Turkish Journal of Chemistry最新文献

[This corrects the article on p. 332 in vol. 40.].

Inflammation is a response to injury and infection in an organism. It can be categorized as acute or chronic. Chronic inflammation is the underlying cause of many diseases such as Alzheimer disease, diabetes, rheumatoid arthritis, atherosclerosis, and cardiovascular diseases. Recent studies have proven the antiinflammatory properties of 1,4-dihydropyridines (1,4-DHPs) and their derivatives, which have many biological activities including the blocking of calcium channels. In this study, 15 compounds that are condensed derivatives of 1,4-DHPs, with the general structure of hexahydroquinoline-3-carboxylate, were synthesized. These compounds, expected to show inhibitory activity against inflammatory mediators, were obtained by the reaction of 4-(difluoromethoxy)benzaldehyde, substituted/nonsubstituted 1,3-cyclohexanedione derivatives, and appropriate alkyl acetoacetate compounds in the presence of ammonium acetate as a nitrogen source according to the Hantzsch synthesis method. The structures of the synthesized compounds were elucidated by IR, ¹H NMR, ¹³C NMR, and HRMS methods. The cytotoxic properties of the compounds were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method in the 3T3 cell line. Among the 15 compounds, the three compounds with the lowest levels of cytotoxic effects were selected for further experiments. Inflammation was induced by lipoxygenase and the effects of the selected compounds on the levels of reactive oxygen species, cytokines, and complement C3 and C9 regulatory proteins were investigated. It was found that the three selected compounds decreased the levels of transforming growth factor-beta 1 (TGF-β1). Among these compounds, compound 3e provided the most significant decrease in this cytokine. Moreover, 3e increased both C3 and C9 levels. Molecular modeling studies also showed that 3e had better affinity for TGF-β1. When the binding modes of these compounds in the active site of TGF-β1 were analyzed, it was found that compound 3e had hydrophobic interactions with amino acids Leu142, Tyr84, and Ile13; halogen bond interactions with Asp92; and hydrogen bond interactions with Ser89, Gly88, and Gly14 in the active binding site. Further in vitro and in vivo studies are needed to show the possible mechanism of action of compound 3e.

A novel Fe₃O₄@coPPy-PTH nanocomposite-based sorbent was prepared via in situ oxidative polymerization using Fe₃O₄ nanoparticles with spherical and flower-like morphologies of thiophene and pyrrole as the feedstocks. The synthesized nanocomposite displayed sensitive extraction and determination of metal ions Co(II), Cr(III), and Ni(II) without a chelating agent, followed by microsample injection system-flame atomic absorption spectrometry. Advanced spectroscopic and imaging techniques including scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy were used to characterize the composition and morphology of the Fe₃O₄@coPPy-PTH nanocomposite. SEM observations showed that the size of the Fe₃O₄ nanoparticles changed from 30 nm to 120 nm in diameter after copolymer (PPy-PTH) coating. The Fe₃O₄@coPPy-PTH nanocomposite has good dispersion properties and stability in strong acid solutions. For effective extraction of the studied analytes, the influence of sample pH, volume of sample solution and eluent, amount of adsorbent, and interference of coexisting metal ions were optimized. Under the optimum conditions, preconcentration factors were obtained as 25 for all analytes. The calibration curves were linear in the range of 0.0-10.0 μg L^-1 with coefficients of determination (R²) greater than 0.9957 for all three analytes. Limits of detection (S/N = 3) were calculated in the range of 0.17-0.23 μg L^-1. Precision values, expressed as relative standard deviations, were lower than 3.0%, and relative recoveries were obtained in the range of 88.6%-103.6%. The proposed method (Fe₃O₄@coPPy-PTH/MSPE/MIS-FAAS) was successfully applied to extract and determine the studied metal ions in beer, wine, and nonalcoholic beverage samples.

The analysis of substances and samples obtained from a crime scene is very important in solving forensic cases. To determine the variables involved in a crime and to expedite the investigation process, the rapid analysis of body fluids in small quantities and within environments containing diverse components is particularly necessary. For this reason, it is of great importance to analyze biological fluids with rapid, noncontaminating, nondestructive, low-cost, and accurate techniques. In recent years, with advancements in laser technology, spectroscopic methods have been introduced as analytical techniques in forensic medicine and chemical studies. This study focuses on surface-enhanced Raman spectroscopy (SERS) to demonstrate the detection of blood samples in simulated crime scenes. To minimize the background signal from fluorescent biomolecules in blood, dilution was performed with two different components and Raman analysis was performed for four different concentrations of blood. In general, a decrease in noise in the spectra was observed as the blood was diluted. Crime scenes consisting of pure blood, blood diluted with ethanol and distilled water (1:2, 1:4, and 1:8), a blood-mineral water mixture, a blood-cherry juice mixture, and silver nanoparticle-added mixtures were simulated, and their spectra were examined. Chemometric analyses of the data were performed. Despite high noise and low peak intensities, blood-identifying signals were detected when examining different blood concentrations. It was observed that silver nanoparticles provided high enhancement of blood peaks thanks to their strong plasmonic properties.

The reaction solvent and catalyst play essential roles in the Prins reaction for the synthesis of 3-methyl-3-buten-1-ol (MBO) from formaldehyde and isobutene. The reactivity of the solid base-catalyzed Prins condensation reaction by formaldehyde and isobutene in supercritical CO₂ was investigated using CsH₂PO₄-modified HZSM-5. We found that the alkaline sites of the alkali-loaded catalyst could extract the α-H on isobutene to generate olefin carbon-negative ions, while the supercritical CO₂ with weak Lewis acidity could activate formaldehyde to carbon-positive ions, which can combine more easily with carbon-negative isobutene to react, thus improving the reactivity of the reaction system.

Exploring the materials that effectively capture radioactive iodine is crucial in managing nuclear waste produced from nuclear power plants. In this study, a β-ketoenamine-linked covalent organic framework (bCOF) is reported as an effective adsorbent to capture iodine from both vapor and solution. The bCOF's high porosity and heteroatom-rich skeleton offer notable iodine vapor uptake capacity of up to 2.51 g g^-1 at 75 °C under ambient pressure. Furthermore, after five consecutive adsorption-desorption cycles, the bCOF demonstrates high reusability performance with significant iodine vapor capacity retention. The adsorption mechanism was also investigated using various ex situ structural characterization techniques, and these mechanistic studies revealed the existence of a strong chemical interaction between the bCOF and iodine. The bCOF also showed good iodine uptake performance of up to 512 mg g^-1 in cyclohexane with high removal efficiencies. The bCOF's performance in adsorbing iodine from both vapor and solution makes it a promising material to be used as an effective adsorbent in capturing radioactive iodine emissions from nuclear power plants.

Tar build-up is one of the bottlenecks of biomass gasification processes. Dry reforming of tar is an alternative solution if the oxygen chemical potential on the catalyst surface is at a sufficient level. For this purpose, an oxygen-donor perovskite, LaCoO₃, was used as a catalyst for the dry reforming of tar. To circumvent the complexity of the tar and its constituents, the benzene molecule was chosen as a model compound. Dry reforming of benzene vapor on the LaCoO₃ catalyst was investigated at temperatures of 600, 700, and 800 °C; at CO₂/C₆H₆ ratios of 3, 6, and 12; and at space velocities of 14,000 and 28,000 h^-1. The conventional Ni(15 wt.%)/Al₂O₃ catalyst was also used as a reference material to determine the relative activity of the LaCoO₃ catalyst. Different characterization techniques such as X-ray diffraction, N₂ adsorption-desorption, temperature-programmed reduction, and oxidation were used to determine the physicochemical characteristics of the catalysts. The findings demonstrated that the LaCoO₃ catalyst has higher CO₂ conversion, higher H₂ and CO yields, and better stability than the Ni(15 wt.%)/γ-Al₂O₃ catalyst. The improvement in activity was attributed to the strong capacity of LaCoO₃ for oxygen exchange. The transfer of lattice oxygen from the surface of the LaCoO₃ catalyst facilitates the oxidation of carbon and other surface species and leads to higher conversion and yields.

Injectable hydrogels play an important role in tissue engineering as a filling and repairing material. This study aimed to develop a new injectable hydrogel based on hyaluronic acid (HA) and quince seed gum (QSG) and investigate the effect of QSG on hydrogel performance. The amount of unreacted 1,4-Butanediol diglycidyl ether is maintained at an undetectable level for HA-QSG hydrogels. Amino acid analysis showed that the HA-QSG hydrogel had rich amino acid concentrations of leucine, arginine, and valine. After thermal sterilization, the elastic modulus of HA-QSG gels for dermal and intraarticular filler applications is 63 Pa and 92 Pa, respectively. Pore size was found below 200 μm and the dense homogeneous pore structure was observed.

Two 3-(p-substituted phenyl)-3a,8a-dihydro-4H-cyclohepta[d]isoxazoles were synthesized by 1,3-dipolar cycloaddition of the corresponding nitrile oxides with cycloheptatriene. Two endoperoxides were synthesized as facially selective and single products in high yields (93%-95%) from the reactions of isoxazole derivatives with singlet oxygen. The exact configurations of the endoperoxide with a methyl group in the phenyl ring and the diol synthesized from it were confirmed by X-ray analysis. To elucidate the mechanism, the formation energy of the endoperoxide was investigated by simulations using the software package Gaussian 09 and density functional theory calculations via the M06-2X/6-311+G(d,p) level method in dichloromethane. The results were consistent with experimental findings showing the formation of isoxazole products.

The insertion reactions of p-complex (RP) and three-membered ring configuration (RS) of stannylenoid H₂SnLiF with NH₃, H₂O and HF have been studied theoretically by quantum chemical calculation. The structures of reactants, precursors, transition states, intermediates and products have been fully optimized at the M06-2X/def2-TZVP level. The single point energy of all fixed points were calculated using the QCISD method. The calculation results show that the three-membered ring configuration is easier to conduct the insertion reaction. Comparing the reaction energy barriers of RP, RS to NH₃, H₂O and HF, we found that the difficulty of the insertion reaction is NH₃ > H₂O > HF. The solvent corrected calculation results show that in THF, the reaction energy barrier of RP is lower than that in vacuum, while the reaction energy barrier of RS is higher. This work provides theoretical support for the reaction properties of stannylenoid.