This study presents a comprehensive density functional theory (DFT) investigation into the stepwise reduction of nitrobenzene to aniline via nitroso and hydroxylamine intermediates. Two mechanistic pathways were explored: a non-catalyzed route in both gas and ethanol phases and a surface-catalyzed route facilitated by a palladium (Pd) catalyst. Geometry optimizations, thermodynamic parameters, frontier molecular orbital (FMO) analysis, and vibrational frequency (IR) simulations were carried out for all key species involved: nitrobenzene (Ph-NO₂), nitrosobenzene (Ph-NO), phenylhydroxylamine (Ph-NHOH), and aniline (Ph-NH₂). A comparison of gas-phase and solvent-phase geometries revealed solvent-induced elongation of N–O and N–H bonds, particularly in polar intermediates, consistent with ethanol’s stabilizing effect. FMO analysis showed a notable decrease in HOMO–LUMO energy gaps in the solvent phase, indicating enhanced reactivity. IR spectra further supported these findings, with observable shifts in characteristic stretching frequencies upon solvation. In the Pd-catalyzed pathway, adsorption of reactants and intermediates on the Pd surface significantly altered molecular geometries and lowered reaction energy barriers. Calculated adsorption energies and bond elongations suggest strong Pd–O and Pd–N interactions that facilitate bond activation. The overall energy profile indicates a smoother and more favorable reduction pathway on the Pd surface compared to the noncatalyzed routes. These results provide mechanistic insight into the catalytic role of Pd in hydrogenation reactions and highlight the importance of solvent effects in modulating electronic and structural properties. This comparative approach enhances our understanding of nitroarene reductions and offers valuable guidance for catalyst design and process optimization.
Polyacrylic acid has been utilized to react with a variety of substances to create novel compounds with biological activity because it is a recognized safe material to work with. In this work, the AB chemical was created by reacting polyacrylic acid with benzidine. It was then combined with a class of cyclic aldehydes to create novel Schiff-base compounds with biological advantages. FT-IR and 1H-NMR spectroscopy were used to characterize them. Their melting point, solubility in various solvents, viscosity, and biological activity against gram-positive and gram-negative bacteria were all measured. Each sample's antioxidant activity was assessed and compared to ascorbic acid.
The current work aims to develop new hybrid nanostructures films to apply in various radiation shielding and optoelectronics nanodevices fields. The tungsten carbide (WC)-silicon dioxide (SiO2)-doped chitosan (CS)-po1yviny1a1cohol (PVA) new nanocomposites films were fabricated. The (CS-PVA/WC-SiO2) films exhibit outstanding properties compared to other nanomaterials, including low cost, excellent optical characteristics, flexibility, and lightweight nature. The microstructural, morphological and optical features for CS-PVA/WC-SiO2 films were investigated. The results indicated that the optical absorbance increased of (85
This work reports the fabrication and comprehensive characterization of polyvinyl alcohol-chitosan/graphene oxide (PVA-CS/GO) nanocomposite films with different graphene oxide (GO) nanoparticle concentrations (0-6 wt%). The nanocomposites were prepared using a simple solution casting technique and systematically investigated to understand the influence of GO incorporation on the structural, optical, dielectric, and sensing properties of the polymer matrix. FTIR analysis confirmed strong interfacial interactions between PVA-CS chains and GO nanoparticles through hydrogen bonding, while optical microscopy revealed a homogeneous dispersion of GO within the polymer network. The optical analysis demonstrated a significant enhancement in light-matter interaction after GO incorporation. The optical band gap decreased from 5.49 to 4.60 eV for allowed indirect transitions and from 5.12 to 4.19 eV for forbidden transitions with increasing GO content, indicating the formation of localized energy states within the polymer matrix. Additionally, key optical parameters such as the refractive index, dielectric constants (epsilon ' and epsilon ''), and optical conductivity increased with GO loading, whereas transmittance decreased due to enhanced photon absorption. Nonlinear optical parameters including linear susceptibility chi (1), third-order susceptibility chi (3), and nonlinear refractive index (n2) exhibited noticeable improvement, suggesting enhanced optical polarizability of the nanocomposite films. Furthermore, dielectric analysis showed that the dielectric constant, dielectric loss, and AC electrical conductivity increase with nanoparticle concentration due to enhanced charge carrier mobility and interfacial polarization. The Urbach energy also increased, confirming the creation of additional defect states in the electronic structure. Pressure sensing measurements revealed improved mechanical flexibility, environmental stability, and high-pressure sensitivity compared with conventional polymer sensors. These results demonstrate that the incorporation of graphene oxide significantly tailors the optical and electrical properties of PVA-CS matrices, highlighting the novelty of this nanocomposite system as a promising material for flexible pressure sensors, optoelectronic devices, and nonlinear optical nanodevices.
In this study, NiFe₂O₄ nanoparticles were synthesized using a sol–gel auto-combustion technique and incorporated into a biopolymer matrix composed of PVA and chitosan to produce flexible nanocomposite films aimed at EMI shielding applications. The structural analysis confirmed a clear an increase in crystallite size and crystallinity of the NiFe₂O₄ nanophase, while inducing partial amorphization in the polymer matrix due to strong interfacial interactions. FTIR results confirmed strong interactions between Ni2⁺/Fe3⁺ ions and the polymer functional groups, leading to partial amorphization of the matrix. The incorporation of these nanofillers significantly enhanced the dielectric properties, electrical conductivity, and nonlinear optical performance of the nanocomposites. This study examined the optical, structural, morphological, and electromagnetic interference (EMI) properties of (PVA–Cs/NiFe2O4) nanocomposites. The optical microscope images illustrate a uniform distribution of blended nanoparticles, forming a cohesive network within the polymer matrix. The findings regarding the optical characteristics show that absorbance, absorption coefficient, refractive index, dielectric constant (both real and imaginary), and optical conductivity rise with increased concentrations of (NiFe2O4) nanoparticles. Simultaneously, the transmittance of the nanocomposites diminishes with an increase in nanoparticle concentration. The band gaps of (PVA–Cs/NiFe2O4) polymer nanocomposites diminish from 4.56 to 3.63 eV for permitted transitions and from 4.21 to 3.26 eV for forbidden transitions when the concentration of (NiFe2O4) nanoparticles increases the results indicate that the dispersion energy (Ed), average oscillator strength (So), and single oscillator energy (Eo) decrease progressively with increasing nanoparticle content. Conversely, the Urbach energy (Eu), linear optical susceptibility (χ1), third-order nonlinear susceptibility (χ3), nonlinear refractive index (n₂), oscillator wavelength parameter (λo), static dielectric constant (εo), and zero-frequency refractive index (no) show a consistent upward trend with higher nanofiller concentrations. From an electrical standpoint, the dielectric constant (ε′), dielectric loss (ε″), and electrical conductivity also increase as the nanoparticle loading rises, indicating enhanced polarization effects and improved charge carrier mobility within the nanocomposite matrix. The nanocomposite containing NiFe₂O₄ exhibited a total shielding effectiveness approaching 65 dB, highlighting its capability to suppress electromagnetic pollution through absorption-dominated mechanisms. These results demonstrate that combining magnetic ferrite nanocrystals with a biodegradable polymer system offers a strategic route for fabricating efficient, lightweight, and flexible EMI shielding materials suitable for advanced electronic, stealth, and communication technologies.
