European Journal of Chemistry
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Comprehensive DFT analysis of BeHfO3 perovskite: Exploring the structure, mechanical, thermodynamic, and optic properties
Full text linkWe performed a thorough study of the electronic, mechanical, thermodynamic, and optical properties of the BeHfO3 perovskite crystal using first-principles calculations featuring density functional theory (DFT). Electronic band structure analysis manifested the material to be semiconducting in nature with calculated band gap values of 0.873 eV (PBE), 0.887 eV (RPBE), 0.781 eV (PBEsol), 0.890 eV (LDA), 1.71 eV (HSE06) and 2.925 eV (B3LYP), reflecting considerable uncertainty in terms of exchange-correlation functionals and emphasizing the utility of hybrid functionals in estimating the band gap. Density of states (DOS) and partial density of states (PDOS) analyses were vital in revealing the role of the participating atoms (Be, Hf, and O) in electronic contribution, orbital hybridization, and the major states close to the Fermi level, highlighting the dominant states near the Fermi level and the role played by them in bonding. The Mulliken population analysis also described the electrostatic interaction and charge reorganization, confirming the mixed ionic-covalent nature of the bonds and revealing the complexity in the nature of bonds in the BeHfO3 lattice. Mechanical stability was thoroughly analyzed using the Born mechanical stability criteria (BMS) which validated the mechanical stability of the compound. The calculation of the elastic constants helped to establish Poisson’s ratio and Pugh’s modulus ratio (B/G) to confirm the mechanical strength and ductility of the compound along with the pronounced anisotropy in the elastic properties, which could be valuable in applications requiring directional devices. The calculation of the optical properties in terms of the frequency-dependent dielectric functions and the absorption coefficients using different DFT approaches proved the material to be a powerful absorber in both the ultraviolet (UV) and visible parts of the spectrum, which establishes the material as a valuable contender in the field of optoelectronic and photocatalytic technology
Structural and surface properties of polyvinylpyrrolidone and aloe vera - capped iron oxide nanoparticles: Application in the photocatalytic degradation of methylene blue
Full text linkIron oxide nanoparticles were synthesized by the chemical precipitation method at 25 and 80 °C using polyvinylpyrrolidone (PVP) and aloe vera/polyvinyl pyrrolidone (AP) as capping agents. FTIR bands at 1584-1455 and 522-561 cm-1 confirm the formation of PVP- and AP-capped iron oxide nanoparticles. The formation of magnetite and hematite phases was confirmed by powder X-ray Diffraction patterns. The elemental composition of the synthesized particles was confirmed by EDX. SEM analysis revealed a mixed morphology of spherical and irregular-shaped particles of average crystallite sizes ranging from 9 to 58 nm, as estimated from XRD and SEM measurements. Both PVP- and AP-capped nanoparticles were used as catalysts for the photocatalytic degradation of methylene blue under ultraviolet (UV) irradiation. After 180 min of irradiation with 20 mg of photocatalyst, degradation efficiencies of 53-82% were obtained, with AP-capped nanoparticles being more efficient, suggesting their potential as effective materials for the photocatalytic degradation of toxic dyes in wastewater
Synthesis and crystal structure of [HexNH3]2[HC2O4]2·H2O: A novel hydrogen oxalate hydrate organic salt showing antimicrobial activity against Streptomyces
Full text linkThe new monohydrated n-hexylammonium hydrogen oxalate salt [HexNH3]2[HC2O4]2·H2O (1) (HexNH3 = C6H16N+) has been prepared at room temperature, by mixing dehydrated oxalic acid with n-hexylamine. Salt 1 isolated as single-crystals, crystallizes in the orthorhombic system (space group Pna21) with cell constants of a = 14.1534(8) Å, b = 5.6656(3) Å, c = 26.8153(16) Å, V = 2150.3(2) Å3 and Z = 4. Two n-hexylammonium cations, two hydrogen oxalate anions, and one water molecule compose the asymmetric unit. All components of salt 1 are linked through N-H···O and O-H···O hydrogen bonding interactions leading to an extended supramolecular self-assembly. Structural characterization of 1 was completed by infrared and UV-visible spectroscopy. Elemental analysis (C, H, and N) also corroborates the X-ray crystal structure. The antibacterial activity of salt 1 against a bacterial species of the genus Streptomyces, extracted from potatoes, was then investigated. The antibiotic susceptibility test revealed that the bacteria were highly sensitive to salt, from a concentration of 6 mg/mL, thus acting as an effective bactericide
Kinetic study on the adsorption of pollutants from olive mill wastewater onto granular activated carbon
Full text linkThis research aimed to examine the effect of contact time on total organic carbon (TOC) removal rates associated with adsorption of pollutants from different olive mill wastewater (OMW) samples onto activated granular activated carbon (GAC). The first sample was a raw OMW that was microfiltered through a 100 µm membrane and the second sample was an OMW’s permeate from a 50 kDa filtration. The TOC removal rate (%) of pollutants from prefiltered OMW increased over time, reaching its peak after 34 h (2040 min). Subsequently, the system reached adsorption equilibrium, corresponding to a removal rate of 60%. Then, it stabilized at this value till the end of adsorption at 48 h (2880 min). TOC removal rates (%) (corresponding to adsorption at different concentrations of GAC) of pollutants permeating 50 kDa also increased over time, reaching their peaks after 2040 minutes. The highest TOC removal rate was around 85%. This study also investigated the kinetics associated with this adsorption. To gain a comprehensive process understanding, pseudo-first-order (PFO) and pseudo-second-order (PSO) were employed as kinetic models. The second-order model best expressed the adsorption process which achieved equilibrium within 34 h
Theoretical study of the paracetamol adsorption over a graphene oxide sheet
Full text linkIn recent decades, the detection of non-steroidal anti-inflammatory drugs (NSAIDs) in various water bodies has raised concerns for their environmental impact, since conventional wastewater treatment plants are inefficient for removing these pharmaceutical contaminants. In this way, many researchers have proposed various techniques, including the use of adsorbent materials. In this work, we conducted a theoretical study of the adsorption of the paracetamol (PCT) molecule on a large cluster (C80H26O24) of graphene oxide (GO) that simulates a sheet. The calculations were based on the DFT formalism using the combination M06-2X/6-31G**. The GO sheet used, with a C/O ratio of 3.5 and an oxygen content of 17%, exhibited a high adsorption capacity and stability. The adsorption energies for the most preferred complexes were 22 kcal/mol with adsorption distances between 1.84 and 2.60 Å, which allowed us to conclude that this is a very favored chemisorption process. The interaction distances and adsorption energies obtained were compared with those from other studies, confirming that the DFT approach used in this work, as well as the GO sheet modeled, were suitable. The percentages of elongation of the bonds in the PCT molecule, calculated from the bond distances before and after the adsorption process, evidenced a weakening of certain bonds in the molecule related to its most likely fragmentations. Therefore, it is concluded that these adsorption processes mediated by GO sheets can help, together with other methods, with PCT degradation
Crystal structure and supramolecular features of O-ethyl pivaloylcarbamothioate: insights from Hirshfeld surface and energy framework analyses
Full text linkThe crystal structure of O-ethyl pivaloylcarbamothioate has been determined by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic crystal system, the space group Pbca, with unit-cell dimensions a = 10.144(9) Å, b = 10.230(6) Å, c = 19.934(19) Å. The unit-cell volume is 2069(3) Å3 with Z = 8 at 298.15(2) K. A crystal specimen of size 0.241 × 0.217 × 0.124 mm3 was used for data collection using CuKα radiation (λ = 1.54178 Å). The measured reflections (25,062 in total) covered the index ranges −12 ≤ h ≤ 12, −12 ≤ k ≤ 13, and −25 ≤ l ≤ 25, of which 2246 were unique (Rint = 0.1349, Rsigma = 0.0658). The refinement converged with the final values R1 = 0.0942 [I > 2σ(I)] and wR2 = 0.2485 (all data), giving a calculated density of 1.216 g/cm3 and the absorption coefficient μ = 2.506 mm-1. The crystal structure of the title compound is stabilized by a hierarchical supramolecular architecture involving both classical (N-H···O) and non-classical (C-H···O, C-H···N, C-H···S) hydrogen bonds, giving rise to triangular, zigzag, and cyclic motifs as well as and synthons. Hirshfeld surface and fingerprint analyses confirm that H···H contacts dominate the packing, whereas directional H···O and H···S interactions play a crucial role in lattice cohesion. Interaction energy calculations further reveal that electrostatic and dispersion forces are the main contributors to the stabilization of the three-dimensional framework
Synthesis and characterization of 2-formylthymol-based azo-aldehyde dyes: Probing their efficacy as a radical scavenger in antioxidant applications
Full text linkA new series of azo-aldehyde dyes has been derived by performing a diazocoupling reaction between 2-isopropyl-5-methyl phenol and diazonium salts obtained by diazotization of differently substituted aromatic amines. The structures of newly synthesized azo-aldehydes were confirmed by modern analytical spectroscopic techniques such as 1H NMR, 13C NMR, FT-IR, and Mass. Thereafter, all synthesized azo-aldehyde dyes were evaluated for their in vitro antibacterial activity against S. aureus, S. typhumurium, E. coli, and P. aeruginosa strains using the plate method. The formed compounds were also evaluated for antioxidant activity. The present results provide new data to support that the thymol-based azo-aldehyde dyes have a potential to explore a variety of applications in the modern field of molecules and materials of high biological relevance
Enhanced photoconversion efficiency in organic polymer solar cells: Synthesis, structural analysis and computational modelling of 4,8-dichlorobenzo[1,2-b]difuran-2,6-dicarboxylic acid-based composite
Full text linkImproving the photoconversion efficiency (PCE) of organic polymer-based solar cells (SCs) is crucial to their competitiveness with conventional SCs. This study presents a novel approach to improve PCE of an organic composite solar cell incorporating 4,8-dichlorobenzo[1,2-b]difuran-2,6-dicarboxylic acid. The molecular composite was designed based on the photoactive donor-π-acceptor (D-π-A) architecture and computationally modeled to optimize its efficiency. The synthesized material was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectral analysis, confirming the formation of a perovskite lattice. Photovoltaic performance was evaluated using simulated device measurements, which produced a fill factor (FF) of 0.708, a short-circuit current density (JSC) of 12.8 mA/cm2, an open-circuit voltage (VOC) of 1.22 V, and an overall PCE of 12.78%. The active exciton diffusion path length was measured at < 9 Å, with a direct band gap of 2.05 eV. The stabilized Urbach energy of the material ranged from 110 to 220 meV. Furthermore, the active single-layer film was interfaced with both a small work function electrode (SWFE) and a long work function electrode (LWFE). The material exhibited high polarizability (αtot = 483.34×10-33 esu, Δα = 332.68×10-33 esu), indicating a strong potential for efficient photoconversion. This study demonstrates the feasibility of using 4,8-dichlorobenzo [1,2-b] difuran-2,6-dicarboxylic acid-based composite for high-performance organic solar cells, offering a promising alternative to conventional SCs
Theoretical DFT study of stereoselective hydrolysis of enantiomers of naproxen
Full text linkEster hydrolysis is a common and important reaction in organic chemistry. It is catalyzed by acid or base. This phenomenon becomes very interesting when it attains enantioselectivity. Its most common example is the enantioselective hydrolysis of the S-naproxen ester. When the hydrolysis of R/S-naproxen ester is performed, only the S-naproxen ester takes part in the hydrolysis, but the R-naproxen ester does not. Because of this, the hydrolysis of R/S naproxen ester is used to gain pharmaceutically and biologically active S-naproxen. The data in the literature describe why the hydrolysis of only the S-naproxen ester is possible, while that of the R-naproxen ester is not. Furthermore, another notable question is the acid-catalyzed nature alone, while simple ester hydrolysis is an acid-base-catalyzed phenomenon. The theoretical DFT study answers these complicated questions. In the presented article, different parameters of the ester group (-COO-) constituents of the simple ester as well as the R/S naproxen ester in water were theoretically studied. These parameters were the same between the S-naproxen ester and the simple ester after DFT calculation in water. On the other hand, the R-naproxen ester did not show similarities to that of simple ester in water
Environmentally friendly syntheses of flavone derivatives from chalcones and the evaluation of their antimicrobial activity
Full text linkPolyphenolic flavonoid compounds are commonly found in colorful vegetables and fruits, as well as other foods such as coffee, tea, wine, beer, and chocolate. Recent studies have highlighted their potent antioxidant properties, which contribute significantly to various biological functions and overall health. Chalcones and flavones represent important subclasses of flavonoids. In addition to their natural occurrence, these compounds can also be synthesized in the laboratory using chemical methods. In this study, chalcones and flavones were synthesized through Claisen-Schmidt condensation. To produce flavone derivatives (4a-e) from their corresponding chalcones (3a-e), microwave irradiation (MWI) and conventional heating (CH) methods were employed. The MWI technique proved to be more eco-friendly and cost-effective and offers greater yields and reduced reaction time compared to the conventional method. The structures of the synthesized compounds were confirmed by ultraviolet (UV) spectroscopy, nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, and elemental analysis. Using Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), the antibacterial activities of the synthesized compounds were analysed. All synthesized flavones showed significant antibacterial activity but zero activity against Gram-negative bacteria, Pseudomonas aeruginosa, in different concentrations. Compound 4a showed highest activity 19 mm zone of inhibition against Gram-positive bacteria Staphylococcus aureus with concentration 128 µg/disc