Quaternary Nitrogen Research Articles

Thiazolopyrimidinium systems with a quaternized nitrogen atom as promising anticancer agents

Thiazolopyrimidinium systems with a quaternized nitrogen atom are attracting increasing attention in the development of new anticancer drugs. Their unique chemical structure and potential biological properties make them promising candidates for the development of effective drugs. In recent years, researches have shown that these compounds have significant activity against various types of tumors due to their ability to interact with cellular targets, disrupting processes critical for the survival and proliferation of tumor cells. This review examines the current state of researches on thiazolopyrimidines, including synthesis, mechanisms of action, and evaluation of their antitumor potential, with an emphasis on the importance of the quaternized nitrogen atom in their biological activity.

Merging experimental and theoretical approaches towards understanding real diesel fuel desulfurization by nanoporous carbons

Experimental tests combined with theoretical calculations have yielded new insights into real diesel fuel desulfurization (rDeSulfur) using activated nanoporous carbons. The carbons were selected for their varying physicochemical properties and further were chemically treated to modify their surface chemistry, aiming to investigate the impact of the major physicochemical features on rDeSulfur. The experimental findings demonstrated that both porosity and surface chemistry play complex roles. Specifically, a high degree of graphitization and diverse pore size distributions enhanced adsorptive capabilities, with some carbon samples achieving ultra-deep desulfurization levels (<1 ppmwS). Theoretical calculations indicated that π-π stacking through dispersion forces was the primary mechanism of adsorption. While surface functionalities at the edges of graphene had minimal impact on interaction strength, structural defects, especially clusters of three quaternary nitrogen atoms or single defected vacancy with OH group, improved interaction energies, boosting adsorption effectiveness compared to pristine graphene. The study concludes that the effectiveness of carbons in diesel desulfurization depends heavily on graphitization levels, defects, and where specific functionalities are located. Lastly, although aromatic compounds in diesel, like benzene, toluene, and naphthalene, compete with thiophenics for adsorption, they have lower interaction energies, suggesting preferential adsorption of sulfur compounds over the aromatics.

The embedding of 1,8-diazabicyclo[5.4.0]undec-7-ene into hyper-crosslinked ionic polymers for efficient CO2 conversion at atmospheric pressure

The preparation of cyclic carbonates via CO2 cycloaddition reaction was crucial for the lithium industry. Herein, a series of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based hyper-crosslinked ionic polymers with different ionic site densities were prepared by simultaneously Friedel-Crafts alkylation and quaternization reactions. The obtained P[DBU]DCX(1:1) with a high ionic site density (1.45 mmol‧g−1), prepared by the equimolar ratio of 1,8-diazabicyclo[5.4.0]undec-7-ene and α,α′-dichloro-p-xylene, exhibiting excellent catalytic performance with a chloropropylene carbonate (CPC) yield of 98.8 % and selectivity of 99.3 % at atmospheric pressure. Meanwhile, the conversion capacity was comparable with other catalysts. Moreover, the CO2 cycloaddition reaction over P[DBU]DCX(1:1) catalyst followed pseudo-first-order kinetics, and the activation energy (Ea) was obtained to be 28.7 kJ/mol by performing kinetic experiments at different temperatures. In addition, it also had a good reusability and universality for different epoxides. The synergistic effects of abundant quaternary nitrogen cations derived from DBU and chlorine anions on the activation of CO2 and epoxide were explored based on density functional theory calculation. This study offers a new approach for the design and application of hyper-crosslinked ionic polymers for efficient CO2 conversion at atmospheric pressure.

Dynamic annealing assisted near-surface structural and bond stabilization in high-temperature low-energy N2+ implanted diamond.

Nitrogen-rich ultra-thin (1-2nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C-N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500-600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented.

Amidation modified hollow composite microspheres as a self-floating adsorbent for efficient capture of anionic dye DB86 and heavy metal nickel (II).

The co-contamination of dyes and heavy metal ions often used as mordants poses potential risks to environment and public health, and is a challenging problem that needs to be solved in water treatment. Meanwhile, improving the solid-liquid separation capability of adsorbents is of great significance for the application of adsorption technology. Herein, amidation modified hollow composite microspheres were prepared using hollow glass microsphere (HGM) as matrix through hydrolysis and condensation of silane coupling agent (A-1100) and subsequent amidation reaction. The material (HGMNE) not only exhibited good adsorption performance for DB86 and Ni2+ but also had stable self-floating capability. The adsorption of DB86 by HGMNE is mainly carried out by the electrostatic interaction between positively charged quaternary amine nitrogen and negatively charged DB86, while the adsorption of Ni2+ is achieved by the carboxyl group in EDTA group through complexation interaction to adsorb Ni2+ to form Ni complex. This research not only is devoted to the utilization of HGMNE to achieve the co-removal of DB86 and Ni2+ and flexible self-floating solid-liquid separation but also verifies the feasibility and applicability of the modification method of introducing organic adsorption functional groups through amidation reaction, so as to expand the preparation path of HGM-based adsorbents.

Synergistic on engineering layered N-doped carbon/MXene heterostructure: A potential scaffold for simultaneous electrochemical detection of Cu2+ and Hg2+ ions

The presence of heavy metal ions (HMIs) like Cu2+ and Hg2+ in natural water and foods is a major health and environmental concern. Thus advanced electrochemical sensors are required to monitor these ions. Herein, we introduce a nitrogen-rich carbon-MXene composite (layered N-doped carbon/MXene) as an electrochemical sensor suitable for the simultaneous detection of Cu2+ and Hg2+. Synthesizing 2D/2D heterostructure interfaces using controlled thermal decomposition conditions with the incorporation of quaternary nitrogen from choline chloride and the formation of hydrogen bonds of urea within the MXene (Ti3C2Tx) provided active surfaces area that is suitable for the detection of Cu2+ and Hg2+. The intermediate structure of layered N-doped carbon/MXene, had a nitrogen content of ∼6 %, maximized sensitivity for Cu2+ and Hg2+. The layered N-doped carbon/MXene composite exhibited excellent electrochemical sensing for Cu2+ and Hg2+ in 0.1 M acetate buffer at low sensing potentials. The limits of detection (LODs) of layered N-doped carbon/MXene were 0.019 and 0.056 µM with a sensitivity of 114.54 and 64.317 µA µM−1 cm−2 for Cu2+ and Hg2+, respectively. Furthermore, the layered N-doped carbon/MXene heterostructure exhibited high selectivity for Cu2+ and Hg2+ in the presence of potentially interfering common metal ions. This study introduces a promising advanced material for rapid Cu2+ and Hg2+ detection in food and environmental applications.

Antimicrobial cetylpyridinium chloride suppresses mast cell function by targeting tyrosine phosphorylation of Syk kinase.

Cetylpyridinium chloride (CPC) is a quaternary ammonium antimicrobial used in numerous personal care products, human food, cosmetic products, and cleaning solutions. Yet, there is minimal published data on CPC effects on eukaryotes, immune signaling, and human health. Previously, we showed that low-micromolar CPC inhibits rat mast cell function by inhibiting antigen (Ag)-stimulated Ca 2+ mobilization, microtubule polymerization, and degranulation. In this study, we extend the findings to human mast cells (LAD2) and present data indicating that CPC's mechanism of action centers on its positively-charged quaternary nitrogen in its pyridinium headgroup. CPC's inhibitory effect is independent of signaling platform receptor architecture. Tyrosine phosphorylation events are a trigger of Ca 2+ mobilization necessary for degranulation. CPC inhibits global tyrosine phosphorylation in Ag-stimulated mast cells. Specifically, CPC inhibits tyrosine phosphorylation of specific key players Syk kinase and LAT, a substrate of Syk. In contrast, CPC does not affect Lyn kinase phosphorylation. Thus, CPC's root mechanism is electrostatic disruption of particular tyrosine phosphorylation events essential for signaling. This work outlines the biochemical mechanisms underlying the effects of CPC on immune signaling and allows the prediction of CPC effects on cell types, like T cells, that share similar signaling elements.

A highly efficient adsorbent adapting to low pH condition for Pb(II) sequestration from aqueous solution − marine diatom: Laboratory and pilot scale tests

Highly efficient, economically feasible and environmentally friendly adsorbents have been a research hotspot for heavy metal sequestration. In the present study, dried marine diatom biomass (mainly composed of Chaetoceros sp.), which possessed high suface area and cumulative pore volume of 5.72 m2/g and 0.028 cm3/g, respectivly, were used to adsorb Pb(II) from aqueous solution. The immoblized marine diatom beads and an adsorption reactor filled with the beads were further investigated for continuous Pb(II) removal. The removal efficiency was evaluated as a function of contact time, initial concentration, pH and co-existing cations. Results indicated that the dried diatom biomass and the immobilized diatom beads effectively adsorbed Pb(II) under pH > 3.0 and pH > 4 0.0 conditions, respectively. The optimal conditions for the immobilized diatom beads preparation were: diatom powder dosage of 5.0 g / 100 mL sodium alginate solution, sodium alginate concentration of 20 g/L, CaCl2 concentration of 2 %, and cross linking time of 1 h. The Pb(II) adsorption on the marine diatom biomass and the immobilized beads were both well described by pseudo-second-order kinetic and Langmuir model. The maximumPb(II) adsorption capacities of the immobilized beads were 919.1 mg/g, which were much higher than that of the most of adsorbents reported elsewhere. Adsorption mechanism analysis demonstrated that Pb(II) was adsorbed onto the diatom biomass mainly through interaction with nitrogen bonds (mainly with pyrrolic nitrogen) and carboxylic groups, and ion exchange with light metals and hydrogen ions in quaternary nitrogen bonds. The diatom beads were used as adsorbents in a continuous Pb(II) treatment reactor, and the Pb(II) removal efficiency of the reactor reached to almost 100 % from the initial concentration of Pb(II) = 50 mg/L.

New Heterostilbene and Triazole Oximes as Potential CNS-Active and Cholinesterase-Targeted Therapeutics.

New furan, thiophene, and triazole oximes were synthesized through several-step reaction paths to investigate their potential for the development of central nervous systems (CNS)-active and cholinesterase-targeted therapeutics in organophosphorus compound (OP) poisonings. Treating patients with acute OP poisoning is still a challenge despite the development of a large number of oxime compounds that should have the capacity to reactivate acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The activity of these two enzymes, crucial for neurotransmission, is blocked by OP, which has the consequence of disturbing normal cholinergic nerve signal transduction in the peripheral and CNS, leading to a cholinergic crisis. The oximes in use have one or two pyridinium rings and cross the brain-blood barrier poorly due to the quaternary nitrogen. Following our recent study on 2-thienostilbene oximes, in this paper, we described the synthesis of 63 heterostilbene derivatives, of which 26 oximes were tested as inhibitors and reactivators of AChE and BChE inhibited by OP nerve agents-sarin and cyclosarin. While the majority of oximes were potent inhibitors of both enzymes in the micromolar range, we identified several oximes as BChE or AChE selective inhibitors with the potential for drug development. Furthermore, the oximes were poor reactivators of AChE; four heterocyclic derivatives reactivated cyclosarin-inhibited BChE up to 70%, and cis,trans-5 [2-((Z)-2-(5-((E)-(hydroxyimino)methyl)thiophen-2-yl)vinyl)benzonitrile] had a reactivation efficacy comparable to the standard oxime HI-6. In silico analysis and molecular docking studies, including molecular dynamics simulation, connected kinetic data to the structural features of these oximes and confirmed their productive interactions with the active site of cyclosarin-inhibited BChE. Based on inhibition and reactivation and their ADMET properties regarding lipophilicity, CNS activity, and hepatotoxicity, these compounds could be considered for further development of CNS-active reactivators in OP poisoning as well as cholinesterase-targeted therapeutics in neurodegenerative diseases such as Alzheimer's and Parkinson's.

Insights into the Electrocatalytic Activity of Fe,N-Glucose/Carbon Nanotube Hybrids for the Oxygen Reduction Reaction

Glucose-derived carbon hybrids were synthesized by hydrothermal treatment in the presence of oxidized carbon nanotubes. Additionally, iron and nitrogen functionalities were incorporated into the carbon structure using different methodologies. The introduction of iron and nitrogen in a single step under a H2 atmosphere favored the formation of quaternary nitrogen and oxidized nitrogen, whereas the incorporation of nitrogen under an N2 atmosphere after doping the hybrids with iron mainly produced pyridinic nitrogen. The samples were characterized by scanning electron microscopy, X-ray spectroscopy, adsorption isotherms, inductively coupled plasma optical emission spectrometry, and Raman spectroscopy. The presence of iron and nitrogen in the carbons increases the onset potential toward oxygen reduction in KOH 0.1 mol L−1 by 130 mV (0.83 V), in comparison to carbonized glucose, whereas the reaction mechanism shifts closer to a direct pathway and the formation of HO2− decreases to 25% (3.5 electrons). The reaction rate also increased in comparison to the carbonized glucose, as observed by the decrease in the Tafel slope value from 117 to 61 mV dec−1. Furthermore, the incorporation of iron and nitrogen in a single step enhanced the short-term performance of the prepared electrocatalysts, which may also be due to the higher relative amount of quaternary nitrogen.

Transformation of organic to inorganic nitrogen in NH4+-illite-bearing and Ga-Al-REE-rich bituminous coals: Evidence from nitrogen isotopes and functionalities

Nitrogen is one of the most important elements and mainly occurs as organic forms in coal, and in a few cases, in an inorganic form. Organic nitrogen in coal is mainly derived from the proteins of plants and micro-organisms but sources of inorganic nitrogen remain controversial. One hypothesis for the source of inorganic nitrogen is the organic matter of coal, but this lacks strong evidence. In the Daqingshan Coalfield of Inner Mongolia, northern China, an igneous intrusion in the east of the coalfield led to a coal rank increase from the Hailiushu through the Datanhao mines to the Adaohai mine from the west to east, with NH4+-illite being detected in the coals from the Datanhao and Adaohai mines. These coals are highly enriched in Ga, Al, and rare earth elements (REE). This study aims to explore the transformation of organic to inorganic nitrogen in these coals by means of nitrogen isotopes, element distribution in NH4+-illite, and nitrogen functional groups.The analysis of NH4+-illite by Electron Probe Microanalysis (EPMA) indicates partial substitution of nitrogen during the transition from kaolinite to NH4+-illite. Thermal metamorphism has resulted in the organic nitrogen isotope (δ15No) values in coals from the Adaohai Mine being more positive than those in the Datanhao and Hailiushu mines. 15N is more enriched in NH4+-illite than in the associated organic matter. The distribution of nitrogen functional forms showed a decrease in pyrrolic nitrogen (N-5) and an increase in pyridinic nitrogen (N-6) from coals in the Hailiushu to Datanhao and Adaohai mines. Ammonium quaternary nitrogen (N-Q) was detected in the NH4+-illite-bearing samples. This study provides significant evidence for the conversion of organic nitrogen to inorganic nitrogen in coals as a result of thermal metamorphism.

Process for preparing polycarbonates using a catalyst system having a quaternary nitrogen compound and a quarternary phosphorous compound

Process for preparing polycarbonates using a catalyst system having a quaternary nitrogen compound and a quarternary phosphorous compound

Corrosion inhibition of P110 carbon steel useful for casing and tubing applications in 3.5% NaCl solution using quaternary ammonium-based copolymers

In this study, two quaternary ammonium-based copolymers (DAC-DAD10 and DAC-DAD20) with varying hydrophilicity/hydrophobicity are synthesized, characterized, and their capacity to suppress P110 carbon steel (P110 CS) corrosion in 3.5% NaCl is examined. DAC-DAD10 and DAC-DAD20 were synthesized using diallylammonium chloride (DAC) and N1, N1-diallyl-N6-dodecyl-N6, N6-dimethylhexane-1,6-diaminium dichloride (DAD) and their inhibition potential (%IE) and mechanism were studied by different experimental and computational methods. The outcomes suggest that the %IE of DAC-DAD10 and DAC-DAD20 increases on increasing the hydrophobicity as DAC-DAD20, having a large hydrophobic alky chain, showed relatively better %IE than DAC-DAD10. DAC-DAD10 and DAC-DAD20 manifest the best %IE of 88.68% and 96.17%, respectively, at concentrations as low as 3 mgL-1. Potentiodynamic polarization studies indicate that they behave as cathodic-type inhibitors. Their adsorption on the metallic surface followed the Langmuir adsorption isotherm. Various surface analyses, including SEM-EDS, and XPS, confirm that they adsorb at the metal and electrolyte interface and build a corrosion protective layer. DFT study suggests that quaternary nitrogen atoms easily deprotonate and coordinate with the metallic surface using their unshared electron pairs. The corrosion inhibition based on experimental and computational analyses is schematically presented and described.

Polyacrylonitrile‐based porous polymer spheres and their conversion to N‐doped carbon materials for adsorption and electrocatalysis

AbstractBecause of their tunable porosity and specific surface area, porous materials are of high interest for the purification of wastewater by adsorption as well as in electrocatalysis, where, in particular, developing metal‐free carbon‐based catalysts for the oxygen reduction reaction (ORR) is researched. The carbon spheres presented here can meet these two requirements simultaneously. Porous polyacrylonitrile (PAN) spheres were firstly prepared by droplet shaping cum nonsolvent induced phase separation. Then, they were converted to nitrogen‐doped carbon spheres by two‐step carbonization via preoxidation and pyrolysis. During the pyrolysis step, carbon dioxide was used to reopen the pores of the materials that had been blocked after the preoxidation step. By this way, specific surface area values of carbon spheres of more than 1000 m2/g could be obtained. Best performing carbon materials (C#3) showed high adsorption capacity (e.g., 296 mg/g for methyl orange at solute equilibrium concentration of 24 mg/L in water). The XPS analysis revealed that only quaternary (N‐Q) and pyridinic (N‐6) nitrogen sites were found in these carbon spheres. The best ORR performance was found also for C#3 carbon spheres, with a potential of 0.81 V versus reversible hydrogen electrode (RHE) at −1 mA/cm2 and electron transfer number of 3.5 at 0.6–0.8 V versus RHE, as determined by rotating disk or rotating ring disk electrode tests. In conclusion, all results confirm that these PAN‐derived carbon spheres are potentially valuable materials for both wastewater treatment by adsorption and electrocatalytic oxygen reduction.

Functionalization of sterculia gum for making platform hydrogels via network formation for use in drug delivery

Recently, various advancements have been made in the development of functional polymeric materials for innovative applications. Herein this work, functionalization of sterculia gum (SG) was carried out via grafting of poly(2-(methacryloyloxy) ethyltrimethylammonium chloride) (METAC)-polyvinyl pyrrolidone (PVP) to develop hydrogel dressings as a platform for use in drug delivery (DD). The innovation of the present work is the exploration of inherent antioxidant and antimicrobial properties of the SG along with antimicrobial characteristic of poly(METAC) and PVP, to design the doxycycline encapsulated hydrogel dressings for better wound healing. FESEM, EDS and AFM analyzed the surface morphology of hydrogels. FTIR, 13C NMR and XRD inferred inclusion of poly(METAC)-PVP into polymers. 13C NMR confirmed the incorporation of poly(METAC) and PVP onto gum by the presence of a peak at 54.74 ppm because of methyl carbon attached to quaternary nitrogen of poly(METAC) and at 45.48 ppm due to the ring carbon of PVP along with FTIR peak at 949 cm−1 because of CN bending of quaternary nitrogen of poy (METAC). Thermal characterization of copolymers has been performed using TGA analysis. One gram of copolymeric hydrogel dressing absorbed 6.51 ± 0.03 g simulated salivary fluid (SSF) and 7.65 ± 0.03 g simulated wound fluid (SWF). Release of doxycycline drug occurred in a sustained manner and followed the Non-Fickian diffusion mechanism from hydrogels. The release profile was most effectively described by Hixon-Crowell kinetic model. Hydrogel demonstrated biocompatibility and expressed thrombogenicity 79.7 ± 4.9 % during its polymer-blood interactions. Copolymer revealed mucoadhesive property, requiring a force of 77.00 ± 0.01 mN to detach from bio-membrane. Additionally, it exhibited antioxidant features, showing 43.81 ± 0.286 % free radical scavenging. Hydrogel dressings were mechanically stable and revealed 0.76 ± 0.09 N mm−2 tensile strength and 9.18 ± 0.01 N burst strength. Polymer films were permeable to oxygen and water vapor and were impermeable to microorganisms. Hydrogel dressings exhibited antimicrobial properties against Pseudomonas aeruginosa and Staphylococcus aureus bacteria. Overall, these properties displayed the suitability of hydrogels for wound dressing (WD) applications which may actively enhance wound healing.

Ammonia assimilation coupled with rapid humification increases recalcitrant nitrogen reservoirs during bioaugmented mechanical composting

The bioaugmented mechanical composting (BMC) of kitchen waste with rapid heating, dehydration, and humification is promising for nitrogen conservation. The combination of ammonia assimilation and rapid humification in BMC may be a distinct nitrogen conservation pathway, converting NH4+-N to recalcitrant organic nitrogen reservoirs. However, questions remain regarding the existence of this pathway and its enhancing mechanism. Thus, nitrogen transformation during a BMC process and a conventional pile composting (CPC) process were compared in this study. Results indicated a significant increase (68.53–75.56%) in the proportion of initial total nitrogen in raw materials preserved in recalcitrant humins in BMC compared to CPC. The significantly higher activity of glutamate dehydrogenase (64.65 ± 7.10 U·mg−1) and glutamine synthase (29.92 ± 3.37 U·mg−1) associated with ammonia assimilation in BMC facilitated the conversion of NH4+ from ammonification into amino acids at the thermophilic phase. These amino acids were then rapidly polymerised with other humic precursors and gradually condensed into heterocyclic and quaternary nitrogen in humins. Further analysis of the bacterial communities and their potential functions revealed that Firmicutes (e.g., Bacillus) and Proteobacteria (e.g., Acinetobacter), which are capable of mineralisation, were enriched by rapid heating and dehydration in BMC. The resulting accumulated NADPH, α-ketoglutaric acid, and humic precursors activated thermophiles associated with ammonia assimilation (e.g., Ureibacillus, Kroppenstedtia, Virgibacillus, and Tepidimicrobium) and humification (e.g., Sacchsromonospora and Bacilli), accelerating nitrogen transformation. This study provides a theoretical foundation for the development of novel nitrogen conservation strategies of coupling ammonia assimilation with rapid humification through enhanced mineralisation during composting.

Structural Characterization and Molecular Model Construction of Lignite: A Case of Xianfeng Coal

The object of the study is lignite. Analytical testing techniques, such as elemental analysis, 13C nuclear magnetic resonance (13C NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM), were used to acquire information on the structural parameters of lignite. The aromaticity of Xianfeng lignite is 43.57%, and the aromatic carbon structure is mainly naphthalene and anthracene/phenanthrene. The aliphatic carbon structure is dominated by cycloalkanes, alkyl side chains, and hydrogenated aromatics. Oxygen is mainly present in ether oxygen, carboxyl, and carbonyl groups. Nitrogen is mainly in the form of pyrrole nitrogen and quaternary nitrogen. Sulfur is mainly thiophene sulfur. According to the analysis results, the molecular structure model of XF lignite was constructed. The molecular formula is C184H172O39N6S2. The 2D structure was converted to a 3D structure using computer simulation software and optimized. The optimized model has a remarkable stereoconfiguration, and the aromatic lamellae are irregularly arranged in space. The aromatic rings were mainly connected by methylene, hypomethylene, methoxy, and aliphatic rings. In addition, the simulated 13C NMR spectra are in good agreement with the experimental spectra. This shows the rationality of the 3D chemical structure model.

Oxolane Ammonium Salts (Muscarine-Like)-Synthesis and Microbiological Activity.

Commercially available 2-deoxy-D-ribose was used to synthesize the appropriate oxolane derivative-(2R,3S)-2-(hydroxymethyl)oxolan-3-ol-by reduction and dehydration/cyclization in an acidic aqueous solution. Its monotosyl derivative, as a result of the quaternization reaction, allowed us to obtain eight new muscarine-type derivatives containing a quaternary nitrogen atom and a hydroxyl group linked to the oxolane ring. Their structure was fully confirmed by the results of NMR, MS and IR analyses. The crystal structure of the pyridinium derivative showed a high similarity of the conformation of the oxolane ring to previously published crystal structures of muscarine. Two reference strains of Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853), two reference strains of Gram-positive staphylococci (Staphylococcus aureus ATCC 25923 and Staphylococcus aureus ATCC 29213) and four reference strains of pathogenic yeasts of the genus Candida spp. (Candida albicans SC5314, Candida glabrata DSM 11226, Candida krusei DSM 6128 and Candida parapsilosis DSM 5784) were selected for the evaluation of the antimicrobial potential of the synthesized compounds. The derivative containing the longest (decyl) chain attached to the quaternary nitrogen atom turned out to be the most active.

Synthesis, characterization, and corrosion protection potential of a highly effective and water‐miscible surfactant for mild steel in sulfuric acid solution

AbstractIn the current study, a tetracationic quaternary ammonium salt (TCQAC) was synthesized and characterized and its ability to suppress corrosion on mild steel (MS) in a 0.5 M H2SO4 solution was examined. Various chemical, electrochemical, and surface characterization techniques were utilized to study the inhibition efficiency of TCQAC. The TCQAC manifests 99.83% efficiency at 20 ppm concentration. Out of all the examined isotherm models, the Langmuir isotherm offered the best fit for the TCQAC adsorption on the MS surface. A very high negative value of ΔGads (−45.18 kJ mol−1) suggests that the adsorption of TCQAC followed the chemisorption mechanism. Electrochemical studies indicate that TCQAC increases the linear and charge transfer resistances (LPR and Rct, respectively). TCQAC slows down the anodic and cathodic Tafel reactions; however, it acts as an anodic‐type inhibitor at 5, 10, and 20 ppm. The appearance of extra Cl and N signals in the energy dispersive x‐ray (EDX) spectrum and an improvement in surface smoothness in the scanning electron microscope (SEM) image of the inhibited sample corroborated the adsorption method of corrosion inhibition. X‐ray photoelectron spectroscopy (XPS) study indicates that TCQAC creates corrosion preventive layers by chemical adsorption. In Frontier molecular orbitals (FMOs), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were delocalized around the central part that comprises two benzyls, four allyls, and one hydrocarbon ((CH2)6) moieties and two quaternary nitrogen atoms. The outcomes of XPS and density functional theory (DFT) analyses indicate that the chemisorption of TCQAC occurs by dπ–pπ bonding with the surface iron atoms. The π‐electrons of aryl and allyl moieties extensively participate in the bonding.

Impact of the Hydrocarbon Chain Length of Biodegradable Ester-Bonded Cationic Gemini Surfactants on Self-Assembly, In Vitro Gene Transfection, Cytotoxicity, and Antimicrobial Activity.

Gemini surfactants, due to their unique structural features and enhanced properties compared to conventional surfactants, are becoming more popular in the domain of colloid and interface science, drug delivery, and gene delivery science. This distinct class of surfactants forms a wide range of self-assembled aggregates depending on their chemical structure and environmental conditions. The present work aims to develop Gemini with three distinct chain lengths linked through the ester group and quaternary nitrogen head groups that can bind DNA molecules and ultimately serve as vectors for DNA transfection. Thus, we synthesized three distinct cationic Gemini with 12, 14, and 16 carbons in their tails and studied the effect of the hydrocarbon chain length on their physicochemical properties and biological applications. The self-assembly of these Geminis in aqueous solution was investigated by a number of techniques, including surface tension, electrical conductivity, fluorescence probe, calorimetry, dynamic light scattering, and atomic force microscopy. All three Gemini were extremely surface active and self-assembled above a very low critical micelle concentration. Calorimetric studies suggested the formation of thermodynamically favorable aggregates in an aqueous medium. Chain length dependence was observed in the size as well as the morphology of the aggregates. These Gemini ions were found to bind DNA strongly, as indicated by the high binding constant values. In vitro gene transfection studies using the RAW 264.7 cell line suggested that all three cationic Gemini had transfection efficiencies comparable to that of commercial standard turbofectamine. MTT assay was also performed for concentration selection while using these Gemini as transfection vectors. Overall, it was observed that Gemini had very little cytotoxicity within the investigated concentration range, highlighting the significance of the ester link within the structure. When compared with known antimicrobials such as kanamycin and ampicillin, all three Gemini furnished excellent antimicrobial activity in both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms.