Turkish Journal of Chemistry最新文献

This study investigated the influence of synthetic sulfenimides on biodiesel-diesel fuel blends. Three previously synthesized sulfenimide derivatives were structurally characterized using spectroscopic techniques. We evaluated their antioxidant properties through phosphomolybdenum activity and reducing power capacity assays. The tested fuel samples were designated as D100, B10D90, B10D90_AA (ascorbic acid), B10D90_3, B10D90_2, and B10D90_1. The effect of adding 2000 ppm of the additive was measured using an Oxifast instrument following the ASTM D7545 standard, and the results were compared to those of the chemical antioxidant ascorbic acid. Inhibition time values were derived from the oxidation stability results. The starting temperatures for crystallization (Tc) of the mixtures were found using differential scanning calorimetry (DSC), and the measured temperatures were -7.24, -7.64, -7.89, -8.06, -8.39, and -8.52 °C. FT-IR spectra exhibited characteristic absorption bands associated with antioxidant functional groups, which means the sulfenimide compounds were successfully added. The addition of sulfenimides improved the oxidative stability of biodiesel blends. Furthermore, we conducted thermogravimetric analysis (TGA) at multiple heating rates to investigate the thermal decomposition kinetics of the sulfenimides. The activation energies for compounds 1, 2, and 3 were calculated using the Kissinger-Akahira-Sunose (KAS) method and were found to be 125.28, 111.34, and 88.11 kJ mol^-1, respectively.

CaMoO₄:Eu³⁺-functionalized hydroxyapatite-silica (HAp-SiO₂-CaMoO₄:Eu³⁺) core-shell nanocomposites were synthesized for the first time and evaluated as a multifunctional drug delivery and imaging platform. HAp-SiO₂ nanocomposites were prepared via a hydrothermal route and subsequently functionalized with a luminescent CaMoO₄:Eu³⁺ shell using the Pechini sol-gel method. Structural analyses confirmed the successful coexistence of HAp, SiO₂, and CaMoO₄:Eu³⁺ phases, while electron microscopy revealed spherical core-shell morphologies. Dynamic light scattering measurements showed average hydrodynamic particle sizes of approximately 1085 nm for HAp-SiO₂ and 1427 nm for HAp-SiO₂-CaMoO₄:Eu³⁺ nanocomposites, indicating particle clustering in aqueous media, which is consistent with the low surface charge of the particles. The Eu³⁺-doped shell exhibited a strong red emission centered at 615 nm, demonstrating suitability for luminescence-based imaging. Zoledronic acid (ZA) was efficiently loaded onto the nanocomposites under supercritical CO₂ conditions, providing high loading efficiency and sustained release behavior. In vitro release studies in phosphate-buffered saline (pH 7.4, 37 °C) followed the Korsmeyer-Peppas kinetic model (n = 0.83), indicating a non-Fickian diffusion mechanism. Cytotoxicity assays on Saos-2 osteosarcoma cells demonstrated that ZA-loaded nanocomposites exhibited enhanced antiproliferative activity, with an IC₅₀ value of 56.33 μM after 48 h. These results highlight the potential of HAp-SiO₂-CaMoO₄:Eu³⁺ nanocomposites as an integrated theranostic system for targeted bone cancer therapy. Overall, the results demonstrate that the proposed nanocomposite design successfully translates the intended theranostic concept into experimentally validated structural, optical, and biological performance.

Lanthanum metal complexes were synthesized using a classical condensation method by reacting lanthanum nitrate salts with a bidentate ligand in a 1:2:1 molar ratio (M:L:L). The formation and structure of the resulting complexes were confirmed through a combination of analytical techniques, including Fourier transformation infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction, elemental microanalysis, and scanning electron microscopy. The lanthanum complexes synthesized exhibited strong in vitro antimicrobial activity. Antibacterial screening showed inhibition zones of 18-26 mm against Staphylococcus aureus and Escherichia coli, surpassing those of the reference drug ciprofloxacin (16-20 mm). Antifungal studies demonstrated inhibition zones of 15-23 mm against Candida albicans and Aspergillus niger. The MIC values ranged from 25 to 50 μg/mL, indicating high potency. Additionally, moderate antimalarial activity was observed against Plasmodium falciparum (IC₅₀ = 12.4 μM). These findings confirm that lanthanum complexes possess potent antibacterial and antifungal properties, highlighting their promise as potential candidates for novel antimicrobial and antimalarial drug development.

Abelson-1 (ABL-1) is a nonreceptor tyrosine kinase that plays essential roles in various cellular processes, including proliferation, survival, differentiation and its kinase activity is tightly regulated. The dysregulated ABL-1 kinase activity is linked to disease pathogenesis like Chronic Myeloid Leukemia (CML), where the BCR::ABL-1 fusion oncoprotein drives oncogenic signaling. Due to its central role in CML pathogenesis, understanding the structure of ABL-1 is crucial for the effective management of the disease and drug development studies. This study focuses on optimizing the expression, purification and crystallization of the recombinant human ABL-1 kinase domain for its structural analysis via X-ray crystallography and structure-based drug screening applications. The human ABL-1 kinase domain, fused with a SUMO-tag, was expressed in Escherichia coli Rosetta2 BL21 using the pET28(a)+ expression vector. The ABL-1 aggregates seen under native culture conditions were successfully solubilized by the mild ionic detergent sarkosyl. After obtaining soluble expression of the protein, Ni-NTA affinity chromatography was performed and high yield of purified ABL-1 was obtained. The 6X-His-SUMO-tag of purified ABL1 was cleaved by ULP1 protease. The recombinant ABL-1 was subsequently used in crystallization trials to enlighten structural features of ABL-1 that could guide the development of novel therapeutics and drug screening platforms targeting ABL-1 in CML.

A multiscale computational investigation integrating density functional theory (DFT) and molecular dynamics (MD) simulations was conducted to elucidate the mechanisms through which sulfur-containing donor molecules stabilize the photoactive α-phase of formamidinium lead iodide (FAPbI₃) perovskites. The binding energetics, charge-transfer behavior, and hydrogen-bonding interactions of thiourea (TU), thiosemicarbazide (TSC), thiocyanate (SCN^-), and diethyldithiocarbamate (DTC) were systematically analyzed. DFT results revealed pronounced Pb-S coordination and multidentate hydrogenbonding, with binding energies following the trend SCN->TSC>DTC>TU. Thermodynamic analysis demonstrated that these additives lower the Gibbs free energy difference, thereby stabilizing the black α-phase, with TSC, TU, and to a lesser extent DTC exhibitingthe most pronounced effects. Projected density of statesanalysis confirmed that TU and DTC effectively suppressed trap states near the band edges without introducing midgap defects. MD simulations demonstrated preferential adsorption of all S-donors on FAPbI₃ (001) surfaces, forming three to four hydrogen bonds per frame and achieving adsorption energies up to -52 kJ·mol^-1. These findings reveal a direct correlation between coordination strength, electronic coupling, and thermodynamic stabilization, establishing TU, TSC, and DTC as promising additives for improving the phase stability and electronic performance of FAPbI₃-based perovskite solar cells.

This study investigated the effects of different plasticizers-castor oil (CO), polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG) with varying molecular weights (MWs)-on the structure and drug-release performance of low-methoxyl pectin (LM-pectin) hydrogels. Theophylline was used as a model drug to evaluate release behavior under physiologically relevant conditions. The incorporation of plasticizers modulated polymer-polymer interactions, swelling behavior, and thermal properties, thereby affecting drug-release kinetics. CO, a hydrophobic triglyceride, created microdomain-induced diffusion pathways; PVP, containing water-affinitive lactam units, facilitated moisture-driven plasticization; and PEG (MW 400/1000/1500), with hydroxyl-terminated chains, established hydrogen bonds with pectin. Structural analyses (FTIR and DSC) revealed that CO disrupted pectin packing, leading to a flexible yet crystalline matrix and enabling the highest cumulative drug release. PVP-based hydrogels exhibited enhanced crystallinity and slower release, whereas PEG formulations showed molecular-weight-dependent behavior. Kinetic calculations confirmed similar patterns, demonstrating non-Fickian transport for PEG400 and PEG1000 (diffusion associated with polymer relaxation) and an additional diffusion-limited profile for PEG1500 attributed to network densification. Among the methods evaluated, CO improved cumulative release, while PEG1500 and PVP promoted extended, lower-rate delivery. The selection of plasticizers must correspond with the design objective: CO for high cumulative release and PEG1500 or PVP for prolonged, diffusion-controlled administration. These results highlight the critical role of the plasticizer type in tailoring hydrogel performance. The LM-pectin formulations developed herein demonstrate potential for application in controlled dermal and mucosal drug-delivery systems.

This study investigated the crystallization behavior of dextromethorphan hydrobromide, a class II drug, to improve understanding of its supersaturation potential and formulation design. Conventional methods often lack the sensitivity or scalability needed for accurate detection of early nucleation events. To overcome these limitations, a novel process tracks real-time absorbance below turbidity levels to detect early molecular aggregation and phase separation. Crystallization kinetics of the drug was assessed at concentrations of 0.1, 0.2, and 0.3 mg/mL using three analytical techniques, namely, isothermal crystallization (baseline), ultraviolet (UV) absorbance (turbidity monitoring, UV-TM), and an optimized UV absorbance graphical method (UV-GM) (novel process). Induction times were recorded for each method, and statistical analysis was performed. In the descriptive statistics analysis, the one-sample test, and Pearson's correlation were applied to evaluate consistency, variance, and the strength of association (R² values) among the methods, thereby validating the reliability and precision of the developed UV-GM. As a result, at drug concentrations of 0.1, 0.2, and 0.3 mg/mL, nucleation induction times for isothermal crystallization were 80, 40, and 20 min; for UV-TM, 30, 20, and 5 min; and for UV-GM, 20, 20, and 10 min. The UV-GM demonstrated the highest precision with R² values ranging from 0.8611 to 0.9439, compared to UV-TM (0.8223-0.9443) and isothermal crystallization (0.5444-0.6525), confirming itss superior reliability. Thus, it was concluded that the UV-GM offers a consistent, precise, cost-effective, and time-saving approach for estimating nucleation induction time. It also enables characterization of liquid-liquid phase separation, metastable zone width, and supersaturation potential, supporting rational formulation design and prediction of oral absorption in supersaturated systems.

Determination of trace cobalt(II) (Co(II)) in real samples remains challenging because of its very low concentration and strong matrix interferences. In this study, a simple and green magnetic solid-phase extraction (mSPE) method was developed for the selective separation and preconcentration of Co(II) ions using a newly designed iron oxide/hexagonal boron nitride (IOhBN) nanocomposite. The material was synthesized through a one-step, surfactant-free coprecipitation process, combining the high surface area, stability, and layered structure of hBN with the magnetic and reactive features of Fe₃O₂ nanoparticles. This hybrid structure provided abundant active sites and rapid magnetic separability, enabling efficient extraction within 5 min using only 15 mg of sorbent. The optimized conditions were pH 7.0, eluent type and volume (3.0 mol L^-1 of HNO₃, 0.5 mL), and total extraction time of 5 min. The method exhibited reliable and environmentally efficient analytical performance with a limit of detection of 0.67 μg L^-1, a relative standard deviation of 4.2%, and an enrichment factor of 20. Validation with certified reference materials (water, BCR 505; onion NCS ZC 73033; spinach leaves, NIST1570a) and successful applications to water and food samples confirmed its reliability. The results demonstrate that the proposed IOhBN-based mSPE method is a novel, rapid, and environmentally sustainable approach for ultra-trace Co determination in complex matrices.

The direct synthesis of boron nitride nanotubes (BNNTs) via chemical vapor deposition (CVD) in high-temperature furnaces remains highly challenging due to difficulties in optimizing key experimental parameters such as synthesis temperature and catalyst composition. These challenges often result in uncontrolled growth behavior, adversely affecting the quality and yield of the BNNTs. In this study, colemanite was effectively utilized as a boron source for the high-yield synthesis of directionally aligned BNNTs. The synthesis was carried out using a CVD method that used a dual-catalyst system comprising Fe₂O₃ and MgO in conjunction with a silicon carbide template under high-temperature conditions. The resulting BNNTs were characterized using scanning electron microscopy and high-resolution transmission electron microscopy, as well as spectroscopic methods including Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. This innovative CVD strategy offers a cost effective and efficient way to produce high-purity BNNTs from colemanite, significantly expanding their potential for various applications.

This study investigates the extraction behavior of Y³⁺ ions using a Multi-Dropped Liquid Membrane (MDLM) system that employs di(2-ethylhexyl) phosphoric acid (D₂EHPA) as the carrier ligand. The focus is on the system's ability to transport ions between aqueous phases selectively. The extracted complex was analyzed spectrophotometrically via ultraviolet-visible (UV-Vis) measurements after complexation with 0.05% Arsenazo III. The aim of this study was to determine the influence of the optimum D₂EHPA carrier concentration, together with the pH and temperature conditions of the donor and acceptor phases, on the system's extraction performance. Accordingly, a series of extraction experiments was performed at different D₂EHPA concentrations, pH values, and temperatures to assess their combined effects on transport kinetics. The MDLM system achieved a maximum transport efficiency of 99.90% for Y³⁺ ions at a D₂EHPA concentration of 0.0045 mol/L, with a corresponding extraction time of 160 min. The shortest transport time of 120 min was observed at a carrier concentration of 0.0075 mol/L, confirming the strong influence of carrier concentration on extraction kinetics. The calculated low activation energy of 31.446 kJ/mol suggests that the transport of Y³⁺ ions through the MDLM system into the organic phase containing D₂EHPA is diffusion-controlled.