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Aromatic amines are important commercial chemicals, but their carcinogenicity poses a threat to humans and other organisms, making their rapid quantitative detection increasingly urgent. Here, amorphous MoO3 (a‐MoO3) monolayers with localized surface plasmon resonance (LSPR) effect in the visible region are designed for the trace detection of carcinogenic aromatic amine molecules. The hot‐electron fast decay component of a‐MoO3 decreases from 301 fs to 150 fs after absorption with methyl orange (MO) molecules, indicating the plasmon‐induced hot‐electron transfer (PIHET) process from a‐MoO3 to MO. Therefore, a‐MoO3 monolayers present high SERS performance due to the synergistic effect of electromagnetic enhancement (EM) and PIHET, proposing the EM‐PIHET synergistic mechanism in a‐MoO3. In addition, a‐MoO3 possesses higher electron delocalization and electronic state density than crystal MoO3 (c‐MoO3), which is conducive to the PIHET. The limit of detection (LOD) for o‐aminoazotoluene (o‐AAT) is 10−9 M with good uniformity, acid resistance, and thermal stability. In this work, trace detection and identification of various carcinogenic aromatic amines based on a‐MoO3 monolayers is realized, which is of great significance for reducing cancer infection rates. [ABSTRACT FROM AUTHOR]

Aromatic amines are important commercial chemicals, but their carcinogenicity poses a threat to humans and other organisms, making their rapid quantitative detection increasingly urgent. Here, amorphous MoO3 (a‐MoO3) monolayers with localized surface plasmon resonance (LSPR) effect in the visible region are designed for the trace detection of carcinogenic aromatic amine molecules. The hot‐electron fast decay component of a‐MoO3 decreases from 301 fs to 150 fs after absorption with methyl orange (MO) molecules, indicating the plasmon‐induced hot‐electron transfer (PIHET) process from a‐MoO3 to MO. Therefore, a‐MoO3 monolayers present high SERS performance due to the synergistic effect of electromagnetic enhancement (EM) and PIHET, proposing the EM‐PIHET synergistic mechanism in a‐MoO3. In addition, a‐MoO3 possesses higher electron delocalization and electronic state density than crystal MoO3 (c‐MoO3), which is conducive to the PIHET. The limit of detection (LOD) for o‐aminoazotoluene (o‐AAT) is 10−9 M with good uniformity, acid resistance, and thermal stability. In this work, trace detection and identification of various carcinogenic aromatic amines based on a‐MoO3 monolayers is realized, which is of great significance for reducing cancer infection rates. [ABSTRACT FROM AUTHOR]

One hundred and twenty samples of meat products represented by grilled kofta, grilled meat, charcoal grilled kofta, and charcoal grilled meat (30 pieces each) were randomly collected from different markets in Kalyobia Governorate, Egypt. Each sample was individually packed in a plastic bag and taken directly to the laboratory. Collected samples were analyzed for heterocyclic aromatic hydrocarbons (HAAs). This study aimed to reduce the amount of carbonization and fat pyrolysis by reducing the amount of meat droplets using antioxidants such as butylhydroxytoluene (0.02%) and carvacrol (1%). The observed findings showed that the average levels of HAAs (pg/kg) in charcoal-grilled meat samples, left untreated (n = 30), were as follows: BhIP, MelQx, 4,8-DiMelQx and Norharman were Norharman while IQ was beyond the undetected limit (UDL). Meanwhile, the treated samples with (BHT 0.0% and carvacrol 1%) showed that individuals; BhIP, MelQx, 4,8-DiMelQx, and Norharman were 3.8±0.3, 0.5±0.1, 1.2±0.1 and 1.8±0.1 with reduction percentage 41.5%, 28.6%, 36.8% and 47.1%, respectively for BHT concentration 0.02%. While for carvacrol concentration 1% individuals; BhIP, MelQx, 4,8-DiMelQx, and Norharman were 3.1±0.2, 0.4±0.2, 1.0±0.1 and 1.5±0.1 with reduction percentages 52.3%, 42.9%, 47.4%, and 55.9%, respectively. In conclusion, this study recommends the treatment of charcoal grilled meat with antioxidants, such as BHT 0.0% and carvacrol 1%, to reduce HAAS concentrations in the examined samples. [ABSTRACT FROM AUTHOR]

Primary aromatic amines (PAAs) may be found in food contact materials and can potentially migrate from packaging material into the packed foodstuffs. Certain members of this substance class are of particular concern due to their toxicological properties. Legislators and authorities require a risk assessment regarding the transfer of PAAs into food. The evaluation of PAAs' migration into food relies on migration or extraction tests using aqueous and acidic food simulants or solvents. However, PAAs exhibit stability issues in acidic media, which could lead to an underestimation of migration. Therefore, a systematic stability study was conducted for 28 PAAs in 3% acetic acid and water at different storage conditions. Standard solutions of 2 and 10 ng/ml of the amines in these media were prepared and stored under the following conditions: 2 h at 40 °C, 70 °C, and 100 °C, and 10 days at − 20 °C, 4 °C, 20 °C, 40° C, and 60 °C. The test solutions were analyzed using liquid chromatography coupled to mass spectrometry, and recovery was calculated against freshly prepared standard solutions. It was found that several PAAs undergo a loss of recovery under the investigated conditions; 7 of the substances were identified to be the most unstable: 3,3ʹ-dimethoxybenzidine, 3,3ʹ-dimethylbenzidine, 6-methoxy-m-toluidine, 4-methoxy-m-phenylendiamine, 2,6-toluenediamine, benzidine and 2,4-toluenediamine. It was concluded that both time and storage temperature play a pivotal role in the stability of PAAs. The experiments also demonstrated that PAAs exhibit greater stability in water than in 3% acetic acid. [ABSTRACT FROM AUTHOR]

Despite the importance of difluoromethylene fragments in medicine, agrochemistry, and materials science, the precise and sustainable C–H difluoromethylation of aryl rings remains a challenge. Studies of metal-free difluoromethylation at room temperature would be advanced if methods were as reliable and modular as metal catalysis. Herein, we present a green and environmentally friendly modular platform for the sustainable para-difluoromethylation of readily available aromatic amines via a metal-free photocatalytic system. The reaction, for the first time, exhibits excellent functional group tolerance and broad substrate scope with a radical–radical coupling C–H functionalization strategy, rapidly delivering a variety of valuable difluoromethylated products. Furthermore, the derivatization of various complex molecules with high atom economy further demonstrates the synthetic utility and practicality of this protocol. A series of experimental studies and DFT calculations corroborate the plausible reaction mechanism. [ABSTRACT FROM AUTHOR]

As the global production of polymers exceeded 400 million tons in 2022, it is imperative that recycling rates are increased to prevent the predominant end-of-life handling through landfilling and incineration processes. With an increasing reliance on polyurethane (PU), the 2022 global production of PU reached almost 26 million tons. As PU is mainly utilised as a thermoset material, the extensive cross-linked networks render melting and remolding processes known from thermoplastic materials incompatible. As such, the majority of PU that is recycled is processed through mechanical shredding and gluing processes or chemical recycling via glycolysis and acidolysis processes for polyol recovery, all providing a secondary material with properties different from the parent material. Here, we show that the well-established acidolysis process can be used to both depolymerise PU and separate the polyol and dianiline adducts with a specific focus on analysing and valorising the dianiline component arising from the hard segment of PU. By evaluation of the reaction outcome from acidolysis of flexible PU foam with succinic acid, adipic acid or phthalic acid under neat conditions, succinic acid was found to form the corresponding succinimide of toluene diamines that is readily separable from the polyol. The toluene diamine could in turn be reformed through ruthenium-catalysed hydrogenation or simple hydrolysis. Ultimately, the combined acidolysis/hydrolysis of a flexible PU foam yields the polyol and dianiline in a combined 83 wt% recovery. A similar recovery rate was achieved for a commercial rebonded flexible foam. As current PU recycling methods only target the polyol fraction often obtained in a low quality, this advancement shows that current industrially applied acidolysis could be altered so that both the diamines and polyol can be obtained from flexible PU foam. Preliminary results show that the process is applicable to rigid PU foams, a PU fraction that is difficult to recycle due to its molecular complexity. Finally, a mechanistic pathway is suggested to account for the observed product distributions. [ABSTRACT FROM AUTHOR]

The formation of amide bonds via aminolysis of esters by lipases generates a diverse range of amide frameworks in biosynthetic chemistry. Few lipases have satisfactory activity towards bulky aromatic amines despite numerous attempts to improve the efficiency of this transformation. Here, we report the discovery of a new intracellular lipase (Ndbn) with a broad substrate scope. Ndbn turns over a range of esters and aromatic amines in the presence of water (2 %; v/v), producing a high yield of multiple valuable amides. Remarkably, a higher conversion rate was observed for the synthesis of amides from substrates with aromatic amine rather than aliphatic amines. Molecular dynamics (MD) and quantum mechanical/molecular mechanical (QM/MM) studies showcase the mechanism for the preference for aromatic amines, including a more suitable orientation, shorter catalytic distances in the active site pocket and a lower reaction barrier for aromatic than for aliphatic amines. This unique lipase is thus a promising biocatalyst for the efficient synthesis of aromatic amides. [ABSTRACT FROM AUTHOR]

The formation of hazardous substances, heterocyclic aromatic amines (HAAs) and two representative advanced glycation end products (AGEs), Nε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL) in five kinds of fish with different fat contents during thermal processing was investigated. The results indicated that HAAs, AGEs produced is related to the lipids in varying degrees. The variation of key precursors were examined to explain the relationship between fat oxidation and molecular pathway of HAAs and AGEs formation. The current research may help us better understand the overall generation of hazardous substances in food systems, and provide new ideas for formulating prevention in future production. [ABSTRACT FROM AUTHOR]

Carbon substituted cobalt bis(dicarbollide) alkyl halides [(1-X-(CH2)n-1,2-C2B9H10)(1,2-C2B9H11)-3,3′-Co]Me4N (X = Br, I; n = 1–3) are prepared in high yields (>90%) from their corresponding alcohols without side skeletal substitutions. These species offer access to the synthesis of aromatic cobalt bis(dicarbollide) amines, however only for particular terminal halogen substitution, the propylene pendant arm, and under appropriately controlled reaction conditions. Thus, the compounds substituted at cage carbon atoms with a propylene linker and terminal aromatic amine groups could be prepared. In other cases, numerous irregular reaction pathways occur, undoubtedly as a consequence of the bulky anionic boron cage in close proximity to the reaction site. Among them, an unusual intramolecular hydroboration forming rigidified carbon-to-boron bridged isomeric anions with an asymmetric structure that correspond to formulae [(1,8′-μ-C2H4)-(1,2-C2B9H10)(1′,2′-C2B9H10)-3,3′-Co]− and [(1,7′-μ-C2H4)-(1,2-C2B9H10)(1′,2′-C2B9H10)-3,3′-Co]− is described herein and the former isomer is structurally characterized. This product with a restrained geometry is widely accessible through nucleophile and/or thermally induced decomposition of (pseudo)halides attached to the cage via an ethylene linker. Surprisingly enough, also doubly bridged isomeric species [(1,8-μ-C2H4-1,2-C2B9H9)2-3,3′-Co]− and [(1,7-μ-C2H4-1,2-C2B9H9)2-3,3′-Co]− are available in good yield using these methods. Furthermore, other more typical side reactions are discussed, i.e. nucleophilic reactions of propyl halides with Me3N formed apparently by disproportionation of Me4N+ at higher temperatures or with pyridine used as a base. [ABSTRACT FROM AUTHOR]

Experimental and theoretical study of the regioselectivity and mechanism of polycyclic aromatic amine (PAA) electrochemical oxidation is important for designing nitrogen doped large π‐conjugated functional molecules. Herein, we used binary‐, ternary‐, and quaternary‐fused PAAs as electro‐oxidative reaction substrates to investigate the yield changes of carbazole and phenazine based aza‐helicene other than oligomers, which were obtained through pyrrole and pyrazine annulation pathways. Combined with the restrained electrostatic potential (RESP) and steric hindrance factor analysis of the substrate, the electron spin density distribution of free radical resonance hybrid and the spin population analysis of the atoms in the structure of each free radical tautomer indicate that the degree of delocalized dispersion of N free radical and the resulting change in the spin density distribution of C free radical tautomers determine the reaction regioselectivity. The potential charge of the K‐region, Bay‐region, and L‐region adjacent to the C(α)−C(β1) bond is higher than that of other regions within the molecule, and the charge in these high RESP regions tends to delocalize more strongly toward electron‐deficient N free radicals. Thus, the activity of N−C(α)−C(β1) region is increased, which supports the proposed free radical addition and free radical coupling mechanism for the electro‐oxidative reaction of PAA. [ABSTRACT FROM AUTHOR]

Meta‐aramid fibre exhibits poor dyeing performance when treated using conventional dyeing methods. In this study, coloration of meta‐aramid fabrics was performed at room temperature utilising diazonium salts from weakly basic aromatic amines and was achieved via in situ construction of azo chromophores on the meta‐phenylenediamine moiety. To promote diazonium‐salt penetration into the meta‐aramid fibre, the pretreatment of meta‐aramid fabrics with dimethyl sulfoxide at 55°C for 30 min and the utilisation of methanol were involved during the coloration process. As a result, the fabrics could be coloured with deep, levelled and firm shades of brown series. The azo chromophore is derived from the skeleton of the polyamide chain. Therefore, the coloured fabrics exhibit good resistance to organic solvents as well as good to excellent colour fastness to soaping, rubbing and sublimation. A study of the coloration mechanism revealed that the terminal and middle meta‐phenylenediamine moieties serve as the main coupling reaction sites. When treated with a diazonium salt, the highly reactive terminal meta‐phenylenediamine moiety reacted first and generated chromophores with an absorption peak in the long‐wavelength region. However, such chromophores only contributed a limited colour depth owing to the limited number of the terminals. If excess diazonium salts were used, the main hue can be attributed to the azo chromophores based on the massive middle meta‐phenylenediamine moieties, although these moieties are less reactive than the terminal meta‐phenylenediamine moieties. [ABSTRACT FROM AUTHOR]

Some aromatic amines (AA) have been classified as carcinogens to humans. After entering the body, mainly through tobacco smoke, they can be detected in urine. Thus, their trace analysis as biomarkers in biofluids is of high relevance and can be achieved with gas chromatography (GC–MS), usually after derivatization. This study compares three gas chromatographic methods for the analysis of ten iodinated derivatives of AA: GC–MS in single-ion monitoring (SIM) mode with (1) electron ionization (GC-EI-MS) and (2) negative chemical ionization (GC-NCI-MS), and (3) GC-EI-MS/MS in multiple reaction monitoring (MRM) mode using electron ionization. All methods and most analytes showed good coefficients of determination (R2 > 0.99) for broad linear ranges covering three to five orders of magnitude in the picogram-per-liter to nanogram-per-liter range, with one and two exceptions for (1) and (2) respectively. Excellent limits of detection (LODs) of 9–50, 3.0–7.3, and 0.9–3.9 pg/L were observed for (1), (2), and (3) respectively, and good precision was achieved (intra-day repeatability < 15% and inter-day repeatability < 20% for most techniques and concentration levels). On average, recoveries between 80 and 104% were observed for all techniques. Urine samples of smokers and non-smokers were successfully analyzed, and p-toluidine and 2-chloroaniline could be found at significantly (α = 0.05) higher concentrations among smokers. [ABSTRACT FROM AUTHOR]

In this study, a TiO2-P25 photocatalyst was chemically complexed with a triethanolamine (TEOA) molecule using visible light irradiation and its photocatalytic activity was evaluated in the photoreduction of a wide range of nitroaromatic compounds. The chemically adsorbed TiO2-TEOA complexes were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, N2 adsorption/desorption isotherm analysis and dynamic light scattering (DLS) analysis. The TEOA-functionalized TiO2-P25 surface complex shows enhanced photocatalytic activity under visible light irradiation (λ = 400 nm) when compared to pure TiO2-P25. This enhancement results from the charge transfer (CT) complex formation between TiO2 and TEOA, as well as electron transfer via a ligand-to-metal charge transfer (LMCT) mechanism. Interestingly, in the presence of a nitro compound (NC), the chemically absorbed TiO2-TEOA forms a TiO2-TEOA-NC triad complex system. The three components spontaneously self-assemble into a heterosupramolecular system that performs electron transfer as a single function. As a result, after absorbing visible light, the triad system demonstrates unique photocatalytic performance as compared to both TiO2-TEOA and TEOA-nitro complexes. The increased charge separation in the triad system was demonstrated by photocurrent and electrochemical impedance spectroscopy (EIS) under visible light irradiation. Electrochemical techniques, including photocurrent, impedance, light absorption and emission spectroscopies, demonstrated that increasing the current and charge separation within the triad system effectively inhibits the recombination of electron-hole pairs. The results of the study indicate that the conversion of nitroarenes to their corresponding amines can take place rapidly and on a large scale, yielding excellent results even under atmospheric pressure and air. It is noteworthy that this is the first study in this area, which highlights the potential of reducing nitroarenes into their corresponding amines with a high efficiency of up to 5 mmol using a photocatalytic procedure. The chemoselectivity of this system was excellent, even in the presence of other reducible groups in the nitro compound. Additionally, a one-pot reductive conversion of nitroarenes to amides was carried out with high efficiency using triethyl orthoformate, acetic anhydride, and benzoic anhydride. [ABSTRACT FROM AUTHOR]

Although aromatic amines are widely used as raw materials for dyes, some, such as o-toluidine and o-anisidine, have shown concerning results regarding carcinogenicity in the urinary bladder. We have recently developed a short-term detection method for bladder carcinogens using immunohistochemistry for γ-H2AX, a DNA damage marker. Here, using this method, we evaluated aromatic amines with structures similar to o-toluidine and o-anisidine for bladder mucosal damage and potential carcinogenicity. In total, 17 aromatic amines were orally administered to male F344 rats for 28 days, and histopathological examination and γ-H2AX immunostaining of the urinary bladder were performed. Histopathological analysis revealed that seven aromatic amines, including 4-chloro-o-toluidine (4-CT), o-aminoazotoluene, 2-aminobenzyl alcohol (ABA), o-acetotoluidine (o-AT), 3,3ʹ-dimethoxybenzidine, 4-aminoazobenzene (AAB), and 4,4′-methylenedianiline (MDA), induced various bladder lesions, such as hemorrhage, necrosis, and urothelial hyperplasia. The morphological characteristics of mucosal damage induced by these substances were divided into two major types: those resembling o-toluidine and those resembling o-anisidine. Six of these aromatic amines, excluding MDA, also caused significant increases in γ-H2AX formation in the bladder urothelium. Interestingly, 4-CT did not cause mucosal damage or γ-H2AX formation at the lower dose applied in previous carcinogenicity studies. These results showed for the first time that o-AT and ABA, metabolites of o-toluidine, as well as AAB caused damage to the bladder mucosa and suggested that they may be bladder carcinogens. In addition, 4-CT, which was thought to be a noncarcinogen, was found to exhibit bladder toxicity upon exposure to high doses, indicating that this compound may contribute to bladder carcinogenesis. [ABSTRACT FROM AUTHOR]

The global demand for intelligent sensing of aromatic amines has consistently increased due to concerns about health and the environment. Efforts to improve material design and understand mechanisms have been made, but highly efficient non‐contact sensing with host–guest structures remains a challenge. Herein, we report the first example of non‐contact, high‐contrast sensing of aromatic amines in a hydrogen‐bonded organic framework (HOF) based on a nitro‐modified stereo building block. Direct observation of binding interactions of trapped amines is achieved, leading to charge separation‐induced emission quenching between host and guests. Non‐contact sensing of aniline and diphenylamine is realized with quenching efficiencies up to 91.7 % and 97.0 %, which shows potential for versatile applications. This work provides an inspiring avenue to engineer multifunctional HOFs via co‐crystal preparations, thus enriching applications of porous materials with explicit mechanisms. [ABSTRACT FROM AUTHOR]

The global demand for intelligent sensing of aromatic amines has consistently increased due to concerns about health and the environment. Efforts to improve material design and understand mechanisms have been made, but highly efficient non‐contact sensing with host–guest structures remains a challenge. Herein, we report the first example of non‐contact, high‐contrast sensing of aromatic amines in a hydrogen‐bonded organic framework (HOF) based on a nitro‐modified stereo building block. Direct observation of binding interactions of trapped amines is achieved, leading to charge separation‐induced emission quenching between host and guests. Non‐contact sensing of aniline and diphenylamine is realized with quenching efficiencies up to 91.7 % and 97.0 %, which shows potential for versatile applications. This work provides an inspiring avenue to engineer multifunctional HOFs via co‐crystal preparations, thus enriching applications of porous materials with explicit mechanisms. [ABSTRACT FROM AUTHOR]

The reactions of saturated monobasic carboxylic acids with functionally substituted primary aromatic amines (3-amino-2-naphthol, benzo[d]thiazol-2-amine, and 4,4′-oxydianiline) with TaCl5 (0.2 equiv.) were found to be accompanied by the selective formation of carboxylic acid amides of various structures. A mechanism for the amidation of carboxylic acids in the presence of TaCl5 was proposed. [ABSTRACT FROM AUTHOR]

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In the current study, the impacts of using cumin (0.5% and 1%, w/w) in beef meatballs on heterocyclic aromatic amines (HAAs) formation and some quality characteristics when cooked at 150 and 250 °C were investigated. It was found that using of cumin at different ratios in beef meatballs showed a significant (p < 0.01) effect on pH, thiobarbituric acid reactive (TBARS) value, and total HAA. The cooking process significantly (p < 0.01) affected the meatballs' water content, pH, and TBARS values, while the cooking loss and total HAA content of meatballs were significantly (p < 0.01) affected by cooking temperature. It was found that the cumin usage rate in meatballs increased the pH value, while it was found to decrease the TBARS value. As expected, the cooking process was associated with a reduction in water, while it was found to result in an increase in the pH and TBARS values. On the other hand, both cooking temperature and cumin addition to meatballs led to an increase in their total HAA content. Diverse samples exhibited detectable levels of IQx, MeIQx, MeIQ, and PhIP compounds. The presence of MeIQx compound was found in all samples, except for the control group cooked at 150 °C. Additionally, the use of 0.5% and 1% cumin in meatballs cooked at temperature of 250 °C had an inhibitory effect on MeIQx compound. Our results revealed that the incorporation of cumin in the meatballs resulted in an increase in the total HAA content, likely due to its prooxidant effect. However, it was found that the use of cumin at certain rates could reduce the formation of MeIQx compound with an antioxidant effect. However, in this study found that even if 100 g of meatballs with the highest concentration of total HAA were consumed, the maximum HAA exposure limit value (0–15 µg/day) was not exceeded. [ABSTRACT FROM AUTHOR]

Synthesis of 2-aryl substituted benzoxazoles, benzothiazoles, and quinoxalinones via decarboxylative coupling of α-keto acids with 2-aminophenol, 2-aminothiophenol, and OPD (o-phenylenediamine), using K2CO3 as a base in water at room temperature, and as well as solvent-free grinding and the synthesis of benzoxazinones from the reaction of α-keto acids with 2-aminophenol at 60 °C have been reported. Both the protocols afforded a wide range of desired products with excellent functional group tolerance in yields of 87-99%. The major advantages of these approaches are catalyst-free protocol, short reaction times, straightforward workup, and chromatographyfree processing of the products. Additionally, to test the translational demand of this methodology, the synthesis of 2-(3,5-dichlorophenyl)- 6-methylbenzo[d]oxazole was carried out which is a key structure of tafamidis, a commercially available drug. [ABSTRACT FROM AUTHOR]

Herein, the catalytic effects of aromatic amines with different structures on the room temperature curing of bisphenol E cyanate (BECy) have been studied using differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. Our results revealed that the mixed amine comprised of aniline and N,N-dimethyl-p-phenylenediamine (AN/NNDPA) bearing primary amino groups in its structure was a highly effective catalyst for the room temperature curing of cyanate esters. When the cyanate ester and mixed amine were combined at a molar ratio of 100:5 and cured at room temperature for 5 days, the curing degree of BECy resin reached 79.7%. The room temperature curing mechanism of the BECy-AN/NNDPA system was investigated using pyrolysis gas chromatography-mass spectrometry (PY GC-MS). Our results showed that the formation reactions of the intermediate structure and cyclotrimerization reactions occurred during the room-temperature curing process. The activation energies of BECy and different aromatic amine systems at different heating rates were determined using non-isothermal DSC. The results further demonstrated the catalytic effect of AN/NNDPA on the cyanate ester curing reaction. BECy-AN/NNDPA cured at room temperature has suitable heat resistance and a 5% weight loss temperature (Td5) of 361°C. [ABSTRACT FROM AUTHOR]

The results of application of new catalytic reagents based on cerium dioxide nanoparticles and its composites with gold, hydroxyapatite, and polyvinylpyrrolidone to the reductive alkylation of heteroaromatic and heterocyclic amines with methyl 4formylbenzoate are presented. A highly efficient method for preparation of benzylated heterocyclic and aromatic amines is proposed. [ABSTRACT FROM AUTHOR]

Five new Betti base copper(II) complexes (C1–C5) are successfully synthesized and characterized spectroscopically. X-ray diffraction analysis confirmed the square planar geometry of complex C4. Their catalytic application in the C–H functionalization of aromatic amines for azidation was successfully demonstrated under ultrasonication. Complex C5 showed better catalytic activity and produced 2-azidoaniline with a yield of 85%, which is higher than the existing methods; it also performed better than commercial catalysts, with a higher efficiency. The reaction involves a lower catalytic loading and a short reaction time. Control experiments were carried out to predict the reaction pathway. Based on the results, a plausible mechanism involving a free radical pathway accompanied by a single electron transfer mechanism is proposed. The substrate scope was also studied with different aromatic amines, and the corresponding azides were obtained successfully. All the synthesized azides were employed in click reactions to obtain the respective triazoles. The biological relevance of the triazoles was also explored successfully using molecular docking studies against SARS-CoV-2 main protease Omicron P132H. [ABSTRACT FROM AUTHOR]

In this work, we present a rapid, metal‐free and efficient method for thiocyanation of aromatic amines under microwave irradiation for the synthesis of aryl thiocyanates using inexpensive and nontoxic NH4SCN as thiocyanato source and K2S2O8 as an oxidant. This protocol tolerates a wide range of substituted anilines to provide the corresponding thiocyanated products in good to excellent yields. The features of this strategy include a broad substrate scope, high functional group tolerance, mild reaction conditions, and short reaction time. [ABSTRACT FROM AUTHOR]

Aromatic amines (AA) are carcinogenic compounds that can enter the human body through many sources, one of the most important being tobacco smoke. They are excreted with the urine, from which they can be extracted and measured. To that end, hollow fiber-liquid-phase microextraction (HF-LPME) and parallel artificial liquid membrane extraction (PALME) were optimized for the analysis of representative aromatic amines, as alternatives to liquid–liquid extraction (LLE). Relevant extraction parameters, namely organic solvent, extraction time, agitation speed, and acceptor solution pH, were studied, and the two optimized techniques—HF-LPME: dihexyl ether, 45 min, 250 rpm, and pH 1; PALME: undecane, 20 min, 250 rpm and pH 1—were compared. Comparison of the optimized methods showed that significantly higher recoveries could be obtained with PALME than with HF-LPME. Therefore, PALME was further validated. The results were successful for nine different AA, with regression coefficients (R2) of at least 0.991, limits of detection (LOD) of 45–75 ng/L, and repeatability and peak area relative standard deviations (RSD) below 20%. Furthermore, two urine samples from smokers were measured as proof of concept, and 2-methylaniline was successfully quantified in one of them. These results show that PALME is a great green alternative to LLE. Not only does it use much smaller volumes of toxic organic solvents, and sample—enabling the study of samples with limited available volumes—but it is also less time consuming and labor intensive, and it can be automated. [ABSTRACT FROM AUTHOR]

Aromatic amines are a class of carcinogenic compounds in tobacco smoke that are listed on the FDA list of harmful and potentially harmful constituents (HPHCs). A method using solid-phase microextraction-coupled to gas chromatography-triple quadrupole mass spectrometry (SPME headspace GC–MS/MS) was developed and validated for the quantitative determination of six aromatic amines, including 1-aminonaphthalene (1-AN), 2-aminonaphthalene (2-AN), 3-aminobiphenyl (3-ABP), 4-aminobiphenyl (4-ABP), o-toluidine (o-TOL), and o-anisidine (o-ANI), in the mainstream smoke of cigarettes, cigars, and heated tobacco products. The method developed here combines high sensitivity with simple sample preparation and has demonstrated satisfactory linearity for all six aromatic amines with correlation coefficients greater than 0.9994. The limits of detection range and the limits of quantitation range were 12–96 pg/mL and 41–320 pg/mL, respectively. Their recoveries and coefficients of variation (CV%) were 90–112% and 2.1–6.6%, respectively. The new SPME headspace GC/MS/MS method has been successfully applied to measure the contents of the six aromatic amines in the mainstream smoke of cigarettes, cigars, and heated tobacco products. [ABSTRACT FROM AUTHOR]

In order to determine optimum and ecologically acceptable conditions for aromatic amines (benzidine was chosen as an example) elimination by chara algae Nitella sp. a multi-factor experiment has been undertaken. The benzidine elimination process by chara algae was studied by variation of four factors, such as benzidine initial concentration in water solution, algae biomass, temperature, time and at the interaction of these factors as well. A mathematical model adequately describing the benzidine elimination process by chara algae at the optimal conditions has been obtained by means of design of experiments method. Suggested model might be useful for obtaining the data important for hydro botanical treatment facilities design and self-cleaning processes understanding. [ABSTRACT FROM AUTHOR]

With commericially available braised squab as research object, UHPLC-Q-Orbitrap HRMS was established. Eleven polar heterocyclic aromatic amines in braised squab were detected by UHPLC-Q-Orbitrap HRMS. The results showed that the method had good linearity and high mass accuracy. The mass accuracy of 11 heterocyclic aromatic amines was <3x10-6. The determination coefficients were greater than 0. 997 2. The limit of detection was 0. 03~0. 60 μg / kg, and the limit of quantification was 0. 10 ~ 2. 00 μg / kg. This method had stable recovery and certain accuracy. The recovery of 11 heterocyclic aromatic amines at 3 spiked concentrations ranged from 83. 40% to 114. 80%, and the precision ranged from 1. 40% to 7. 20%. The main heterocyclic aromatic amines detected in braised squab were MeIQx (0. 10 ~ 0. 46 μg / kg), PhIP (0. 10 ~ 0. 53 μg / kg) and DMIP (0. 10 ~ 0. 25 μg / kg). The total content of heterocyclic aromatic amines in 4 parts of braised squab was the heel, breast, wing and leg in descending oder. [ABSTRACT FROM AUTHOR]

Heterocyclic aromatic amine molecularly imprinted polymer nanospheres with surface-bound dithioester groups (haa-MIP) were firstly synthesized via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization. Then, a series of core-shell structural heterocyclic aromatic amine molecularly imprinted polymer nanospheres with hydrophilic shells (MIP-HSs) were subsequently prepared by grafting the hydrophilic shells on the surface of haa-MIP via on-particle RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA), and diethylaminoethyl methacrylate (DEAEMA). The haa-MIP nanospheres showed high affinity and specific recognition toward harmine and its structural analogs in organic solution of acetonitrile, but lost the specific binding ability in aqueous solution. However, after the grafting of the hydrophilic shells on the haa-MIP particles, the surface hydrophilicity and water dispersion stability of the polymer particles of MIP-HSs greatly improved. The binding of harmine by MIP-HSs with hydrophilic shells in aqueous solutions is about two times higher than that of NIP-HSs, showing an efficient molecular recognition of heterocyclic aromatic amines in aqueous solution. The effect of hydrophilic shell structure on the molecular recognition property of MIP-HSs was further compared. MIP-PIA with carboxyl groups containing hydrophilic shells showed the highest selective molecular recognition ability to heterocyclic aromatic amines in aqueous solution. [ABSTRACT FROM AUTHOR]

Heterocyclic aromatic amines (HAAs) are mutagenic/carcinogenic compounds that can be formed during the cooking process of proteinaceous foods such as meat. Therefore, it is needed to inhibit or reduce their formations in cooked meats. Hereby, the effects of sumac usage (0.5%, w/w) in beef meatball preparation on the formation of HAAs and some quality parameters (water, pH, cooking loss, and lipid oxidation values) of meatballs cooked at 150 and 250 °C were investigated. The sumac usage caused a reduction in pH (p < 0.01), cooking loss (p < 0.05), lipid oxidation level (TBARS, p < 0.01), and total HAA amount (p < 0.05) of the samples. In addition, increasing the cooking temperature significantly decreased the pH value (p < 0.01) and increased the cooking loss (p < 0.05) of the samples. Only one compound, 2-amino-3,8-dimethylimidazo [4,5-ƒ]quinoxaline (MeIQx), from nine different HAAs studied in this study, could be determined, and the levels of the other HAAs studied were lower than their detection limits. On the other hand, MeIQx was not detected in the samples cooked at 150 °C, it was only determined in the control group samples cooked at 250 °C. The sumac usage completely inhibited MeIQx formation in the samples. Due to its positive effect on cooking loss value, lipid oxidation level, and MeIQx formation, it can be suggested to use sumac powder in meatball preparation. [ABSTRACT FROM AUTHOR]

Photoelectrochemistry is becoming an innovative approach to organic synthesis. Generally, the current photoelectrocatalytic organic transformations suffer from limited reaction type, low conversion efficiency and poor stability. Herein, we develop efficient and stable photoelectrode materials using metal oxide protective layer, with a focus on achieving regioselective activation of amine compounds. Notably, our photoelectrochemistry process is implemented under mild reaction conditions and does not involve any directing groups, transition metals or oxidants. The results demonstrate that beyond photocatalysis and electrocatalysis, photoelectrocatalysis exhibits high efficiency, remarkable repeatability and good functional group tolerance, highlighting its great potential for applications. [ABSTRACT FROM AUTHOR]

Photoelectrochemistry is becoming an innovative approach to organic synthesis. Generally, the current photoelectrocatalytic organic transformations suffer from limited reaction type, low conversion efficiency and poor stability. Herein, we develop efficient and stable photoelectrode materials using metal oxide protective layer, with a focus on achieving regioselective activation of amine compounds. Notably, our photoelectrochemistry process is implemented under mild reaction conditions and does not involve any directing groups, transition metals or oxidants. The results demonstrate that beyond photocatalysis and electrocatalysis, photoelectrocatalysis exhibits high efficiency, remarkable repeatability and good functional group tolerance, highlighting its great potential for applications. [ABSTRACT FROM AUTHOR]

Heterocyclic aromatic amines (HAAs) are hazardous carcinogenic/mutagenic compounds formed during heat exposure of meat products. The purpose of the present study was to investigate the efficiency of white tea and oolong tea marinations on reducing HAAs formation. Raw chicken thigh meat samples were marinated with various concentrations (0%, 0.5% and 1%) of white tea and oolong tea, and pan fried at 150, 200 and 250 °C for 7 min on both sides. Ten HAAs were analyzed, and various levels of IQx (up to 1.56 ng/g), IQ (up to 0.80 ng/g), MeIQx (up to 0.63 ng/g), MeIQ (up to 3.32 ng/g), 7,8-DiMeIQx (up to 3.75 ng/g), 4,8-DiMeIQx (up to 0.55 ng/g), Trp-P-2 (up to 11.43 ng/g), PhIP (up to 28.35 ng/g) and AαC (up to 0.21 ng/g) were quantified in cooked samples. The total HAA levels ranged from 0.55 to 29.33 ng/g across all samples analyzed. Cooking temperature, tea marinade type and concentration affected individual and total HAA levels. White tea and oolong tea marinades had reducing effects on total HAAs at 150 °C (up to 75.8% and 88.4%, respectively) and 250 °C (up to 75.6% and 94.4%, respectively), whereas only oolong tea showed inhibitory effects at 200 °C (up to 18.9%). [ABSTRACT FROM AUTHOR]

Bacon manufacturing involves several processing steps including nitrite curing, followed by cooking processes, typically frying. During these processes, harmful processing contaminants such as N-nitrosamines (NAs) and heterocyclic aromatic amines (HAAs) can be formed. Consequently, we developed and validated a multi-class method for quantification of the most frequently reported HAAs and NAs in fried bacon. Satisfactory repeatability and reproducibility with limits of quantification between 0.1 and 0.5 ng g−1 for most of the compounds were achieved. Quantification in pan-fried bacon cubes and slices revealed generally low levels of individual HAAs (≤1.5 ng g−1), except in ready-to-eat bacon (0.9–2.9 ng g−1). Differences in amounts of individual HAAs were observed in cubes and slices, most likely due to meat thickness. Among volatile NAs (VNAs), only N-nitrosopiperidine (NPIP), N-nitrosopyrolidine (NPYR), and N-nitrosodibutylamine (NDBA) were found at generally low concentrations (≤5 ng g−1). In contrast, non-volatile NAs (NVNAs) were present in all tested samples at considerably higher amounts, for example, N-nitroso-thiazolidine-4-carboxylic acid (NTCA) at 12–77 ng g−1. N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA) were not detected in any samples. Statistical evaluation and principal component analysis revealed some differences among tested samples. Dietary exposure estimation of the Danish population to HAAs and NAs showed the highest exposure in the teenage group (10–17 years). [ABSTRACT FROM AUTHOR]

The nutritional status of meat is tarnished by its association with the induced cooking contaminants. The aim of this study was to assess the heterocyclic aromatic amines profile and contents in processed chicken in Burkina Faso. Eight polar and apolar heterocyclic aromatic amines (HAAs) including 2-mino-3-methylimidazo[4,5-f]quinolone (IQ), 3-amino-1,4-dimethyl-5H-pyrido[4, 3-b]indole (Trp-P1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P2), 2-mino-9H-pyrido-[2,3-b]indole (AαC), 2-amino-1-methyl-6-phenylimidazo[4, 5– ]pyridine (PhIP), 2-amino-3-methyl-9H-pyrido[2,3-b] indole (MeAαC), 2-amino-3,4,8-rimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) and 2-amino-3,8-imethylimidazo[4,5–]quinoxaline (MeIQx) were screened by high performance liquid chromatography from 29 samples of flamed chicken and 66 samples of braised chicken collected in Ouagadougou city. Apolar HAAs and polar HAAs were respectively 12 and 3 times more abundant in flamed chickens (32.66±10 and 3.48±10.39 ng/g, respectively) than in braised chickens (2.70±9.67 and 0.92 ng/g, respectively). The maximum levels of AαC were in the same proportions in flamed (12.01 ng/g) and braised chickens (14.13 ng/g). Flamed chicken had the highest Trp-P1 content (530.31 ng/g). The 4,8-DiMeIQx was not detected in braised chicken. The AαCs were more abundant in flamed than in braised chicken. The profile and the contents of the HAAs in processed chicken are related to cooking methods. Because of the high variability observed on the obtained concentrations, investigations on the contents of precursors in raw chicken, the effect of marinating ingredients on the formation of HAAs are needed. [ABSTRACT FROM AUTHOR]

Owing to various chemical structures and different basicity of amines, a fluorescent probe that could distinguish aromatic and aliphatic amines is highly desirable for practical applications. Herein, an olefin‐based, fluorescent COF (COF−Py−AN) with unique π‐electron deficient groups was synthesized, which was a functionalized platform to realize sensing of π electron‐rich aromatic amines. COF−Py−AN displayed fluorescence quenching in the presence of aromatic amines like aniline, with excellent selectivity against a variety of aromatic molecules, and the detection limit of COF−Py−AN toward aniline was as low as 1.29 μM. More importantly, COF−Py−AN could realize discriminating between aromatic and aliphatic amines. Furthermore, density functional theory calculations showed that the photoinduced electron transfer mechanism contributes to fluorescence sensing. This is the first example of olefin‐based fluorescent COF materials for selective sensing of aromatic amines. [ABSTRACT FROM AUTHOR]

Summary: Spiced pork shoulder is a traditional Chinese meat product that is loved by consumers. However, heterocyclic aromatic amines (HAAs) formed by spiced pork shoulder during processing endanger human health. The present study determined the HAA contents of seven kinds of spiced pork shoulder, and examined the effects of soy sauce, cooking wine and sugar on the formation of HAAs. The total HAAs of the seven samples were between 0.10 ng/g and 56.82 ng/g. There were Harman (0.03–39.77 ng/g) and Norharman (0.06–18.76 ng/g) correlations in all samples. Not all samples had higher HAAs levels in the skin than the whole shoulder. Creatine and creatinine were more actively involved in the formation of HAAs than glucose. Soy sauce contributed the most to the formation of HAAs, followed by cooking wine and sugar. Compared to spiced pork shoulder, the soup contained more HAAs. Exogenous contamination of HAAs in soy sauce, cooking wine and soup was an important source of HAAs in spiced pork shoulder. [ABSTRACT FROM AUTHOR]

The bio-oxidation of a series of aromatic amines catalyzed by T. versicolor laccase has been investigated exploiting either commercially available nitrogenous substrates [(E)-4-vinyl aniline and diphenyl amine] or ad hoc synthetized ones [(E)-4-styrylaniline, (E)-4-(prop-1-en-1-yl)aniline and (E)-4-(((4-methoxyphenyl)imino)methyl)phenol]. At variance to their phenolic equivalents, the investigated aromatic amines were not converted into the expected cyclic dimeric structures under T. versicolor catalysis. The formation of complex oligomeric/polymeric or decomposition by-products was mainly observed, with the exception of the isolation of two interesting but unexpected chemical skeletons. Specifically, the biooxidation of diphenylamine resulted in an oxygenated quinone-like product, while, to our surprise, in the presence of T. versicolor laccase (E)-4-vinyl aniline was converted into a 1,2-substited cyclobutane ring. To the best of our knowledge, this is the first example of an enzymatically triggered [2 + 2] olefin cycloaddition. Possible reaction mechanisms to explain the formation of these products are also reported. [ABSTRACT FROM AUTHOR]

Chinese prickly ash and cinnamon contain many antioxidants, which scavenge free radicals and can reduce many harmful compounds, such as heterocyclic aromatic amines (HAAs). Modern technologies used for cooking, such as the use of superheated steam roasting, are beneficial in decreasing the development of HAAs. The current study was based on the use of these two spices in roasted lamb patties to mitigate the formation of HAAs in superheated steam roasted patties. Results exhibited significant differences (p < 0.05) in the content of both polar and non-polar HAAs as compared to control patties. In cinnamon roasted patties, polar HAAs were reduced from 23.76 to 10.56 ng g−1, and non-polar HAAs were reduced from 21.34 to 15.47 ng g−1. In Chinese prickly ash patties, polar and non-polar HAAs were 43.60 ng g−1 and 35.74 ng g−1, respectively. Similarly, cinnamon-treated patties showed a significantly higher (p < 0.05) reduction in polar HAAs (23.52 to 12.41 ng g−1) than non-polar (16.08 to 9.51 ng g−1) at concentrations of 0.5–1.5%, respectively, as compared to the control, with 45.81 ng g−1 polar and 35.09 ng g−1 non-polar HAAs. The polar HAAs tested were PhIP, DMIP, IQx, and 8-MeIQx, while the non-polar were harman and norharman. Both spices and superheated steam controlled HAAs to a significant level in lamb meat patties. [ABSTRACT FROM AUTHOR]

An efficient and stable fiber coating is of great importance for solid-phase microextraction (SPME). In this study, carboxylated mesoporous carbon hollow spheres (MCHS-COOH) were developed as an efficient SPME coating of polar aromatic amines (AAs) for the first time. The MCHS-COOH coating material with high specific surface area (1182.32 m2 g−1), large pore size (10.14 nm), and rich oxygen-containing groups was fabricated via a facile H2O2 post-treatment. The as-prepared MCHS-COOH-coated fiber exhibited fast adsorption rate and excellent extraction properties, mainly due to its π–π interactions, hollow structure, and abundant affinity sites (carboxyl groups). Subsequently, coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method with low limits of detection (0.08–2.0 ng L−1), a wide linear range (0.3–500.0 ng L−1), and good repeatability (2.0–8.8%, n = 6) was developed for the analysis of AAs. The developed method was validated against three river water samples, with satisfactory relative recoveries being obtained. The above results demonstrated that the prepared MCHS-COOH-coated fiber exhibited good adsorption capacity, suggesting a promising application to monitor trace polar compounds in real environment. [ABSTRACT FROM AUTHOR]

Herein we present a nickel‐catalyzed regio‐ and enantioselective ring opening reaction of 3,4‐epoxy amides and esters with aromatic amines as nucleophiles. This method features high regiocontrol, diastereospecific SN2 reaction pathway, broad substrate scope, and mild reaction conditions, furnishing a wide range of γ‐amino acid derivatives in a highly enantioselective manner. Notably, the selective nucleophilic attack to the C‐4 position of epoxides is controlled by the directing effect of the pendant carbonyl group. [ABSTRACT FROM AUTHOR]

In the present work, alginate magnetic graphene oxide biocomposite was synthesized for the removal and extraction of aromatic amines (aniline, p-chloroaniline (PCA), and p-nitroaniline (PNA)) from water samples. The biocomposite was investigated for its physiochemical characteristics such as surface morphology, functional groups, phase determination, and elemental composition. The results revealed that the functional groups of graphene oxide and alginate retained in biocomposite with magnetic properties. The biocomposite was applied to water samples for the removal and extraction of aniline, p-chloroaniline, and p-nitroaniline through adsorption process. The adsorption process was studied under various experimental conditions like time, pH, concentration, dose, and temperature, and all the parameters were optimized. The maximum adsorption capacities at room temperature have an optimum pH = 4 for aniline = 18.39 mg g−1, for PCA = 17.13 mg g−1, and for PNA = 15.24 mg g−1. Kinetic and isotherm models showed that the experimental data is best fitted to pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic study suggested that the adsorption process is exothermic and spontaneous. Ethanol was found to be the best eluent for the extraction of all the three analytes suggested by the extraction study. The maximum percent recoveries from spiked water samples were calculated for aniline = 98.82%, PCA = 96.65%, and PNA = 93.55% which showed that alginate magnetic graphene oxide biocomposite could be a useful and ecofriendly adsorbent for the removal of organic pollutants in water treatment processes. [ABSTRACT FROM AUTHOR]

Aims: Aromatic amines with diverse physical characteristics are often employed as antioxidants and precursors to pharmaceutical products. As the traditional chemical methods pose serious environmental pollution, there is an arising interest in biomanufacturing aromatic amines from renewable feedstocks. Materials and results: We report the establishment of a bacterial platform for synthesizing three types of aromatic amines, namely, tyramine, dopamine and phenylethylamine. First, we expressed aromatic amino acid decarboxylase from Enterococcus faecium (pheDC) in an Escherichia coli strain with increasing shikimate (SHK) pathway flux towards L‐tyrosine. We found that glycerol served as a better carbon source than glucose, resulting in 940 ± 46 mg/L tyramine from 4% glycerol. Next, the genes of lactate dehydrogenase (ldhA), pyruvate formate lyase (pflB), phosphate acetyltransferase (pta) and alcohol dehydrogenase (adhE) were deleted to mitigate the fermentation by‐product formation. The tyramine level was further increased to 1.965 ± 0.205 g/L in the shake flask, which was improved by 2.1 times compared with that of the parental strain. By using a similar strategy, we also managed to produce 703 ± 21 mg/L dopamine and 555 ± 50 mg/L phenethylamine. Conclusions: We demonstrated that the knockout of ldhA‐pflB‐pta‐adhE is an effective strategy for improving aromatic amine productions. Significance and Impact of the Study: This study achieved the highest aromatic amine titres in E. coli under shake flask reported to date. [ABSTRACT FROM AUTHOR]

We have developed a short and highly efficient microwave-enhanced protocol for the synthesis of new Schiff bases, (E)-N-[(2-arylimidazo[1,2-a]pyridine-3-yl)methylidene]pyridin-2-amines, by the condensa-tion of 2-arylimidazo[1,2-a]pyridine-3-carbaldehydes with 2-aminopyridine in polyethylene glycol-400 as a green reaction medium in the presence of a catalytic amount of acetic acid. The essential features of this protocol are enhanced reaction rate, more eco-friendly reaction conditions, high yields, and green aspects such as avoiding toxic catalysts and hazardous organic solvents and reuse of the reaction medium. [ABSTRACT FROM AUTHOR]

In the present work, the fluorescence quenching of novel thiophene substituted1,3,4-oxadiazole derivative 2-(4-(4-vinylphenyl) phenyl)-5-(5-(4-vinylphenyl)thiophen-2-yl)-1,3,4-oxadiazole (TSO) by five different environmental pollutant aromatic amine derivatives like 2,4-dimethylaniline, 3-chloroaniline, 4-chloroaniline, o-anisidine, and m-toluidine has been studied at room temperature through steady-state and time-resolved methods. It is observed that, the quenching efficiency is highest in the case of o-anisidine and least in the case of 3-chloroaniline. The fluorescence quenching mechanism between TSO and aromatic amines is analysed through different quenching models. The results suggest that, the fluorescence quenching is due to diffusion assisted dynamic or collisional quenching according to the sphere of action static quenching model and according to the finite sink approximation model, the bimolecular quenching reactions are due to the collective effect of dynamic and static quenching. Further, cyclic voltammetry and DFT studies suggest that the fluorescence quenching is due to electron transfer. Binding equilibria analysis confirms the 1:1 stoichiometric ratio between fluorophore and the quencher. [ABSTRACT FROM AUTHOR]

The utilization of two‐component systems comprising camphorquinone (CQ) and aromatic amines has become prevalent in the photopolymerization. However, there are still concerns about the safety of this CQ/amine system, mainly because of the toxicity associated with the leaching of aromatic amines. In light of these concerns, this study aims to develop novel coinitiator combinations featuring CQ and amines which cannot be leached out of materials, enabling free radical polymerization of representative dentalmethacrylate resins under blue light irradiation. This approach involves the initial design and analysis of hydrogen donors with low C─H bond dissociation energy through molecular modeling. Subsequently, copolymerizable methacrylate functional groups are incorporated via chemical modification, allowing it to act as both coinitiator and copolymerization monomer to achieve low migrationand leachability properties. This work presents, for the first time, the synthesis of the innovative coinitiator and compares its performance with the benchmark CQ/ethyl‐4‐dimethylaminobenzoate (EDB)‐based photoinitiation system (PIS). The results demonstrate the effectiveness of the newly proposed PIS. Finally, an in‐depth investigation is conducted into the reaction mechanism associated with this PIS through molecular orbital calculations and electron spin resonance studies. [ABSTRACT FROM AUTHOR]

Ebselen (EbSe), a therapeutically significant molecule, is shown to exhibit chalcogen bonding interaction with nitrite anion (ONO−). This report suggests that the σ-holes of EbSe are powerful for offering weak but influential interactions towards biologically relevant ONO−, thereby assisting oxidative transformations like N-nitrosation of aromatic amines. [ABSTRACT FROM AUTHOR]

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The reduction of CO2 is an important method to produce chemicals such as methanol, formic acid, formaldehyde, etc. In general, the reduction of CO2 is carried out at high temperatures and pressures with precious metals as catalysts, which is not favorable for industrial procedures. Thus, it will be very useful if researchers can find cost-effective catalysts for industrial application in CO2 reduction. In this work, commercially available ethylenediaminetetraacetic acid (EDTA) was tested as a cheap, non-toxic, and recyclable catalyst to initiate the N-carbonylation reaction of CO2 with amines. After screening various reaction parameters, including temperature, pressure, time, solvent, and reducing agent, the optimal reaction conditions were obtained: 80 °C, 2 MPa, 6 h, 50 mmol% catalyst dosage, 1 mL DMSO, and 1:1 molar ratio of amine to reducing agent. Notably, further studies confirmed that EDTA could also be effective for N-formylation even under ambient conditions (0.1 MPa and room temperature). The suitability of the catalyst for 26 kinds of substrates (including aliphatic amines, aromatic amines, and alicyclic amines) and its reusability were also investigated, with satisfactory results. Scale-up research has been performed effectively with a high conversion of amine (83%) to obtain the mono-formylated product selectively. Finally, the mechanism of the reaction between amine and CO2 has been proposed via control experiments and compared with results in the literature. [ABSTRACT FROM AUTHOR]