Turkish Journal of Chemistry最新文献

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.

This study highlights the potential of organometallic carbonyl complexes as selective markers for biomolecules, enabling sensitive infrared (IR) detection. The regio- and stereoselective coupling of N-acetylhistamine, a histidine analogue, with the precursor complex 1 [Fe(CO)₃(1,4-η⁵-N-pyridiniocyclohexa-1,3-diene)] BF₄ affords the labeled complex 3 [Fe(CO)₃(1,4-η⁵-N-acetylhistaminocyclohexa-1,3-diene)]. X-ray diffraction (XRD) confirms the exo stereochemistry and reveals a rigid, well-defined architecture. IR and ¹H nuclear magnetic resonance spectroscopic studies combined with IR-monitored acid-base titration demonstrate the complex's stability in aqueous media between pH 5 and 8, alongside a modest increase in basicity relative to the free ligand. These findings establish the Fe(CO)₃ moiety as a robust platform for selective labeling of peptides and proteins, paving the way for targeted applications in bioorganometallic chemistry and spectroscopic imaging.

Novel coumarin-triazole-coumarin dyads were synthesized and characterized, and their α-glycosidase inhibitory activities were evaluated spectrophotometrically. Compound 4e exhibited the most pronounced inhibitory effect, with an IC₅₀ value of 38.98 ± 0.77 μM. The IC₅₀ values for 4d and 4a were 93.55 ± 1.70 μM and 95.04 ± 3.55 μM, respectively. The Lineweaver-Burk plot showed that 4e inhibited α-glycosidase in a mixed type. In addition, the K _i value obtained from the Dixon plot was 19.95 ± 0.15 μM for α-glycosidase.

In this work, electrochemical biosensors utilizing tyrosinase (Tyr) for the detection of the nonselective beta-adrenergic agonist isoproterenol (ISO) are presented. Three different configurations for immobilizing Tyr on a graphite electrode (GE) are compared: (1) GE modified with poly(diallyldimethylammonium chloride) (PDADMAC), PDADMAC/Tyr/GE; (2) PDADMAC combined with iridium nanoparticles (IrNPs) in a stepwise preparation, resulting in PDADMAC/IrNPs/Tyr/GE; and (3) a composite of PDADMAC and IrNPs mixed with Tyr at a 1:1 (v:v), forming PDADMAC/(IrNPs-Tyr)/GE. Surface morphology was characterized using scanning electron microscopy (SEM). Cyclic voltammetry (CV) and amperometry were applied to characterize the biosensor's performance. Within the linear range of 5 μM to 211 μM, the biosensor PDADMAC/Tyr/GE exhibited a limit of detection (LOD) of 1.4 μM and a limit of quantification (LOQ) of 4.1 μM. PDADMAC/IrNPs/Tyr/GE displayed improved sensitivity with an LOD of 0.9 μM and an LOQ of 2.8 μM. The configuration PDADMAC/(IrNPs-Tyr)/GE demonstrated the best performance with an LOD of 0.3 μM and an LOQ of 0.8 μM. The slopes (0.0147 μA/M, 0.0096 μA/M, and 0.0031 μA/M for PDADMAC/(IrNPs-Tyr)/GE, PDADMAC/IrNPs/Tyr/GE, and PDADMAC/Tyr/GE, respectively) of the concentration dependencies for the three sensor modifications (which represent the analytical sensitivity) demonstrate the achieved enhancement of analytical performance by IrNPs. Furthermore, the biosensor's ability to detect ISO in the presence of potential interferences, such as ascorbic acid, uric acid, and paracetamol, was assessed. Additionally, we demonstrated the biosensor's potential to detect ISO in diluted spiked human serum samples.

Human serum albumin (HSA) is a ubiquitous, multifunctional protein responsible for the systemic distribution of both endogenous metabolites and exogenous pharmaceuticals. Its inherent properties, particularly its ability to seep into tissues and its multiple ligand-binding sites, have rendered HSA an attractive vehicle for nanoparticle-based drug delivery systems, particularly for cancer targeting. In this study, we present high-resolution crystallographic data revealing two distinct dimerization patterns of HSA (Protein Data Bank [PDB] ID: 9V61) obtained under high-concentration crystallization conditions, along with results from dipyridamole docking. Both dimer types demonstrate extensive interface areas and a significant number of electrostatic interactions. Comparative analysis with a previously reported dimer structure (PDB ID: 3JQZ) and other high-interface-area structures (PDB ID: 5Z0B, PDB ID: 8CKS) indicates similarities in contact regions but unique residue-level differences in bonding interactions. Interface surface area distribution and space group histograms further support the rarity and potential physiological relevance of the identified dimer forms. Importantly, these dimer configurations do not disrupt Sudlow's drug-binding sites, as the dipyridamole docking analysis shows strong affinity for sites I and III without affecting their utility in engineered drug delivery. Our findings open new avenues for structure-based mutagenesis and nanoparticle design strategies centered on HSA dimerization dynamics.

In recent years, new treatment methods have been developed in addition to traditional treatments to eliminate cancer, one of the deadliest diseases. Given the shortcomings of conventional therapies, including the emergence of drug resistance and selectivity to the target cell, a considerable number of researchers have directed their attention toward the investigation of alternative, less invasive strategies for the treatment of cancer. Photodynamic therapy (PDT) has received great attention in the scientific community as it is seen as a promising method of cancer treatment. Various approaches have been adopted to identify new and more effective photosensitizers (PSs) that reduce adverse effects. In this context, it is suggested that squaraine dyes could potentially overcome the disadvantages associated with conventional PSs. Moreover, conjugating targeting agents such as folic acid (FA) to these PSs is suggested as a promising approach that can provide rational solutions for their applications in PDT. In this study, the SQ-FA compound, obtained by conjugation of squaraine dye and folic acid (SQ-FA), was synthesized, its structure was characterized by various methods, and cytotoxicity studies were presented. SQ-FA is designed as a diagnostic and therapeutic tool for use in cancer treatment for human lung carcinoma epithelial cells (A549). In addition, biocompatibility studies of dermal fibroblast cell lines (L929) were carried out. SQ-FA can function as a PS and be used as a targeting agent. Spectroscopic analysis and optical properties of SQ-FA, a new dye belonging to the squaraine family, were investigated.

This study used single-crystal X-ray diffraction, elemental analysis, infrared (IR) spectroscopy, theoretical nuclear magnetic resonance (NMR), and theoretical ultraviolet spectroscopy to characterize 3 newly synthesized crystalline compounds. Additionally, the nonlinear optical, highest occupied molecular orbital energies, lowest occupied molecular orbital energies, band gap, molecular electrostatic potential, and thermodynamic parameters of the 3 crystalline compounds were examined. The strong correlation between experimental IR spectra and theoretical NMR chemical shifts confirmed the accuracy of computational predictions. The molecular formulas of the 3 newly synthesized crystalline compounds, each containing different ligand molecules, were: C₈H₁₄O₄·2(C₆H₄N₂), C₅H₇N₂·NCS, and Ni(CN)₄·2(C₅H₇N₂)·2(H₂O) for compounds 1, 2, and 3, respectively. Crystallographic analysis showed that the compounds crystallize in the space groups P1̄, P2₁/n and C2/m, respectively. Their molecular packing is stabilized by a network of hydrogen bonds (C-H···O, O-H···N, N-H···N, N-H···S, O-H···N, and N-H···O) and noncovalent interactions (C-H···μ and μ···μ). Computational studies using Gaussian 03 and CrystalExplorer further elucidated their structural, magnetic, electrooptic, and electrochemical properties.

Gold is abundant in nature, however, precise and reliable analytical methods for its detection are required stemming from its increasing prevalence in environmental, biological, and industrial systems, as well as the growing interest in understanding its function in living organisms and its effects on human health. This study investigates the use of biogenically synthesized silver nanoparticles (AgNPs) for the preconcentration and determination of gold ions prior to determination by UV-Vis spectrophotometry. AgNPs were synthesized by reducing silver nitrate through the use of an apricot kernel extract as both reducer and stabilizer agent. The colloidal yellowish AgNPs interacted with gold ions, leading to a distinct color change and a considerable decrease in the surface plasmon resonance (SPR) intensity at 415 nm in the UV-Vis absorption band, indicating a highly sensitive and selective colorimetric detection of gold ions. Under optimized conditions, the proposed method achieved satisfactory limit of detection (LOD) and limit of quantification (LOQ) values of 2.9 and 9.7 mg/L, respectively. A matrix matching calibration strategy was used to enhance quantification accuracy, resulting in satisfactory percent recoveries from waste mud samples (88-112%). Overall, the results validated the developed method as a green, simple, rapid, and accurate analytical approach to the determination of gold.

A series of novel bis-piperazine derivatives (2a-2f) were synthesized and structurally characterized via Fourier transform-infrared and nuclear magnetic resonance spectroscopic techniques. Their gamma-ray shielding efficiencies were investigated through simulations on the Monte Carlo-based Geant4-GATE platform, and the results were benchmarked against data obtained from the XCOM and Phy-X software. A simulation model incorporating an NaI scintillation detector and a point gamma source was developed. Key shielding parameters, including mass attenuation coefficient, linear attenuation coefficient, half-value layer, and mean free path (MFP), were evaluated at gamma energies of 80, 120, 662, 1173, and 1332 keV. Additionally, the energy absorption buildup factor was calculated using EpiXS software, and penetration depths were assessed in the 0.015-15 MeV energy range for 10, 20, and 40 MFP values. Among the synthesized compounds, compound 2f (C₃₅H₅₄N₆O₂) had the highest gamma attenuation performance. The antimicrobial potential of compounds 2a-2f was evaluated in vitro against various microbial strains, including Gram-positive and Gram-negative bacteria as well as a fungal species. Furthermore, in silico molecular docking studies targeting DNA gyrase and GlcN-6-P synthase were performed for compounds 2d and 2f. Docking results indicated significant interactions, supporting their potential as antimicrobial agents. To assess the dynamic stability and binding persistence of the top-scoring complex (2VF5-2d), a 100 ns molecular dynamics simulation was conducted. The complex remained structurally stable throughout the trajectory, and binding free energy calculated via MM/PBSA (ΔG_bind = -27.31 kcal/mol) further supported the strong and favorable interaction. These results highlight compound 2d as a promising candidate for further antibacterial development.