Search Results (172)

Modern agriculture relies heavily on the use of pesticides, with one-third of them being herbicides. Chloroacetamides are the most widely used herbicides because of their high effectiveness, but their extensive use poses environmental challenges and threatens the health of living organisms due to toxicity risks. Since the pharmacokinetic behavior and toxicity of a compound are influenced by its lipophilicity, this essential physicochemical parameter for disubstituted chloroacetamides was determined in silico and experimentally through thin-layer chromatography on reversed phases (RPTLC C18/UV254s) in mixtures of water and distinct organic modifiers. The pharmacokinetic profile of chloroacetamides was analyzed by using the BOILED-Egg model. The correlation between the obtained chromatographic parameters and software-based lipophilicity, pharmacokinetic, and ecotoxicity predictors of the studied chloroacetamides was assessed by using linear regression, but more comprehensive insight was obtained through multivariate methods—Cluster Analysis and Principal Component Analysis. It was observed that the total number of carbon atoms in the structure of their molecules, along with the type of hydrocarbon substituents, are the most important factors affecting lipophilicity, pharmacokinetics, and potential toxicity to non-target organisms. Full article

DFT calculations at the B3LYP/aug-cc-pVDZ level of theory on some aromatic substrates showed that in the HOMO (Highest Occupied Molecular Orbital) of nitrobenzene, the atomic coefficients are not in agreement with the meta-directing behavior of this compound. The atomic coefficients are the same in the ortho and in the meta positions. The HOMO (or NHOMO (Next Occupied Molecular Orbital) in the case of benzaldehyde) is not in agreement with the experimental results when deactivating, meta-orienting compounds are considered. Mulliken charges sometimes are not able to explain the observed reactivity. Hirshfeld charges allow us to predict the orientation of the attack of an electrophile on the aromatic ring, with the exception of nitrobenzene. Both HOMO atomic coefficients and charges are in agreement with the experimental results when deactivating, ortho-para orienting, and activating compounds are tested. Full article

Polyaniline (PANI) based thermoelectric materials have attracted much attention in flexible energy harvesting devices due to their unique molecular structure, excellent chemical stability, and low cost. However, the intrinsic thermoelectric performance of intrinsic PANI makes it difficult to meet the needs of practical applications due to its low electronic transport properties. This review focuses on the preparation methods and key strategies for developing high-performance PANI-based thermoelectric materials. It aims to comprehensively update knowledge regarding synthesis methods, microstructures, thermoelectric properties, and underlying mechanisms. The overall goal is to provide timely insights to promote the development of high-performance PANI-based thermoelectric materials. Full article

Ultra-high-molecular-weight polyethylene (UHMWPE) is a pivotal material in engineering and biomedical applications due to its exceptional mechanical strength, wear resistance, and impact performance. However, its extreme melt viscosity, caused by extensive chain entanglements, severely limits processability via conventional melt-processing techniques. Recent advances in catalytic synthesis have enabled the production of disentangled UHMWPE (dis-UHMWPE), which exhibits enhanced processability while retaining superior mechanical properties. Notably, heterogeneous catalytic systems, utilizing supported fluorinated bis (phenoxy-imine) titanium (FI) catalysts, polyhedral oligomeric silsesquioxanes (POSS)-modified Z-N catalysts, and other novel catalysts, have emerged as promising solutions, combining structural control with industrial feasibility. Moreover, optimizing polymerization conditions further enhances chain disentanglement while maintaining ultra-high molecular weights. These systems utilize nanoscale supports and ligand engineering to spatially isolate active sites, tailor the chain propagation/crystallization kinetics, and suppress interchain entanglement during polymerization. Furthermore, characterization techniques such as melt rheology and differential scanning calorimetry (DSC) provide critical insights into chain entanglement, revealing distinct reorganization kinetics and bimodal melting behavior in dis-UHMWPE. This development of hybrid catalytic systems opens up new avenues for solid-state processing and industrial-scale production. This review highlights recent advances concerning interaction between catalyst design, polymerization control, and material performance, ultimately unlocking the full potential of UHMWPE for next-generation applications. Full article

The synthesis of cannabigerol—a cannabinoid with significant pharmaceutical potential—is described. The synthesis involves four stages. In the first step, (E)-non-3-en-2-one reacts with dimethyl malonate to yield a cyclic enone, which is subsequently oxidized with bromine to produce the olivetol ester. This ester then undergoes an alumina-catalyzed coupling reaction with geraniol, followed by ester hydrolysis to obtain cannabigerol. By modifying the chain length of the enone in the initial step and employing allylic alcohols other than geraniol, a range of cannabigerol derivatives can be synthesized, including the natural product cannabigerovarin. Full article

Density functional theory calculations were performed to elucidate the mechanistic details and origins of the selectivity of the nickel-catalyzed hydroboration of vinylarenes using B₂pin₂/MeOH. The catalytic cycles involved four sequential elementary steps: hydronickelation, anion exchange, transmetalation, and reductive elimination. Kinetic analyses identified hydronickelation as the rate-determining step with an activation barrier of 19.8 kcal/mol, while transmetalation proceeded through a stepwise mechanism characterized by two distinct transition states. Comprehensive analyses of the relevant transition structures and energetics demonstrated that the observed R-enantioselectivity (94% ee) originated from favorable nonbonding interactions. Lastly, our calculations suggested that the Markovnikov regioselectivity was predominantly governed by steric factors rather than electronic effects. Full article

Hydroxymethyl 1,3-diol motifs are common structural motifs in natural products, particularly in polypropionates with important therapeutic potential. However, general and complementary methods for their regio- and diastereoselective synthesis remain limited. In this study, we expanded a second-generation epoxide-based methodology involving the regioselective cleavage of TIPS-monoprotected cis- and trans-2,3-epoxy alcohols using alkenyl Grignard reagents. Regioselective ring opening of cis-epoxides provided anti-1,3-diols, while trans-epoxides afforded the corresponding syn-1,3-diols. The use of cis-propenylmagnesium bromide and vinyl Grignard reagents enabled direct access to cis- and terminal homoallylic 1,3-diols, respectively, with moderate to good yields (46–88%) and excellent regioselectivities (95:5). In contrast, reactions with trans-propenyl Grignard reagent led to partial alkene isomerization, limiting their synthetic utility. To address this, a complementary two-step approach employing propynyl alanate addition followed by sodium/ammonia reduction was incorporated, providing access to trans-homoallylic 1,3-diols with high diastereoselectivity. All 1,3-diols were characterized by NMR spectroscopy, confirming regioselective epoxide opening. These combined strategies offer a practical and modular platform for the synthesis of syn- and anti-hydroxymethylated 1,3-diols and their application to the construction of polypropionate-type fragments, supporting future efforts in the total synthesis of polyketide natural products. Full article

Vancomycin, a cornerstone antibiotic against severe Gram-positive infections, is increasingly challenged by resistance in Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin Enterococcus spp. (VRE), necessitating the development of novel therapeutic strategies. This review examines how structural modifications to vancomycin can enhance its antibacterial activity and explores the critical role of computational approaches in designing the next generation of analogs. By analyzing the existing literature, we highlight how strategic alterations, such as the introduction of lipophilic side chains, substitutions on the sugar moieties, and modifications to the aglycone core, have yielded derivatives with improved antibacterial potency. Notably, certain analogs (e.g., Vanc-83, Dipi-Van-Zn) have demonstrated expanded activity against Gram-negative bacteria and exhibited enhanced pharmacokinetic profiles, including prolonged half-lives and improved tissue penetration, crucial for effective treatment. Semisynthetic glycopeptides like telavancin, dalbavancin, and oritavancin exemplify successful translation of structural modifications, offering sustained plasma concentrations and simplified dosing regimens that improve patient compliance. Complementing these experimental efforts, computational methods, including molecular docking and molecular dynamics simulations, provide valuable insights into drug–target interactions, guiding the rational design of more effective analogs. Furthermore, physiologically based pharmacokinetic modeling aids in predicting the in vivo behavior and optimizing the pharmacokinetic properties of these novel compounds. This review highlights a critical path forward in the fight against multidrug-resistant infections. By meticulously examining the previously carried out structural refinement of vancomycin, guided by computational predictions and validated through rigorous experimental testing, we underscore its immense potential. Full article

Papilloscopy, the science of human identification through fingerprints, has seen notable advancements in developing less toxic latent fingerprint developers (LFDs), especially from natural feedstock. Tannins, the second most abundant natural polyphenol, present a potential eco-friendly and cost-effective alternative, with no record of their use as LFDs in the existing literature. This study characterized four types of tannins from black wattle, using Fourier Transform Infrared Spectroscopy, revealing key functional groups like C=O, C=C, and O–H. Ultraviolet–visible absorption spectra showed similar behaviors for all tannins, indicating phenolic and benzenoid structures. Energy-dispersive X-ray Spectroscopy identified high concentrations of chlorine, sodium, potassium, and sulfur, naturally found in biomass and soil. Finally, elements in significant concentrations, such as sodium, potassium, iron, zinc, and copper, were found through the incineration of the spent bark. On the basis of these findings, the tannin with the highest potential for LFD was selected. Combining this tannin with spent bark ash resulted in a composite whose performance was evaluated using different methods, including depletion studies, tests with various donors, and assessments on different surfaces. The results demonstrated that this combination significantly enhanced the material’s efficiency by integrating organic and inorganic properties, which improved visual contrast and powder adhesion. Full article

The interaction between cucurbit[8]uril (Q[8]) and the guest 1-methyl-4-(4-(1-methylpyridin-1-ium-4-yl)benzamido)pyridin-1-ium (PB²⁺) has been thoroughly investigated. Multiple techniques were employed, including ¹H NMR spectroscopy, mass spectrometry, isothermal titration calorimetry (ITC), UV–vis absorption spectrophotometry, and quantum chemistry calculations. The experimental results and calculation analysis have clearly shown that in aqueous solution, the host Q[8] preferentially encapsulates the phenylpyridinium salt moiety of the PB²⁺ guest within its hydrophobic cavity, forming a 1:2 inclusion complex. Full article

A macrocyclic receptor based on azopyrrole and polyether was synthesized, and its structure was characterized by NMR (¹H and ¹³C), HRMS and X-ray crystallography. In the solid state, the macrocyclic molecules could bind methanol through a pair of N-H…O hydrogen bonds and further self-assembled into tubular structures through C-H…N hydrogen bonds. This revealed that the crystal could still keep its porous properties after the included molecules were removed. The UV–Vis titration indicates that the macrocylic receptor can chromogenically and selectively sense fluoride ion in DMSO solution, and the sensing mechanism was rationalized by ¹H NMR. Full article

A series of previously poorly studied heterocyclic compounds, 10R-pyrido[4,3-a]phenazines, including the previously unknown parent compound, has been synthesized. The proposed synthetic approach is remarkable for its simplicity, due to the ease of the synthesis of the starting materials from readily available precursors, and is characterized by high yields of the target products, achievable under both acidic and basic catalysis. The paper discusses the synthesis conditions, optimization procedures, and X-ray crystallographic data. Full article

Heterocycle cores are widely used in medicinal chemistry for developing bioactive compounds. In this scenario, using cheap and accessible starting material to build these heterocycles is desirable to obtain new drug candidates for cost-efficient processes. One easily accessible source of starting material are amino acids. Usually, these compounds are employed in peptide synthesis, but their use for building heterocycle frameworks presents another appealing opportunity. Therefore, this review highlights the application of histidine and tryptophan, two heteroaromatic amino acids, in fused heterocyclic scaffold synthesis and their use in bioactive compounds. Full article

Metal–organic frameworks (MOFs), particularly zirconium-based frameworks (Zr-MOFs), have gained significant attention in recent years due to their unique structural and functional properties. This review focuses on eco-friendly synthetic methods for producing Zr-MOFs, addressing the environmental impacts and costs associated with conventional synthesis, which often relies on hazardous reagents and harsh conditions. We explore various green synthesis strategies, including the selection of raw materials (such as using zirconium acetate), organic ligands (recycling waste materials for ligand synthesis), and synthesis methods (solvothermal, microwave-assisted, ultrasound-assisted, electrochemical, and mechanochemical approaches). Additionally, the application of Zr-MOFs in photocatalysis and electrocatalysis is examined, highlighting their potential for environmental purification and energy conversion. Despite the progress made in laboratory settings, challenges remain in achieving cost-effectiveness, material stability, and scalability for industrial applications. Future research should concentrate on enhancing synthesis efficiency, optimizing catalytic properties, investigating structure–property relationships, and expanding applications to novel catalytic reactions, thus ensuring Zr-MOFs can contribute to sustainable development in chemical science and technology. Full article

This study concerns the investigation of the sorption and desorption phenomena of the organic dye methylene blue (MB) on three different marine sediments and non-living biomass of the seagrass species Posidonia oceanica. All tested adsorbents were of natural origin and were collected from unpolluted coasts of the North Aegean Sea (Greece). The batch equilibrium technique was applied and MB concentrations were determined by spectrophotochemical analysis (λ = 665 nm). The experimental results showed that all four isotherm models, Freundlich, Langmuir, Henry, and Temkin, could describe the process. The normalized to organic matter content adsorption coefficients (K_OM) ranged between 33.0765 and 34.5279 for the studied sediments. The maximum adsorption capacity (q_max) of sediments was in the range of 0.98 mg g⁻¹ and 6.80 mg g⁻¹, indicating a positive correlation with the adsorbents’ organic matter content, textural analysis of fine fraction (<63 μm), and specific surface area. The bioadsorption of MB on P. oceanica biomass resulted in 13.25 mg g⁻¹ up to 17.86 mg g⁻¹ adsorption efficiency. Desorption studies revealed that the studied dye in most cases was very strongly adsorbed on studied matrices with extremely low quantities of seawater extractable amounts (≤1.62%). According to the experimental findings, phycoremediation by using P. oceanica can be characterized as an efficient method for the bioremediation of dye-polluted wastewater. Full article