Aromatic Amines Research Articles

Covalently bridging graphene edges for improving mechanical and electrical properties of fibers

Assembling graphene sheets into macroscopic fibers with graphitic layers uniaxially aligned along the fiber axis is of both fundamental and technological importance. However, the optimal performance of graphene-based fibers has been far lower than what is expected based on the properties of individual graphene. Here we show that both mechanical properties and electrical conductivity of graphene-based fibers can be significantly improved if bridges are created between graphene edges through covalent conjugating aromatic amide bonds. The improved electrical conductivity is likely due to extended electron conjugation over the aromatic amide bridged graphene sheets. The larger sheets also result in improved π-π stacking, which, along with the robust aromatic amide linkage, provides high mechanical strength. In our experiments, graphene edges were bridged using the established wet-spinning technique in the presence of an aromatic amine linker, which selectively reacts to carboxyl groups at the graphene edge sites. This technique is already industrial and can be easily upscaled. Our methodology thus paves the way to the fabrication of high-performance macroscopic graphene fibers under optimal techno-economic and ecological conditions.

Simultaneous mitigation of heterocyclic aromatic amines and advanced glycation end products in roasted beef patties by plasma-activated water: Effects and mechanisms

Heterocyclic aromatic amines (HAAs) and advanced glycation end products (AGEs) are hazardous substances produced when food is heated. In this study, the ability of plasma-activated water (PAW) to simultaneously mitigate production of HAAs and AGEs in roasted beef patties was investigated. Assays of free radicals, lipid peroxidation, and active carbonyls were used to analyze the mechanisms. PAW treatment decreased the contents of free HAAs, free AGEs, bound HAAs, and bound AGEs to 12.65 ng/g, 0.10 μg/g, 297.74 ng/g, and 4.32 μg/g, with the inhibition rates of 23.88%, 23.08%, 11.02%, and 8.47%, respectively. PAW treatment decreased HAAs and AGEs and mitigated their increase during storage. The decrease of HAAs and AGEs in PAW-treated samples was correlated with the enhancement of antioxidant capacity. The increase of free radical scavenging ability by PAW treatment led to the decrease of lipid peroxidation and the decrease of active carbonyls, HAAs, and AGEs in meat products.

Mechanochemical Synthesis of Trifluoromethyl Arenes: Nanocellulose-Supported Deaminative Trifluoromethylation of Aromatic Amines

Mechanochemical Synthesis of Trifluoromethyl Arenes: Nanocellulose-Supported Deaminative Trifluoromethylation of Aromatic Amines

Introducing Bis(5-(Trifluoromethyl)pyridin-2-yl)amine Chelating Unit via Pd-Catalyzed Amination

We report a one-step synthesis of trifluoromethyl-substituted di(pyridin-2-yl)amine-based ligands. N-(hetero)aryl-substituted bis(5-(trifluoromethyl)pyridin-2-yl)amines were obtained from 2-bromo-5-(trifluoromethyl)pyridine and corresponding aromatic amines via Pd-catalyzed amination reaction in the presence of a Pd(dba)2/BINAP catalytic system. Four new ligands were prepared in good to high yields and characterized by NMR, IR spectroscopies and mass spectrometry. The structure of one of the products was additionally supported by X-ray analysis.

Regioisomerism in Thienothiophene-Based Covalent Organic Frameworks─A Tool for Band-Gap Engineering.

The craft of tuning optical properties is well-established for crystalline inorganic and hybrid solids. However, a far greater challenge is to tune the optical properties of organic materials systematically by design. We now introduce a synthesis concept that enables us to alter the optical properties of crystalline covalent organic frameworks (COFs) systematically using isomeric structures of thienothiophene-based building blocks (T23/32T) combined with a variety of tetratopic aromatic amines, e.g., the Wurster moiety (W-NH2). This concept is demonstrated for the synthesis of COFs in bulk and film forms and provides highly crystalline and porous isomeric COFs featuring predesigned photophysical properties. The band gap of the framework can be tuned continuously and precisely by chemically doping the pristine W23TT COF with its related constitutional isomer building block. Density-functional theory investigations of COF model compounds indicate that the extent of π-conjugation is among the key characteristics enabling the band-gap engineering.

Decolourisation and toxicity reduction of azo dye Bismarck Brown by newly isolated Pseudomonas aeruginosa, JKAK strain

ABSTRACT The decolourisation of Bismarck Brown dye by the newly isolated bacterial strain, Pseudomonas aeruginosa (JKAK), was studied at various parameters. Additionally, decolourisation of Bismarck Brown was studied using previously isolated strains; Bacillus sp. (AK1), Lysinibacillus sp. (AK2) and Kerstersia sp. (VKY1). The studies were carried out at temperature (35–50°C), dye concentration (200–800 mg/L), pH (5.5–10.5), metal ions (200–1000 mg/L) and NaCl (5–30 g/L). The optimum pH and temperature were 8.5 and 40°C, respectively. The strains decolourised over 53.75% of 800 mg/L Bismarck Brown after 24 h of incubation. The JKAK strain showed significant halotolerance and decolourised over 90% of the dye in the presence of 30 g/L NaCl. Further, JKAK decolourised over 86.4% of the dye in the presence of 1000 mg/L of Pb2+ and Zn2+ ions. The products of decolourisation were identified as aromatic amines and showed decreased phytotoxicity when compared to the untreated dye.

Sensitive detection of bilirubin using highly luminescent benzylamine capped CH3NH3PbBr3 perovskite quantum dots

Luminescent organic–inorganic metal halide hybrid perovskite quantum dots (PQDs) as a new class of fluorophores are finding increasing attention towards chemical and biological sensing due to their exceptional photophysical properties. Herein, we synthesized highly fluorescent CH3NH3PbBr3 perovskite quantum dots (B-PQDs) through the ligand assisted reprecipitation method (LARP), using benzylamine as the surface capping ligand. Morphological and opto-structural properties of the as-synthesized B-PQDs were thoroughly investigated using high resolution transmission electron microscopy (HR-TEM), X-Ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), UV–Vis absorption, and fluorescence spectroscopy. The as-synthesized electron-rich amine-capped B-PQDs were employed to study their sensing response towards bilirubin (BL). The aromatic amine capped B-PQDs enhance the sensory response towards BL due to the π-π interaction with BL’s conjugated system. The B-PQDs were found to be highly sensitive towards BL with a stern–volmer constant value ≈ 4.3 × 104 M−1 and limit of detection of 0.42 μM. A panel of characterizations were carried out to investigate the detailed sensing mechanism where resonance energy transfer was found to be the dominant quenching mechanism for BL detection. Our results demonstrated the potential for utilizing organic–inorganic halide perovskite quantum dots for sensing applications, through surface ligand modification tailored for detecting specific analytes.

Trioctylphosphine oxide-based hydrophobic magnetic deep eutectic solvent as a novel extractant for the enrichment of primary aromatic amines from juice and environmental water

In this study, a novel technique utilizing vortex-assisted dispersive liquid-liquid microextraction with magnetic deep eutectic solvents (MDESs) was established and coupled with HPLC-UV to analyze six primary aromatic amines (PAAs). A novel hydrophobic MDES prepared from trioctylphosphine oxide, octanol, and CoCl2 was used as the extractant, which could be dispersed uniformly during extraction, then floated onto the sample surface and re-aggregated into a single drop spontaneously after the extraction. The variables influencing the efficiency of the extraction process were investigated. When performing under the optimal extraction conditions, this method exhibited excellent linearity, low limits of detection (0.2–0.9 ng mL−1), and high precision (RSD ≤ 8.3 %). The enrichment factors ranged from 56 to 182. Satisfactory recoveries in the range of 91.6–109.2 % with RSDs < 7.1 % were obtained from three apple juices and three environmental water samples. The greenness and practicality of the developed method were assessed by AGREE, AGREEprep, and blue applicability grade index metric tools. Overall, the established procedure demonstrated its simplicity, speediness, environmental friendliness, and effectiveness in analyzing PAAs from aqueous matrices.

Synthesis of 6H-Chromeno[4,3-b]quinolin-7-ylphosphonates through Three Component Phosphonylation of Coumarin Carbaldehyde and Their Antimicrobial and Photophysical Properties.

Organophosphorylated coumarin derivatives were synthesized by a three-component reaction of 4-chloro-3-formylcoumarin, aromatic amines, and dialkyl phosphite in the presence of ZnCl2. This process includes the formation of C(sp3)-P and C(sp2)-N bonds in one pot. The modular scope of the reaction allowed rapid access to a variety of 6H-chromeno[4,3-b]quinolin-7-ylphosphonate derivatives in good yields. Furthermore, photophysical studies of the products revealed their stimulating fluorescence properties.

Electrochemical Nitro Reduction to Amines Using Pinacolborane as Reducing Agent

AbstractNitroaromatic compounds, as hazardous industrial pollutants, have long been extensively studied for their conversion into high-value aromatic amines. However, most of these transformation reactions require either transition-metal catalysts or high-temperature conditions. Therefore, we report an electrochemical approach utilizing pinacolborane as the reducing agent for the efficient reduction of nitroaromatic compounds. The reaction is characterized by its mild conditions and simplicity of operation, and it demonstrates excellent substrate adaptability and functional group compatibility.

Evaluation of polypropylene microporous membranes as extraction devices for determination of carcinogenic aromatic amines in smoker urine by GC–MS/MS

Exposure to tobacco smoke is highly correlated to the incidence of different types of cancer due to various carcinogenic compounds present in such smoke. Aromatic amines, such as 1-naphthylamine (1-NA) and 2-naphthylamine (2-NA), are produced in tobacco burning and are linked to bladder cancer. Miniaturized solid phase extraction techniques, such as microporous membrane solid phase extraction (MMSPE), have shown potential for the extraction of aromatic compounds. In this study, a bioanalytical method for the determination of 1-NA and 2-NA in human urine was developed using polypropylene microporous membranes as a sorptive phase for MMSPE. Urine samples were hydrolyzed with HCl for 1 h at 80 °C, after which pH was adjusted to 10. Ultrasound-assisted MMSPE procedure was optimized by factorial design as follows. To each sample, 750 µL of methanol was added, and ultrasound-assisted MMSPE was conducted for 1 h with four devices containing seven 2 mm polypropylene membrane segments. After extraction, the segments were transferred to 400 µL of hexane, and desorption was conducted for 30 min. Extracts were submitted to a simple and fast microwave-assisted derivatization procedure, by the addition of 10 µL of PFPA and heating at 480 W for 3 min, followed by clean-up with phosphate buffer pH 8.0 and GC–MS/MS analysis. Adequate linearity was obtained for both analytes in a range from 25 to 500 µg L−1, while the multiple reaction monitoring approach provided satisfactory selectivity and specificity. Intra-day (n = 6) and inter-day (n = 5) precision and accuracy were satisfactory, below 15 % and between 85 and 115 %, respectively. Recovery rates found were 91.9 and 58.4 % for 1-NA and 2-NA, respectively, with adequate precision. 1-NA was found in first-hand smokers’ urine samples in a concentration range from 20.98 to 89.09 µg in 24 h, while it could be detected in second-hand smoker's urine samples, and 2-NA detected in all first and second-hand smokers’ urine samples. The proposed method expands the applicability of low cost MMSPE devices to aromatic amines and biological fluids.

Metal-acid synergistic catalysis accelerates the hydrogen borrowing amination of alcohols by confining Ru sites in Beta zeolite

Direct hydrogen transfer amination of alcohols with amines is an environmentally friendly and atom-economical route for the synthesis of N-alkylamines. Noble metal species are highly catalytic active sites, but the exorbitant price makes the urgency to boost the atom efficiency with stable recyclability. Herein, we demonstrated that encapsulation of Ru nanoparticles (NPs) within BEA zeolite through direct hydrothermal approach greatly promoted the catalytic efficiency in the N-alkylation of aromatic alcohols and amines under additive- and solvent-free conditions, resulting in the high yield (∼93 %), maximum turnover number (TON) of 12,822 and turnover frequency (TOF) of 9012 h−1, with stable recyclability and extendable substrate scope. The kinetic studies and in-situ characterizations revealed that the synergy of confined Ru NPs and adjacent acid sites of BEA zeolite significantly promoted the C–H bond activation in the rate-determining step of alcohol dehydrogenation into aldehydes. Besides, the acid sites also accelerated the condensation of aldehyde intermediates and anilines to promote the kinetic equilibrium, while the moderate strength of the Ru–H bond resulting from the confined Ru NPs is advantageous to balance the dehydrogenation and hydrogenation steps to reach the fascinating H-transfer process.

Tattoos as a risk factor for malignant lymphoma: a population-based case–control study

The popularity of tattoos has increased dramatically over the last few decades. Tattoo ink often contains carcinogenic chemicals, e.g., primary aromatic amines, polycyclic aromatic hydrocarbons, and metals. The tattooing process invokes an immunologic response that causes translocation of tattoo ink from the injection site. Deposition of tattoo pigment in lymph nodes has been confirmed but the long-term health effects remain unexplored. We used Swedish National Authority Registers with full population coverage to investigate the association between tattoo exposure and overall malignant lymphoma as well as lymphoma subtypes. We performed a case-control study where we identified all incident cases of malignant lymphoma diagnosed between 2007 and 2017 in individuals aged 20-60 years in the Swedish National Cancer Register. Three random age- and sex-matched controls per case were sampled from the Total Population Register using incidence density sampling. We assessed exposure through a questionnaire in 2021, and data on potential confounders were retrieved from registers. We used multivariable logistic regression to estimate the incidence rate ratio (IRR) of malignant lymphoma in tattooed individuals. The study population consisted of 11,905 individuals, and the response rate was 54% among cases (n=1398) and 47% among controls (n=4193). The tattoo prevalence was 21% among cases and 18% among controls. Tattooed individuals had a higher adjusted risk of overall lymphoma (IRR=1.21; 95% CI 0.99-1.48). The risk of lymphoma was highest in individuals with less than two years between their first tattoo and the index year (IRR=1.81; 95% CI 1.03-3.20). The risk decreased with intermediate exposure duration (three to ten years) but increased again in individuals who received their first tattoo ≥11 years before the index year (IRR=1.19; 95% CI 0.94-1.50). We found no evidence of increasing risk with a larger area of total tattooed body surface. The risk associated with tattoo exposure seemed to be highest for diffuse large B-cell lymphoma (IRR 1.30; 95% CI 0.99-1.71) and follicular lymphoma (IRR 1.29; 95% CI 0.92-1.82). Our findings suggested that tattoo exposure was associated with an increased risk of malignant lymphoma. More epidemiologic research is urgently needed to establish causality. The Swedish Research Council for Health, Working Life and Welfare.

Substituted Pyrrole‐based Schiff Bases: Effect On The Luminescence Of Neutral Heteroleptic Cu(I) Complexes

AbstractNeutral Cu(I) complexes containing Schiff bases as chelating N‐donors and phosphines as P‐donors were efficiently isolated and characterized. The imines were obtained by straightforward condensation between pyrrole‐2‐carboxaldehyde and the corresponding aromatic amines. The structure of most of the Cu(I) species was elucidated through single‐crystal X‐ray diffraction. The Cu(I) complexes exhibited intense absorptions around 400–500 nm ascribed to MLCT transitions. For some Cu(I) derivatives, orange‐ and red‐orange emissions were detected upon excitation with near‐UV and blue irradiation in the solid state. The emission maxima were red‐shifted once the benzothiazole‐derived Schiff base or Xantphos were employed as chelating ligands. Microsecond‐long lifetimes, wide emissions, and large Stokes shifts suggest the involvement of triplet states in the luminescent process. Electrochemical measurements and DFT calculations were employed to rationalize the photoluminescence properties, which were ascribed to mixed 3LC/3MLCT transitions.

Heterogeneous catalytic aerobic oxidation of primary amines to amides using unsupported nanoporous palladium catalyst

An efficient and highly selective heterogeneous catalyst system for aerobic oxidation of primary amines was developed using unsupported palladium nanopores (PdNPore). A variety of aromatic, aliphatic, and heterocyclic primary amines were oxidized to the corresponding amides in satisfactory to excellent yields using ambient air as an oxidant. No palladium was leached from PdNPore during the oxidation reaction. The catalyst could be readily recovered and reused without a decrease in catalytic activity. The kinetic studies and control experiments demonstrated that nitrile acts as an intermediate, which undergo hydration to afford amide as the final product.

A general catalyst for the base-free mono-N-alkylation of aromatic and aliphatic amines with alcohols

A general catalyst for the base-free mono-N-alkylation of aromatic and aliphatic amines with alcohols

CVO/TiO2 Heterojunction Photocatalyst for the Synthesis of Arylamines via Oxidative Aromatization of Amines and Cyclohexenones

A novel CVO/TiO2 heterojunction material has been prepared and used to catalyze the oxidative aromatization of amines and cyclohexenones under visible light irradiation, avoiding the use of noble metal catalysts and providing an environmentally friendly alternative for the synthesis of aromatic amines. The catalytic reaction uses oxygen as the final oxidant and provides good yields over a wide range of substrates. Notably, the recyclable heterogeneous semiconductor photocatalyst can be readily recovered and reused for at least four cycles. In addition, several biologically active molecules were successfully synthesized using the photocatalytic method.

Copper-Catalyzed Multicomponent Coupling Reaction of Primary Aromatic Amines, Rongalite, and Alkynes: Access to N-Aryl Propargylamines.

In this work, a practical copper-catalyzed multicomponent coupling reaction of primary aromatic amines, rongalite, and alkynes for the direct synthesis of N-aryl propargylamines has been developed. This method could overcome the substrate limitation in A3 coupling reactions of primary aromatic amines, formaldehyde, and alkynes. Mechanistic studies revealed that rongalite acts as not only the active C1 unit but also the accelerator to activate the in situ-generated N-arylmethanimines for the coupling reaction with alkynes. This coupling reaction is highly efficient and features a broad substrate scope, as well as utility with scale-up synthesis and converting the corresponding product N-aryl propargylamines into useful heterocyclic skeletons.

Capture of volatile iodine by aromatic amines solutions

Abstract The presence of an excessive amount of iodine, especially radioactive iodine, is dangerous to the environment. Amine solutions are the most common and technically mature class of chemical sorption used for the capture of the pollutants. The iodine vapor diffusion and release capabilities of the aromatic amine solutions have been investigated. The iodine diffusion and release experiments were examined by UV-visible spectroscopy. Many electronic spectrophotometric studies have been reported in the coordination chemistry field on complexes. Generally, these complexes were obtained by using different electron donors with various organic or metallic electron acceptors in polar and non-polar solvents. The absorption spectra of the donor, acceptors, and the resulted complexes were carried out in methanol in the region of 200–600 nm. The correlation between the spectral characteristics of molecular complexes of iodine with various aromatic amines and the ionization potentials of the donor molecules is discussed. The concentrations of the diffused iodine and the formed complex were calculated using mathematical models and calibration curves. The values of the formation constant (k AD), molar extinction coefficient (ε AD), and absorption band energy of complexes were estimated. The ionization potential of the donor I D was calculated from the complex band energies. The kinetic of the above association and reverse reactions was studied, and some kinetic parameters have been estimated.

Palladium-Catalyzed Three-Component Cascade Carbonylation Reaction to Construct Benzofuran Derivatives.

A novel three-component cyclization carbonylation reaction of iodoarene-tethered propargyl ethers with amine and CO is reported. This palladium-catalyzed cascade reaction undergoes a sequence of oxidative addition, unsaturated bond migration, carbonyl insertion, and nucleophilic attack to deliver the benzofuran skeleton. Both aromatic amines and aliphatic amines could proceed smoothly in this transformation under one atm of CO.