Search Results (3,138)

This study synthesizes three new composites: chitin-cross-linked poly(ortho-phenylenediamine)-grafted silicon dioxide (CT-PoPD-grafted SiO₂), chitosan-cross-linked PoPD-grafted SiO₂ (CS-PoP-grafted SiO₂), and guar-gum-cross-linked PoPD-grafted SiO₂ (GG-PoPD-grafted SiO₂). These biopolymer-based materials were developed as cost-effective, biocompatible adsorbents with increased surface area for removing Acid Red 1 AR1) and Crystal Violet (CV) dyes. Structural and morphological analyses through Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) confirmed their successful synthesis. Adsorption studies were conducted under various conditions, including adsorbent dosage, pH, temperature, and contact time. Among the composites, GG-PoPD-grafted SiO₂ demonstrated superior performance, achieving 99.1% and 95.6% removal of AR1 and CV, respectively. Kinetic analysis revealed a pseudo-second-order model, while thermodynamic results indicated a spontaneous and endothermic adsorption process. In conclusion, the GG-PoPD-grafted SiO₂ composite exhibits significant potential as an effective and sustainable material for wastewater treatment. Full article

Zinc oxide (ZnO) nanomaterials have emerged as promising candidates for gas sensing applications due to their high sensitivity, fast response–recovery cycles, thermal and chemical stability, and low fabrication cost. However, the performance of pristine ZnO remains limited by high operating temperatures, poor selectivity, and suboptimal detection at low gas concentrations. To address these limitations, significant research efforts have focused on dopant incorporation and polymer hybridization. This review summarizes recent advances in dopant engineering using elements such as Al, Ga, Mg, In, Sn, and transition metals (Co, Ni, Cu), which modulate ZnO’s crystal structure, defect density, carrier concentration, and surface activity—resulting in enhanced gas adsorption and electron transport. Furthermore, ZnO–polymer nanocomposites (e.g., with polyaniline, polypyrrole, PEG, and chitosan) exhibit improved flexibility, surface functionality, and room-temperature responsiveness due to the presence of active functional groups and tunable porosity. The synergistic combination of dopants and polymers facilitates enhanced charge transfer, increased surface area, and stronger gas–molecule interactions. Where applicable, sol–gel-based studies are explicitly highlighted and contrasted with non-sol–gel routes to show how synthesis controls defect chemistry, morphology, and sensing metrics. This review provides a comprehensive understanding of the structure–function relationships in doped ZnO and ZnO–polymer hybrids and offers guidelines for the rational design of next-generation, low-power, and selective gas sensors for environmental and industrial applications. Full article

Herein, the synthesis and crystallization of the unreported compound N-(2-fluoro-2-propen-1-yl)-5-(trifluoromethyl)-2-pyridinecarboxamide is achieved via amide coupling with a (2-fluoroallyl)ammonium salt. The structural properties are analyzed via single-crystal X-ray crystallography. Hydrogen bonding interactions between the amide groups and pyridine nitrogen atoms create a unique linear array of molecules in the crystal packing diagram. Furthermore, to validate the crystallographic data, the structural features of the compound are evaluated and compared to values reported in the literature. Full article

N-vinylindoles have attracted attention for their promising role in medicinal chemistry. Therefore, developing new synthetic methods that enable access to diverse functionalized N-vinylindoles with potential pharmacological properties is highly valuable. 1-[2-aryl-1-(4,5-dihydro-1H-imidazol-2-yl)vinyl]-1H-indoles 2a-i were prepared via Knoevenagel condensation promoted by 1H-benzotriazole, and characterized by IR, NMR, and MS spectroscopic data as well as a single-crystal X-ray diffraction-based study of the representative derivative 2g. The obtained compounds 2a-i were screened for their cytotoxic potency against human cancer cell lines (HeLa, SKOV-3, AGS) and non-cancerous cell line (HaCaT) using the MTT assay. Additional apoptosis analysis and cell cycle assay on SKOV-3 cells were conducted. Their antimicrobial activity was determined using reference strains of S. aureus, E. coli, C. albicans, and C. glabrata. The potent inhibitory activity against AGE2-BSA/sRAGE interaction of selected N-vinylindoles 2b, 2d-f, and 2h-i was evaluated by ELISA assay. A facile approach has been developed for the synthesis of a novel class of N-vinylindoles. The preliminary structure–activity considerations indicated that the presence of substituents R, such as 4-bromophenyl (compound 2f) or 2-naphthyl (compound 2i) is optimal for anticancer activity and the AGE2-BSA/sRAGE interaction inhibition. The most prominent (Z)-1-[1-(4,5-dihydro-1H-imidazol-2-yl)-2-(naphthalen-2-yl)vinyl]-1H-indole (2i) was found to strongly arrest cell cycle in the SKOV-3 cell line in the subG0 phase, inducing apoptosis. Notably, derivative 2i also exhibited the highest activity against S. aureus and C. albicans strains within the tested series. These findings highlight the substantial potential of N-vinylindole derivative 2i as a lead compound for the development of anticancer drugs with additional inhibitory activity on the AGE/RAGE interaction. Full article

An investigation of the molecular structure of a series of phenolphthalein derivatives is presented. The X-ray structures of thymolphthalein, 2,5-dimethylphenolphthalein, and 2,6-dimethylphenolphthalein have been determined for the first time. Furthermore, a series of related 3-(4-hydroxy-dialkyl)-3-(4-hydroxyphenyl)isobenzofuran-1(3H)-ones have also been prepared, and X-ray structures obtained. The present study allows for comparison of the structures of substituted phenolphthalein derivatives, with a particular focus on the effect of different alkyl groups on the structures. Full article

This study presents a novel dual-temperature synthesis strategy for cobalt, zinc, and iron-based metal–organic frameworks (MOFs) integrated with tannic acid (TA) surface modification to enhance oxygen evolution reaction (OER) performance. MOFs were synthesized at room temperature and 80 °C, enabling controlled crystal growth and distinct morphologies. Subsequent TA treatment effectively tuned surface chemistry without altering core crystallinity, as confirmed by PXRD, FT-IR, and XPS analyses. Surface modification introduced oxygen-containing functional groups, improved charge transfer, and increased active-site accessibility. Among the catalysts, the tannic acid-modified Fe-based MOF synthesized at 80 °C (TAFeM-2) exhibited outstanding OER activity, achieving an overpotential of only 254 mV at 10 mA cm⁻², outperforming benchmark RuO₂ (276 mV) and unmodified counterparts. Tafel slope analysis revealed faster reaction kinetics for surface-tuned MOFs, while electrochemical impedance spectroscopy indicated reduced charge-transfer resistance (12 Ω for TAFeM-2). Chronoamperometry demonstrated exceptional long-term stability, maintaining constant current density over 20 h with minimal performance loss. Post-OER characterization suggested surface oxidation to iron oxyhydroxides without significant structural degradation. This work demonstrates that combining dual-temperature synthesis with TA surface engineering yields MOF-based catalysts with superior activity, conductivity, and durability, offering a promising pathway for developing high-performance electrocatalysts for sustainable energy applications. Full article

This study reports the synthesis, structural characterization, and electromagnetic shielding performance of tantalum (Ta)-doped nickel ferrite (NiFe₂O₄) composites reinforced with chopped strands. Ta-doped NiFe₂O₄ powders were prepared via the conventional mixed-oxide route and sintered at 1200 °C for 4 h, resulting in a well-crystallized single-phase spinel structure. Comprehensive structural and chemical analyses were carried out using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), confirming the successful incorporation of Ta into the NiFe₂O₄ lattice and the uniform microstructural distribution. The ferrite powders were subsequently embedded with chopped strands and epoxy resin through hot pressing to fabricate composites with varying filler contents. The electromagnetic interference (EMI) shielding effectiveness (SE) of the composites was systematically evaluated in the 7–18 GHz frequency range using a network analyzer (NA). The optimized composite, with a thickness of 1.2 mm, demonstrated a maximum SE of 34.74 dB at 17.4 GHz, primarily attributed to interfacial polarization, dipolar relaxation, and multiple scattering effects induced by the chopped strands. The results indicate that the shielding performance of the composites can be precisely tuned by modifying the filler concentration and microstructural characteristics, enabling selective frequency-band applications. Overall, this work highlights the potential of Ta-doped NiFe₂O₄/chopped strand composites as lightweight, cost-effective, and high-performance candidates for advanced microwave absorption and electromagnetic shielding applications in defense, and next-generation communication technologies. Full article

This work quantifies how varying the Na/OSDA ratio in the synthesis gel (at fixed total [OH] content) affects the formation of SSZ-39, its growth kinetics, and the composition of the products obtained. It was found that it is possible to make phase-pure SSZ-39 with Si/Al ratios varying from 6.3 to 10.7 with Na/OSDA ratios from 9.1 to 1.7 in the synthesis gel. Higher Na/OSDA ratios lead to faster crystallization, supporting the hypothesis that FAU dissolution is the rate-limiting step in SSZ-39 synthesis when FAU serves as the aluminum source. DFT modeling suggests that, in the presence of OSDA molecules, increased Na content lowers the energy penalty for placing Al atoms in close proximity, which may explain why higher NaOH/OSDA ratios experimentally yield lower Si:Al ratios. This work offers another way to control the framework composition and potentially impact the local structure of the SSZ-39 that is obtained. Cobalt titration was performed to probe the presence of so-called aluminum pairs in samples made with different Na/OSDA ratios. The cobalt uptake in the H-form products is consistently low and suggests that factors other than aluminum pairing, such as solution pH, could be important in influencing the cobalt uptake. Full article

This work reports the synthesis and characterization of a novel rhenium(I) complex incorporating a phosphorus–nitrogen (P,N) ligand. The compound crystallizes in a distorted octahedral geometry, as confirmed by single-crystal X-ray diffraction analysis. The complexes were evaluated as catalysts in the transfer hydrogenation of acetophenone using 2-propanol as the hydrogen source. Comparative studies with other rhenium(I) complexes bearing polypyridine ligands revealed high catalytic performance, achieving conversions between 68% and 99%. These results highlight the promising potential of P,N-ligand rhenium complexes in homogeneous transfer hydrogenation catalysis. The optimal reaction time was found to be 4 h for the complexes studied, with only the fac-[Re(CO)₃(PN)Cl] complex showing improved conversion upon extending the reaction time to 7 h, likely due to the donor effects provided by the P,N-ligand. Full article

This study aimed to develop an industrially scalable coating route for enhancing the oxidation resistance of carbon fiber fabrics, a critical requirement for next-generation aerospace and high-temperature composite structures. To achieve this goal, synthesis of hexagonal boron nitride (h-BN) layers was achieved via a single wet step in which the fabric was impregnated with an ammonia–borane/THF solution and subsequently nitrided for 2 h at 1000–1500 °C in flowing nitrogen. Thermogravimetric analysis coupled with X-ray diffraction revealed that amorphous BN formed below ≈1200 °C and crystallized completely into (002)-textured h-BN (with lattice parameters a ≈ 2.50 Å and c ≈ 6.7 Å) once the dwell temperature reached ≥1300 °C. Complementary XPS, FTIR and Raman spectroscopy confirmed a near-stoichiometric B:N ≈ 1:1 composition and the elimination of O–H/N–H residues as crystallinity improved. Low-magnification SEM (100×) confirmed the uniform and large-area coverage of the BN layer on the carbon fiber tows, while high-magnification SEM revealed a progressive densification of the coating from discrete nanospheres to a continuous nanosheet barrier on the fibers. Oxidation tests in flowing air shifted the onset of mass loss from 685 °C for uncoated fibers to 828 °C for the coating produced at 1400 °C; concurrently, the peak oxidation rate moved ≈200 °C higher and declined by ~40%. Treatment at 1500 °C conferred no additional benefit, indicating that 1400 °C provides the optimal balance between full crystallinity and limited grain coarsening. The resulting dense h-BN film, aided by an in situ self-healing B₂O₃ glaze above ~800 °C, delayed carbon fiber oxidation by ≈140 °C. Overall, the process offers a cost-effective, large-area alternative to vapor-phase deposition techniques, positioning BN-coated carbon fiber fabrics for robust service in extreme oxidative environments. Full article

The Na₂O-SrO-SiO₂ system shows promise in the development of glasses that can be transformed into electrically conductive glass ceramics. The conventional processing of such materials usually involves the synthesis of a parent glass, followed by a complex devitrification treatment. This study proposes a simplified approach based on the use of preceramic polymers, namely silicone resins combined with oxide fillers. These systems yield silicate-based ceramics through direct heat treatment, replicating the phase assembly of traditional glass ceramics with no need for prior glass melting. A printable formulation was developed by mixing a silicone resin with an acrylate-based photocurable resin, sodium nitrate and strontium carbonate. The resulting ‘suspension-emulsion’ was later shaped into monolithic components using digital light processing. After pyrolysis in nitrogen atmosphere, the components transformed into SrSiO₃ crystals embedded in a composite matrix, in turn composed of glass and turbostratic carbon (the latter specifically offered by the silicone polymer). This combination of crystalline silicates and carbon resulted in measurable electrical conductivity. This study confirms that silicone-derived systems can serve as effective precursors for conductive glass-ceramic analogues, providing an alternative to conventional methods with single-step processing. This approach enables structural shaping through 3D printing and the development of functional properties suitable for electronic or electrochemical applications. Full article

Two phenanthroline derivatives, 2-(2,6-diisopropylphenoxy)-9-phenyl-1,10-phenanthroline and 2,9-bis(2,6-diisopropylphenoxy)-1,10-phenanthroline, were synthesized. The unsymmetrical derivative was obtained in high yield through a sequence combining Suzuki coupling and nucleophilic substitution. The crystal structures of both compounds were determined by single-crystal X-ray diffraction and examined by Hirshfeld surface analysis, which outlined the main intermolecular interactions responsible for the packing. The optical properties were studied by UV–Vis absorption and fluorescence spectroscopy in different solvents. The unsymmetrical compound showed stronger intramolecular charge transfer and more pronounced solvatochromism, while the symmetrical analog had a higher fluorescence quantum yield and longer excited-state lifetime. These results demonstrate the role of substitution symmetry in controlling molecular organization and photophysical properties of phenanthroline derivatives, with relevance to sensing and optoelectronic applications. Full article

A novel Ag(I) coordination polymer, [Ag₂(bipy)(btca)]_n, (SCP 1) was synthesized using 4,4′-bipyridyl (bipy) and 1,2,4,5-benzene-tetracarboxylic acid (H₄BTC). Characterization by FT-IR, ¹H/¹³C NMR, and single-crystal X-ray diffraction confirmed its 3D network structure. The structure of SCP 1 consists of two chains arranged in …ABAB… fashion. Chain A is one-dimensional, containing [Ag(4,4′-bipy)]_n chain, while chain B is free, containing uncoordinated 1,2,4,5-benzene tetracarboxylate and water molecules. The stacking and argentophilic interactions extend the chain A of [Ag(4,4′-bipy)]_n into a two-dimensional layer. In contrast, chain B of uncoordinated 1,2,4,5-benzene tetracarboxylate and water molecules form a 1-D chain through extensive hydrogen bonds between water molecules and BTC ions and between water molecules themselves. Chains A and B are connected through extensive hydrogen bonds, generating a three-dimensional network structure. This Silver I supramolecular coordination polymer (SCP 1) demonstrated high catalytic activity as a recyclable heterogeneous catalyst for the synthesis of 5-substituted 1H-tetrazoles via [3+2] cycloaddition of NaN₃ and terminal nitriles under solvent-free conditions in a Q-tube pressure reactor (yields: 94–99%). A mechanistic proposal involving cooperative Lewis acidic Ag(I) sites and Brønsted acidic -COOH groups facilitates the cycloaddition and protonation steps. SCP 1 catalyst exhibits reusability up to 4 cycles without significant loss of activity. The structural stability of the SCP 1 catalyst was assessed based on PXRD and FTIR analyses of the catalyst after usage, confirming its integrity during the recycling process. Full article

Metal–organic frameworks (MOFs) are a class of highly ordered nanoporous crystals that possess a designable framework and unique chemical versatility. MOF thin films are ideal for nanotechnology-enabling applications, such as optoelectronics, catalytic coatings, and sensing. Mg-MOF-74 has been drawing increasing attention due to its remarkable CO₂ uptake capacity among MOFs and other commonly used CO₂ absorbents. Mg-MOF-74 thin films are currently fabricated by immersing selected substrates in precursor solutions, followed by a traditional solvothermal synthesis process. Herein, we introduce a rapid, easy, and cost-effective synthesis protocol to fabricate MOF thin films in an additive manner. In this work, the controllable synthesis of Mg-MOF-74 thin films directly on optical supports is reported for the first time. Dense, continuous, and uniform Mg-MOF-74 thin films are successfully fabricated on bare glass slides, with an average growth rate of up to 85.3 nm min⁻¹. The structural and optical properties of the resulting Mg-MOF-74 thin films are characterized using X-ray diffraction, atomic force microscopy, scanning electron microscopy, UV-Vis-NIR spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR). The CO₂ adsorption performance of the resulting Mg-MOF-74 thin films is studied using FTIR for the first time, which demonstrates that, as per the length of the light path for gas absorption, 1 nm Mg-MOF-74 thin film could provide 400.9 ± 18.0 nm absorption length for CO₂, which is achieved via the extraordinary CO₂ adsorption by Mg-MOF-74. The synthesis protocol enables the rapid synthesis of MOF thin films, highlighting Mg-MOF-74 in more CO₂-related applications, such as enhanced CO₂ adsorption and MOF-enhanced infrared gas sensing. Full article

The investigation of the structure–function relationship in hypoxanthine-guanine phosphoribosyltransferases (HGPRT) is a direction that is relevant for the development of drugs and approaches of enzymatic synthesis of modified nucleosides and nucleotides. This research paper is dedicated to the investigation of binding of sulphonate molecules, such as HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) in the active sites of HGPRT and similar proteins. We report the crystal structure of HGPRT from Escherichia coli (EcoHGPRT) in a complex with HEPES. In the obtained X-ray structure, a HEPES molecule binds to the active site in a position that mimics one of the HGPRT substrates, namely phosphoribosylpyrophosphate (PRPP). Enzymological study has shown that HEPES is an inhibitor of EcoHGPRT, along with two structurally similar molecules, namely MES and PIPES. Comparison of the observed EcoHGPRT/HEPES complex to other reported structures in the context of inhibition study results provides an opportunity to explore the variety of binding modes of HEPES and similar molecules and to discuss the structure–function relationship in this enzyme and similar proteins. Full article