Search Results (208)

A series of water-soluble molecules based on 8-isopropyl-2-methyl-5-nitroquinoline and 1,10-phenanthroline core were designed by introducing a π-conjugated bridge, vinyl unit –CH=CH–. We present the selective conversion of methyl groups located on the C2 and C9 positions in the constitution of selected quinoline or 1,10-phenanthroline derivatives, respectively, into vinyl (or styryl) products by applying Perkin condensation. The two groups of ligands differ in the presence of one or two arms. The structure of the molecule ((1E,1′E)-(1,10-phenanthroline-2,9-diyl)bis(ethene-2,1-diyl))bis(benzene-4,1,3-triyl) tetraacetate was determined by single-crystal X-ray diffraction measurements. The X-ray, NMR, and DFT computational studies indicate the influence of rotation (rotamers) on the physical properties of studied styryl molecules. The results show that the styryl molecules with the vinyl unit –CH=CH– exhibit significant static and dynamic hyperpolarizabilities. Quantum chemical calculations using density functional theory and B3LYP/6-311++G(d,p) with Grimme’s dispersion correction approach predict the existence and relative stability of different spatial cis(Z)- and trans(E)-conformers of styryl derivatives of quinoline and 1,10-phenanthroline, which exhibit different electronic distribution and conjugation within the molecular skeleton, dipole moments, and steric interactions, leading to variations in their photophysical behavior and various applications. Our studies indicate that the rotation and isomerization of aryl groups can significantly influence the electronic and optical properties of π-conjugated systems, such as vinyl units (–CH=CH–). The rotation of aryl groups around the single bond that connects them to the vinyl unit can lead to changes in the effective π-conjugation between the aryl group and the rest of the π-conjugated system. The rotation and isomerization of aryl groups in π-conjugated systems significantly impact their electronic and optical properties. These changes can modify the efficiency of π-conjugation, affecting charge transfer processes, absorption properties, light emission, and electrical conductivity. In designing optoelectronic materials, such as organic dyes, organic semiconductors, or electrochromic materials, controlling the rotation and isomerization of aryl groups can be crucial for optimizing their functionality. Full article

Multidrug resistance (MDR) poses a significant challenge in cancer therapy, often leading to treatment failure and relapse. ATP-binding cassette (ABC) transporters, particularly ABCG2, play a pivotal role in MDR development by actively expelling chemotherapeutic agents from cancer cells. This study investigates the effects of two groups of primaquine derivatives—fumardiamides (1a–d) and bis-ureas (2a, b), both bearing halogenated benzene rings—on the activity of P-glycoprotein (P-gp) and ABCG2. Their potential to reverse MDR was evaluated through a series of functional assays aimed at comparing transporter–compound interactions. The results indicated that fumardiamide derivatives, specifically 1a, 1b, and 1d, exhibited potent inhibition of ABCG2 while having no effect on P-gp, demonstrating a selective mode of action. The tested derivatives displayed low to moderate cytotoxicity and did not affect ABCG2 expression or localization. Moreover, these compounds enhanced the sensitivity of drug-resistant cancer cell lines to mitoxantrone, underscoring their potential to overcome ABCG2-mediated MDR. These findings suggest that chemical modifications of primaquine, particularly the incorporation of fumardiamide moieties, confer novel biological properties, providing promising leads for the development of selective ABCG2 inhibitors. Full article

We report the synthesis, structural characterization, and magnetic properties of three pentacoordinate Co(II) complexes [CoX(dppb)₂]X (X = Cl (1Cl), Br (2Br), and I (3I)) supported by the bidentate phosphine ligand 1,2-bis(diphenylphosphino)benzene (dppb). Single-crystal X-ray diffraction reveals that all three complexes adopt similar vacant octahedron (C_4v) geometries with the halide ligand in one axial position. Magnetic studies demonstrate that these complexes exhibit field-induced slow magnetic relaxation behaviors, with positive D values of 25.3(2), 21.6(1), and 19.4(2) cm⁻¹ for 1Cl, 2Br, and 3I, respectively. Detailed analysis of the relaxation dynamics reveals that Raman processes dominate at higher temperatures, with systematic variations in relaxation parameters across the series. The systematic variations in magnetic anisotropy and slow magnetic relaxation behaviors of the three complexes correlate with the decreasing electronegativity of the halide ligands. Full article

Silicon–lithium clusters are promising candidates for hydrogen storage due to their lightweight composition, high gravimetric capacities, and favorable non-covalent binding characteristics. In this study, we employ density functional theory (DFT), global optimization (AUTOMATON and Kick–MEP), and Born–Oppenheimer molecular dynamics (BOMD) simulations to evaluate the structural stability and hydrogen storage performance of key Li–Si systems. The exploration of their potential energy surface (PES) reveals that the true global minima of Li₆Si₆ and Li₁₀Si₁₀ differ markedly from those of the earlier Si–Li structures proposed as structural analogs of aromatic hydrocarbons such as benzene and naphthalene. Instead, these clusters adopt compact geometries composed of one or two Si₄ (T_d) units and a Si₂ dimer, all stabilized by surrounding Li atoms. Motivated by the recurrence of the Si₄–T_d motif, we explore oligomers of Li₄Si₄, which can be viewed as electronically transmuted analogues of P₄, confirming the additive H₂ uptake across dimer, trimer, and tetramer assemblies. Within the series of Si–Li clusters evaluated, the Li₁₂Si₅ sandwich complex, featuring a σ-aromatic Si₅¹⁰⁻ ring encapsulated by two Li₆⁵⁺ moieties, achieves the highest hydrogen capacity, adsorbing 34 H₂ molecules with a gravimetric density of 23.45 wt%. Its enhanced performance arises from the high density of accessible Li⁺ adsorption sites and the electronic stabilization afforded by delocalized σ-bonding. BOMD simulations at 300 and 400 K confirm their dynamic stability and reversible storage behavior, while analysis of the interaction regions confirms that hydrogen adsorption proceeds via weak, dispersion-driven physisorption. These findings clarify the structure–property relationships in Si–Li clusters and provide a basis for designing modular, lightweight, and thermally stable hydrogen storage materials. Full article

This study explores the selective hydrogenation of cinnamaldehyde using a series of metal catalysts supported on reduced graphene oxide (rGO) and conventional activated carbon (AC). Catalysts based on Pt, Pd, Rh, Ru, and Co were synthesized with controlled metal loading and characterized by XRD, SEM-EDS, XRF, and TEM. Among all tested materials, Pd supported on rGO synthesized via the Tour method (Pd/rTOGO) exhibited the highest catalytic activity, achieving 62% conversion of cinnamaldehyde and superior selectivity toward hydrocinnamaldehyde (HCAL). The support material had a significant influence on performance, especially for Pd catalysts, where 2D rGO outperformed 3D AC in both conversion and selectivity. In contrast, other metals (Pt, Rh, Ru, Co) showed only modest activity and limited selectivity tuning via support choice. Notably, GC-MS analysis revealed the formation of a previously underreported side product, 3-isopropoxy-propan-1-yl benzene (ether), likely formed via reductive etherification in isopropanol. The combined kinetic and selectivity data enabled the proposal of reaction pathways, including rapid transformation of cinnamylalcohol (COL) to hydrocinnamal alcohol (HCOL) and HCAL to ether. These findings emphasize the importance of support structure and surface functionality, particularly in 2D carbon materials, for designing efficient and selective hydrogenation catalysts. Full article

This paper reports a comparative study on the high temperature pyrolysis characteristics of three C₉H₁₂ isomers, including n-propylbenzene (PBZ), 1,3,5-trimethylbenzene (T135MBZ), and 1,2,4-trimethylbenzene (T124MBZ), via single-pulse shock tube (SPST) experiments and kinetic simulations. The SPST experiments were conducted in the temperature range of 1100–1700 K, at pressures of 10 bar and 15 bar, with a fixed fuel concentration of 200 ppm. The reaction time was approximately 1.8 ms for all of the experiments. The distributions of the pyrolysis products were quantitatively analyzed as functions of pressure and temperature. A detailed kinetic mechanism was used to simulate the experimental results, and it is demonstrated that the mechanism can capture the pyrolysis characteristics reasonably well. Both experimental and simulation results reveal that PBZ exhibits higher fuel reactivity than T124MBZ and T135MBZ under the studied conditions. Pyrolysis of all three C₉H₁₂ isomers generates key soot precursors, including acetylene and benzene. Sensitivity and rate-of-production (ROP) analyses indicate similar primary pyrolysis pathways. The benzyl radical is first formed through the dehydrogenation reaction and then it undergoes a series of decomposition reactions leading to the detected small hydrocarbon species. This study not only provides an in-depth understanding of the high temperature pyrolysis characteristics of the three C₉H₁₂ isomers, but also provides essential validation data for the development and optimization of chemical kinetic mechanisms for alkyl aromatic hydrocarbons. Full article

A series of porphyrinoids fused to highly electron-withdrawing bis(thiadiazolo)benzene units have been prepared and spectroscopically characterized. These structures have modified chromophores and exhibit large bathochromic shifts. The nickel(II), copper(II) and zinc complexes of a bis(thiadiazolo)benzoporphyrin were prepared, and these showed strong absorptions above 600 nm that shifted to longer wavelengths with increasing atomic number for the coordinated metal cations. Although the investigated porphyrinoids were poorly soluble, proton NMR data could be obtained, and these demonstrated that the structures possess global aromatic character. This was confirmed with nucleus-independent chemical shift (NICS) calculations and anisotropy of induced current density (AICD) plots. The AICD plots also demonstrate that the fused heterocyclic unit is disconnected from the porphyrinoid π-system, and in this respect, it differs from phenanthroline-fused porphyrinoids as it shows the presence of extended conjugation pathways. Full article

A series of novel hydrazones bearing diphenylamine and 5-oxopyrrolidine moieties, along with benzene and naphthalene rings substituted with hydroxy, alkoxy, or carboxylic groups, were synthesized. Their anticancer activity was evaluated in vitro using both 2D (MTT and ‘wound healing’ assays) and 3D (cell spheroid) models against human melanoma IGR39 cells, the triple-negative breast cancer cell line MDA-MB-231, and pancreatic carcinoma Panc-1 cell line. Compounds 8 (2-hydroxybenzylidene derivative) and 12 (2-hydroxynaphthalenylmethylene derivative) demonstrated the highest cytotoxicity in both 2D and 3D assays, while compounds 4 (2,5-dimethoxybenzylidene derivative) and 6 (2,4,6-trimethoxybenzylidene derivative) were most effective at inhibiting cell migration. Notably, all compounds exhibited lower activity against the Panc-1 cancer cell line in a cell monolayer, but the effects on spheroid cell viability in 3D models were comparable across all tested cancer cell lines. Molecular docking studies of the most active hydrazones suggested that these compounds may act as multikinase inhibitors. In particular, 2-hydroxynaphthalenylmethylene derivative 12 showed high binding affinity values (−11.174 and −11.471 kcal/mol) to the active sites of two key protein kinases—a non-receptor TK (SCR) and STPK (BRAF)—simultaneously. Full article

A group of silica-based supports with varying Al/Si ratios (S−x) was synthesized using the sol–gel method, followed by a chlorosulfonic acid modification to produce supported sulfonic acids (SA−x). The S−x and SA−x materials, along with their adsorption products, were characterized via techniques such as FTIR, BET, and HPLC-MS. The analysis revealed that the sulfonic acid groups in the SA−x materials existed in two anchoring states: the covalently bonded (CB) state [SiOx–O]^ɗ−–SO₃H^ɗ+ and the ion-paired (IP) state AlO_y⁺:OSO₃H⁻. The sulfonation reactivity of the CB-state sulfonic acid was enhanced, whereas that of the IP-state counterpart was diminished. The incorporation of a minor quantity of aluminum ions (x = 0.1) markedly enhanced the adsorption efficiency of SAs for o-xylene, extending the reaction temperature range to 110–190 °C and increasing the breakthrough adsorption capacity (Q_B) to 946.1 mg g⁻¹. However, excessive aluminum ion incorporation was detrimental to the adsorption performance of SAs for o-xylene. SA−0.1 showed superior adsorptive capabilities and excellent recyclability, maintaining its performance over four consecutive adsorption/regeneration cycles with only a minor decrease of 4.5%. These findings suggest that SAs prepared with a minor amount of aluminum ions have significant potential for application as adsorbents for the removal of benzene series pollutants. Full article

Aromatic properties of two series of quinoline derivatives were studied theoretically using the Density Functional Theory (DFT) approach. One series of compounds possesses antimalarial activity while the other does not have such properties. The B3LYP functional and the 6-311++G** basis set were employed in the study. The optimized geometries of the studied compounds were used for aromaticity level determination using several aromaticity indices, like HOMA, NICS, PDI, I₆, FLU, and PLR. It was shown that the level of aromaticity seems to be a feature that differentiates these two series of compounds. This is reasonable because it has been presented, previously in the literature, that this type of drug acts as an antimalarial drug through the formation of the π-π complex with ferriprotoporphyrin. There are two types of rings in the quinoline system, a benzene type, and a pyridine type. The aromaticity of the benzene-type ring in both series of studied compounds is similar while the aromaticity of the pyridine-type ring is lower for compounds that have antimalarial properties. It is derived on the basis of performed research that the properties of the pyridine-type ring are more important for the drug activity of studied compounds. Full article

The increasing demand for non-alcoholic beverages has led to the development of dealcoholized wines. However, current dealcoholization techniques often negatively impact wine aroma due to the loss of volatile compounds. This study investigates the impact of incorporating an aromatic distillate, collected during the spinning cone column (SCC) dealcoholization process, back into dealcoholized Tempranillo rosé wines. The aromatic distillate was added to dealcoholized wine in varying concentrations (0.5%, 1.0%, and 1.5% v/v). A total of 57 volatile compounds, including 25 varietal and 32 fermentative compounds, were identified and quantified using gas chromatography–mass spectrometry (GC-MS). The addition of the aromatic distillate significantly increased the concentration of several volatile compounds, notably C₆ compounds, terpenes, benzene compounds, and esters. The odor activity values (OAVs) reveal that increasing distillate concentrations led to a higher number of compounds with OAVs greater than 1, indicating enhanced individual aroma contributions. The fruity and sweet aromatic series were predominant in all samples, with their total intensity increasing with higher distillate concentrations. However, the addition of 1.5% v/v of the aromatic distillate (AW3) resulted in an alcohol content exceeding the legal limit for dealcoholized wine, classifying it as a reduced-alcohol wine. The study concludes that adding 1% v/v of the aromatic distillate to dealcoholized Tempranillo rosé wine effectively enhances the aroma profile while remaining within regulatory limits for dealcoholized wine. This approach presents a viable method for producing high-quality, aromatic, dealcoholized wines that meet consumer demand for non-alcoholic beverages. Full article

A series of layered compounds of the formula {[Mn₂(radical)₃](ClO₄)}_n was obtained by a reaction (in methanol) of manganese(II) acetate with 2-(2-benzimidazolyl)-4,4,5,5-tetramethylimidazolidinyl-1-oxy-3-oxides fluorinated on the benzene ring and by successive addition of sodium perchlorate. This study showed that the magnetic properties of the complexes are sensitive to the number and arrangement of fluorine atoms in the paramagnetic ligands. It was found that the heterospin complex with 4-FBzIm-NN behaves as a magnet with Curie temperature T_C = 50 K, which is close to that of the {[Mn₂(BzIm-NN)₃](ClO₄)}_n complex containing a nonfluorinated ligand. Meanwhile, no 3D ordering was noted for complexes with difluorinated and 5-fluoro-substituted ligands. Full article

A covalent organic framework (COF) based on imine was synthesized using 2,5-dihexoxyterephthalaldehyde (DHT) and 1,3,5-tris(4-aminophenyl) benzene (TAPB) as starting materials. The TAPB-DHT-COF exhibited satisfactory chemical stability, making it a promising adsorbing material for stir bar sorptive extraction (SBSE) of four estrogens, including estrone (E1), β-estradiol (E2), hexestrol (HES), and mestranol (MeEE2), in ambient water samples. The extracted analytes were subsequently analyzed using a high-performance liquid chromatography-diode array detector (HPLC-DAD). A series of parameters affecting the SBSE process, such as solution pH, ionic strength, extraction time, and desorption solvent, were investigated by the controlled variable method. Under optimal conditions, the limit of detection (LODs) for the four targeted estrogens ranged from 0.06 to 0.15 µg/L, with a linear range from 0.2 to 100 µg/L. The observed enrichment factor (EF) ranged from 39 to 49, while the theoretical EF was estimated to be 50-fold. This methodology can be applied to the identification of estrogens in three environmental water samples. Full article

A series of Fe–Ba mixed oxides, including a pure Fe-containing sample as a reference, have been synthesized via a sol–gel process using Fe³⁺ or Fe²⁺ salts and BaSO₄ as raw materials, with Pluronic P123 serving as a template. These oxides have been thoroughly characterized and subsequently utilized as catalysts for the chlorination of various organic molecules. Commercial hydrochloric acid, known for its relative safety, and environmentally friendly aqueous hydrogen peroxide were employed as the chlorine source and oxidant, respectively. The pure Fe-containing catalyst displays excellent thermal stability between 600 and 800 °C and exhibited moderate to high conversions in the chlorination of toluene, benzene, and tert-butyl hydroperoxide, with remarkable ortho-selectivity in chlorination of toluene. The combination of Fe³⁺ salt with BaSO₄ in the sol–gel process results in a Fe–Ba mixed oxide catalyst composed of BaO₂, BaFe₄O₇, and Fe₂O₃, significantly enhancing the chlorination activity compared to that displayed by the pure Fe catalyst. Notably, the chlorination of tert-butyl hydroperoxide (TBHP) does not require additional oxidants such as H₂O₂, and involves both electrophilic substitution and nucleophilic addition. Notably, the chlorination of bromobenzene yields chlorobenzene as the sole product, a transformation that has not been previously reported. Overall, this catalytic chlorination system holds promise for advancing the chlorination industry and enhancing pharmaceutical production. Full article

Dental caries are treated using dental composite restorative materials (DCRM). However, commercial DCRMs lack antibacterial activity. This research aimed to analyze the in vitro antibacterial activity of a series of copolymers consisting of a urethane–dimethacrylate monomer (UDMA), bisphenol A glycerolate dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA) and urethane–dimethacrylate monomer with two quaternary ammonium groups and a 1,3-bis(1-isocyanate-1-methylethyl)benzene core (QAn+TMXDI, where n = 8, 10, or 12 is the number of carbon atoms in the N-alkyl substituent). QAn+TMXDI contents in copolymers were 20 and 40 wt.%. The results of the Staphylococcus aureus and Escherichia coli adhesion test demonstrated that the logCFU/mL decreased as the length of the N-alkyl chain decreased and QAn+TMXDI content increased. The copolymers of QA8+TMXDI 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.% showed the highest antibacterial activity, with a logCFU/mL of 2.39 for S. aureus and no viable E. coli cells. Full article