Tài liệu miễn phí Hoá học
Download Tài liệu học tập miễn phí Hoá học
Synthesis, reaction, and evaluation of the anticancer activity of 6,7,8,9-tetrahydro-5H -cyclohepta[4,5]selenopheno[2,3-d]pyrimidine derivatives
The cyclocondensation of 2-amino-5,6,7,8-tetrahydro-4H -cyclohepta[b] selenophene-3-carbonitrile (1) with formic acid and formamide gave the selenophenopyrimidine 15 and selenophenopyrimidone 6 derivatives. The reaction of 6 with phosphorus oxychloride produced 4-chloro-6,7,8,9-tetrahydro-5H -cyclohepta[4,5] seleno[2,3-d]pyrimidine (12), the key compound for our nucleophilic substitution reactions.
4/5/2023 5:38:39 AM +00:00
Characterization of an Al3+-selective fluorescent probe based on a benzoyl hydrazine derivative and its application in cell imaging
A fluorescent probe based on benzoyl hydrazine was synthesized and characterized as an Al3+-selective fluorescent probe. This probe showed good selectivity towards Al 3+ compared to other common ions. Under optimized experimental conditions, the probe exhibited a linear dynamic response for Al 3+ from 5.0 × 10−7 to 4.5 × 10−6 M with a detection limit of 1.3 × 10−7 M in ethanol–water solution (9:1, v:v, pH 6.8, 20 mM HEPES). Furthermore, it was used for imaging of Al3+ in living cells with satisfying results.
4/5/2023 5:38:32 AM +00:00
Electrochemical investigation of 2-[8-hydroxyquinoline-5-yl)azo]benzo[ c]cinnoline on a platinum electrode in dimethysulfoxide
The electrochemical reduction of 2-[8-hydroxyquinoline-5-yl)azo]benzo[c]cinnoline was investigated by cyclic voltammetry, controlled potential electrolysis, and chronoamperometry techniques in the presence of 0.10 mol L−1 tetrabutylammonium tetrafluoroborate in dimethyl sulfoxide at platinum electrode. 2-[8-Hydroxyquinoline-5-yl)azo]benzo[c] cinnoline displays three sharp cathodic peaks and three anodic peaks in the cyclic voltammogram. The diffusion coefficients and the number of electrons transferred were calculated by using an ultramicroelectrode and platinum electrode.
4/5/2023 5:38:25 AM +00:00
Synthesis and computational studies of new metallo-phthalocyanines bearing dibenzoxanthenes and evaluation of their optical properties in solution and solid PMMA/ZnPc/Al nanocomposite films
Then we successfully prepared the poly(methyl methacrylate) (PMMA)/ZnPc/Al nanocomposite films by incorporating Al nanoparticles into a transparent PMMA/ZnPc matrix. The structure and morphology of nanocomposite films were studied using X-ray diffraction and scanning electron microscopy. The optical absorption spectra of PMMA/ZnPc/Al nanocomposite films showed red shifting in the Q-band in the polymeric matrix. The geometrical structure of two phthalocyanines was investigated at the RHF/3-21G* computational level.
4/5/2023 5:38:18 AM +00:00
The mediatory activity of meso-tetraphenylporphyrin iron(III) complex immobilized in Nafion film on a Pt electrode in the oxidation of 1,2- and 1,4-hydroquinones
This paper presents the results of an investigation of the properties of a modified platinum electrode with meso-tetraphenylporphyrin iron(III) complex immobilized in Nafion film and its catalytic activity in the electrochemical oxidation of selected hydroquinone and catechol derivatives. The redox activity of iron complexes of porphyrins was characterized in aqueous solutions of perchloric acid by means of cyclic voltammetry and differential pulse voltammetry. Both the increase in the anodic peak currents of the investigated compounds during oxidation on the platinum electrode modified with meso-tetraphenylporphyrin iron(III) complex immobilized in Nafion film (FeTPhP/Nafion/Pt) and the considerable decrease in the cathodic peak currents related to the porphyrine complexes reduction point to mediatory activity.
4/5/2023 5:38:11 AM +00:00
CO2 adsorption behavior and kinetics on chemically modified activated carbons
CO2 adsorption capacities of activated carbon-based adsorbents subjected to different treatments, such as HNO3 oxidation, air oxidation, alkali impregnation, and heat treatment under helium gas atmosphere, were determined by gravimetric analyses and reported previously by our group. In the current work, the experimental adsorption isotherms of these modified activated carbon samples were fitted to Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) models. The best fits were obtained to the D-R equation, indicating competitive or multilayer CO2 adsorption occurring in the micropores of the adsorbents.
4/5/2023 5:38:05 AM +00:00
Preparation, characterization, and adsorption studies of core@shell SiO2@CeO2 nanoparticles: a new candidate to remove Hg(II) from aqueous solutions
SiO2 supported core@shell nanoparticles (CSNs) have recently attracted great attention due to their unique, tunable, optical, photocatalytic, and higher adsorption properties. In this study, SiO2@CeO2 CSNs were synthesized using a chemical precipitation technique and characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) analysis. XRD analysis showed that SiO2 particles were the core while CeO2 particles were the shell.
4/5/2023 5:37:57 AM +00:00
Preparation and characterization of ZnO/MMT nanocomposite for photocatalytic ozonation of a disperse dye
The influence of various operational parameters including initial dye concentration, catalyst concentration, pH value, inlet gas concentration, and type of irradiation source was investigated on the efficiency of the photocatalytic ozonation removal of DR54. Various inorganic and organic reactive oxygen species (ROS) scavengers were applied to investigate the mechanism of photocatalytic ozonation. In addition, a three-layer perceptron neural network was developed for modeling the relationship between the operational parameters and decolorization efficiency of the dye. High R2 values were obtained for both the training and test data.
4/5/2023 5:37:45 AM +00:00
Prostereoisomerism and biological activity: possible implications for drug design
Prostereoisomerism (PIM), representing a subgroup within the achiral class of molecules, is manifested in a chiral environment. Although this is regardless of the orientation of the prostereoisomeric (PIC) molecule, PIM is manifested most emphatically in relation to a chiral surface (‘two-dimensional chirality’). Then PIM is tantamount to ‘de facto chirality’ as attachment of the PIC molecule to the surface leads to diastereomeric possibilities (cf. Ogston’s hypothesis).
4/5/2023 5:37:35 AM +00:00
Synthesis, and prediction of molecular properties and antimicrobial activity of some acylhydrazones derived from N -(arylsulfonyl)methionine
The MIC value of compound 30 against Enterococcus faecalis, Listeria monocytogenes, and Bacillus cereus was 8 µg/mL. A computational study for prediction of ADME and drug-like properties (solubility, drug-likeness, and drug score) as well as potential toxicity profiles of compounds 2–40 was performed using the Molinspiration online property calculation toolkit and Osiris Property Explorer. As most of our compounds meet Lipinski’s rule of five, they promise good solubility and permeability. According to Osiris calculations, the majority of our compounds are supposed to be nonmutagenic and nonirritating.
4/5/2023 5:37:25 AM +00:00
Comparative density functional study of antioxidative activity of the hydroxybenzoic acids and their anions
Hydroxybenzoic acids (HBAs) and their anions play an important role in the food and pharmaceutical industries because of their antioxidant activity. In this study, we examined the mechanisms of the free radical scavenging action of HBAs and their anions using density functional theory (DFT) methods. Reaction enthalpies related to the mechanisms of free radical scavenging by the investigated species were calculated by DFT methods in water, DMSO, pentylethanoate, and benzene.
4/5/2023 5:37:16 AM +00:00
Ecofriendly one-pot synthesis and antiviral evaluation of novel pyrazolyl pyrazolines of medicinal interest
The latter compounds react also by grinding method with nitrogen nucleophiles such as hydrazine hydrate, phenylhydrazine, and thiosemicarbazide to afford the corresponding pyrazol-3-yl pyrazolines. A series of 6-pyrazolylpyrimidine2-thione derivatives were prepared by reaction of the above chalcones with thiourea by grinding method in the presence of a catalytic amount of sodium hydroxide at room temperature. In addition, 7-pyrazolylpyridopyrimidine-3-thione was prepared by reaction of chalcone with 6-aminothiouracil.
4/5/2023 5:37:08 AM +00:00
Experimental and theoretical approaches for structural and mechanical properties of novel side chain LCP-PP graft coproducts
The monomers p-biphenyloxycarbonylphenyl acrylate (BPCPA) and p-biphenyloxycarbonylphenyl methacrylate (BPCPMA) were synthesized by the reaction of p-acryloyloxybenzoyl chloride and p-methacryloyloxybenzoyl chloride with 4-hydroxybiphenyl, respectively, and polymerized by bulk polymerization in vacuum by using dicumyl peroxide. The graft copolymerization of the monomers onto polypropylene were carried out by bulk melt polymerization at 170◦C with various concentration levels of the monomers and the initiator in reaction mixtures. The content of monomers in their graft coproducts increased with monomer-initiator percentage in the reaction medium.
4/5/2023 5:36:53 AM +00:00
Visible light photocatalysis of a textile dye over ZnO nanostructures covered on natural diatomite
In the present study, ZnO nanostructures were ultrasonically synthesized and immobilized on the surface of diatomite and used for visible light photocatalysis of Acid Red 88 (AR88) in the aqueous phase. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were employed for characterization of the samples. The process was optimized via response surface methodology (RSM) on the basis of central composite design (CCD). Based on numerical optimization, for the maximized color removal of 96% the initial dye concentration, the catalyst dosage, the reaction time, and the initial pH were 13 mg/L, 1.5 g/L, 85 min, and 4, respectively.
4/5/2023 5:36:28 AM +00:00
Synthesis and evaluation of some novel thiazoles and 1,3-thiazines as potent agents against the rabies virus
A series of novel thiazoles and 1,3-thiazine derivatives were synthesized in good yield via reaction of ethyl 3-(1-(2-thiocarbamoylhydrazono)ethyl)-1,5-diphenyl-1H -pyrazole-4-carboxylate with hydrazonoyl halides and arylidenemalononitriles, respectively. The structure of the newly synthesized products was elucidated via elemental analysis, spectral data, and alternative routes whenever possible. Moreover, the antiviral screening of the products was evaluated and the results revealed that some of them have strong to moderate potency against the rabies virus compared with the reference drug.
4/5/2023 5:36:19 AM +00:00
An efficient one-pot, three-component synthesis of 6-cyano-hexahydro-4H-thieno[3’,2’:5,6]pyrimido[1,2-a]quinoline-2-carboxylates and their spiro derivatives from β-enaminones
A simple and efficient one-pot synthesis of novel thieno[3’,2’:5,6]pyrimido[1,2-a]quinoline-2-carboxylates (5a– d) and their spirooxindole derivatives (12a–d) was accomplished. Thus, the Michael addition reaction of the cyclic β-enaminone 3 with the corresponding α, β-unsaturated nitrile derivatives 4a–d in refluxing EtOH in the presence of piperidine afforded 5a–d in good yields. On the other hand, spirooxindole derivatives 12a–d were synthesized by the reaction of cyclic β-enaminone 3 with the corresponding 3-cyanomethylidene-2-oxoindoles 11a–d in refluxing EtOH.
4/5/2023 5:36:13 AM +00:00
Synthesis and application of polyvinylimidazole-based Brønsted acidic ionic liquid grafted silica as an efficient heterogeneous catalyst in the preparation of quinoxaline derivatives
Two types of polymer-grafted silica based on polyvinylimidazole Brønsted acidic ionic liquids were prepared and used as new heterogeneous catalysts for the preparation of pharmaceutically important quinoxaline derivatives. These catalysts were characterized by thermogravimetric analysis, FT-IR spectroscopy, and titration. They could be recycled without considerable loss in their catalytic activity. High efficiency of the catalysts along with short reaction times, high yields, easy purification, recyclability, and simple procedure are among the advantages of these catalytic systems.
4/5/2023 5:36:06 AM +00:00
Simple and rapid voltammetric determination of boron in water and steel samples using a pencil graphite electrode
This paper presents a simple, rapid, and accurate voltammetric method for determination of boron in water and steel samples using a disposable pencil graphite electrode. The oxidation of Tiron in the boron–Tiron complex in phosphate buffer at pH 7.5 was measured as a response. Type and concentration of supporting electrolyte, pH, ionic strength, Tiron concentration, scan rate, step amplitude, pulse amplitude, and pencil grade were investigated as the parameters affecting the peak current.
4/5/2023 5:35:59 AM +00:00
Photocatalysis of formaldehyde in the aqueous phase over ZnO/diatomite nanocomposite
In the present study, ZnO nanostructures were synthesized and immobilized on the surface of diatomite via a simple sonochemical method for the photocatalytic degradation of formaldehyde in the aqueous phase. The characterization of as-prepared ZnO/diatomite nanocomposite was carried out by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The photocatalysis of formaldehyde was favored at neutral pH. At a ZnO to diatomite ratio of 0.3, increasing the photocatalyst dosage from 0.2 to 1.5 g/L resulted in increasing the photocatalytic removal of formaldehyde from 37.51% to 88.05%.
4/5/2023 5:35:48 AM +00:00
Synthesis and evaluation of novel N, N′ -disubstituted benzimidazolium bromides salts as antitumor agents
Novel benzimidazolium bromides salts having (4-methoxyphenyl)ethyl, (phthalimide-2-yl)methyl, 4-nitrobenzyl, 2-phenylethyl, penthyl, or allyl groups were synthesized and their characterizations were conducted by 1 H and 13 C NMR and IR spectroscopic methods, and microanalysis. In vitro antitumor activities of the novel benzimidazole compounds (1–7) were determined by using ovarian (A2780) and prostate (PC-3) cancer cell lines. Antitumor properties of all compounds were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.
4/5/2023 5:35:41 AM +00:00
New antimicrobial biscembrane hydrocarbon and cembranoid diterpenes from the soft coral Sarcophyton trocheliophorum
The sensitivity of some pathogenic bacteria used as test organisms to the new compounds 1–3 was determined. 1 showed appreciable antimicrobial activity with the diameter of inhibition zones ranging from 11 to 18 mm. 1 was active against the two multidrug resistant bacteria Acinetobacter baumannii and Staphylococcus aureus. Minimal inhibitory concentrations (MICs) of compound 1 were recorded for all the tested bacteria using the fluorescein diacetate method and the recorded MIC values ranged from 4 to 6 µM.
4/5/2023 5:35:34 AM +00:00
Suppression of interfering ions by using ionic liquid and micelle moieties in spectrofluorimetric analysis of manganese
Eosin-Y exhibits high affinity and emission based spectral response to most of the major ions in water samples. In the present study we performed selective spectrofluorimetric analysis of manganese with eosin-Y in the presence of potential interferents. We employed green chemistry reagents, ionic liquids (ILs) and two different micelles, to suppress the effect of conventional cations and anions on the response of eosin-Y. The experimental data revealed that different test moieties caused enhanced analytical response to Mn2+.
4/5/2023 5:35:28 AM +00:00
Impregnation of different ionic liquids onto cationic starch and their comparison in the extraction of Th(IV)
Cationic starch (CS) was prepared by using epichlorohydrin (EPI) and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMA) and ionic liquids (ILs) having different anionic groups [1-butyl-3-methyl imidazolium tetrafluoroborate (BMI+BF−4), 1-butyl-3-methyl imidazolium bromide (BMI+Br−), 1-butyl-3-methyl imidazolium hexafluorophosphate (BMI+PF−6), and 1-butyl-3-methyl imidazolium bis-[(trifluoromethyl)sulfonyl]imide (BMI+[(TF)2N]−)] were impregnated onto CS. Thorium(IV) ions were preconcentrated by using IL impregnated CS.
4/5/2023 5:35:20 AM +00:00
Heterogeneous Fenton-like degradation of Acid Red 17 using Fe-impregnated nanoporous clinoptilolite: artificial neural network modeling and phytotoxicological studies
Heterogeneous Fenton-like removal of Acid Red 17 (AR17) from aqueous solution was investigated. Feimpregnated nanoporous clinoptilolite (Fe-NP-Clin) was prepared by an impregnation method and used as a catalyst. A complete characterization including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), inductively coupled plasma (ICP), and Brunauer–Emmett–Teller (BET) analyses was done to describe the physical and chemical properties of NP-Clin and Fe-NP-Clin samples.
4/5/2023 5:35:11 AM +00:00
Polybrominated methoxy- and hydroxynaphthalenes
: Regio- and stereoselective synthesis are described for convenient preparation of hydroxy- and methoxynaphthalenes starting from naphthalene (1). cis,cis,trans-2,3,5,8-Tetrabromo-4-methoxy-1,2,3,4-tetrahydronaphthalen-1-ol (6), cis,cis,trans-2,3,5,8-tetrabromo-1,4-dimethoxy-1,2,3,4-tetrahydronaphthalene (7), and cis,cis,cis-2,3,5,8-tetrabromo1,4-dimethoxy-1,2,3,4-tetrahydronaphthalene (8) were obtained with silver-induced substitution of trans,cis,trans-1,2,3,4, 5,8-hexabromo-1,2,3,4-tetrahydronaphthalene (3). Base-promoted aromatization of dimethoxides 7 and 8 afforded 3,5,8-tribromo-1-methoxynaphthalene (9) and 2,5,8-tribromo-1-methoxynaphthalene (10).
4/5/2023 5:35:04 AM +00:00
Investigation of long-term water absorption behavior of carbon fabric reinforced epoxy composites containing hydrophobic nanosilica
Samples were molded under a hot press and for each sample 50 test samples obtained by cutting them with a water jet. The obtained samples were characterized by TG, FTIR, and SEM. The effect of water absorption was evaluated by measuring percentage water absorption and flexural strength of samples over 9 months. The results revealed that filler addition lowers the damage created by distilled water a considerable amount and addition of hydrophobic fillers to epoxy matrix composites can be especially beneficial for applications where long-term water exposure is desired.
4/5/2023 5:34:54 AM +00:00
Oxidative dehydrogenation of propane over V2O5 and K2O-V2O5 impregnated MgAl2O4 catalysts
The catalytic tests were performed in a fixed bed tubular quartz reactor system between 450 and 550◦C. It was observed that the conversion of propane increased but hydrocarbon selectivity decreased with increasing temperature over the V2O5/MgAl2O4 catalysts. The BET surface area values and surface acidities decreased upon potassium addition for the K-V2O5/MgAl2O4 catalysts, which resulted in a drastic drop in the conversion values obtained. The propylene and total hydrocarbon selectivities increased with increasing temperature.
4/5/2023 5:34:47 AM +00:00
Enhanced delivery of epirubicin by polyoxometalate-based magnetic nanocarriers: controlled drug loading and pH-sensitive drug release
A series of polyoxometalate-based magnetic nanoparticles were developed as novel carriers for anticancer drugs. Characterization of the nanoparticles was done by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), wavelength dispersive X-ray (WDX), and laser particle size analyzer. Epirubicin (EPI) was selected as a model drug. EPI loading efficiency, EPI loading content, and EPI release profiles were studied. Drug loading was controlled using acid-base titration since H + was released during the loading process.
4/5/2023 5:34:40 AM +00:00
The role of N-heterocyclic carbene substituents on ruthenium(II) complexes in the catalytic transfer hydrogenation of acetophenone
The novel ruthenium(II) complexes [RuCl2(NHC)(p-cymene)], 3a–e, containing 1-alkyl-3-benzylimidazol2-ylidene ligands were prepared. All synthesized compounds were characterized by NMR spectroscopy and elemental analyses. Ru(II)-NHC complexes were tested as catalysts for the transfer hydrogenation of acetophenone, showing modest to high activity in this reaction. The results revealed that efficiencies depend on the substituents of the benzene ring of the benzyl on the N atom of the NHC ring.
4/5/2023 5:34:34 AM +00:00
Synthesis of graft copolymer of kappa-carrageenan using microwave energy and studies of swelling capacity, flocculation properties, and preliminary acute toxicity
Grafting of acrylamide (AAm) onto kappa-carrageenan (KC) was carried out using microwave irradiation in the presence of ammonium persulfate (APS) as initiator. The effect of reaction variables including the concentration of APS, AAm, and KC; time duration; and microwave power was studied. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were carried out to characterize the graft copolymer.
4/5/2023 5:34:23 AM +00:00