Carbon-13 Nuclear Magnetic Resonance Spectroscopy Research Articles

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).

Synthesis and characterization of mono- and bi-iron chalcogeno-ferrocenylcarboxylato complexes

Chalcogenocarboxylato complexes of iron bearing ferrocenyl moieties having two iron atoms in different electronic environments have been synthesized and characterized. Synthesis is accomplished by reactions of (μ-Ex)[CpFe(CO)2]2 (E = S, x = 2–4; E = Se, x = 1) with ferrocenoyl chloride (ClCOC5H4)FeCp which generated CpFe(CO)2ECOC5H4FeCp (E = S (1), Se (2)) in good isolated yields. The analogous reaction with bi-functional ferrocene dicarbonyl dichloride (ClCOC5H4)2Fe gave both the mono substituted products CpFe(CO)2ECOC5H4Fe(C5H4COOH) (E = S (3), Se (4)) or the di-substituted species [CpFe(CO)2ECOC5H4]2Fe (E = S (5), Se (6)). The authentication details of complexes 1–6 are presented along with the results from infrared, ultraviolet-visible, proton and carbon-13 nuclear magnetic resonance spectroscopies. In addition, the structures of 2, 3 and 4 were determined by single crystal X-ray diffraction, evidencing both the half-sandwich and sandwich geometries of the two iron centers.

Isolation, Characterisation and In-vitro Antioxidant activities of Flavonoid Compounds from Methanolic fraction of Aspidopterys indica

Aspidopterys indica belongs to the family Malphigiaceae and is used to treat hypertension and skin diseases. In the current investigation, methanolic extract was fractionated using vacuum liquid chromatography, and the methanolic fraction was subjected to column chromatography for isolation and characterized by fourier transform infrared spectroscopy (FTIR), Mass, proton nuclear magnetic resonance (1H-NMR), and carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy. The compounds isolated were assessed for their in-vitro DPPH antioxidant activity. Two compounds, AI-1 and AI-2, established after spectral analysis, were identified as catechin flavan-3-ol and isoorientin flavone C-glucoside. The results indicated that the compounds showed concentration-dependant DPPH scavenging action and IC50 of catechin 93.66 μg/mL, isoorientin 92.09 μg/mL. This study concludes that catechin and isoorientin with known antioxidant potential were isolated from the methanolic fraction of A. indica, which could effectively manage oxidative stress-related diseases.

Construction of macromolecular structure in KunNing coal and analysis of Macro-Micro oxidation characteristics

To explore the macro–micro coal oxidation characteristics for the purpose of preventing coal spontaneous combustion and achieving efficient coal conversion and utilization, the enclosed coal oxidation characteristics of KunNing coal sample (KN) under 25–70 °C were investigated. KN coal molecular models were constructed based on analysis and testing results of X-ray Photoelectron Spectroscopy (XPS), Carbon-13 Nuclear Magnetic Resonance Spectroscopy (13C NMR), Fourier Transform Infrared Spectroscopy (FTIR) and other techniques. The pyrolysis processes of coal-oxygen reaction systems with different oxygen contents were simulated using ReaxFF force field. The results show that the oxygen consumption rate, CO release rate, CO2 release rate and oxidation heat release intensity of coal increase exponentially with rising temperature. The ratio of aromatic bridge carbon to peripheral carbon in KN coal molecular structure is 0.08, and the molecular formula is C149H76O15N2S2. In the later stage of the experimental and molecular dynamics simulation processes, the CO content decreased while the growth rate of CO2 increased. Different indicator gases exhibit varied responses to oxygen content. The C-atom labeling and traceback results for the four indicator gas molecules demonstrate that CO2 mainly comes from aldehyde, hydroxyl, carboxyl and methoxy groups in coal molecules, CO is primarily generated from esters, phenols, carbonyls, C2H2 is predominantly derived from ring-opening and cracking of cycloalkanes, and the source of C2H4 is related to cycloalkanes and alcohols.

Methyl 4-pyridyl ketone thiosemicarbazone (4-PT) as an effective and safe inhibitor of mushroom tyrosinase and antibrowning agent

Enzymatic browning is of concern as it can affect food safety and quality. In this study, an effective and safe tyrosinase inhibitor and anti-browning agent, methyl 4-pyridyl ketone thiosemicarbazone (4-PT), was synthesised and characterised using Fourier-transform infrared (FTIR) spectroscopy, CHNS elemental analysis, and proton (1H) and carbon-13 (13C) nuclear magnetic resonance (NMR) spectroscopy. The vibrational frequencies of 4-PT were studied theoretically using vibrational energy distribution analysis (VEDA). Density functional theory (DFT) was applied to elucidate its chemical properties, including the Mulliken atomic charges, molecular electrostatic potential (MEP), quantum theory of atoms in molecules (QTAIM) and reduced density gradient non-covalent interactions (RDG-NCIs). Moreover, 4-PT was compared with kojic acid in terms of its effectiveness as a tyrosinase inhibitor and anti-browning agent. The toxicity and physicochemical properties of 4-PT were predicted via ADME evaluation, which proved that 4-PT is safer than kojic acid. Experimentally, 4-PT (IC50 = 5.82 μM, browning index (10 days) = 0.292 ± 0.002) was proven to be an effective tyrosinase inhibitor and anti-browning agent compared to kojic acid (IC50 = 128.17 μM, browning index (10 days) = 0.332 ± 0.002). Furthermore, kinetic analyses indicated that the type of tyrosinase inhibition is a mixed inhibition, with Km and Vmax values of 0.85 mM and 2.78 E-09 μM/s, respectively. Finally, the mechanism of 4-PT for tyrosinase inhibition was proven by 1D, second derivative and 2D IR spectroscopy, molecular docking and molecular dynamic simulation approaches.

Preparation and Application of a Fast, Naked-Eye, Highly Selective, and Highly Sensitive Fluorescent Probe of Schiff Base for Detection of Cu2+

A fluorescent probe, N′-((3-methyl-5-oxo-1-phenyl-4, 5-dihydro-1H-pyrazol-4-yl) methylene)-2-oxo-2H-chromene-3-carbohydrazide (MPMC), was synthesized and characterized. Characterizations of the synthetic MPMC were conducted via proton nuclear magnetic resonance (1HNMR) spectroscopy and carbon-13 nuclear magnetic resonance spectroscopy (13C NMR). The fluorescence emission behaviors of the MPMC probe towards diverse metal ions were detected, and the probe exhibited high sensitivity and selectivity towards Cu2+ over other metal ions via the quenching of its fluorescence. Furthermore, the existence of other metal actions made no apparent difference to the fluorescence intensity of the MPMC-Cu2+ system; that is, MPMC displayed a good anti-interference ability. Job’s plot of the MPMC and copper ions indicated that the detection limit was 10.23 nM (R2 = 0.9612) for the assayed actions, with a stoichiometric ratio of 1:1 for MPMC and Cu2+. Additionally, the color of the MPMC probe solution changed from nearly colorless to yellow in the presence of Cu2+ in visible light, and the color change could be observed by the naked eye. Similarly, the color resolved from bright yellow into blue in ultraviolet light. Moreover, reusability studies indicated that the MPMC probe was reusable. The pH effect of the MPMC probe on Cu2+ had a broad range of pH detection, i.e., from 4.0 to 11.0. The response time of the MPMC probe for determining Cu2+ was within 1 min. The recognition of Cu2+ via MPMC performed on pre-treated paper under sunlight and UV light both had a distinct colour change. Thus, the solid-state method for detecting Cu2+ with the naked eye was both economical and convenient.

Enantioselective Synthesis, Computational Molecular Docking and In Vitro Anticoagulant Activity of Warfarin-based Derivatives

Abstract: Warfarin containing a 4-hydroxycoumarin moiety possesses excellent anticoagulant activity, with the (S) enantiomer being the eutomer. The present work is designed to synthesize warfarin based derivatives enantioselectivity to explore their anticoagulant potential. The substituted chalcones were reacted with 4-hydroxycoumarin in the presence of the chiral organocatalyst 9-amino-9-deoxyepiquinine to afford warfarin-based analogues 5a- 5k. The structures of synthesized compounds 5a-5k were confirmed by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) and electron ionization mass spectroscopy (EIMS) data. The enantiomeric excess (ee) has been found in the range of 16-99% as determined by chiral high-performance liquid chromatography (HPLC) analysis. The in vitro anticoagulant activity of the products 5a-5k was evaluated by plasma recalcification time (PRT) method, and it was found that most of the derivatives showed good anticoagulant activity, specifically compound 5b exhibited excellent results compared to that of warfarin. Compound 5b displayed an IC50 value of 249.88 μM, which is better than that of warfarin (IC50 408.70 μM). The molecular docking studies have been performed against vitamin K epoxide reductase with PDBID 3kp9. The synthesized compounds bind well in the active binding site of the target enzyme. The derivative 5b showed π-π stacking interactions with the amino acid phenylalanine (Phe 114). The antimicrobial activity of synthesized compounds has also been evaluated, and results showed moderate antimicrobial activity. Based on our results, it is proposed that derivative 5b may act as a lead compound to design more potent anticoagulant derivatives.

Quinolone Tethered 1,2,3-triazole Conjugates: Design, Synthesis, and Computational Docking Studies on New Heterocycles as Potent Antimicrobial Targets

Abstract: The synthesis and biological properties of molecules simultaneously comprising various heterocycles, such as fused 2-quinolones and 1,2,3-triazoles, have been evaluated as a part of our ongoing research in medicinal and organic chemistry. We were successful in developing a synthetic procedure for 1,2,3-triazole substituted quinolone derivatives. Infrared, proton, and carbon nuclear magnetic resonance, mass spectroscopy and elemental analysis were used to characterise the structures of the recently synthesised triazole derivatives. From screening results, all the compounds demonstrated increased antibacterial action against both Gram-positive and Gram-negative bacteria. Moreover, 1,2,3-triazoles linked to tert-butyl benzyl (3a), trifluoromethyl benzyl (3b), 3-chlorobenzyl (3c), 4- hydroxy-3-nitrobenzyl (6b), 4-hydroxy-4-trifluoromethylbenzyl (6d), and 4-hydroxy-2,4- difluorobenzyl (6e) compounds showed promising antibacterial and antifungal activities with MICs values of 1.07-4.33 μg/mL. The prepared ligand 4-hydroxy-2,4-difluoro benzyl-1,2,3-triazole (6e) exhibited the highest docking score of -6.34 kcal/mol and showed interacting amino acid residues ArgB:1122, MetB:1121, AspB:1083, TryB:1087, AlaB:1118, AlaB:1120, GluB:1088, GlyB:1117, SerB:1084, and AlaB:1119 within the active site of 2XCT. Final scaffolds were further evaluated for their ADMET and physicochemical properties by using ADMETlab2.0 and SwissADME web servers as good oral bioavailability drugs.

Construction of three-dimensional porous organic polymers with enhanced CO2 uptake performance via solid-state thermal conversion from tetrahedral benzoxazine-linked precursor

Porous organic polymers (POPs) with three-dimensional (3D) linkages have drawn great interest due to their potential applications in separation, adsorption, and sensing fields. Herein, a new 3D benzoxazine (BZ)-linked porous organic polymer (TPM-BZ-Py POP) was synthesized by linking a tetrahedral benzoxazine (TPM-BZ-Br4) with tetraethynylpyrene (Py-T) via Sonogashira coupling. Specifically, the synthesis of the tetrahedral benzoxazines with four oxazine rings in a single monomer involved the utilization of Schiff base formation, NaBH4 reduction as well as Mannich condensation reactions. To confirm the chemical structure of the benzoxazine monomers and their corresponding polybenzoxazines, Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H NMR), and carbon nuclear magnetic resonance (13C NMR) spectroscopy techniques were employed. The pore volume and specific surface area of the 3D TPM-BZ-Py POP were determined through N2 adsorption/desorption isotherms, and they were found to be 0.52 cm3/g and 185 m2/g, respectively. In addition, the solid-state chemical transformation occurred during thermal ring-opening polymerization (ROP), and the resulting 3D poly(TPM-BZ-Py) POP displayed higher CO2 capture ability (1.81 mmol/g) compared with TPM-BZ-Py POP (0.60 mmol/g) at room temperature. Such enhancement observed in poly(TPM-BZ-Py) POP was proposed to be caused by the formation of phenolic units and Mannich bridges within the polymer network by taking into consideration the structural transformation during the ring-opening polymerization (ROP). The functionalities in poly(TPM-BZ-Py) have great potential to interact with CO2 molecules through strong intermolecular hydrogen bonding or acid/base interactions, which further supports the benefit of incorporating oxazine rings into POP frameworks.

Margin of exposure to free formaldehyde in personal care products containing formaldehyde-donor preservatives: Evidence for consumer safety

Formaldehyde has been classified as carcinogenic to humans by International Agency for Research on Cancer and found in personal care (PC) products containing formaldehyde-donor (FD) preservatives. However, the cancer risk associated with the use of FD-containing PC products has not been well established. Our study provides the quantitative cancer risk assessment of formaldehyde in FD-containing PC products. The carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy was used in this risk assessment to provide reliable exposure information to formaldehyde in PC products and aqueous solutions containing sodium hydroxymethylglycinate. The risk assessment was conducted using the margin of exposure (MOE) approach with benchmark doses (BMDs) for 10% effect. For hemolymphoreticular neoplasias in male rats, a BMD of 28.03 mg/kg/day and a BMD lower confidence limit (BMDL) of 2.52 mg/kg/day were calculated from available long-term animal experiments. The worst-case consumer exposure to formaldehyde from FD-containing PC products was 0.007 μg/kg/day. Comparing the consumer exposure with BMDL, the resulting MOE was 360,000 for the worst-case scenario. The consumer exposure to formaldehyde (0.007 μg/kg/day) from using FD-containing PC products represents less than 1.0 × 10−6 % of background level endogenous formaldehyde (878–1310 mg/kg/day). The cancer risk from formaldehyde to consumers using FD-containing PC products is negligible.

Synthesis, polymerization and thermal properties of bio‐based benzoxazine resins containing imide or amide functionality

AbstractTwo novel bio‐based benzoxazine monomers containing imide or amide group (HPIDD‐fa and HPBA‐fa) were synthesized from raw materials of benzoyl chloride/phthalic anhydride, tyramine, furfurylamine and paraformaldehyde via a two‐step reaction. Fourier transform infrared spectroscopy (FT‐IR), proton and carbon nuclear magnetic resonance (NMR) spectroscopies were performed to characterize the structures of the benzoxazine monomers. The curing behavior was investigated by using differential scanning calorimetry (DSC) and in situ FT‐IR, and the DSC results indicate that the peak curing temperatures of HPIDD‐fa and HPBA‐fa are centered at 248.5 and 230.1°C, respectively. In addition, thermogravimetric analysis (TGA) suggests that the newly developed bio‐based benzoxazine‐derived polybenzoxazines present excellent thermal stability with Td10 (temperature at 10% weight loss) of 385 and 368°C for poly(HPIDD‐fa) and poly(HPBA‐fa), respectively. The current investigation suggests that our newly obtained bio‐based thermosetting resins are promising materials for high‐tech applications.