Search Results (1,433)

Cytisine, a naturally occurring alkaloid and partial agonist of nicotinic acetylcholine receptors (nAChRs), has long been used as a smoking cessation aid and serves as the pharmacophore for varenicline. Recent research has expanded its therapeutic scope to neurodegenerative and neurological disorders, motivating the development of new cytisine derivatives. Among these, N-propargylcytisine combines the biological activity of the parent compound with the synthetic versatility of the terminal alkyne group. Herein, we report the synthesis and characterization of N-propargylcytisine, and its symmetrical dimer linked through 1,3-diyne moiety obtained via a copper-mediated Glaser–Hay oxidative coupling. The products were analyzed by NMR, FT-IR, and mass spectrometry, confirming the introduction of the propargyl moiety and the formation of the diyne bridge. Solvatochromic study of both compounds were performed using UV-VIS absorption spectroscopy in solvents of varying polarity, including protic solvents capable of hydrogen bonding. The 1,3-diyne motif, commonly found in bioactive natural products, endows the resulting dimer with potential for further derivatization and biological evaluation. This study demonstrates the utility of the Glaser–Hay reaction in the functionalization of alkaloid scaffolds and highlights the prospects of N-propargylcytisine derivatives in drug discovery targeting the central nervous system. Full article

We report the synthesis and characterization of the novel pyridinium salts from (E)-2-(pyridin-4-ylmethylene)hydrazine-1-carboximidamide. The pyridinium salts were obtained via the reaction of guanylhydrazone derived from pyridine-4-carbaldehyde with phenacyl bromides. Structural characterization was carried out using IR, ¹H, and ¹³C NMR spectroscopy and mass spectrometry. Full article

2,2-Bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethanol (HL) is a heteroscorpionate ligand capable of coordinating metal ions through two nitrogen atoms and one oxygen atom. We report a base free synthetic route to metal complexes of L and explore the resulting structural diversity. Notably, complex composition varies substantially depending on the metal ion, including dinuclear molybdenum species and distinct coordination behavior with silicon and copper. The isolated compounds include the dinuclear, oxygen-bridged complexes (LMoO₂)₂O and (LMoO)(μ-O)₂, as well as the mononuclear complexes LTi(NMe₂)₃, LZrCl₃, LGeCl₃, LWO₂Cl, LCu(acetate)₂H, and LSiMe₂Cl. Single crystal X-ray diffraction reveals that the bulky complex structures generate cavities in the crystal lattice, frequently occupied by solvent molecules. The titanium, zirconium, molybdenum, tungsten, and germanium complexes exhibit octahedral coordination, while structural peculiarities are observed for copper and silicon. The copper(II) complex shows a distorted octahedral geometry with one elongated ligand bond; the silicon complex is pentacoordinated in the solid state. Additional characterization includes melting points, NMR, and IR spectroscopy. The developed synthetic strategy provides a straightforward and versatile route to heteroscorpionate metal complexes. Full article

Cyclodextrin-based nanosponges (CDNSs) are novel polymers composed of cross-linked cyclodextrin (CD) macrocyclic units, whose characteristics make them great candidates for drug delivery systems with adjustable properties for the drug release process. Examination of the molecular structure and dynamics of CDNSs is a necessary starting point in the first step toward their broad application. Spectroscopic methods are effective analytical tools for probing the structure–property relationships of polymer structures. Infrared (IR) and Raman spectroscopies provide insight into the behavior of hydrogen bond (H-bond) networks influencing the properties of CDNS polymeric networks. Scattering techniques such as inelastic neutron scattering (INS) and Brillouin light scattering (BLS) probe elastic properties, while small-angle neutron scattering (SANS) examines the structural inhomogeneities and water sorption abilities of CDNS materials. Complete evaluation is possible using nuclear magnetic resonance (NMR), which can provide data on CDNS network dynamics. This article summarizes the results of a wide examination of CDNSs with the use of spectroscopic methods and reveals the links between the microscopic behavior and macroscopic properties of CDNSs, enabling the customization of their properties for various biomedical purposes. Full article

Amorphous solid dispersions (ASDs) represent a promising formulation strategy for improving the solubility and bioavailability of poorly water-soluble drugs, a major challenge in pharmaceutical development. This review provides a comprehensive analysis of the physicochemical principles underlying ASD stability, with a focus on drug–polymer miscibility, molecular mobility, and thermodynamic properties. The main manufacturing techniques including hot-melt extrusion, spray drying, and KinetiSol^® dispersing are discussed for their impact on formulation homogeneity and scalability. Recent advances in excipient selection, molecular modeling, and in silico predictive approaches have transformed ASD design, reducing dependence on traditional trial-and-error methods. Furthermore, machine learning and artificial intelligence (AI)-based computational platforms are reshaping formulation strategies by enabling accurate predictions of drug–polymer interactions and physical stability. Advanced characterization methods such as solid-state NMR, IR, and dielectric spectroscopy provide valuable insights into phase separation and recrystallization. Despite these technological innovations, ensuring long-term stability and maintaining supersaturation remain significant challenges for ASDs. Integrated formulation design frameworks, including PBPK modeling and accelerated stability testing, offer potential solutions to address these issues. Future research should emphasize interdisciplinary collaboration, leveraging computational advancements together with experimental validation to refine formulation strategies and accelerate clinical translation. The scientists can unlock the full therapeutic potential with emerging technologies and a data-driven approach. Full article

With the increasing demand for soil modification technologies in the field of civil engineering, this study employed cement-stabilized soil and MBER (Material Becoming Earth into Rock) stabilized soil as controls to investigate the modification effects of an N-MBER (nanosilica reinforced MBER) stabilizer on the mechanical properties and microstructure of loess. The mechanical and water stability characteristics of N-MBER-stabilized loess under varying moisture contents and compaction degrees were analyzed through unconfined compressive strength (UCS) tests, softening coefficient tests, falling-head permeability tests, and wet–dry cycle tests. Combined with scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance (NMR) techniques, the underlying mechanism of the N-MBER stabilizer in loess stabilization was thoroughly revealed. The results indicate that the N-MBER stabilizer significantly enhances the UCS and softening coefficient of loess. Particularly, under conditions of 28-day curing, a moisture content of 16%, and a compaction degree of 1, the compressive strength achieves a local optimum value of 3.68 MPa. Compared to soils stabilized with MBER stabilizers and cement stabilizers, the N-MBER-stabilized loess exhibits superior water resistance and microstructural density, with a significant reduction in the proportion of pore defects. Specifically, after five wet–dry cycles at a curing age of 28 days, the strength loss rates for MBER-stabilized soil and cement-stabilized soil were 24.4% and 27.54%, respectively, while that for N-MBER-stabilized soil was 18.23%, demonstrating its enhanced water resistance. Additionally, compared to cement-stabilized soil, the N-MBER-stabilized soil exhibited a 21.63% reduction in total pore number, with a 41.64% reduction specifically in large pores. The extremely small particle size and large specific surface area of the nanomaterial enable more effective interactions with soil particles, promoting hydration reactions. The resulting ettringite (AFt) and three-dimensional networked C-S-H gel tightly interweave with soil particles, forming a stable cemented structure. Compared to traditional concrete roads, stabilized soil roads enable the utilization of locally available materials and demonstrate a significant cost advantage. This study provides theoretical support and experimental evidence for the application of nanomaterials in loess improvement engineering. Full article

A novel quinoline-containing benzoxazine resin, 8HQ-fa, has been successfully synthesized at room temperature using sustainable raw materials, such as 8-hydroxyquinoline and furfurylamine as the phenol and amine source, respectively. The chemical structure of the hereinafter referred to as quinolinoxazine is fully characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR), as well as by 2D ¹H–¹H nuclear Overhauser effect spectroscopy (NOESY) and ¹H–¹³C heteronuclear multiple quantum correlation (HMQC) NMR. Thermal properties and polymerization behavior of the monomer are studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The resulting polymer is also characterized in terms of its thermal and fire-related properties by DSC, TGA, and microscale combustion calorimetry (MCC). The resulting thermoset, poly(8HQ-fa), presents good thermal stability as evidenced by its T_g (201 °C), T_d5 and T_d10 (307 and 351 °C, respectively), and char yield (42%), and low flammability as determined by the LOI, heat release capacity, and total heat released values (34.3, 143 J/gK, and 10.8 kJ/g, respectively), making it a self-extinguishing thermoset. The combination of properties and advantages in the synthesis of 8HQ-fa, accompanied by a low polymerization temperature, suggests its great potential in the field of high-performance polymers. Full article

Syringic acid (1) is a naturally occurring compound with diverse biological activities. Structural modification of syringic acid often enhances its utility; however, the spectroscopic data for several derivatives remain unreported, and the procedures to obtain them can be synthetically challenging. In this study, we report the allylation of syringic acid (1) to afford a novel derivative, allyl syringate (1c). The structure of this compound was confirmed by IR, NMR, and MS spectroscopy and compared with those of closely related derivatives (1a and 1b). These findings provide a useful foundation for further studies on the allylation of syringic acid and related phenolic acid derivatives. Full article

Euphorbia esula is widely distributed across China, Central Asia and other regions worldwide. For centuries, it has been applied in folk and traditional medicine as a cure for diverse ailments. Nevertheless, the bioactive components responsible for anti-inflammatory and cytotoxic effects remain incompletely identified. In this study, two undescribed chemical constituents, a pyrrole alkaloid (1) and a loliolide analogue (2), alongside nine known components (3–11) were separated from the aerial parts of Euphorbia esula indigenous to Uzbekistan. Their chemical structures were comprehensively elucidated utilizing HRESIMS, NMR, IR and UV spectroscopy. Corresponding absolute configurations were determined based on comparison of experimental and calculated ECD data. Compounds 3–11 were firstly isolated from Euphorbia esula, among which 4, 5, 7 and 9–11 were yielded from the genus Euphorbia for the first time. Chemically, the discovery of various skeletons covering pyrrole alkaloids (1, 9), norisoprenoids (2–8), furanone (10) and unusual cyclooct-2-enone (11) particularly highlighted the structural diversity. Bioactivity assays revealed that some compounds (1, 3, 5, 6, 7 and 8) exhibited certain anti-inflammatory effects via inhibiting the NO release in LPS-induced RAW 264.7 macrophages. Full article

This study developed a novel adsorbent for Cr (VI) removal from wastewater by grafting N-[(dimethylamino)methylene]thiourea (TUFA) onto lignin. The resulting TUFA-functionalized lignin adsorbent AL was comprehensively characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS). Batch adsorption experiments systematically evaluated the influence of solution pH, contact time, temperature, initial Cr (VI) concentration, and adsorbent dosage. AL exhibited high adsorption capacity (593.9 mg g⁻¹ at 40 °C), attributed to its abundant nitrogen and sulfur-containing functional groups. Kinetic analysis revealed that the adsorption process followed pseudo-second-order kinetics. Equilibrium isotherm data were best described by the Langmuir model, indicating predominant monolayer chemisorption. Thermodynamic parameters demonstrated that Cr (VI) adsorption onto AL is spontaneous, endothermic, and entropy-driven. The adsorption mechanism involves membrane diffusion and intra-particle diffusion processes. This work successfully synthesized a stable, effective, and low-cost adsorbent (AL) using an amine agent incorporating both nitrogen and sulfur functional groups, offering a promising approach for treating Cr (VI)-contaminated wastewater. Full article

A new family of monothiooxalamide derived from 2-aminobenzothiazole was synthesized with the purpose of investigating its anticancer activity. The design of the compounds was focused on targeting the HDAC6 enzyme, a target for antineoplastic drugs. The in silico affinity of compounds to HDAC6 was performed and confirmed by docking simulation. The structures of monothiooxalamide–benzothiazole hybrids were characterized by 1D and 2D NMR experiments, as well as through mass spectrometry and IR spectroscopy. In addition, the antiproliferative activity of compounds was assessed in human breast cancer cell lines (MCF-7 and MDA-MB231) and non-malignant cells (MCF-10A and NIH/3T3). The most active compound was N-(benzo[d]thiazol-2-yl)-2-((4-methoxybenzyl)amino)-2-thioxoacetamide (1c), which inhibited breast cancer cell growth and invasiveness in vitro and induced late apoptosis in the MCF-7 cell line. The molecular structure of 1c was solved by single-crystal X-ray diffraction. The supramolecular arrangement of benzothiazole and 4-methoxy-benzylamine moieties, present in the crystal structure of 1c, was consistent with the interactions on the docked DD2-HDAC6 catalytic site. Full article

An amino acid-derived 2-thiohydantoin, 5-(2-methylsulfanylethyl)-3-prop-2-enyl-2-sulfanylideneimidazolidin-4-one, obtained from l-methionine, was synthesized in a two-step reaction protocol with allyl isothiocyanate. The compound was obtained in an 82% yield and was fully structurally characterized by NMR and IR spectroscopy. The crystal structure, molecular packing, and intermolecular interactions were characterized by X-ray diffraction analysis. Full article

A pressing scientific task is the development of modern extractants that meet the increased requirements for efficiency and safety. In this work, a new three-component eutectic solvent based on bis(2,4,4-trimethylpentyl)phosphinic acid (BTMPPA), tributyl phosphate (TBP) and phenol was proposed. The formation of the eutectic solvent was confirmed by IR and ³¹P NMR spectroscopy. The temperature dependences of the main physical properties of the proposed eutectic solvent—the refractive index, density and viscosity—were determined. For the first time, the extraction properties of the eutectic solvent BTMPPA/TBP/phenol (1:1:2) were studied using the example of the extraction of metal ions from aqueous nitrate solutions. The extraction efficiencies of Pr, Nd and Dy in a single stage were 34, 38 and 81%, respectively. The extraction behaviour of Pr, Nd and Dy with the eutectic solvent BTMPPA/TBP/phenol was studied as a function of pH, salting-out agent concentration, component ratio in the eutectic mixture, phase volume ratio, etc. Nitric acid with a concentration of 0.5 mol/L was chosen as a stripping agent, and the chemical stability of the eutectic solvent BTMPPA/TBP/phenol during extraction–stripping cycles was evaluated. In summary, the proposed hydrophobic eutectic solvent has good physical characteristics and enables a more efficient recovery of rare-earth elements from nitrate solutions. Full article

The search for bioactive compounds with antioxidant properties is critical in combating oxidative stress-related diseases and advancing novel therapeutic agents. Azo dyes, traditionally used in textiles, food, and cosmetics, have recently attracted attention due to their emerging biological activities, including antioxidant potential. In this study, we synthesized and characterized 267 azo dyes derived from natural phenolic cores such as salicylic acid, syringol, and 5,6,7,8-tetrahydro-2-naphthol. Eighteen of these compounds are novel. Structural characterization was performed using NMR, UV-Vis, IR spectroscopy, and mass spectrometry. Antioxidant activity was assessed using in vitro assays with ABTS radical scavenging method. SAR analysis revealed that dyes derived from syringol and 5, 6, 7, 8-tetrahydro-2-naphthol showed the most consistent and potent antioxidant activity. Notably, azo dyes bearing fluoro and nitro substituents in the para position exhibited the lowest IC₅₀ values, highlighting the influence of electron-withdrawing groups and substitution patterns on antioxidant behavior. This work establishes a precedent for SAR-driven evaluation of azo dyes using ABTS and supports their further exploration as functional antioxidant agents in medicinal chemistry. Full article