Tài liệu miễn phí Hoá học
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Synthesis and characterization of novel indanone-based spiro-dihydrobenzofuran derivatives
In this study, the synthesis and characterization of novel indanone-based spiro-dihydrobenzofuran derivatives were examined. Firstly, chalcone-like compounds 4a–k, (E)-2-benzylidene-2,3-dihydro-1H -inden-1-one derivatives, were synthesized by the base-catalyzed addition of benzaldehyde derivatives to 2,3-dihydro-1H -inden-1-one. Then Mn(OAc) 3 -mediated addition of dimedone (2) to the chalcone-like compounds gave two novel spiro-dihydrobenzofuran isomers: (3S)-6,6-dimethyl-3-aryl-6,7-dihydro-3H -spiro [benzofuran-2,2’-indene]-1’,4(3’H ,5H)-dione (5a–k) and (2’S)- 6,6-dimethyl-2-aryl-6,7-dihydro-2H -spiro[benzofuran-3,2’-indene]-1’,4(3’H ,5H)-dione (6a–k) in good yields.
4/3/2023 10:54:24 PM +00:00
Acetylene-bridged triazine π-conjugated structures: Synthesis and liquid crystalline properties
We report the synthesis and liquid crystalline properties of a new type of tribranched compound built up from triazine as the central core and electron-rich triazine rings as peripheral groups. An equimolar mixture of the star-shaped compound based on the 1,3,5-triazine core with 4-dodecyloxybenzoic acid produced an organic salt exhibiting a columnar mesophase with a dendritic growing texture at low temperatures. The liquid crystalline properties of the triazine-based compound and organic salt were investigated by differential scanning calorimetry and polarizing optical microscopy.
4/3/2023 10:54:07 PM +00:00
The promoted synthesis of minoxidil by magnetic nanoparticles of cobalt ferrite (CoFe2O4) as a heterogeneous reusable catalyst
Minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide) was primarily recognized as a drug for reducing vascular resistance to blood flow. It was later introduced as a more important medicine for topical stimulation of hair growth and baldness reverting as well as treatment of androgenic alopecia through increasing prostaglandin endoperoxide synthesis. In this study, magnetic nanoparticles (MNPs) of spinel ferrites (MFe2O4 , M = Co, Ni, Fe, Cu, and Zn) via solid-state grinding procedure were prepared and then characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared techniques.
4/3/2023 10:53:45 PM +00:00
ANN-assisted forecasting of adsorption efficiency to remove heavy metals
In wastewater treatment, scientific and practical models utilizing numerical computational techniques such as artificial neural networks (ANNs) can significantly help to improve the process as a whole through adsorption systems. In the modeling of the adsorption efficiency for heavy metals from wastewater, some kinetic models have been used such as pseudo first-order and second-order. The present work develops an ANN model to forecast the adsorption efficiency of heavy metals such as zinc, nickel, and copper by extracting experimental data from three case studies. To do this, we apply trial-and-error to find the most ideal ANN settings, the efficiency of which is determined by mean square error (MSE) and coefficient of determination (R2).
4/3/2023 10:53:37 PM +00:00
Electrochemical responses of flexible graphite in H2SO4
Asymmetric capacitors are gaining attention due to their hybrid nature with higher power and energy density compared to individual batteries or capacitors. Electrochemical and structural characteristics of flexible graphite in 40% H2SO4 electrolyte are investigated using electrochemical and microscopy techniques. There is a correlation between intercalation of electrolyte and the enlargement of interlayer spacing and electrochemical response. Conditions favoring planar orientation are electrochemically less active and more stable in such corrosive electrolytes.
4/3/2023 10:53:27 PM +00:00
Ionic liquid-based graphene oxide-coated fiber for headspace-solid phase microextraction of polycyclic aromatic hydrocarbons in water samples
Ionic liquid (IL) containing amino and vinyl terminated imidazolium cation and bis[(trifluoromethyl)sulfonyl] imide anion-functionalized graphene oxide (GO) coating material was prepared and coated on a stainless steel wire by a sol-gel technique for headspace-solid phase microextraction (HS-SPME). Its extraction performance was checked by HSSPME of polycyclic aromatic hydrocarbons (PAHs) coupled to gas chromatography with mass spectrometry (GC-MS). The extraction capability of the IL-functionalized GO-coated fiber was comparable with that of the commercial fibers of polydimethylsiloxane (PDMS) and polydimethylsiloxane/carboxen/divinylbenzene (PDMS/CAR/DVB).
4/3/2023 10:53:19 PM +00:00
Silylation of epoxidized soybean oil with triethoxysilanes, synthesis and characterization of their polyurethanes
Silylation of epoxidized soybean oil (ESBO) was carried out by epoxy ring opening reaction of methoxy and ethoxy silane compounds. 1H NMR and FTIR spectra confirmed that two novel bio-based polyols, PSiTh and PSiAm, were obtained through the ring opening of epoxy by the mercapto and amino moieties of MPTMS and APTES, respectively. Polyurethanes of these polyols were prepared using 4,4´ - methylene-bis(phenyl isocyanate) (MDI) to incorporate silanol groups into polymer network and were labeled as PUSiTh and PUSiAm, respectively.
4/3/2023 10:53:07 PM +00:00
Natural diterpenoid alysine A isolated from Teucrium alyssifolium exerts antidiabetic effect via enhanced glucose uptake and suppressed glucose absorption
Teucrium species have been used in folk medicine as antidiabetic, antiinflammatory, antiulcer, and antibacterial agents. We have explored in vitro antidiabetic impacts of 2 natural diterpenoids, alysine A and alysine B, isolated from Teucrium alyssifolium. The lactate dehydrogenase (LDH) cytotoxicity assay, glucose uptake test, glucose utilization (glycogen content) test, glucose transport test, glucose absorption (α-glucosidase activity) test, insulin secretion test, RNA isolation and cDNA synthesis assay, qPCR quantification assays, and statistical analyses were carried out in the present study. Alysine A exerted the following effects at non-cytotoxic doses.
4/3/2023 10:53:00 PM +00:00
In silico and in vitro evaluation of the biological activity of some organic sulfur-containing compounds
It was predicted, using the Prediction of Activity Spectra for Substances online software, that organic sulfur-containing compounds 2,6-di-tert-butyl-4-mercaptophenol (1), 2,6-di-tert-butyl-4-(3-mercaptopropyl)phenol (2), bis-3-[3,5-di-tert-butyl-4-hydroxyphenyl)propyl] sulfide (3), bis(3,5-di-tert-butyl-4-hydroxyphenyl) disulfide (4), diphenyl disulfide (5), dibenzyl disulfide (6), dibutyl disulfide (7), di-tert-butyl disulfide (8), diallyl disulfide (9), and methyl propyl trisulfide (10) could possess antioxidant activity and act as active scavengers of oxygen metabolites. The antiradical activity of these species was analyzed and it was shown that they were able to react with electrochemically generated the superoxide anion radical. The rate constants for reactions of 1–10 with the superoxide anion radical were calculated.
4/3/2023 10:52:49 PM +00:00
The effect of starting material types on the structure of graphene oxide and graphene
In this study, the effects of starting material types on graphene oxide (GO) are reported with the aim of developing graphene (GR) synthesis. The GOs were prepared from natural graphite (NG) powder and graphite nanoplate (GNp) based on the Hummers method. Two kinds of GR were successfully synthesized using GOs, which were prepared from NG and GNp in the presence of hydrazine and ammonia for 24 h at a 100◦C reaction temperature. The synthesized GOs and GRs were characterized by X-ray diffraction (XRD) techniques, Fourier transform infrared, highcontrast transmission electron microscopy (HCTEM), dispersive Raman spectroscopic analyses, and elemental analyses.
4/3/2023 10:52:15 PM +00:00
Density functional theory-supported studies of structural and electronic properties of substituted-phenol derivatives synthesized by efficient O- or C-arylation via Chan–Lam or Suzuki cross-coupling reactions
The present study reports the efficient synthesis and computational studies of the structural and electronic properties of some interesting substituted phenol derivatives. Efficient and versatile procedures to synthesize a series of diaryl ether derivatives (2a–2c, 4a–4h) and bis-arylated products (5a–5c) are described. In this manuscript, using the commercially available starting material 1 and 3, a 1-step approach was developed by means of Cu(II)-mediated Chan–Lam and Pd-catalyzed Suzuki cross-coupling reactions to synthesize diaryl ether and bis-arylated products with moderate to good yields.
4/3/2023 10:52:06 PM +00:00
Design, synthesis, biological evaluation and molecular docking of novel molecules to PARP-1 enzyme
A total of 63 newly synthesized compounds were screened in terms of PARP inhibition by cellular PARylation assay in the HeLa cell line. It was found that 19 compounds significantly inhibited the H2O2 -induced cellular PARylation. The chemosensitizer effect of these compounds in cancer cells treated with doxorubicin (doxo) was investigated. It was found that the combination of potent PARP inhibitors with doxo potentiated a cytotoxic effect, similar to that of olaparib. The results of the molecular docking and absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis revealed that compound 60 might be classified as a potential PARP inhibitor candidate. Taken together, all of the results suggested that carbohydrazide derivatives could be a promising lead for the treatment for cancer disorders.
4/3/2023 10:51:56 PM +00:00
Anticancer and antiangiogenesis activities of novel synthesized 2-substituted benzimidazoles molecules
In this study, novel 2-substituted benzimidazoles molecules having triazole, thiadiazole, and oxadiazole rings were synthesized and were evaluated by anticancer, antioxidant/oxidant status, genotoxicity, and antiangiogenesis assays. Anticancer activity of the compounds was determined by MTT (0.5, 5, and 50 µg/mL) and lactate dehydrogenase (LDH) release assays against human prostate and breast cancer cells. Oxidative status of cells was elicited by total oxidative stress and total antioxidant capacity methods. Chick chorioallantoic membrane assay was used to evaluate the antiangiogenic activity.
4/3/2023 10:51:44 PM +00:00
Extraction of high-purity silica from rice husk via hydrochloric acid leaching treatment
The present paper aimed at the investigation of the effect of preliminary acid treatment on the structure and purity of extracted silica. In this study, the acid leaching of rice husk (RH) in 2 M hydrochloric acid solution before the calcination process at 600◦C was proposed to achieve completely white silica with high specific surface area and low content of impurities. RH, selected from the Almaty Region, Kyzylorda Region, and Turkestan Region was used as the main silica source. The results confirmed that the highest purity (98.2%–99.7%) amorphous silica with a specific surface area between 120 and 980 m2 g−1 could be extracted during acid treatment and controlled calcination. The structure is amorphous, porosity diameter decreased from 26.4 nm to 0.9 nm, and specific pore volume increased from 0.5 to 1.2 cm3 g−1 .
4/3/2023 10:51:33 PM +00:00
Reduced graphene oxide supported tin oxide-boron oxide flexible paper anodes for Li-ion batteries
Freestanding tin oxide-boron oxide/reduced graphene oxide (SnO2 -B2 O3 /rGO) nanocomposite anode was produced for Li-ion cells. This binder-free flexible paper anode structure was fabricated by combining SnO2 -B2 O3 composite and graphene oxide which were synthesized through the sol–gel method and Hummers’ method, respectively. Field emission gun scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction were utilized to characterize anode materials. The Williamson-Hall (W-H) analysis was applied using XRD data to determine crystal size and strain of the lattice.
4/3/2023 10:51:13 PM +00:00
MWCNTs-Fe2O3 nanoparticle nanohybrid-based highly sensitive electrochemical sensor for the detection of kaempferol in broccoli samples
This work reports an electrochemical sensor with a modified glassy carbon electrode for the detection of kaempferol. The method was tailored by the immobilization of multiwalled carbon nanotubes (MWCNTs) assimilated with Fe2O3 nanoparticles (NPs) onto the electrode surface to detect kaempferol using differential pulse voltammetry. Thermogravimetric, transmission electron microscopic, cyclic, and differential voltammetric techniques were employed to characterize the developed electrochemical sensor. The kaempferol produces an anodic quasireversible peak at pH 6.6 in phosphate buffer with Fe 2 O3 NPs/MWCNTs/GCE.
4/3/2023 10:50:53 PM +00:00
Magnetic solid-phase extraction based on Coriolus versicolor-immobilized γ-Fe2O3 nanoparticles for preconcentration and determination of Al(III) in water and food samples
A method for preconcentration of Al(III) prior to its determination by inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed because the sensitivity of ICP-OES is insufficient for trace-level measurement of Al(III). The method is based on the use of Coriolus versicolor-immobilized γ-Fe2O3 magnetic nanoparticles as a solid phase sorbent. The best experimental conditions were found as pH 6.0, 2.0 mL/min flow rate, 100 mg amount of C. versicolor on 150 mg of γ-Fe2O3 nanoparticles, and 500 mL of sample volume. The Al(III) absorbed on biosorbent was eluted with 5.0 mL of 1.0 mol/L HCl. Limit of detection, limit of quantitation, linear range, correlation coefficient, relative standard deviation, and preconcentration factor were achieved as 0.03 ng/mL, 0.11 ng/mL, 0.2 to 20 ng/mL, 0.9994, 3%, and 100, respectively.
4/3/2023 10:50:44 PM +00:00
Amino-functionalized mesostructured cellular foam silica: A highly efficient and recyclable catalyst in the Knoevenagel condensation reaction
Mesostructured cellular foam silica was functionalized by an amino group (MCF-NH2) using the postsynthesis grafting method and utilized as a recyclable catalyst for the Knoevenagel reaction to afford α, β-unsaturated compounds. The catalyst was systematically characterized by various analyses such as nitrogen adsorption, X-ray diffraction, Fourier transform infrared spectrophotometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Hammett indicator method. The results showed that MCF-NH2 catalyst was successfully prepared with a high surface area of 215 m2 g−1 and a large pore volume of 1.37 cm3 g−1. Compared with the nonfunctionalized MCF sample, the window and cell sizes of MCF-NH2 decreased after amino group modification, whose NH2 -loading density was 1.56 mmol g−1 .
4/3/2023 10:50:30 PM +00:00
On the azo dyes derived from benzoic and cinnamic acids used as photosensitizers in dye-sensitized solar cells
In order to get a better insight into the relationship between molecular structure and photovoltaic performance, six monoazo dye molecules containing benzoic and cinnamic acid moieties were synthesized and their photovoltaic properties were studied. Three of them have not been previously used in solar cells. Spectroscopic measurements of the investigated compounds coupled with theoretical calculations were performed. Short-circuit current density, open-circuit voltage, and fill-factor were determined. It was found that a larger amount of short-circuit current density will be generated if the HOMO–LUMO energy gap is lower, determined by the stability of the molecule and the electronic effect of the donor moiety.
4/3/2023 10:50:18 PM +00:00
Acetyl- and butyrylcholinesterase inhibitory activity of selected photochemically synthesized polycycles
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the main cause of dementia in the elderly population. Since the treatment of AD has been associated with the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), their inhibitors remain the main focus of AD investigations. In this study we evaluated cholinesterase inhibitory activity of 14 bicyclo[3.2.1]octene/octadiene derivatives and naturally occurring sesquiterpene alcohol cedrol. These 14 compounds have been efficiently and ecologically prepared by a photochemical approach in batch photochemical reactors.
4/3/2023 10:50:02 PM +00:00
Molecular dynamics simulations of adsorption of long pyrene-PEG chains on a thin carbon nanotube
Carbon nanotubes have emerged as highly promising theranostic agents due to their unique structural/physical features, high surface area, and high drug-loading capacity. The high cytotoxicity of carbon nanotubes can be eliminated by noncovalent coating using hydrophilic polymers. We investigated the adsorption of long pyrene functionalized polyethylene glycol (PEG) chains, PEG2000 and PEG5000 , on a single-walled carbon nanotube (SWNT) from a crowded solution. Full-atom molecular dynamics simulations in explicit water were used to mimic the experimental conditions of noncovalent PEGylation with a stoichiometry of one SWNT to ten pyrene-PEG.
4/3/2023 10:49:49 PM +00:00
A novel silver(I)-selective PVC membrane sensor and its potentiometric applications
Silver(I)-selective sensors were prepared from a solid-state contact polyvinyl chloride (PVC) membrane. (Z)-2-(2-((3-(2-hydroxyphenyl)-5-(p-tolyl)-1H -pyrrol-2-yl)imino)-5-(p-tolyl)-2H -pyrrol-3-yl)phenol was synthesized as an ionophore molecule and embedded in the silver(I)-selective PVC membrane composition. The sensor was also successfully applied in the analysis of real water samples. In real water samples prepared by standard addition method, recoveries in the range of 82.30%–95.15% were obtained.
4/3/2023 10:49:41 PM +00:00
N-Acylazole mediated stereoselective and regioselective synthesis of N-substituted azole acrylonitriles
Regio- and stereoselective synthesis of N-substituted azole acrylonitriles has been achieved smoothly in N, N-dimethylformamide (DMF) in the presence of potassium carbonate (K2CO3) as a base catalyst. N-Substituted azole acrylonitriles were obtained in moderate to good yields (39%–87%) with a one-pot reaction between readily available N-acetylazoles and Baylis-Hillman nitriles. The structural determinations were accomplished by NOESY 1H NMR and X-ray crystallography.
4/3/2023 10:49:29 PM +00:00
Synthesis of SMZ derivatives and investigation of effects on germination, root, and plant growth of Arabidopsis thaliana L.
A series of sulfonamide derivatives were synthesized by reactions with various functional groups containing benzenesulfonyl chlorides and aniline derivatives under different substitution reaction conditions. The structures of SMZ derivatives were confirmed with melting point, FT-IR, 1 H NMR, 13 C NMR, and LC-MS/MS techniques. In order to investigate the cytotoxic effects of these derivatives, we used a model plant species. The synthesized compounds (S1–S5) and sulfamethazine (SMZ) as a positive control were applied to Arabidopsis thaliana seeds.
4/3/2023 10:49:14 PM +00:00
Novel voltammetric investigation of dipyridamole at a disposable pencil graphite electrode
The present paper describes the voltammetric analysis of dipyridamole (DIP) at a cheap, disposable pencil graphite electrode (PGE). The working conditions were optimized with regard to the electrode material and the supporting electrolyte. Cyclic voltammetric investigations emphasized that DIP is irreversibly oxidized at the PGE. The electrode process is pH-dependent and controlled by both diffusion and adsorption. For DIP quantitative determination a differential pulse voltammetric (DPV) method in phosphate buffer solution pH 7.00 was developed.
4/3/2023 10:49:03 PM +00:00
Detection of lard contamination in five different edible oils by FT-IR spectroscopy using a partial least squares calibration model
Lard is defined as animal fat acquired from the adipose tissue of pigs and is not permitted for human consumption or external use by certain religions such as Islam and Judaism. Due to its low-cost availability for commercial use, it is often mixed with other vegetable oils mistakenly or deliberately and causes loss of consumer trust; hence, its detection in food products is essential. Consumers tend to know the authenticity of commercially available edible oils. However, edible oils are subjected to adulteration risks with lard, which breaches consumer rights.
4/3/2023 10:48:52 PM +00:00
Coumarin-based benzilmonohydrazone as a new proton-sensitive fluorescence dye: Synthesis and investigation of photophysical and acidochromic properties
Coumarin-based chromogenic and fluorogenic dye 4 was designed and synthesized. The photophysical properties of 4 were determined in solvents with different polarities. Protonation affinity was determined by adding trifluoroacetic acid (TFA) to a dichloromethane solution of dye 4 utilizing the UV-Vis and fluorescence titration methods. The protonation region was investigated by using the 1H NMR method. Additionally, DFT and TDDFT studies were performed to support the structural and absorption spectral properties of 4.
4/3/2023 10:48:34 PM +00:00
Synthesis and bioactivity of sulfide derivatives containing 1,3,4-oxadiazole and pyridine
A series of novel sulfide derivatives containing 1,3,4-oxadiazole and pyridine were synthesized, characterized, and tested for their antibacterial activity against tobacco bacterial wilt and rice bacterial blight and for insecticidal activity toward diamondback moth. The results showed that some compounds had good insecticidal and bactericidal activity, e.g., the activities of compounds 6e and 6g–6j toward tobacco bacterial wilt were much better than those of commercial thiodiazole-copper, and some of the synthesized compounds possessed good insecticidal activity against Plutella xylostella. Compounds 6d, 6h, 6j, 6l, 6p, 6r, and 6p displayed over 93% activity at 500 mg L−1 .
4/3/2023 10:48:24 PM +00:00
Amperometric urea biosensor based on immobilized urease on polypyrrole and macroporous polypyrrole modified Pt electrode
Biosensing of urea by a biosensor as a direct detection method at ambient temperature and pressure instead of chromatography leads to a significant reduction in processing costs. Amperometric biosensors based on urease immobilization on macroporous polypyrrole (MPPy) and pyrrole on the surface of a Pt electrode were developed. Applying cyclic voltammetry (CV), we demonstrated the synthesis of MPPy using monodispersed polystyrene spheres (460 nm) as a template. CV and chronoamperometric studies were conducted to evaluate the electrochemical current of the modified electrodes.
4/3/2023 10:48:04 PM +00:00
Optical characterization of salt-induced swelling behavior of poly(N -isopropylacrylamide) terpolymer hydrogel layers
This study reports for the first time the effect of different sodium halide salts (NaClO4, NaI, and Na2CO3) in the low concentration range (in the range of 10 −7 –1 M) on the swelling behavior of photo-crosslinked, surfaceimmobilized poly(N -isopropyl acrylamide) (PNIPAAm) terpolymer layers. PNIPAAm terpolymer (consisting of N - isopropylacrylamide, methacrylic acid, and 4-methacryloxybenzophenone) was synthesized via free radical polymerization. The PNIPAAm terpolymer layers were prepared on gold substrates via spin coating and crosslinked and surface attached via UV radiation. The swelling behavior of the layers in monovalent (NaClO4 and NaI) and divalent (Na2CO3) solutions was monitored by surface plasmon/optical waveguide spectroscopy.
4/3/2023 10:47:55 PM +00:00