Search Results (347)

A metal-ion-free method was developed to prepare κ-carrageenan/cellulose hydrogel beads for efficient cationic dye removal. The beads were fabricated using a mixture of 1-ethyl-3-methylimidazolium acetate and N,N-dimethylformamide as the solvent system, followed by aqueous ethanol-induced phase separation. This process eliminated the need for metal-ion crosslinkers, which typically neutralize anionic sulfate groups in κ-carrageenan, thereby preserving a high density of accessible binding sites. The resulting beads formed robust interpenetrating polymer networks. The initial swelling ratio reached up to 28.3 g/g, and even after drying, the adsorption capacity remained over 50% of the original. The maximum adsorption capacity for crystal violet was 241 mg/g, increasing proportionally with κ-carrageenan content due to the higher surface concentration of anionic sulfate groups. Kinetic and isotherm analyses revealed pseudo-second-order and Langmuir-type monolayer adsorption, respectively, while thermodynamic parameters indicated that the process was spontaneous and exothermic. The beads retained structural integrity and adsorption performance across pH 3–9 and maintained over 90% of their capacity after five reuse cycles. These findings demonstrate that κ-carrageenan/cellulose hydrogel beads prepared via a metal-ion-free strategy offer a sustainable and effective platform for cationic dye removal from wastewater, with potential for heavy metal ion adsorption. Full article

Series of pyrene-labeled diols (Py₂-DOs) and polyols (Py-POs) were synthesized by coupling a number (n_PyBA) of 1-pyrenebutyric acids to diols and polyols to yield series of end-labeled linear (n_PyBA = 2) and branched (n_PyBA > 2) oligomers, respectively. Pyrene excimer formation (PEF) between an excited and a ground-state pyrene was studied for the Py₂-DO and Py-PO samples by analyzing their fluorescence spectra and decays in tetrahydrofuran, dioxane, N,N-dimethylformamide, and dimethyl sulfoxide. Global model-free analysis (MFA) of the pyrene monomer and excimer fluorescence decays yielded the average rate constant (<k>) for PEF. After the calculation of the local pyrene concentration ([Py]_loc) for the Py₂-DO and Py-PO samples, the <k>-vs.-[Py]_loc plots were linear in each solvent, with larger and smaller slopes for the Py₂-DO and Py-PO samples, respectively, resulting in a clear kink in the middle of the plot. The difference in slope was attributed to a bias for PEF between pyrenes close to one another on the densely branched Py-PO constructs resulting in lower apparent [Py]_loc and <k> values. This study illustrated the ability of PEF to probe how steric hindrance along a main chain affects the dynamic encounters between substituents in multifunctional oligomers such as diols and polyols. Full article

The novel benzanthrone derivative, 2-bromo-3-aminobenzo[de]anthracene-7-one (2-Br-3-NH₂BA), was synthesized and extensively characterized to investigate its photophysical behavior in various solvents. It was prepared through selective bromination of 3-aminobenzanthrone using N-bromosuccinimide in dimethylformamide at −20 °C. Featuring a donor–π–acceptor (D–π–A) structure, 2-Br-3-NH₂BA exhibits pronounced solvatochromism due to the intramolecular charge transfer (ICT) between the amino donor and the carbonyl acceptor groups. Optical measurements conducted in eight solvents of varying polarity revealed a significant bathochromic shift in both absorption and fluorescence emission, with emission maxima red-shifting by over 110 nm from non-polar to polar environments. Corresponding reductions in the optical band gap energies, as calculated from Tauc plots, further support solvent-induced electronic state modulation. Additionally, quantum yield analysis showed higher fluorescence efficiency in non-polar solvents, while polar solvents induced twisted intramolecular charge transfer (TICT), leading to emission quenching. These findings demonstrate the sensitivity of 2-Br-3-NH₂BA to environmental polarity, making it a promising candidate for color-tunable luminescent applications in optoelectronics and sensing. However, further studies in the solid state are required to validate its applicability in device architectures such as OLEDs. Full article

Spherical Cu₂O nanoparticles were obtained by reducing copper acetate in N,N-dimethylformamide (DMF) system using glucose as the reducing agent and polyvinylpyrrolidone (PVP) as the surfactant, with which spherical PdCu nanocatalysts were thus synthesized by disproportionation. The catalyst was used for the activation of peroxymonosulfate (PMS) and showed an excellent degradation effect on rhodamine B and methylene blue-contained printing and dyeing wastewater with good stability. Additionally, the surface morphology analysis of the catalyst was carried out by SEM and TEM. The structure was characterized by XRD and FT-IR. The valence state and composition of the catalyst were characterized by XPS. The catalytic performance of the prepared catalysts was investigated with methylene blue and rhodamine B used as target pollutants. The results showed that the catalytic reduction efficiency of PdCu nanocatalyst for the two pollutants could reach 99% at 20 °C, when catalyst concentration was 60 mg/L and PMS concentration was 1.0 g/L and 0.6 g/L, respectively. The degradation efficiency of the catalyst was significantly reduced when Cl⁻, ${\mathrm{H}\mathrm{C}\mathrm{O}}_3^{-}$ and HA were present in the water. The degradation efficiency was above 90% when the pH was in the range of 5–11. The excellent performance of the PdCu/PMS system in the treatment of RhB-contained wastewater was further confirmed by taking into account of the data of free radical quenching experiment and the results of electron paramagnetic resonance (EPR) experiment. After three cycles, the removal rate of MB and RhB could still be maintained at more than 90%, which proved its excellent recyclability due to its remarkable stability and efficiency. Full article

Improving the aqueous solubility of poorly soluble pharmaceuticals is essential for accurate pharmacotoxicological testing, but the biological safety of solubilizers and hydrotropic agents used for this purpose requires careful evaluation. This study assessed the acute toxicity, physiological parameters (heart rate, claw and appendage movement), behavioral responses (swimming speed), and embryotoxicity of 15 commonly used solubilizers and hydrotropes using Daphnia magna as a biological model. Compounds included surfactants (polysorbate 20 (Tween 20), polysorbate 80 (Tween 80), sodium lauryl sulfate (SLS)), sulfonated hydrotropes (sodium xylene sulfonate (SXS), sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (PTS), sodium 1,3-benzenedisulfonate (SBDS)), and solubilizing solvents (dimethyl sulfoxide (DMSO), glycerol (GLY), propylene glycol (PDO), dimethylformamide (DMF), N,N’-Dimethylbenzamide (DMBA), N,N-Diethylnicotinamide (DENA), N,N-Dimethylurea (DMU), urea). Acute lethality was evaluated across concentration ranges appropriate to each compound group (e.g., 0.0005–0.125% for surfactants; up to 5% for less toxic solvents). Surfactants exhibited extreme toxicity, with Tween 20 and SLS causing 100% lethality even at 0.0005%, while Tween 80 induced 40–50% lethality at that concentration. In contrast, DMSO, GLY, and PDO showed low acute toxicity, maintaining normal heart rate (202–395 bpm), claw and appendage movement, and swimming speed at ≤1%, though embryotoxicity became evident at higher concentrations (≥1–2%). SXS, SBS, PTS, and SBDS displayed clear dose-dependent toxicity but were generally tolerated up to 0.05%. DMBA, DENA, and DMU caused physiological suppression, including reduced heart rate (e.g., DMBA: 246 bpm vs. control 315 bpm) and impaired mobility. Behavioral assays revealed biphasic effects for DMSO and DMBA, with early stimulation (24 h) followed by inhibition (48 h). Embryotoxicity assays demonstrated significant morphological abnormalities and developmental delays at elevated concentrations, especially for DMSO, GLY, and PDO. Overall, DMSO, GLY, PDO, SXS, and DMF can be safely used at tightly controlled concentrations in Daphnia magna toxicity assays to ensure accurate screening without solvent-induced artifacts. Full article

Polyimides (PIs) are materials that are resistant to high temperatures and crucial for the manufacturing of films, fibers, coatings, and 3D-printed items. PIs are widely used as electrically insulating materials in electronics and electrical engineering. This study investigated how the chemical structure (i.e., choice of initial monomers), the synthesis conditions of the prepolymer (i.e., choice of amide solvent), and the conditions for forming polyimide films (i.e., final curing temperature) affect the thermophysical properties and short-term electrical strength of obtained polyimide films of different chemical structures. In this work, we varied the compositions of the dianhydrides used for synthesizing polyamic acids—pyromellitic acid (PMDA), tetracarboxylic acid diphenyl oxide (ODPA) and 1,3-bis(3′,4-dicarboxyphenoxy)benzene acid (R)—with a constant diamine: 4,4′-oxydianiline (ODA). Additionally, we varied the amide solvents employed: N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP). This study represents the first investigation into how the choice of solvent in the synthesis of thermoplastic polyimide prepolymers affects their short-term electrical strength. The molecular weights of the polyamic acids were determined using gel permeation chromatography (GPC). The deformation and strength characteristics of the investigated films were also assessed. The thermophysical properties of the polyimides were evaluated via dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). X-ray diffraction analysis and infrared spectroscopy (IR) were conducted on the examined film samples. The short-term electrical strength was also evaluated. Full article

Perovskite solar cells have garnered significant attention due to their outstanding optoelectronic properties, ease of fabrication, and cost-effectiveness, making them a promising candidate for next-generation photovoltaic technologies. However, CsPbIBr₂-based perovskites currently face critical challenges regarding their limited efficiency and relatively poor long-term stability, hindering their broader commercial applications. In this study, we systematically investigated the morphological effects induced by different solvents, including dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO), on the formation and characteristics of lead bromide (PbBr₂) complexes. Further optimization was achieved through the innovative incorporation of trimesoyl chloride (TMC) doping into the perovskite precursor solution. The optimized precursor solution was subsequently processed using a spin-coating and annealing method, resulting in high-quality CsPbIBr₂ perovskite thin films with improved morphological and optoelectronic properties. The experimental results demonstrated a remarkable enhancement in power conversion efficiency (PCE), with an increase from an initial value of 6.2% up to 10.2%. Furthermore, the optimized CsPbIBr₂ solar cells exhibited excellent stability, maintaining over 80% of their initial efficiency after continuous aging for 250 h in ambient air conditions. This study presents an effective strategy for the controlled morphological and compositional engineering of wide-bandgap perovskite materials, providing a significant step forward in the advancement of perovskite photovoltaic technology. Full article

The separation via the extractive distillation of 1,3-butadiene from C₄ hydrocarbon mixtures is an essential step in synthetic rubber and plastic production. Conventional extractive distillation methods rely on solvents such as N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), which, despite their efficiency, pose significant environmental and health risks. This study investigates the feasibility of replacing these hazardous solvents with 1,2-propylene carbonate (PC), a greener alternative that aligns with REACH restrictions and CEFIC recommendations. The adoption of green solvents closely follows the UN’s Sustainable Development Goals (SDGs). Indeed, by using green solvents, industries reduce pollution, enhance worker safety, and minimize their environmental impact, contributing to multiple SDGs, and thus fostering sustainable economic growth. Advanced solvent screening methodologies, based on thermodynamic solution models (NRTL-RK) and quantum-based approaches (COSMO-RS), were employed to evaluate PC’s viability. Aspen Plus^® simulations were conducted to evaluate the industrial feasibility of PC in the 1,3-butadiene separation process. The results indicate that PC achieves comparable 1,3-butadiene separation efficiency while offering economic, operational, and environmental benefits. These findings underscore the importance of integrating sustainable solvents into industrial processes, reducing reliance on hazardous chemicals, improving compliance with evolving regulatory frameworks, and supporting sustainable industrial development. Full article

In electrospun scaffolds, coaxial electrospinning is gaining increased attention due to its potential for biocomponent encapsulation and controlled delivery. However, the encapsulation of biocomponents, such as liposomes, remains challenging because of their low stability in commonly used electrospinning solvents. This study, therefore, aims to develop a novel coaxial electrospinning formulation for crafting a liposome-encapsulated, rapid-release coaxial fiber. Liposomes demonstrated desirable stability in fish gelatin/phosphate-buffered saline (PBS) solutions, which remain liquid at room temperature and exhibit exceptional spinnability at concentrations exceeding 80 w/v% due to the reduction in surface tension. Fluorescent labelling examinations confirmed the successful encapsulation of liposomes within coaxial fibers electrospun from a 160 w/v% gelatin/PBS core and a 20 w/v% PCL/chloroform/N,N-dimethylformamide (DMF) shell. The gelatin/PBS core solution formed solid ends at the tips of the core-shell fiber post-spinning, while maintaining a liquid state within the shell, thereby enabling the encapsulation of liposomes within the PCL coaxial fiber. Upon exposure to medium, the solid ends dissolve, enabling the rapid release of liposomes. The successful development of this liposome-loaded electrospun coaxial fiber, using fish gelatin, highlights its potential for creating advanced liposome delivery systems. Full article

In previous quests to synthesize fragments of tumor-associated carbohydrate antigens (TACAs), we determined that bromoalkyl β glycosides of N-acetylglucosamine were labile and incompatible with some of the synthetic conditions required for the preparation of oligosaccharides. While N-acetylglucosamine chloroalkyl β glycosides are common intermediates for oligosaccharide synthesis, they exhibit poor yields upon subsequent reactions used to introduce the oxyamine required for further conjugation. Thus, we looked to synthesize these TACAs using chloroalkyl β glycosides and substitute the chlorine for bromine at a later synthetic stage. Upon substitution of the bromine for chlorine using sodium bromide in a dibromomethane (DBM) dimethylformamide (DMF) mixture, we observed the unexpected anomerization of the N-acetylglucosamine β glycosides, yielding up to 90% of the α glycosides. We describe our studies of this unexpected anomerization and report on how the anomeric ratios can be controlled experimentally. Interestingly, we also report the anomerization of alkyl β glycosides of N-acetylglucosamine in a mixture of DBM and DMF without sodium bromide. Further studies are being conducted to determine the mechanism of this anomerization and the scope of this reaction. Full article

The selection of solvent is pivotal in liquid-phase exfoliation (LPE), as an ideal solvent minimizes the energy required to disrupt the interlayer attractive interactions while stabilizing exfoliated layers to prevent re-agglomeration. This study theoretically analyzed the LPE of Mg(OH)₂ in different solvents, including water, dimethyl sulfoxide (DMSO), dimethylformamide, N-methyl-2-pyrrolidone (NMP), isopropyl alcohol, and 2-butanone, through first-principles calculations combined with experimental validation. DMSO was identified as the most effective solvent for reducing the interlayer attraction, based on exfoliation energy calculations, while NMP was the most efficient for stabilizing exfoliated layers, based on binding energy assessments. Principal component analysis of the solvents’ physicochemical properties reduced the original dataset of seven variables to two dominant factors. The binding energy correlates with planarity and polarity, whereas the exfoliation energy is governed by dipole moment and polarity. The biaxial straining theory successfully clarified the underlying mechanisms behind the established criteria for selecting the optimal solvent. Experimental results confirmed that DMSO outperforms water in the LPE of Mg(OH)₂. These results establish a quantitative framework for solvent selection, enhancing the efficiency of the LPE processes. Full article

This study investigates the liquid–liquid equilibrium (LLE) of a cyclohexane (1) + benzene (2) + [N,N-dimethylformamide + sodium thiocyanate] (3) system. Experimental tie-line data were obtained at 298.15 K and 318.15 K under atmospheric pressure (~101 kPa, Maringá, Paraná, Brazil) with varying sodium thiocyanate (NaSCN) concentrations in N, N-dimethylformamide (DMF) (3, 5, 8, and 16 wt%). The results contribute to determining the optimal operating conditions for the liquid–liquid extraction of cyclohexane/benzene mixtures. The Hand and Othmer–Tobias correlations confirm the consistency and accuracy of the experimental data. Furthermore, eNRTL and modified UNIFAC models were employed to correlate the experimental LLE data, achieving a root-mean-square deviation of less than 0.91%. The selectivity and distribution coefficients indicate a high efficiency of benzene distribution into the extract phase, suggesting a low solvent/feed ratio and fewer separation stages required for cyclohexane and benzene separation. Full article

N,N-dimethylformamide’s (DMF) participation in domino reactions has been developed. Starting from substituted halogenobenzenes and selenium powder, versatile biologically active Se-phenyl dimethylcarbamoselenoate derivatives were efficiently synthesized under mild reaction conditions. The reaction mechanism was studied using control experiments. These protocols involve a wider substrate scope and provide an economical approach toward C–selenium bond formation. Full article

Biodegradable polylactic acid (PLA) was used to fabricate nonwoven fabrics via the melt blowing process, followed by electrospinning to deposit a nanofiber membrane. This composite process yielded PLA melt-blown/electrospun composite materials with excellent filtration performance. The effects of the solution concentration and spinning duration on the composite structure and material performance were investigated. The optimal composite was produced using a 10 wt.% PLA spinning solution prepared with a solvent mixture of dichloromethane (DCM) and N, N-dimethylformamide (DMF) in a 75/25 weight ratio. The process parameters included a spinning duration of 5 h, 18 kV voltage, 1.5 mL/h flow rate, and 12 cm collection distance. The resulting composite achieved a filtration efficiency of 98.7%, a pressure drop of 142 Pa, an average pore size of 5 μm, and a contact angle of 138.7°. These results provided optimal process parameters for preparing PLA melt-blown/electrospun composite filtration materials. This study highlights the potential of hydrophobic PLA composites with high filtration efficiency and low air resistance as environmentally friendly alternatives to traditional non-degradable filtration materials. Full article

The HKUST-1 metal-organic framework was synthesized using four different copper(II) salt precursors, namely copper nitrate, copper sulphate, copper acetate, and copper chloride, via the solvothermal method with no mixing. Syntheses were conducted without using the N,N-dimethylformamide to allow for a greener synthesis of MOFs. The selected physicochemical properties of the obtained metal-organic frameworks were determined. The yield of the obtained products changed in the order acetate>nitrate>sulfate, while no product was obtained in the synthesis with copper(II) chloride. The obtained materials were characterized by means of XRD, nitrogen adsorption–desorption at −196 °C, FTIR, XPS, TGA, SEM, and DLS. The morphology of crystallites and their physicochemical properties were significantly affected when different copper(II) salt precursors were used. The comparison of the obtained results with already published works allows for the correlation of the synthesis parameters like synthesis temperature, time, mixing, and copper(II) salt precursor used on selected properties of the final product. Full article