Search Results (280)

Volatile organic compound (VOC) emissions exhibit strong process-level heterogeneity, yet regional source characterization still commonly relies on sector-average profiles, introducing substantial uncertainty into source identification and control prioritization. In this study, process-resolved VOC source profiles were established for five representative industrial sectors in Deyang, a typical industrial city in the Chengdu–Chongqing region, including pharmaceutical manufacturing, industrial coating, chemical industry, food manufacturing, and the textile industry. A total of 19 organized emission samples were collected from 9 enterprises, and 123 VOC species were quantified. These measured profiles were further integrated with literature-derived profiles and a bottom-up emission inventory to construct an emission-weighted regional composite source profile for 17 major industrial sectors. An emission-based hydroxyl radical (OH) reactivity-weighted framework was then introduced to compare mass-dominant and chemically dominant VOC sources. The results showed pronounced process- and sector-specific differences in composition. Pharmaceutical manufacturing was mainly dominated by oxygenated VOCs (OVOCs), industrial coating by low-carbon halocarbons, the chemical industry by methanol and reactive low-carbon compounds, food manufacturing by alkenes and OVOCs, and the textile industry by light alkanes. At the regional scale, industrial VOC emissions were dominated by OVOCs (35.67%), followed by alkanes (19.01%) and aromatics (15.99%). Ethyl acetate, 1,4-dioxane, 1,1,2,2-tetrachloroethane, and m/p-xylene were identified as the most abundant species. However, OH reactivity was largely dominated by alkenes, and substantial discrepancies were observed between emission contribution and OH-reactivity-weighted contribution across sectors. In particular, the chemical industry contributed 21.10 ± 8.43% of reactive organic gas emissions but 28.82 ± 11.61% of OH-weighted emissions, whereas printing contributed 13.55 ± 13.42% of mass emissions but only 7.66 ± 13.08% of OH-weighted emissions. These findings demonstrate that regional VOC management should move beyond bulk mass reduction and prioritize high-reactivity sectors and process units to maximize O₃ mitigation benefits. Full article

Natural products from plants have played an important role in cancer and neurodegenerative diseases. In this context, the root bark of Maytenus chiapensis (Celastraceae) was investigated to examine its chemical constituents and potential biological activities. Chromatographic separation of the root bark extract yielded a new Diels–Alder adduct (morenine) formed by a triterpenophenolic moiety derived from tingenone and a bicyclic guaiane-type sesquiterpene linked through a 1,4-dioxane bridge. In addition, eight previously reported Diels–Alder adducts—retusonine and cheiloclines A–D and F–H—were isolated, together with their biosynthetic precursors, the quinone-methide triterpenoids (QMTs) pristimerin and tingenone. Structural elucidation was achieved through detailed 1D and 2D NMR spectroscopic analyses. The adducts were tested for cytotoxicity against six cancer cell lines (A549, SW1573, MIA PaCa-2, T-47D, HeLa, and WiDr cell lines), showing moderate-to-low activity compared with their precursors. Continuous live cell imaging identified apoptosis and vacuole formation as the main modes of action of pristimerin in SW1573 cells. Moreover, acetylcholinesterase inhibition assays revealed that cheiloclines B–D, F, and H exhibited up to 50% inhibition. These findings reinforce the potential of Celastraceae species as a source of unique and complex compounds and enhance our understanding of their therapeutic potential. Full article

Synthetic auxins are widely used nowadays as plant growth regulators and necessary components of media for micropropagation. Hence, the search for and development of novel auxin-like compounds is an important goal at the intersection of chemistry and biology. In this study, we have suggested alkylphenols as starting materials for the preparation of halogenated phenoxyacetic acids, which are well-known synthetic auxins, to decrease their possible phytotoxicity. Alkylphenoxyacetic acids were obtained with good yields, and their selective halogenation was studied. N-halogensuccinimides and molecular bromine in dioxane were shown as suitable reagents since they allowed for p-halogenophenoxyacetic acids to be synthesized with high yields. We further investigated the auxin-like activity of several obtained compounds. It was estimated that all of them stimulate tobacco Nicotiana tabacum L. pollen germination at concentrations 10⁻⁶–10⁻⁷ M with the maximum effect up to 157%. For the most efficient compounds, the germination of tobacco (Nicotiana tabacum L.) and corn (Zea mays) seeds was studied, as well as seedling growth. The results demonstrate the efficacy of obtained compounds as synthetic auxins, showing that alkylphenols are prospective starting materials for such compounds. Full article

The application of natural polysaccharides and their sulfated derivatives have already been successfully implemented in the pharmaceutical and food industries, in particular. The present study is concerned with modifying a predominant polysaccharide in the composition of spruce wood, galactoglucomannan (GGM), by sulfation via a urea-sulfamic acid complex in a 1,4-dioxane medium. By varying the sulfation process duration from 30 to 180 min, six novel GGM sulfate samples with different degrees of substitution (DS) of 0.4–1.2 were obtained and studied with a combination of modern physicochemical methods: elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and gel permeation chromatography (GPC). It has been revealed that the sulfation of GGM proceeds without degradation of the main polymer chain, as evidenced by the shift in the main peak toward the high-molecular-weight region in the GPC curves. Moreover, modification of the polysaccharide leads to a significant transformation of the molecular conformation from a dense sphere to a random coil (α from 0.30 to 0.76). Furthermore, it has been determined that sulfate-substituted groups of the GGM tended to decrease the scavenging capacity of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. However, the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assay showed an increase in the free radical inhibitory capacity of sulfated polysaccharides. This is attributed to the structural and conformational properties of the polysaccharide sulfate derivatives. The maximum anticoagulant activity (ACA) of sulfated GGM (SGGM) is 21.19 ± 2.89 IU/mg and increases with increasing sulfation duration. Full article

The stability of physical and mechanical properties of highly filled swelling rubbers in polar and nonpolar liquids (oil, mineralized water) was studied. Nitrile butadiene rubber of BNKS-28 AMN grade served as the elastomer matrix, with sodium salt of carboxymethylcellulose (NaCMC) as the swelling filler. Oxal T-92, a mixture of dioxane alcohols (10–50 phr, step 10 phr), was used as a plasticizer due to its good thermodynamic miscibility with rubber (confirmed by Scatchard–Hildebrand calculations). Adding Oxal T-92 to NaCMC-filled compounds markedly reduced Mooney viscosity, improving processing through increased macromolecule mobility, without significantly affecting vulcanization kinetics—indicating chemical inertness toward crosslinking centers. Increasing Oxal T-92 from 10 to 50 phr reduced tensile strength from 4.1 MPa to 2.9 MPa. Swelling in aqueous solutions of varying mineralization was evaluated via volume and mass change. The optimal plasticizer content for high swelling with acceptable strength is 20–30 phr. After 3 days in oil and formation water, NaCMC-filled rubbers retained stable physical and mechanical properties. Full article

This work aimed to synthesize new derivatives of 2-hydrazinylpyridine-3-carbonitrile and to investigate their biological activity as safeners for the 2,4-D herbicide. The new 2-hydrazinylnicotinonitriles were obtained in high yields (up to quantitative) under mild conditions (25 °C, dioxane) by treating 4,6-diaryl-2-bromo-3-cyanopyridines with hydrazine hydrate. The latter were synthesized by brominating 2-(3-oxo-1,3-diarylpropyl)malononitriles, the Michael adducts, which are readily available from 1,3-diarylpropenones (chalcones) and malononitrile. An unusual side product of the bromination/carbocyclization was isolated and characterized; it consisted of co-crystals of 3-benzoyl-4-hydroxy-4-phenyl-2,6-di-(p-tolyl)cyclohexane-1,1-dicarbonitrile and 3-benzoyl-5-bromo-4-hydroxy-4-phenyl-2,6-di-(p-tolyl)cyclohexane-1,1-dicarbonitrile at a ~4:6 ratio. The new 2-hydrazinylnicotinonitriles react with halogen-containing aromatic aldehydes to form the corresponding hydrazones. The biological activity of the new nicotinonitriles was examined for their function as 2,4-D antidotes. It was found that, under laboratory conditions, eight of the synthesized compounds exhibited a notable antidote effect against 2,4-D on sunflower seedlings. Full article

1-Butyl-3-methylimidazolium (bmim) ionic liquids (ILs) are widely used for lignocellulose fractionation, yet their role extends beyond mere solvents. This study revealed that bmim-based ILs act as active chemical reagents, modifying the lignin structure in an anion-dependent manner. Thermal treatment (80–150 °C) of spruce dioxane lignin with [bmim]OAc, [bmim]Cl, and [bmim]MeSO₄ resulted in two distinct transformation pathways. In [bmim]MeSO₄, acidic catalysis dominates, leading to lignin condensation (increase in weight-average molecular weight, M_w, to 15.2 kDa at 150 °C) and intense sulfur incorporation (up to 9.9%) via anion-derived methylation/sulfation. Conversely, [bmim]OAc promotes depolymerization (decrease in M_w to 3.6 kDa) and efficient covalent bonding of the bmim cation to lignin (up to 10.8 cations per 100 aromatic units and a 6.5% nitrogen content at 150 °C), preventing condensation. Two-dimensional NMR and HPLC-HRMS analyses revealed the formation of a C–C bond between the C₂ atom of the imidazole ring and the α-carbon of the phenylpropane lignin fragments and allowed for the identification of a number of individual nitrogen-containing lignin oligomers in the [bmim]OAc-treated samples. Their formation likely proceeds via nucleophilic addition of the N-heterocyclic carbene (NHC), derived from the bmim cation by deprotonation with the highly basic acetate anion, to aldehyde groups. The action of [bmim]Cl primarily induces acid-catalyzed transformations of lignin with minimal covalent modification. These findings redefine imidazolium ILs as reactive media in biorefining, where their covalent interactions can influence the properties of lignin but complicate its native structure and the recyclability of the IL. Full article

We investigated the reactivity of a new sulfur-containing compound derived from Meldrum’s acid and phenyl isothiocyanate, triethylammonium 1-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)(phenylamino)methanethiolate. Under aminomethylation conditions (using aqueous formaldehyde and primary amines), this compound undergoes a double aminomethylation to form novel 1,3,5-thiadiazine derivatives. These new compounds, 2,2-dimethyl-5-(3-phenyl-1,3,5-thiadiazinan-2-ylidene)-1,3-dioxane-4,6-diones, were previously unknown. This study also explores some properties of the synthesized 1,3,5-thiadiazines. Full article

This paper comprehensively reports experimental proof of parity violation in the ground and photoexcited states of three mirror-symmetric Si–Si bond polymers in homogeneous solutions of achiral molecules under non-stirring conditions by analyzing 370 chiroptical datasets relating to multiple second-order helix–helix transitions in the circular dichroism (CD) of poly(di-i-butylsilane) (iBS), poly(di-i-pentylsilane) (iPS), and poly(di-i-hexylsilane) (iHS) in achiral alkanols and p-dioxane-h₈/-d₈. Particularly large (–)-CD of g_abs = −3.1 × 10⁻² at 290 nm was found for iBS in i-pentanol at 25 °C. Notably, iPS in n-propanol at −5 °C generated (–)-CD with g_abs = −0.48 × 10⁻² at 300 nm, but (+)-circularly polarized luminescence (CPL) with g_lum = +0.84 × 10⁻² at 326 nm. In contrast, iHS in n-octanol at 0 °C showed only very weak (–)-CD of g_abs ~−0.03 × 10⁻² at 310 nm. The H/D isotopes of p-dioxane-h₈/-d₈ weakly affected the helix–helix transition characteristics of iBS. (–)-Sign vibrational CD signals assigned to the handed symmetric and asymmetric bending modes of the CH₃ and CH₂ groups of the solvents and other achiral molecules were observed. We assumed (i) three ¹H nuclear-spin-1/2 induced handed motions of CH₃ rotors at i-alkyl side chains and achiral alkanols, and (ii) helical main-chain Si atoms (δ⁺) coordinated by handed lone pairs at oxygen (δ⁻) in gauche-containing n- and i-alkanols induced by the CH₃ rotors. A possible origin of biomolecular handedness is proposed based on the first observation of far-UV CD and UV spectra of zwitterionic glycine bearing H₃N⁺ rotor in neutral H₂O. Full article

Background/Objectives: Ligands blocking σ₁ receptors or NMDA receptors show promising pharmacological properties, such as analgesia or neuroprotection. It had been shown that depending on the stereochemistry and substitution pattern, 1,3-dioxnaes can selectively interact with either σ₁ receptors or the phencyclidine binding site of NMDA receptors. Herein, systematic modifications of homologous aminobutyl substituted 1,3-dioxanes were conducted in order to identify ligands selectively addressing σ receptors or NMDA receptors. Methods: The first step of the synthesis, i.e., the acetalization of benzaldehyde (7a) or propiophenone (7b) with pentane-1,3,5-triol (6), determined the relative configuration of the envisaged 1,3-dioxanes bearing 4-aminobutyl substituents in 4-position. Multi-step homologation of ethanols 8 provided various primary, secondary and tertiary amines 14, 16–19, and 24–27. The affinity towards σ₁ and σ₂ receptors as well as the PCP and ifenprodil binding sites of the NMDA receptor was systematically evaluated in radioligand receptor binding studies. Results: Only the primary amines 14b and 24b derived from propiophenone interacted moderately with the PCP binding site of the NMDA receptor. Within this class of compounds, the N-benzylamines 17 and 18 showed the highest σ₁ affinity with high selectivity over the PCP binding site and at least preference over the σ₂ receptor. The benzylamine 17a (K_i(σ₁) = 31 nM, LLE = 6.19) and the pyrrolidine 19a (K_i(σ₁) = 154 nM, LLE = 6.72) represent the most promising σ₁ ligands of this compound series, when taking the lipophilicity and receptor selectivity into account. Conclusions: Both compounds showed medium metabolic stability in vitro rendering them promising candidates for further studies. Full article

Background: Compound lipophilicity is a fundamental physicochemical property for determining the pharmacokinetic and pharmacodynamic profiles of therapeutic substances. It is successfully used in the early stages of drug candidates’ design and development. Aim: Taking into account the importance of this parameter, we aimed to assess and compare the utility of a hybrid procedure based on calculation methods and an experimental one for rapid and simple estimation of the lipophilicity of selected neuroleptics such as fluphenazine, triflupromazine, trifluoperazine, flupentixol and zuclopenthixol and their potential new derivatives. Methods: Log P values of the studied compounds were predicted by means of different platforms and algorithms: AlogPs, ilogP, XlogP3, WlogP, MlogP, milogP, logPsilicos-it, logP_consensus, logP_chemaxon and logP_ACD/Labs. The experimental determination of lipophilicity was carried out by reverse-phase thin-layer chromatography (RP-TLC) using three types of stationary phases—RP-2F₂₅₄, RP-8F₂₅₄ and RP-18F₂₅₄—and mobile phases consisted of acetone, acetonitrile and 1,4-dioxane as organic modifiers. Results: Our results provide a confident proposal of optimal chromatographic conditions to experimentally determine the lipophilicity of neuroleptic drugs, including new derivatives. Conclusions: Additionally, for the first time, the paper shows the application of selected topological indices in determining lipophilicity factors and other ADMET parameters of neuroleptics and, in the future, the newly synthesized quinoline derivatives of the studied compounds. Full article

This study investigates how phospholipid headgroups influence passive membrane penetration and structural impact of four nitrogen-, sulfur-, and oxygen-containing heterocycles (NSO-HETs)—N-methyl-2-pyrrolidone (PIR), 1,4-dioxane (DIOX), oxane (OXA), and phenol (PHE). Using all-atom molecular dynamics simulations combined with Accelerated Weight Histogram free energy calculations, the passive transport of NSO-HETs across DPPC, DPPE, DPPA, and DPPG bilayers was characterized. DPPG showed the highest membrane affinity, increasing permeability (logP_memb/bulk) by 27–64% compared to DPPE, associated with the lowest permeability and tightest lipid packing. Free energy barriers are also decreased in DPPG relative to DPPE; PIR’s central barrier dropped from 19.2 kJ/mol (DPPE) to 16.6 kJ/mol (DPPG), while DIOX’s barrier decreased from 7.2 to 5.2 kJ/mol. OXA exhibited the lowest central barriers (1.2–2.2 kJ/mol) and uniquely accumulated at higher concentrations in the bilayer center than in bulk water, with free energy ranging from −3.4 to −5.9 kJ/mol. PHE and OXA caused significant bilayer thinning (up to 11%) and reduced lipid tail order, especially in DPPE and DPPA. Concentration effects were most pronounced in DPPE, where high solute loading disrupted lipid order and altered free energy profiles. These results highlight the crucial role of headgroup identity in modulating NSO-HET membrane permeability and structural changes. Full article

In this work, we described the synthesis of 4-(methoxycarbonyl)phenyl 5-bromofuran-2-carboxylate by reacting 5-bromofuroic acid with methylparaben in the incorporation of DCC/DMAP (Steglich esterification) as coupling agents. Later on, we subsequently synthesized a series of 4-(methoxycarbonyl)phenyl 5-aryl furan-2-carboxylates (5a–5e) through Suzuki coupling catalyzed by palladium (0) between 4-(methoxycarbonyl)phenyl 5-bromofuran-2-carboxylate (3) with several substituted arylated and heteroaryl boronic acids (4). DFT calculations were computed to elucidate electronic structural features of synthesized molecules (5a–5e) and to validate these findings by correlating with theoretical and experimental spectroscopic analysis. Furthermore, geometrical optimization, thermodynamic features, as FMO orbitals, MESP maps, NLO behavior and reactivity descriptors, were also determined from the PBE0 D3BJ/def2-TZVP/SMD_1,4-dioxane theory level to confirm the structural features of synthesized molecules. Full article

Series of pyrene-labeled diols (Py₂-DOs) and polyols (Py-POs) were synthesized by coupling a number (n_PyBA) of 1-pyrenebutyric acids to diols and polyols to yield series of end-labeled linear (n_PyBA = 2) and branched (n_PyBA > 2) oligomers, respectively. Pyrene excimer formation (PEF) between an excited and a ground-state pyrene was studied for the Py₂-DO and Py-PO samples by analyzing their fluorescence spectra and decays in tetrahydrofuran, dioxane, N,N-dimethylformamide, and dimethyl sulfoxide. Global model-free analysis (MFA) of the pyrene monomer and excimer fluorescence decays yielded the average rate constant (<k>) for PEF. After the calculation of the local pyrene concentration ([Py]_loc) for the Py₂-DO and Py-PO samples, the <k>-vs.-[Py]_loc plots were linear in each solvent, with larger and smaller slopes for the Py₂-DO and Py-PO samples, respectively, resulting in a clear kink in the middle of the plot. The difference in slope was attributed to a bias for PEF between pyrenes close to one another on the densely branched Py-PO constructs resulting in lower apparent [Py]_loc and <k> values. This study illustrated the ability of PEF to probe how steric hindrance along a main chain affects the dynamic encounters between substituents in multifunctional oligomers such as diols and polyols. Full article