm equilibrium data indicated that phosphorylation enhances the removal of Cu +2 from water by about 20%. The experimental isotherms fit well to Langmuir models with R 2 values close to 0.99.
4/5/2023 5:44:57 AM +00:00
Synthesis and anticancer and cytotoxic effects of novel 1,4-phenylene-bis-N-thiocarbamoylpyrazole and 1,4-phenylene-bis-pyrazolylthiazole derivatives
Thiazolylpyrazoline derivatives were recently reported as potent anticancer agents. In this study, novel 1,4-phenylene-bis-N-thiocarbamoylpyrazoles (3a–h) and 1,4-phenylene-bis-pyrazolylthiazoles (5a–h) were prepared and screened for their anticancer activities against C6 (rat brain tumor cells) and HeLa (human uterus carcinoma). Anticancer activity studies were performed as a dose-dependent assay starting with eight concentrations. 5-Fluorouracil (5-FU) was used as a positive control.
4/5/2023 5:44:50 AM +00:00
Isocoumarins and 3,4-dihydroisocoumarins, amazing natural products: a review
The isocoumarins are naturally occurring lactones that constitute an important class of natural products exhibiting an array of biological activities. A wide variety of these lactones have been isolated from natural sources and, due to their remarkable bioactivities and structural diversity, great attention has been focused on their synthesis. This review article focuses on their structural diversity, biological applications, and commonly used synthetic modes.
4/5/2023 5:44:42 AM +00:00
Synthesis and characterization of magnetic amidoximated chitosan-g poly(polyacrylonitrile)/laponite RD nanocomposites with enhanced adsorption capacity for Cu2+
Magnetic amidoximated nanocomposites based on a combination of chitosan and magnetic laponite RD were prepared and examined for the removal of Cu2+ from aqueous solutions. Magnetic laponite RD was prepared by an in situ method. In order to prepare magnetic amidoximated nanocomposites, acrylonitrile was grafted to chitosan in the presence of magnetic laponite RD. Then the nitrile pendants on magnetic chitosan-g-polyacrylonitrile/laponite RD (mChtioPANLap) were converted to amidoxime groups. We developed a polyamidoximated magnetic nanocomposite based on a mixture of chitosan/laponite RD, possessing a high adsorption capacity for Cu2+. By introducing magnetic laponite RD the adsorption capacity of nanocomposites for Cu2+ was significantly improved.
4/5/2023 5:44:27 AM +00:00
Synthesis and cytotoxicity of novel thioxo-quinazolino[3,4-a]quinazolinones
Various thioxo-quinazolino[3,4-a]quinazolinones were prepared and evaluated for their cytotoxicity in MOLT-4 (lymphoblastic leukemia) and MCF-7 (breast adenocarcinoma) cell lines. Synthesis of the target compounds was started from isatoic anhydride. Successive reaction of isatoic anhydride with benzylamine and 2-nitrobenzaldehyde, reduction of the nitro group, and reaction with CS2 gave 12-benzyl-6-thioxo-6,7,11b,12-tetrahydro-13H-quinazolino[3,4-a]quinazolin13-one. The latter compound reacted with various 2-chloro-N-substituted acetamides to afford the corresponding fused quinazolinone derivatives.
4/5/2023 5:44:20 AM +00:00
Voltammetric analysis of disulfiram in pharmaceuticals with a cyclic renewable silver amalgam film electrode
Electrochemical properties of disulfiram, representative of highly significant bioactive compounds, were studied with a cyclic renewable silver amalgam film electrode (Hg(Ag)FE) using square wave cathodic stripping voltammetry (SWCSV). The influence of various factors such as pH, buffer concentration, buffer composition, and SWCSV parameters on current response was investigated. The applicability of the developed method was tested in the determination of disulfiram in the commercial formulation Anticol. Thin-layer chromatography with image processing software was used to validate the accuracy of the method.
4/5/2023 5:44:13 AM +00:00
Sonochemical degradation of Basic Red 29 in aqueous media
In this work, the degradation of Basic Red 29 (BR29), an azo dye, was investigated using a high-frequency ultrasonic reactor (300 kHz). The influence of several parameters such as initial substrate concentration (5–200 mg L−1 ), pH (3–10.1), ultrasonic power (20–80 W), and nature of the dissolved gas (Ar, air, and N2) on the degradation of BR29 was assessed. Additionally, the impact of natural matrices (seawater and natural and river waters) on the degradation rate of BR29 was clarified.
4/5/2023 5:44:05 AM +00:00
Highly selective Schiff base derivatives for colorimetric detection of Al3+
Schiff base derivatives NBAR and NSAR were developed for selective detection of Al3+ in aqueous solution. UV-vis spectroscopic studies revealed that NBAR and NSAR showed marked sensitivity and selectivity to Al3+ in acetonitrile (ACN)/water (v/v, 1:1, pH 6.80). The NBAR and NSAR receptors bound Al3+ in a 2:1 stoichiometry with apparent binding constants 4.09 × 10 11 M−2 and 1.65 × 10 12 M−2, respectively. They also displayed distinct changes in color upon the alteration of free Al3+ levels in solution with reversible responses and showed little interference with other metal ions.
4/5/2023 5:43:58 AM +00:00
Synthesis and antifungal activity of new dihydrofurocoumarins and dihydrofuroquinolines
We investigated the radical addition of 4-hydroxycoumarin (1a) and 4-hydroxyquinoline (1b) with conjugated dienes (2a–f) mediated by cerium(IV) ammonium nitrate (CAN) resulting in ethenyl substituted 2,3-dihydrofurocoumarin (3a–f) and 3,5-dihydrofuroquinoline (3g, 3h) compounds in moderate to good yields. All compounds were characterized by spectroscopic methods (IR, MS, and 1 H and 13 C NMR) and microanalysis. Antifungal activities of these compounds were investigated against the fungi Candida albicans, C. parapsilosis, C. krusei, C. glabrata, C. tropicalis, and Aspergillus fumigatus.
4/5/2023 5:43:52 AM +00:00
Graphite oxide catalyzed synthesis of β-amino alcohols by ring-opening of epoxides
Graphite oxide as a heterogeneous and recyclable solid acid catalyzed a simple and efficient method for the synthesis of β-amino alcohols by ring opening of epoxides with amines. This method is effective with various aromatic and aliphatic amines under solvent-free conditions. The corresponding β-amino alcohols are obtained in high yields (56%–95%) and short reaction times (15–30 min) with high regio- and chemoselectivity under metal-free conditions.
4/5/2023 5:43:45 AM +00:00
Supramolecular solvent microextraction of uranium at trace levels from water and soil samples
A supramolecular solvent microextraction procedure was established for the separation/preconcentration of uranium(VI) (U(VI)) prior to its determination by UV-Vis spectrophotometry. 1-(2-Pyridylazo)-2-naphthol (PAN) was used to form a red chelate (U-PAN) with U(VI) at pH 10. U-PAN was extracted by undecanol in tetrahydrofuran. All the parameters that affect extraction efficiency like solution pH, amount of ligand, type and volume of supramolecular solvent, sample volume, and diverse ion effect were optimized.
4/5/2023 5:43:37 AM +00:00
Investigation of the effects of purification and characterization of turkey (Meleagris gallopavo) liver mitochondrial thioredoxin reductase enzyme and some metal ions on enzyme activity
The thioredoxin system, found in all living creatures, consists of thioredoxin protein (Trx), thioredoxin reductase enzyme (TrxR), and NADPH. In this study, turkey liver mitochondrial TrxR enzyme with 3.07 EU × mg −1 specific activity was purified 990-fold in a yield of 2.05% using 2’,5’-ADP Sepharose 4B affinity chromatography. The purity of the enzyme was measured and the molecular weight of its subunits was determined to be 45.5 kDa by SDSPAGE. The molecular mass of the enzyme’s natural state was found to be 88 kDa using Sephadex-G 150 gel filtration chromatography.
4/5/2023 5:43:26 AM +00:00
Electrochemical detection of DNA interaction with Mannich base derivatives by disposable graphite electrodes
Four different Mannich base derivatives containing an aromatic/heteroaromatic propanone structure (C1 (3-(dimethylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride); C2 (3-morpholino-1-(pyridin-3-yl)propan-1-one hydrochloride); C3 (3-(dimethylamino)-1-(1H -indol-3-yl)propan-1-one hydrochloride), C4 (3-(piperidin-1-yl)-1-(pyren-1- yl)propan-1-one hydrochloride)) were earlier synthesized and characterized with 1 H NMR, 13 C NMR, MS, and elemental analysis. The interaction of these compounds with fish sperm double stranded DNA (fs-dsDNA) was investigated by using differential pulse voltammetry (DPV) in connection with a disposable pencil graphite electrode (PGE).
4/5/2023 5:43:16 AM +00:00
N-heterocyclic carbenes bearing a naphthyl substituent and their metal complexes: synthesis, structure, and application in catalytic transfer hydrogenation
A series of unsymmetrical imidazolinium bromides (3a–d) bearing naphthyl and benzyl groups (R’ = CH2C6H2(CH3)3-2,4,6 (a); CH2C6H(CH3)4-2,3,5,6 (b); CH2C6(CH3)5 (c); CH2C6F5 (d)) at the N1 and N3 positions were successfully synthesized. [RuCl2(NHC(p-cymene)] (NHC= N-heterocyclic carbene) complexes (4a–d) were prepared by the reaction of [RuCl2(p-cymene)]2 with imidazolinium salts (3a–d). The new salts (3a–d) and their ruthenium(II) complexes (4a–d) were characterized by 1 H, 13 C, 19F NMR, and elemental analysis. The ruthenium(II) complexes (4a–d) were employed as catalysts for the transfer hydrogenation (TH) of ketones in the presence of KOH using 2-propanol as a hydrogen source and the results were compared.
4/5/2023 5:43:09 AM +00:00
Recent advances in thymidine phosphorylase inhibitors: syntheses and prospective medicinal applications
This review paper covers recent advances in the synthetic strategies for novel TPase inhibitors and their potential medicinal applications over the last few decades. A brief introduction covering the structural aspects of TPase inhibitors is also included to facilitate understanding of diverse approaches to monitor the design of new inhibitors. TPase is an essential enzyme and its inhibition is a potential target in the development of anticancer drugs.
4/5/2023 5:43:02 AM +00:00
Development of a method for the determination of cadmium levels in seawater by flame atomic absorption spectrometry using an online cloud-point extraction system
A new system was developed for the preconcentration and determination of cadmium levels in water following online cloud-point extraction and analysis by flame atomic absorption spectrometry. The method uses cloud-point extraction of the complex formed between Cd(II) ions and the reagent 2-(5-bromo-2’-thiazolylazo)- p-cresol (Br-TAC) using Triton X-114 as a surfactant. The main steps of the procedure, extraction, filtration, and detection were conducted online.
4/5/2023 5:42:55 AM +00:00
Biosorption potential of surface-modified waste sugar beet pulp for the removal of Reactive Yellow 2 (RY2) anionic dye
Tetra–n-butylammonium bromide modified sugar beet pulp (TBAB–SBP) with good biosorption and regeneration potential was prepared for removal of dye from contaminated solutions. The decolorization performance of TBAB–SBP was investigated using Reactive Yellow 2 (RY2) as a model dye. The characterization of the modified biosorbent was investigated by IR, SEM, zeta potential, and BET surface area analysis to discuss the decolorization mechanism. The effects of initial pH, biosorbent amount, contact time, dye concentration, and flow rate on the treatment process were examined.
4/5/2023 5:42:47 AM +00:00
Separation and preconcentration of Pb(II) and Cu(II) ions via carrier element-free coprecipitation using an acetohydrazide derivative
A new method based on the combination of carrier element-free coprecipitation and flame atomic absorption spectrometric determination has been investigated for simultaneous separation and preconcentration of Pb(II) and Cu(II) ions in some environmental solid and liquid samples. The 2-{3-(4-methylbenzyl)-4-[2-(1H-indol-3-yl)ethyl]-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}-N’-(phenylmethylene) acetohydrazide (MITA) was utilized as an organic coprecipitating agent without using a carrier element for coprecipitation of the analyte ions. The effects of experimental conditions including aqueous solution pH, MITA quantity, sample volume, standing time, and centrifugation rate and time were investigated in detail and optimized.
4/5/2023 5:42:41 AM +00:00
Ionic liquid based microextraction combined with derivatization for efficient enrichment/determination of asulam and sulfide
This study reports 2 new simple derivatization-based dispersive liquid–liquid microextraction (DLLME) methods for spectrophotometric ultratrace determination of asulam and sulfide. 1-Naphthol (in the presence of nitrite) and N,N-diethyl-p-phenylenediamine (in the presence of Fe(III)) were used to derivatize asulam and sulfide, respectively. In the enrichment methods, the formed derivatives were preconcentrated into microdroplets of the in situ formed water insoluble ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate. Monitoring was performed at 526 nm for asulam and at 664 nm for sulfide, after dissolution of the IL-rich phases into the basic ethanolic solution and ethanol for asulam and sulfide, respectively.
4/5/2023 5:42:34 AM +00:00
Solidified floating organic drop microextraction for speciation of Se (IV) and Se (VI) in water samples prior to electrothermal atomic absorption spectrometric detection
A simple and fast solidified floating organic drop microextraction (SFODME) method is suggested for the speciation of Se (IV) and Se (VI) in water samples prior to electrothermal atomic absorption spectrometric (ETAAS) detection. For that purpose, 1-phenylthiosemicarbazide (PTC) was used as chelating agent and undecanol was used as extraction solvent. The pH of solution, extraction solvent volume, amount of ligand, effect of time for complex formation, and effect of possible foreign ions were also evaluated for quantitative and effective extraction of analyte.
4/5/2023 5:42:28 AM +00:00