Carbon-13 Nuclear Magnetic Resonance Spectroscopy Research Articles

Synthesis, characterization, computational studies and anti-inflammatory activity evaluation of some new indole substituted aryl ethers

A number of anti-inflammatory drugs with an aryl-ether part, such as Nimesulide and Rofecoxibs, have been shown to damage cells and kill liver cells. Keeping in view this rationale, the present work was aimed at synthesising new indole-substituted aryl ethers and evaluating their anti-inflammatory effects, which have minimal side effects. New indole substituted aryl ethers were synthesised. Spectral characterisation of these newly synthesised compounds was done using infrared (IR), proton nuclear magnetic resonance (1H NMR), and carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy techniques. Further, In-silico studies were performed with an aim to evaluate the suitability of synthesised compounds as potential bioactive candidates for anti-inflammatory activity. The synthesised compounds were subjected to anti-inflammatory activity evaluation using the carrageenan-induced rat paw edema model. Primarily, the chemical reaction completion was ensured using TLC and M.P. Further, the structures of all synthesised compounds were confirmed by the results of spectra characterization. Results of in-silico study exhibited the docking of compounds on target proteins. On the basis of experimental findings, it was concluded that compound AG-1 (N-(1H-indol-3yl) methylene)-4-phenoxyaniline) is the most potent anti-inflammatory compound amongst all the newly synthesised compounds. Findings of the present study concluded that AG-1 could be used as a viable new lead bioactive compound to serve as a potent candidate for a new anti-inflammatory drug. The novelty of the present work resides in the simplest way of synthesis, a good docking score, and excellent anti-inflammatory potential when evaluated in vivo.

Synthesis and characterization of 7-diethylamino-4-Chloromethyl coumarin: Spectroscopic analysis, molecular docking, and anticancer activity on large intestine carcinoma cells

Cancer, characterized by uncontrolled cell growth and metastasis, poses a significant global health burden, ranking as a leading cause of mortality worldwide. Colorectal cancer (CRC) specifically accounts for a substantial portion of cancer cases, with increasing incidence projected over the coming decades. While conventional treatments exist, they often entail adverse effects and limited efficacy, driving interest in natural remedies like coumarin derivatives due to their diverse biological activities and perceived safety profile. This study focuses on the synthesis and characterization of a novel compound, 7-diethylamino-4-chloromethyl coumarin (referred to as 7D4C), derived from coumarin. Structural elucidation employed Fourier transform infrared spectroscopy (FT-IR), proton and carbon-13 nuclear magnetic resonance spectroscopy (1H and 13C NMR), and mass spectrometry (MALDI-TOF-MS). Molecular docking studies were conducted to explore potential biological interactions. Furthermore, the anti-cancer potential of 7D4C was assessed using human epithelial adenocarcinom (LoVo) and healthy fibroblast (CCD-18Co) cell lines. Viability analysis, comet assay for DNA damage, and evaluation of cancer biomarkers including apoptosis, intracellular reactive oxygen species (iROS) levels, mitochondrial membrane potential (MMP), intracellular glutathione (GSH) concentration, and intracellular calcium (iCa2+) levels were performed. The synthesis of 7D4C was successfully completed, and its structure was confirmed. Molecular docking results indicate that 7D4C exhibits strong binding affinity to the p53 protein, highlighting its potential as a novel modulator of p53 activity. Subsequent investigations revealed that the synthesized compound induced apoptosis in cancer cells by reducing MMP and triggering DNA damage through the production of iROS. The promising anti-cancer activity of 7D4C in the LoVo cell line highlights its importance in coumarin-based therapies. Introducing 7D4C could significantly enhance future research in this area, leveraging insights from in vitro coumarin studies.

Synthesis, Characterization, Biological Evaluation, DFT, and Molecular Docking Study of a Co(II) Complex Derived from ON Donor Bidentate Schiff Base Ligand

AbstractThe utilization of biologically active metal complexes in medicine is gaining recognition as an alternative approach to traditional biologically active organic molecules, which often exhibit undesirable side effects. This study focuses on the synthesis and characterization of a Co(II) complex derived from the (E)‐2‐((2‐hydroxybenzylidene)amino)‐5‐methylbenzonitrile ligand system (HL) and cobalt(II) acetate tetrahydrate in a dichloromethane/methanol solution. A comprehensive characterization strategy was employed, involving proton and carbon nuclear magnetic resonance, infrared, electronic spectra, PXRD, SEM‐EDX, and mass spectroscopies, as well as elemental analysis (CHN and Co), TGA, and molar conductance, to confirm the chemical structures of the ligand and its complex. The infrared spectral data revealed the ligand as a bidentate ligand, chelating the Co(II) ion through the oxygen and nitrogen atoms of the phenolate and imine groups. Additionally, PXRD and SEM analyses indicated crystalline and amorphous properties for the ligand and complex, respectively. Assessment of antimicrobial potential using a modified disc diffusion method, with streptomycin as the positive control, demonstrated the complex's enhanced antibacterial activity compared to the ligand against all tested bacteria, showing a concentration‐dependent response. Similarly, antioxidant studies revealed promising results, with the complex exhibiting superior DPPH radical scavenging activity (IC50 values: ligand 64.5 μg.mL−1, complex 43.1 μg.mL−1). Theoretical analysis through DFT calculations and molecular docking provided insights into the electronic properties and binding affinity of the ligand and complex, supporting the experimental findings and affirming the biological activities exhibited by the compounds. Overall, this research showcases the synthesis, characterization, and biological evaluation of a promising Co(II) complex, highlighting its potential as an effective antimicrobial and antioxidant agent.

Assessing Popper Purity—Implications for the Regulation and Recreational Use of Alkyl Nitrites

Alkyl nitrites (“poppers”) are a diverse class of volatile chemical compounds with a varied legal and medical history. Though once commonly prescribed to treat angina, popper use is now almost exclusively recreational. Currently, poppers are widely available and sold legally under labels like “solvent cleaner”, despite marketing suggesting they are meant to be consumed. As a result, there is little incentive for producers to implement robust quality controls to protect users. In this study, nine common popper brands were analyzed using hydrogen-1 and carbon-13 nuclear magnetic resonance spectroscopy to assess the presence of impurities. Physical labels on all nine samples indicated the contents were “pure” isobutyl nitrite, despite contradictory online marketing in several cases. Spectral results showed isobutyl nitrite was present in all popper samples. However, there was evidence that various unlabeled compounds were also present in all samples. The identity and concentration of these contaminants were not clear, but the seemingly ubiquitous presence of impurities and lack of consistency in the tested samples are concerning and may represent a threat to users’ health. We hope the results of this study draw attention to the potential dangers of recreational popper use and the need to reassess how these compounds are regulated.

Identification and characterization of phytochemicals in methanolic extract of roots of Datura fastuosa using various techniques

BackgroundPlant extracts have attracted significant interest among researchers due to their potential bioactivity and crucial contribution to the production of pharmaceutical compounds. In this study, the primary objective was to extract, analyze and characterize the bioactive compounds found in the methanol root extract of Datura fastuosa (D. fastuosa). This was achieved using various analytical techniques such as gas chromatography/mass spectrometry (GC–MS), ultra-violet visible spectrophotometry, Fourier-transform infrared (FT-IR), nuclear magnetic radiation spectrometry (NMR) and DPPH free radical scavenging activity assay.ResultsGC–MS analysis of the methanol root crude extract identified 49 compounds. Three compounds were isolated via column chromatography; one was pure, with a sharp melting point and clean IR spectrum, while the other two showed broad melting points and IR interferences. Comprehensive investigation of the pure extract revealed a UV profile with two distinct bands (300–800 nm) and confirmed functional groups (alcohol, alkanes, alkenes, carbonyl, methylene, and methyl) through FT-IR analysis. The 1HNMR (proton nuclear magnetic resonance spectroscopy) signal confirmed the presence of forty-nine non-equivalent protons, 13CNMR (Carbon-13 nuclear magnetic resonance spectroscopy) signal confirmed the presence of 32 non-equivalent carbons and DEPT-135 (distortionless enhancement by polarization transfer-135) signal confirmed the presence of 24 carbons (17 for odd and 7 for even) which are protons containing carbons in the compound. Combining the above mentioned analyses with data obtained from the GC/MS analysis of National Institute of Standards and Technology (NIST) library, the isolated pure compound exhibited a structural similarity to 1-(7-(3-hydroxyphenyl)-1,1,4a,5,6,9,10a,10b-octamethyl-1,2,3,4,4a,4b,6a,7,8,9,10,10a,10b,11,12,12a-hexadecahydrochrysen-2-yl)propan-1-one, with a chemical formula of C35H50O2.ConclusionsThe presence of various notable compounds, including phenolics, flavonoids, alkaloids, steroids etc., within the methanol root extract of D. fastuosa signifies its pharmacological potential. The methanol crude extract demonstrated antioxidant potential compared to standard ascorbic acid, exhibiting DPPH scavenging activity. Previous research has demonstrated the bioactivity of some of these compounds, further elucidating the plant’s medicinal properties. These findings not only suggest opportunities for developing synthetic drugs but also underscore its direct therapeutic potential in addressing diverse ailments.

The thermal stability mechanism of MBA-crosslinked PPGs: Insights from macroscopic phenomena to chemical reactions

Preformed particle gels (PPGs) is one of the most efficient enhanced oil recovery techniques used for conformance control. Evaluating the thermal stability of PPGs and understanding their thermal stability mechanism are crucial for the development and application of high-temperature-resistant PPGs. We focused on conventional N, N′-methylene-bis-acrylamide (MBA) crosslinked PPGs, systematically analyzing the macroscopic state changes, microstructural changes, and chemical reactions occurring during the ageing process in 1 % NaCl solution at different temperatures, and delved into their thermal stability mechanism. Our findings revealed that the swelling ratio (SR) of PPGs during ageing is correlated with temperature, showing three distinct patterns: a stable SR at low temperatures (<60 °C), a period of unchanged swelling followed by a continuous increase within the intermediate temperature range (70–90 °C), and a rapid swelling leading to sol conversion at high temperatures (>95 °C). Scanning electron microscope observations and elastic modulus analysis confirmed that the microstructure of PPGs remains stable when the SR was unchanged, while continuous increases in the SR indicated damage to the gel's micro-network structure. X-ray photoelectron spectrum and carbon nuclear magnetic resonance spectroscopy indicated that no chemical reactions occurred in PPGs at temperatures not exceeding 60 °C. When temperature was 70–100 °C, a small amount of acrylamide (AM) hydrolysis occurred initially, which then sequentially triggered the hydrolysis of MBA crosslinkers and 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) due to the catalytic effect of undissociated carboxyl. At temperatures above 100 °C, hydrolysis reactions occurred simultaneously in AM, MBA crosslinkers, and AMPS. The thermal stability of MBA-crosslinked PPGs is indeed related to the thermal stability of the MBA, but it can be reduced by the influence of other non-temperature-resistant monomers, such as AM. This study provides insights into the thermal stability mechanisms of PPGs and guidance for the development of high-temperature-resistant PPGs.

Grafting of -Electroactive Probe onto the glassy carbon electrode for the Detection of Tetracycline in Milk sample

ABSTRACT This paper presents a new Schiff base molecule of (Z)-N’-(2-hydroxy-5-nitrobenzylidene) nicotinohydrazide (BNH) that has been synthesised and characterised using Fourier transform infrared spectroscopy, Proton and Carbon-13 Nuclear Magnetic Resonance and High-resolution Ionisation Mass Spectroscopy. The study herein describes the novel chemical modification of glassy carbon electrode (GCE) by drop casting method using the synthesised Schiff base molecule to detect tetracycline (TC) antibiotic. Improved sensitivity of the electrode to the analyte results from the electrode modification using functional group present in the Schiff bases. The electrochemical behaviour of a modified electrode on tetracycline using voltammetric techniques were studied and optimised. The modified electrode showed a good selectivity in the presence of some interferences. The calibration curve for TC was achieved in a linear range of 10–60 μmol L−1 under optimised conditions. The detection limit and quantification for TC was found to be 2.1 μmol L−1 and 9 μmol L−1. The obtained results suggested that tetracycline may be measured in milk samples using the BNH modified glassy carbon electrode.

Bioactive molecules isolated from Cymbopogon flexuosus and Monarda citriodora essential oils: Chemical profiling, antimycotic potential, and molecular docking studies against green and blue molds of Kinnow

Among the most alarming postharvest fungal pathogens affecting the shelf life of citrus fruits are green (Penicillium digitatum) and blue (Penicillium italicum) molds. This in vitro study was aimed to evaluate the essential oils (EOs) of Cymbopogon flexuosus (CF) and Monarda citriodora (MC) and their principal components against these fungal pathogens. The composition of selected EOs was analyzed using Gas Chromatography- Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detector (GC-FID). Citral (83.81%) and thymol (62.51%) were identified as major components and were isolated by column chromatography from CF and MC EO respectively followed by characterization using spectral techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR) and Carbon Nuclear Magnetic Resonance Spectroscopy (13C-NMR). Among EOs and their major components, thymol displayed promising potential against both Penicillium species with MIC values of 50 and 80 mg L-1 respectively. Molecular docking studies also confirmed the stable binding interaction of both components, particularly thymol with the active sites of target proteins i.e. 14-α-demethylase and chitin synthase of P. digitatum and P. italicum with the docking scores of -5.07, -5.41 kcal/mol and -5.78, -5.23 kcal/mol respectively. Optical microscopy studies revealed hyphal thinning and fragmentation at frequent sites with contraction of cytoplasmic content indicating incipient plasmolysis. The tested principal components, citral and thymol were predicted to exhibit similar mechanism of action to that of synthetic recommended molecules as revealed by molecular docking. Therefore, these findings provide empirical support to explore thymol as a promising eco-friendly antifungal agent for postharvest application in Kinnow.

Proteomic Characterization of Human Placenta: Insights into Potential Therapeutic Applications for Osteoarthritis.

Biologics have become increasingly prominent as therapeutics in recent years due to their innate immune-privileged nature, biocompatibility, and high levels of protein biofactors. The aim of the study is to characterise the biologic, lyophilized human placenta (LHP) and explore its therapeutic potential for osteoarthritis (OA). The presence of six bioactive constituents that regulate cell-extracellular matrix interaction was identified by liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS). Metalloproteinase inhibitor 3 (TIMP3), alpha-1 anti-trypsin (a1AT), basic fibroblast growth factor (bFGF), and transforming growth factor β1 (TGFβ1) were detected and quantified using ELISA. The total protein content present in LHP by Bradford assay was found to be 409.35 ± 0.005μg/ml. The analytical techniques such as Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), solid state carbon-13 Nuclear Magnetic Resonance (ssC13 NMR) spectroscopy, and Differential Scanning Calorimetry (DSC) revealed the secondary structure and conformational stability of LHP. X-Ray diffraction (XRD) studies showed its amorphous nature. Bioactivity assessment of LHP was performed in human keratinocytes (HaCaT) and human dermal fibroblasts (HDF) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The LHP was highly proliferative against skin cells and non-toxic, based on the findings of the bioactivity assay. LHP has the potential to be used as a therapeutic agent for OA, as its characterisation unveiled its physical stability, significant concentration of bioactive components that are pertinent to cartilage repair and its conformational stability.

Multi-molar absorption of CO2 by a novel dual-functionalized ionic liquid solution: Experimental and DFT mechanistic study

Viscosity and absorption capacity are the main indexes to evaluate functionalized ionic liquids. Based on the precise design strategy of both anion and cation absorption, a dual-functionalized protic IL diethylenetriamine methylurea ([DETAH][MEUR]) for trapping CO2 was successfully synthesized. The absorption and regeneration properties of the ILs solution were tested, and the changes in the physical properties of ILs before and after CO2 absorption were compared. The experimental results showed that the [DETAH][MEUR] solution had relatively low viscosity, excellent absorption property with 2.05 mol CO2/mol IL at 40 °C and 0.5 mol/L concentration, and its regeneration efficiencies still kept above 90.09 % after five cycles. In addition, the mechanism of the absorption reaction was explored by combining Fourier transform infrared (FT-IR) spectroscopy, carbon nuclear magnetic resonance (13C NMR) spectroscopy, and density functional theory (DFT) calculation methods. It shows that in [DETAH][MEUR] solution, the N atom losing proton (-NH) in the anion is the main absorption site, and the primary amine (-NH2) in the protonated cation [DETAH]+ of secondary amine is used as an auxiliary cooperative trapping CO2. Hopefully, this work can provide a new way for the research and development of green CO2 absorbents.

Structure effects of imidazolium ionic liquids on integrated CO2 absorption and transformation to dimethyl carbonate

The integration of chemical absorption of CO2 and in situ transformation to highly valuable chemicals is a promising process as an alternative toward fossil fuels. Here, three imidazolium ionic liquids (ILs), 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium 1,2,4-triazole ([Bmim][Tz]), and 1-butyl-2,3-dimethylimidazolium 1,2,4-triazole were synthesized to absorb and activate CO2 by the formation of CO2-adducts, which can be in situ converted into dialkyl carbonates with alcohols (ROH, R = CH3, C2H5, and C4H9) in solvent diiodomethane under ambient temperature and pressure. The results show [Bmim][Tz] exhibits the best CO2 absorption capacity and dimethyl carbonates (DMC) yield, where CO2 capacity is up to 0.216 gCO2/gIL and DMC yield (based on methanol) is as high as 20.2 %. The structures of imidazolium ILs have significant effects on the absorption of CO2 and subsequent transformation process. Fourier transform infrared and carbon nuclear magnetic resonance spectroscopies demonstrate ILs structures influence binding sites for CO2 absorption, which can combine with CO2 to form CO2-adducts, zwitterion [Bmim-CO2], and [Tz-CO2]−. Furthermore, density functional theory calculations verify the structure effects (binding sites and steric hindrance) of ILs on the activation of CO2 and methanol, through the elongated CO bond lengths of CO2-adducts and O-H bond lengths of methanol in IL-methanol complexes, respectively, leading to different DMC yields. The integrated process is promising for the energy-efficient capture and utilization of CO2 under ambient conditions.

CPD model prediction of oil sand pyrolysis based on structural parameters from 13C NMR and FTIR measurements

Here, carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) and Fourier transform infrared spectroscopy (FTIR) techniques were used to study the chemical structure characteristics of oil sand and its pyrolysis oil. The FTIR results showed that the values of the CH2/CH3 ratio, A-factor, and DOC1 of the pyrolysis oil decreased during the pyrolysis process, while the C-factor showed a maximum value with increasing pyrolysis temperature. The 13C NMR results showed that methylides and methylides were mainly contributed to oil production. The aliphatic chain in the pyrolysis oil has little alterations during pyrolysis, while the extent of aromatic ring substitution increases from 0.46 to 0.58. Furthermore, a correlation was obtained between the chemical structure of oil and the pyrolysis product yields of oil sand. Moreover, using chemical structure parameters investigated with FTIR and 13C NMR and kinetic parameters based on the thermogravimetric data, the chemical percolation devolatilization (CPD) model was applied to simulate the pyrolysis of oil sand. The results showed that the simulated results for tar and light gas were in good agreement with the experimental data, while those for char underpredicted the experimental data. Overall, the CPD model can effectively predict the pyrolysis of oil sand.

Enhancing Corrosion Resistance of Mild Steel in 1M HCl: Investigation of New Benzoxazepine Derivatives Through Synthesis, Electrochemical Analysis, Surface Analysis, XPS, DFT, and Molecular Dynamics Simulation

AbstractThis research delineates the corrosion inhibitory efficiency of two newly synthesized benzoxazepine derivatives – [3,3‐dimethyl‐11‐phenyl‐3,4,5,11‐tetrahydrodibenzo[b,e] [1,4]oxazepine‐1(2 H)‐one (S1)] and [11‐(4‐chlorophenyl)‐3,3‐dimethyl‐3,4,5,11‐tetrahydrodibenzo[b,e][1,4]oxazepine‐1(2 H)‐one (S2)] – on mild steel in 1M HCl milieu. These derivatives were characterized by proton (1H NMR) and carbon (13C NMR) nuclear magnetic resonance spectroscopy. The experimental approach encompassed potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The corrosion inhibition efficacy of S1 and S2 was concentration‐dependent, with their efficiencies peaking at 92.0 % and 92.1 %, respectively, at a 10−3 M concentration. Surface characterization, conducted using scanning electron microscopy (SEM), energy‐dispersive X‐ray analysis (EDS), X‐ray diffraction (XRD), contact angle measurements, and X‐ray photoelectron spectroscopy (XPS), corroborated the formation of a protective barrier layer on the mild steel surface. Additionally, using an inductive approach, UV‐visible spectrometry was employed to elucidate the adsorption behaviors of these inhibitors on the steel surface. Density functional theory (DFT) and molecular dynamics (MD) simulations were utilized to decipher the interaction mechanisms and adsorption modalities, unveiling critical insights into the interactions of S1 and S2 with the mild steel surface. This comprehensive analysis highlights the robust corrosion inhibition potential of the newly synthesized benzoxazepine derivatives and illuminates their prospective utility as effective inhibitors for mild steel in corrosive environments.

Construction of a microscopic molecular model of Hongqingliang long-flame coal for potential application in adsorption simulation

The present study aims to develop a tailored microscopic molecular model for analyzing the adsorption properties of Hongqingliang (HQL) coal. The chemical structure of the coal was thoroughly analyzed through the utilization of various techniques, including elemental analysis, Carbon-13 Nuclear Magnetic Resonance spectroscopy (13C NMR), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FTIR). Subsequently, a three-dimensional periodic microscopic molecular model for HQL coal was constructed, followed by the development of a 4 nm fracture pore model. To validate the modeling approach, a comprehensive comparative analysis was conducted utilizing nitrogen adsorption isotherms at 77.35 K. The results indicate that the amorphous cell model constructed in Material Studio solely comprises micropores narrower than 1 nm, making it unsuitable for simulating coal's pore characteristics. Conversely, the nitrogen adsorption isotherm of the 4 nm fracture pore model matches actual results. Therefore, to analyze the pore adsorption characteristics of coal, it is necessary to utilize the amorphous cell model to construct a characteristic pore model for coal.

Structure Damage on Cotton Fiber via Coupling Effect of Moisture Regains and Low Temperature

ABSTRACT The most crucial variables that influence the characteristics and quality of cotton fibers during the cotton growth and ginning processes are temperature and moisture regains. Here the cotton fiber samples were generated with pre-treatment using a synergistic strategy of moisture regains and low temperatures, the morphology and structure of the fibers with different pre-treatments were analyzed by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray Photoelectron Spectrometer (XPS), X-ray diffraction (XRD), and Carbon-13 Nuclear Magnetic Resonance Spectrometry (13C NMR). Further, the mechanical properties of the cotton fibers were evaluated using LLY-06E tensile. The results shown that, with 3 days of freezing in -18℃, the linear density variation of the cotton fiber samples reached maximum, and the surface of the fibers showed noticeable fractures, local holes, and folded damage. Moreover, the low temperature and high moisture regain caused the internal water molecules of the cotton fibers interact in complex ways, altering the intermolecular forces but without changing the chemical composition. This research expands the temperature field of cotton fibers, particularly in the ginning process, by investigating the damage to the mechanical characteristics of cotton fibers caused by the combined effect of low temperature and moisture regain.

Isolation and Identificationof Octadecane-3-on Compound From Ethyl Acetate Fraction of Momordica balsamina L. Leaves

Momordica balsamina L. is a wild plant that generally grows in moist soil and gets a lot of sunlight. The leaves and fruit are reported to have various medicinal and nutritional properties. This study aimed to isolate and identify the compounds contained in the ethyl acetate fraction in Momordica balsamina L The isolation stage was carried out by the maceration method and the separation and purification of the compounds using gravity column chromatography methods to obtain isolate fraction F1.6.2 with a sample weight of 2.4 mg. Identification of compounds using proton nuclear magnetic resonance (1H-NMR) and carbon nuclear magnetic resonance (13C-NMR) spectroscopy techniques. The proposed identified compound is octadecan-3-one or 3-octadecanone with the molecular formula C18H36O

Analytical tools for monitoring glycol degradation

This paper aims to develop new methods for monitoring oxidative and thermal glycol degradation through solvent analysis. Methods for quantifying TEG, and for quantifying some degradation products (small glycols and acids), were successfully developed. The results were validated by applying two independent analytical methods for each compound monitored. The glycols were successfully quantified with gas chromatography coupled with flame ionization detection (GC-FID) and with quantitative carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy. The acidic degradation compounds were successfully quantified with high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) and heat-stable salt (HSS) analysis. The thermal stability of TEG decreased with the addition of impurities, especially formic acid. Some color changes were observed during the degradation, but they were not linked with the amount of TEG degraded. Finally, it was found that TEG samples have limited stability, even if stored cold.

Spectroscopic and microscopic characterization of humic acids from composts made by co-composting of green waste, spent coffee and OMWW sludge

ABSTRACT Due to its important role in the formation of humic acids (HA), improving lignin degradation during composting has usually been considered a challenge. One practice that could stimulate the biodegradation of this recalcitrant molecule is inoculation with exogenous lignolytic fungal strains. Two composts (C1) and (C2) from piles (H1) and (H2) were evaluated. H1 was the control pile and H2 was inoculated at maturity with Trametes trogii, resulting in a 35% increase in lignin degradation rate compared to H1. The aim of this study was to show the main effects of this increase on the humification process in the co-composting of green waste, coffee grounds and olive mill wastewater sludge (OMWWs). Microstructure of HA1 and HA2 extracted from C1 and C2, respectively, was also investigated by scanning electron microscopy (SEM) and SEM coupled with energy-dispersive X-ray spectroscopy (X-EDS). The results showed that there were several similarities between the compost samples tested. These included the mineral content, the degree of polymerization (PD)> 1 and the compact and rigid surface of the extracted HA. However, C2 was characterized by a higher humic content (HC), degree of polymerization (PD), humification index (HI) and percentage of humic acids (PHA) than C1. Carbon-13 nuclear magnetic resonance (13C-NMR) and Fourier transmission-infrared spectroscopy (FTIR) analysis showed that aliphatic groups such as hydroxyls, alcohols and carboxyls were predominant in both composts. SEM analysis in conjunction with X-EDS analysis of HA2 showed a higher proportion of carbon and potassium (18 and 7.93%) than in HA1 (14 and 0.95%).

Large-scale atomistic model construction of subbituminous and bituminous coals for solvent extraction simulations with reactive molecular dynamics

Large-scale atomistic models for complex polycyclic aromatic hydrocarbon systems help understand the chemical properties and behaviors of complex feedstocks such as coal or petroleum. However, the development and utilization of large-scale models remain limited due to the difficulty in achieving the varied structural characteristics necessary to capture stochastic nature of these feedstocks. We demonstrate a systematic workflow to construct stochastic molecular systems from a broad analytical suite: high-resolution transmission electron microscopy (HRTEM), carbon-13 nuclear magnetic resonance spectroscopy (13C NMR), laser desorption ionization mass spectroscopy (LDI-MS), and elemental analysis. We present a model construction and analysis utility of a new Python-based module. We selected one subbituminous and three high-volatile bituminous coals to construct large-scale models (∼40,000 atoms). The constructed models were utilized to examine the affinity for solvent extraction (naphthalene or tetralin) and the effect of structural properties (e.g., aromatic cluster size, functional groups, and cross-linking) in reactive molecular dynamics simulations. Complex chemical reactions were monitored with bond order transitions, intermediates formation, and mass distributions. Reactive molecular dynamics simulations suggest a plausible chemical extraction process and products for the complex fossil feedstocks. The results indicated that radical formations with bond breaking of bridging oxygens and carbons were required at high temperatures to facilitate hydrogeneration and extraction of gas molecules from radical-free molecules. We observed that aliphatic chains of tetralin were easily decomposed and combined with radicals to form small size of molecules with aryl bonding, mainly increasing molecules in the 500–1000 Da, while naphthalene had little impact on chemical extraction process.

POPs to COFs by post-modification: CO2 chemisorption and dissolution.

Porous organic polymers (POPs) and covalent organic frameworks (COFs) are hierarchical nano materials with variable applications. To our knowledge, this is the first report of a post-modified, non-renewable, DMSO-soluble M-POP/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) upon atmospheric H2O/CO2 trapping after 48 h, forming a DBUH+·HCO3- adduct, as verified by solution carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy. The success of the post-modification resulting from aldehyde enriched POPs was proven spectroscopically. The accessible functional group was reacted with excess monoethanolamine (MEA) resulting in the formation of M-POP. Away from CO2 physisorption, only few examples have been reported on the chemisorption process. One such example is the ethylene diamine-functionalized E-COF, capable of capturing CO2via carbamation. This was evidenced by several qualitative measurements including colorimetry and conductivity, which showed an unprecedented water solubility for a 2D COF material. The crystallinity of COFs as a result of post-modification was proven by powder X-ray diffraction (PXRD).