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Aromatic amines (AAs) are an important class of organic compounds that find their application in various industries, such as dye production, rubber manufacturing, and pharmaceutical synthesis. Despite the various applications, they significantly harm human health and the environment. This article provides an overview of the toxicity, hazards, and safe handling of some primary aromatic amines (PAAs), focusing on representative examples, such as aniline, toluidine, nitroaniline, chloroaniline, and naphthylamine. The carcinogenicity and mutagenicity of PAAs are a matter of concern that impacts the health of workers who are occupationally exposed to such chemicals. Nonoccupational exposure to tobacco smoke and household products also causes health issues in elderly patients who remain indoors. Water and soil contamination by these pollutants adversely affects aquatic organisms and groundwater quality. Thus, proper handling and disposal protocols must be followed to minimize their impact on human health and the environment. Additionally, this review discusses the discrepancies between the European Union (EU) and Japan's hazard categorization for aniline as a specific example. The information presented in this review emphasizes the importance of understanding toxicity, hazards, and safe handling practices associated with PAAs to ensure their responsible use and mitigate potential risks. [ABSTRACT FROM AUTHOR]

The bidentate aromatic adsorbate, 5-(octadecyloxy)-1,3-benzenedimethanethiol (R1ArmDT), with a specific design of extended S-S distance and a geometric constraint to resist cyclic disulfide formation was synthesized. The film formation and thermal stability of self-assembled monolayers (SAMs) derived from R1ArmDT were investigated and compared to those of SAMs derived from an analogous bidentate dithiol 2-(4-(octadecyloxy)-phenyl)propane-1,3-dithiol (R1ArDT), in which the two sulfur atoms can readily form a cyclic disulfide upon reductive elimination from the surface. Although the SAMs derived from R1ArmDT were less densely packed than those derived from R1ArDT, as judged by the data obtained by X-ray photoelectron spectroscopy and polarization modulation infrared reflection absorption spectroscopy, the SAMs derived from R1ArmDT were markedly more thermally stable than those derived from R1ArDT. The greater thermal stability of the R1ArmDT SAMs can be rationalized on the basis of the structure of the bidentate R1ArmDT headgroup, in which the two pendant sulfur atoms cannot access each other intramolecularly to form a cyclic disulfide upon reductive elimination from the surface. [ABSTRACT FROM AUTHOR]

Aromatic amines and amine hydrochloride salts play an important part in certain large-scale isocyanate production chains. For the first time, via a combination of periodic-DFT calculations, infrared spectroscopy, and inelastic neutron scattering, this work provides a comprehensive vibrational assignment of 4-benzylaniline (C6H4CH2C6H4NH2), 4,4'-methylenedianiline (H2NC6H4CH2C6H4NH2), and their associated amine hydrochloride salts. Deuterated analogues are additionally utilized to assist vibrational assignments. The heightened awareness of vibrational transitions for these technically relevant reagents and byproducts provides the opportunity to apply infrared spectroscopy as an in-line diagnostic tool within the industrial-scale process operation. [ABSTRACT FROM AUTHOR]

A Lewis base/Bronsted acid catalyzed aromatic sulfenylation is reported. These studies demonstrated that the incorporation of electron-rich sulfenyl groups proceeded in the absence of a Lewis base, with kinetic studies indicating an autocatalytic mechanism. The incorporation of electron-poor sulfenyl groups demonstrated little autocatalysis necessitating the use of a Lewis base. This method proved amenable to diverse arenes and heterocycles and was effective in the context of the late-stage functionalization of biologically active small molecules. [ABSTRACT FROM AUTHOR]

An efficient and stereoselective one-pot, two-step tandem α-arylation of glycals from readily available aryl amines via stable diazonium salts has been developed. Moreover, the stereoselective preparation of the challenging β-C-glycosyl arenes by the anomerization of α-C-glycosides using HBF4 is also described. This protocol has a broad substrate scope and a wide functional-group tolerance. It can be used for the gram-scale preparation of 3-oxo-C-glycosides, which are versatile substrates for the preparation of many biologically important C-glycosides. [ABSTRACT FROM AUTHOR]

A nonmetal catalyst [Ph3C][B(C6F5)4] has been developed to catalyze hydroarylation reaction of alkenes with aromatic primary, secondary, and tertiary amines, which generated aniline derivatives in 32-98% yields. This method is applicable to a wide range of substrates, is highly chemo- and regioselective, and provides a simple and efficient approach for aniline derivative preparation. [ABSTRACT FROM AUTHOR]

In this work, a new dual photoredox nickel catalysis system has been utilized for the synthesize of aryl amines. Previously, our group has shown that a nickel catalyst in conjunction with a photosensitizer and a sacrificial electron donor can cross-couple C-C bonds via photoredox-assisted reductive coupling. Here we have built upon that system to develop a redox-neutral cross-coupling system for the formation of C-N bonds. The catalytic system is composed of just a nickel cross-coupling catalyst, a Ru photocatalyst, and base and is capable of coupling amines with aryl halides in good to excellent yields. Furthermore, it was found that these reactions are functional under ambient conditions with catalyst loadings of 1 mol %. Spectroscopic studies provide support that this amination mechanism proceeds via a nitrogen-based radical intermediate. This N-radical mechanism offers direct synthetic access to di- and triaryl amines from nickel photocatalysis. [ABSTRACT FROM AUTHOR]

We report the use of microfluidics to functionalize suspended reduced graphene oxide flakes through the addition of aryl radical, generated in situ by reaction between aryl amines and isopentyl nitrite. Microfluidic enabled a tight control of temperature, reaction times, and stoichiometric ratios, making it possible to tune the growth of oligomers on the surface of the flakes, which in turn affects the interactions of the functional material with the surrounding environment. The results suggest that shear stress phenomena within the reactor may play a role in the chemistry of graphene materials by providing a constant driving force toward exfoliation of the layered structures. Scale-up of the functionalization process is also reported along with the grafting of dyes based on squaric acid cores. Photophysical characterization of the dye-modified flakes proves that the microfluidic approach is a viable method toward the development of new materials with tailored properties. [ABSTRACT FROM AUTHOR]

N-Sulfonylhydrazones generate sulfinates selectively when treated with a stabilized Wittig ylide in a polar aprotic solvent at elevated temperature. The transition metal and base free decomposition method is applicable to N-sulfonylhydrazones generated from a number of aromatic and heteroaromatic aldehydes and ketones. In the case of N-tosylhydrazones derived from O-allyl and O-propargyl salicylaldehydes, selective formation of sulfinate occurs over intramolecular [3 + 2]-cycloaddition reaction. [ABSTRACT FROM AUTHOR]

The synthesis of di(hetero)arylamines by a transition-metal-free cross-coupling between nitrosoarenes and boronic acids is reported. The procedure is experimentally simple, fast, mild, and scalable and has a wide functional group tolerance, including carbonyls, nitro, halogens, free OH and NH groups. It also permits the synthesis of sterically hindered compounds. [ABSTRACT FROM AUTHOR]

A novel N-oxygenase-coated core-shell nanoparticle was generated through the coassembly of poly(4-vinylpyridine) (P4VP) and arylamine N-oxygenase CmlI. The resulting enzyme-hybridized particles, P4VP-CmlI, showed excellent catalytic activities on the oxidation of two arylamine substrates, i.e., p-aminophenol (pAP) and p-aminobenzoic acid (pABA), using a surrogate redox system or a peroxide shunt as co-oxidants. In comparison with the free enzyme, P4VP-CmlI particles exhibited a significantly enhanced catalytic efficiency when using pyridine nucleotide (NADH) and proper redox mediators. Products at different oxygenation stages were observed. On the contrary, the activity of the enzyme-containing nanoparticles was very similar to the free enzyme when using the peroxide shunt. The enhanced catalytic efficiency of the P4VP-CmlI assemblies is attributed to a more efficient electron delivery. [ABSTRACT FROM AUTHOR]

The first highly enantioselective hydrogenation of carbocyclic aromatic amines has been successfully realized using in situ-generated chiral ruthenium complex as catalyst, affording facile access to chiral exocyclic amines with up to 98% ee. [ABSTRACT FROM AUTHOR]

A photoredox catalytic approach to synthetically valuable N-acyl-N'-aryl-N,N'-aminals is described. This method uses the addition of a radical precursor to enamides, with subsequent interception of the cationic iminium intermediate with an arylamine. The reaction has been shown to be compatible with electron-rich and electron-deficient arylamines, and moderate to good levels of diastereoselectivity can be attained using a chiral enamide. Furthermore, the N-acyl-N'-aryl-N,N'-aminal reaction products can be readily cyclized, providing a novel synthetic route to valuable γ-lactams. [ABSTRACT FROM AUTHOR]

A hydrogen-transfer strategy for the catalytic functionalization of benzylic alcohols via electronic arene activation, accessing a diverse range of bespoke diaryl ethers and aryl amines in excellent isolated yields (38 examples, 70% average yield), is reported. Taking advantage of the hydrogen-transfer approach, the oxidation level of the functionalized products can be selected by judicious choice of simple and inexpensive additives. [ABSTRACT FROM AUTHOR]

Damage to DNA from the metabolites of drugs and pollutants constitutes a major human toxicity pathway known as genotoxicity. Metabolites can react with metal ions and NADPH to oxidize DNA or. participate in SN2 reactions to form covalently linked adducts with DNA bases. Guanines are the main DNA oxidation sites, and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) is the initial product Here we describe a novel electrochemiluminescenl (ECL) microwell array that produces metabolites from test compounds and measures relative rates of DNA oxidation and DNA adduct damage. In this new array, films of DNA, metabolic enzymes, and an ECL metallopolymer or complex assembled in microwells on a pyrolytic graphite wafer are housed in dual microfluidic chambers. As reactant solution passes over the wells, metabolites form and can react with DNA in the films to form DNA adducts. These adducts are detected by ECL from a RuPVP polymer that uses DNA as a coreactant. Aryl amines also combine with Cu2+ and NADPH to form reactive oxygen species (ROS) that oxidize DNA The resulting 8-oxodG was detected selectively by ECL-generating bis(2,2'-bipyridine)-(4-(l,10-phenanthrolin-6-yl)-benzoic acid)Os(ll). DNA/enzyme films on magnetic beads were oxidized similarly, and 8-oxodG determined by LC/MS/MS enabled array standardization. The array limit of detection for oxidation was 720 8-oxodG per 106 nudeobases. For a series of aryl amines, metabolite-generated DNA oxidation and adduct formation turnover rates from the array correlated very well with rodent l/TD50 and Comet assay results. [ABSTRACT FROM AUTHOR]

2,4-Dinitrosanisole (DNAN) is an insensitive munitions component replacing conventional explosives. While DNAN is known to biotransform in soils to aromatic amines and azo-dimers, it is seldom mineralized by indigenous soil bacteria. Incorporation of DNAN biotransformation products into soil as humus-bound material could serve as a plausible remediation strategy. The present work studied biotransformation of DNAN in soil and sludge microcosms supplemented with uniformly ring-labeled 14C-DNAN to quantify the distribution of label in soil, aqueous, and gaseous phases. Electron donor amendments, different redox conditions (anaerobic, aerobic, sequential anaerobic-aerobic), and the extracellular oxidoreductase enzyme horseradish peroxidase (HRP) were evaluated to maximize incorporation of DNAN biotransformation products into the nonextractable soil humus fraction, humin. Irreversible humin incorporation of 14C-DNAN occurred at higher rates in anaerobic conditions, with a moderate increase when pyruvate was added. Additionally, a single dose of HRP resulted in an instantaneous increased incorporation of 14C-DNAN into the humin fraction. 14C-DNAN incorporation to the humin fraction was strongly correlated (R² = 0.93) by the soil organic carbon (OC) amount present (either intrinsic or amended). Globally, our results suggest that DNAN biotransformation products can be irreversibly bound to humin in soils as a remediation strategy, which can be enhanced by adding soil OC. [ABSTRACT FROM AUTHOR]

The first example of nickel(II)-catalyzed site-selective C-H bond trifluoromethylation of arylamine in water is established. In this transformation, a coordinating activation strategy is performed by the utilization of picolinamide as a directing group, and target products are obtained in moderate to good yields. In addition, the catalyst-in-water system can be reutilized eight times with a slight loss of catalytic activity and applied in the green, concise synthesis of acid red 266. Furthermore, a series of control experiments verify that a single-electron transfer mechanism is responsible for this reaction. [ABSTRACT FROM AUTHOR]

Arylamines and nitroarenes are intermediates in the production of pharmaceuticals, dyes, pesticides, and plastics and are important environmental and occupational pollutants. N-Hydroxyarylamines are the toxic common intermediates of arylamines and nitroarenes. N-Hydroxyarylamines and their derivatives can form adducts with hemoglobin (Hb-adducts), albumin, DNA, and tissue proteins in a dose-dependent manner. Most of the arylamine Hb-adducts are labile and undergo hydrolysis in vitro, by mild acid or base, to form the arylamines. According to current knowledge of arylamine adduct-formation, the hydrolyzable fraction is derived from the reaction products of the arylnitroso derivatives that yield arylsulfinamide adducts with cysteine. Hb-adducts are markers for the bioavailability of N-hydroxyarylamines. Hb-adducts of arylamines and nitroarenes have been used for many biomonitoring studies for over 30 years. Hb-adducts reflect the exposure history of the last four months. Biomonitoring of urinary metabolites is a less invasive process than biomonitoring blood protein adducts, and urinary metabolites have served as short-lived biomarkers of exposure to these hazardous chemicals. However, in case of intermittent exposure, urinary metabolites may not be detected, and subjects may be misclassified as nonexposed. Arylamines and nitroarenes and/or their metabolites have been measured in urine, especially to monitor the exposure of workers. This review summarizes the results of human biomonitoring studies involving urinary metabolites and Hb-adducts of arylamines and nitroarenes. In addition, studies about the relationship between Hb-adducts and diseases are summarized. [ABSTRACT FROM AUTHOR]

Incorporation of green chemistry techniques in undergraduate (UG) laboratories has a great demand. The challenge is to select and modify the known fundamental reactions in a greener way to implement into UG laboratories. A practical, two-step synthesis of 4-bromoacetanilide from aniline through a greener approach is described. Design of the synthetic route is based on the fundamental concepts of green chemistry. It can be adapted in most of the UG laboratories, including those with limited facilities. In the first step, aniline is converted to acetanilide using Zn dust/Fe powder-acetic acid instead of conventional acetic anhydride. In the second step, acetanilide is brominated using ceric ammonium nitrate-KBr combination in ethanolic-aqueous medium instead of bromine. The overall concept of modification could be useful to teach students about the concept of green chemistry, functional group protection, aromatic electrophilic substitution, and laboratory techniques such as reaction setup, isolation, purification, and product analysis. [ABSTRACT FROM AUTHOR]

An alkylation of C-H bonds with maleimides by a rhodium-catalyzed reaction of aromatic amides containing an 8-aminoquinoline moiety as the directing group is reported. Various N-substituents in the maleimide, including methyl, ethyl, cyclohexyl, benzyl, and phenyl groups and even H, are applicable to the reaction. The reaction is highly regioselective at the less hindered ortho-C-H bond when meta-substituted aromatic amides are used as substrates. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed insertion and cycloaddition of CO2 and isocyanide into 2-iodoanilines under atmospheric pressure has been developed and affords quinazoline-2,4(1H,3H)-diones through the formation of new C-C, C-O, and C-N bonds under mild conditions. This reaction provides a new and practical method not only for the construction of quinazoline-2,4(1H,3H)-diones but also for the efficient utilization of carbon dioxide. [ABSTRACT FROM AUTHOR]

Photoenols generated in situ from ortho-methyl-substituted phenylketones such as benzophenones and acetophenones were trifluoromethylated with Togni reagent without any additive or catalyst. This trifluoromethylation reaction proceeded smoothly under photoirradiation conditions (365 nm). Various functional groups were tolerant of the reaction conditions. Interestingly, the trifluoromethyl group was exclusively introduced at the ortho-benzylic position. Mechanistic studies suggested that this reaction proceeds via formation of a photoenol, not via a radical pathway. [ABSTRACT FROM AUTHOR]

In recent years, there has been encouraging progress in the engineering of enzymes that are designed to catalyze reactions not accelerated by natural enzymes. We tested the possibility of reengineering an existing enzyme by introducing a fast protein motion that couples to the reaction. Aromatic amine dehydrogenase is a system that has been shown to use a fast substrate motion as part of the reaction mechanism. We identified a mutation that preserves this fast motion but also introduces a favorable fast motion near the active site that did not exist in the native enzyme. Transition path sampling was used for the analysis of the atomic details of the mechanism. [ABSTRACT FROM AUTHOR]

The design of trisubstituted triazoles set the stage for proximity-induced iron-catalyzed C-H activation of benzyl and aryl amines with ample scope. Thereby, C-H alkylations and C-H arylations proved viable with high levels of chemo and positional selectivities by means of racemization-free iron catalysis with the reusable triazole being removed in a traceless fashion. [ABSTRACT FROM AUTHOR]

A Rh(III)-catalyzed carboamination of alkynyl cycloalkanols with arylamines has been developed. This transformation involves a novel Csp²-H/Csp³-Csp³ activation relay and provides an efficient approach to versatile 1,2,3-trisubstituted indoles with a broad range of functional group tolerance. [ABSTRACT FROM AUTHOR]

A detailed kinetic study is described for the insertion of carbenes from methyl diazoacetate into the N-H bond of aniline, using Ir(TTP)CH3 (TTP = tetratolylporphyrinato) as a catalyst. Aniline strongly coordinates to the Ir center with a binding constant of K = (2.5 ± 0.5) × 104 at 296 K, forming an inactive hexacoordinate complex, (aniline)Ir(TTP)CH3. The rate of N-H insertion is first order in both diazo ester and catalyst. When the true amount of active, five-coordinate Ir(TTP)CH3 is taken into account, the insertion rate is found to be independent of the aniline concentration. This indicates that the rate-limiting step in the catalytic cycle occurs prior to the nucleophilic attack of aniline on an Ir carbene complex to generate a coordinated ylide. Thus, with N-H insertion catalyzed by Ir(TTP)CH3, aniline is both a strong ligand and a potent nucleophile. This is in contrast to the analogous catalytic insertion of carbenes into S-H bonds. p-Toluenethiol is a more weakly binding ligand toward Ir(TTP)CH3 (K = 680 ± 20 at 296 K). Moreover, the rate of S-H insertion is first order in diazo reagent, catalyst, and thiol concentrations. In this case, the slow step is nucleophilic attack of the thiol on the Ir carbene complex to form a coordinated sulfonium ylide intermediate. In comparison to aniline, p-toluenethiol is a weaker ligand and a poorer nucleophile. The consequence of these differences is that the rate of aniline attack on the carbene intermediate is much faster than the rate of formation of the intermediate carbene complex; whereas the rate of nucleophilic addition of the thiol is slower that the rate of carbene complex formation. [ABSTRACT FROM AUTHOR]

Compounds that contain the 1-heteroaryl-3-azabicyclo[3.1.0]hexane architecture are of particular interest to the pharmaceutical industry yet remain a challenge to synthesize. We report herein an expedient and modular approach to the synthesis of 1-heteroaryl-3-azabicyclo[3.1.0]hexanes by Suzuki-Miyaura and Chan-Evans-Lam coupling reactions of tertiary trifluoroborate salts. Our Suzuki-Miyaura cross-coupling protocol is compatible with a broad range of aryl and heteroaryl bromides and chlorides. The unprecedented Chan-Evans-Lam coupling of tertiary trifluoroborates allows the facile construction of 1-heteroaryl-3-azabicyclo[3.1.0]hexanes containing C-tertiary arylamines at the ring juncture. [ABSTRACT FROM AUTHOR]

Tetrabenzo[7]circulene, a new member of aromatic saddles, was conveniently synthesized from 2-(1-naphthoyl)benzoic acid with the seven-membered ring constructed at an early stage of the synthesis. This method, upon minor modification, was also useful for synthesis of thiophene-annulated [7]circulenes. The structures of tetrabenzo[7]circulene and [7]circulene were compared in terms of symmetry, flexibility, and curvature on the basis of DFT calculations and X-ray crystallography. It was also found that tetrabenzo[7]circulene functioned as a p-type semiconductor in thin-film transistors and cocrystallized with C60. [ABSTRACT FROM AUTHOR]

Triarylamines oxidized to radical cations can be used as stable spins sources for the design of high-spin compounds. Here, we present the synthesis of the polyarylamine-containing hexaazacyclophanes linked via meta-terphenyl bridges. Spins, created after oxidation of the polymer, can be coupled magnetically in cyclophane moieties via meta-phenyl and along the polymer chain via meta-terphenyl units. The formation of a quintet spin state was evidenced by pulsed-EPR nutation spectroscopy. Two exchange coupling constants via both couplers were determined experimentally and corresponded to J/k = 89 K in the cyclophane moiety and j/k = 17 K via meta-terphenyl. Most importantly, in this polymer, four spins can be ferromagnetically ordered via both couplers, which leads to the high spin state. [ABSTRACT FROM AUTHOR]

An air-stable, thermally robust, and well-defined Cu(I) PNP pincer complex based on the 2,6-diaminopyridine scaffold is described. This complex is an active catalyst for the cross-couplings of a range of aryl and heteroaryl (including benzoxazole, thiazole, pyridine, and thiophene) halides with different organomagnesium reagents, alkynes, and aryl-amines giving excellent to good isolated yields. [ABSTRACT FROM AUTHOR]

Aromatic amines are one of the most important classes of compounds contributing to surface water mutagenicity due to their widespread occurrence as precursors and transformation products of dyes, pharmaceuticals, agrochemicals, and other compound classes. In this study, we implemented a workflow including novel analytical and data evaluation methods aiming to identify aromatic amines in six mutagenic wastewater effluents from a chemical-industrial area in Germany, collected by the passive sampler Blue Rayon. We identified 14 amines including the two potent mutagenic aromatic amines 2,3- and 2,8-phenazinediamine, which were reported for the first time as environmental contaminants. These two isomers accounted between 4.2 and 86% of the mutagenicity of the blue rayon extracts and may be byproducts of dye production at the studied site. [ABSTRACT FROM AUTHOR]

A highly efficient I2-promoted formal [4 + 2] cycloaddition has been developed for the synthesis of 2-acylquinolines from methyl ketones and arylamines using 1,4-dithane-2,5-diol as an ethylene surrogate. Moreover, the investigation of the mechanism suggested that this reaction occurred via an iodination/Kornblum oxidation/Povarov/aromatization sequence. It is noteworthy that the arylamine substrate also played an important role in promoting the reaction. [ABSTRACT FROM AUTHOR]

The synthesis of complex protein-based bioconjugates has been facilitated greatly by recent developments in chemoselective methods for biomolecular modification. The oxidative coupling of o-aminophenols or catechols with aniline functional groups is chemoselective, mild, and rapid; however, the oxidatively sensitive nature of the electron-rich aromatics and the paucity of commercial sources pose some obstacles to the general use of these reactive strategies. Herein, we identify o-methoxyphenols as air-stable, commercially available derivatives that undergo efficient oxidative couplings with anilines in the presence of periodate as oxidant. Mechanistic considerations informed the development of a preoxidation protocol that can greatly reduce the amount of periodate necessary for effective coupling. The stability and versatility of these reagents was demonstrated through the synthesis of complex protein-protein bioconjugates using a site-selective heterobifunctional cross-linker comprising both o-methoxyphenol and 2-pyridinecarboxaldehyde moieties. This compound was used to link epidermal growth factor to genome-free MS2 viral capsids, affording nanoscale delivery vectors that can target a variety of cancer cell types. [ABSTRACT FROM AUTHOR]

Three metal-free molecular photosensitizers (S1-S3) featuring a starburst triarylamine donor moiety have been synthesized. They show attractive photocatalytic performance in visible light-driven H2 production from water in their platinized TiO2 composites. A remarkable H2 turnover number (TON) of 10-200 (48 h) was achieved in an S1-anchored system. [ABSTRACT FROM AUTHOR]

A novel method for the construction of 1-azaspirocycles from 5-alkyl-/-arylamine furylcarbinols though intramolecular aza-Piancatelli rearrangement was developed. By using PPh3/diethyl azodicarboxylate instead of a Lewis acid, 1-azaspirocyclic compounds were obtained in good yields and the reaction temperature was reduced to room temperature. In addition, substrates with groups that are sensitive to high temperatures or Lewis acids are tolerated under these reaction conditions. This is the first method that is applicable not only to 5-(N-arylaminoalkyl)furylcarbinols with better yields but also to 5-(N-alkylaminoalkyl)furylcarbinols. [ABSTRACT FROM AUTHOR]

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed during the high-temperature cooking of meats. The cytochrome P450-mediated N-hydroxylation of the exocyclic amine group of PhIP produces 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine, an electrophilic metabolite that forms adducts with DNA and proteins. Previous studies conducted by our laboratory showed that the reaction of N-oxidized PhIP metabolites with human albumin in vitro primarily occurs at the Cys34 residue, to produce an acid-labile linked sulfinamide adduct. On the basis of these findings, we developed a sensitive ultraperformance liquid chromatography-mass spectrometry method to measure acid-labile albumin-PhIP adducts in human volunteers administered a dietary-relevant dose of 14C-labeled PhIP [Dingley, K. H., et al. (1999) Cancer Epidemiol., Biomarkers Prev. 8, 507-512]. Mild acid treatment of albumin (0.1 N HCl, 37 °C for 1 h) or proteolytic digestion with Pronase [50 mM ammonium bicarbonate buffer (pH 8.5) at 37 °C for 18 h] released similar amounts of covalently bound PhIP, which was characterized by multistage scanning and quantified by Orbitrap mass spectrometry. The amount of [14C]PhIP recovered by acid treatment of albumin 24 h following dosing accounted for 7.2-21.3% of the [14C]PhIP bound to albumin based on accelerator mass spectrometry measurements. 2-Amino-1-methyl-6-(5-hydroxy)phenylimidazo[4,5-b]pyridine, a hydrolysis product of the Cys34 S-N linked sulfenamide adduct of PhIP, was not detected in either acid-treated or protease-treated samples. These findings suggest that a portion of the PhIP bound to albumin in vivo probably occurs as an acid-labile sulfinamide adduct formed at the Cys34 residue. [ABSTRACT FROM AUTHOR]

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 μg·kg-1), low limits of detection (LODs, 0.003-0.060 μg·kg-1), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 μg·kg-1) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs). [ABSTRACT FROM AUTHOR]

A Pd(0)-catalyzed double C-N coupling of 5,5′-dibromo-2,2′-bithiazoles with (het)arylamines and subsequent in situ Ag2O-mediated oxidation provides access to cross-conjugated quinoidal 5,5′-diarylimino-2,2′-bithiazoles in moderate to high yield. The highly colored quinoidal 2,2′-bithiazoles were studied by UV/vis spectroscopy, cyclic voltammetry and computational methods. [ABSTRACT FROM AUTHOR]

Chagas disease is a neglected tropical disease with 6-7 million people infected worldwide, and there is no effective treatment. Therefore, there is an urgent need to continue researching in order to discover novel therapeutic alternatives. We present a series of arylaminoketone derivatives as means of identifying new drugs to treat Chagas disease in the acute phase with greater activity, less toxicity, and a larger spectrum of action than that corresponding to the reference drug benznidazole. Indexes of high selectivity found in vitro formed the basis for later in vivo assays in BALB/c mice. Murine model results show that compounds 3, 4, 7, and 10 induced a remarkable decrease in parasitemia levels in acute phase and the parasitemia reactivation following immunosuppression, and curative rates were higher than with benznidazole. These high antiparasitic activities encourage us to propose these compounds as promising molecules for developing an easy to synthesize anti-Chagas agent. [ABSTRACT FROM AUTHOR]

The first asymmetric synthesis of a, adisubstituted allylic N-arylamines based on a palladiumcatalyzed allylic animation has been developed. The protocol uses highly modular vinyl cyclic carbonates and unactivated aromatic amine nucleophiles as substrates. The catalytic process features minimal waste production, ample scope in reaction partners, high asymmetric induction up to 97% ee, and operational simplicity. [ABSTRACT FROM AUTHOR]

We investigate the surface and subsurface morphology of stearylamine-modified graphene oxide sheets and polystyrene-grafted functionalized graphene oxide sheets through atomic force microscopy (AFM) operated in multi-set point intermittent contact (MUSIC) mode. This allows a depth-resolved mapping of the nanomechanical properties of the top surface layer of the functionalized graphene oxide sheets. On the surface of stearylamine-functionalized graphene oxide sheets, we can distinguish areas of hydrophilic graphene oxide from hydrophobic areas functionalized with stearylamine. We find that every sheet of graphene oxide is functionalized with stearylamine on both sides of the sheet. The exposure of polystyrene-grafted functionalized graphene oxide to chloroform vapor during the AFM measurement causes a selective swelling and a softening of the polystyrene envelope. The depth-resolved mapping of the tip-sample interaction allows the shape of the folded and wrinkled graphene oxide sheets within the polystyrene envelope to be imaged; furthermore, it allows the thickness of the swollen polystyrene envelope to be measured. This yields the swelling degree, the grafting density, and the average chain conformation of the grafted polystyrene chains, which we find to be in the brush regime. Our work demonstrates a versatile methodology for imaging and characterizing functionalized and polymer-grafted two-dimensional materials on the nanometer scale. [ABSTRACT FROM AUTHOR]

A late-stage amination of a bifunctional dihydroxanthene (DHX) scaffold is reported to access a wide variety of new near-infrared (NIR) chromophores/fluorophores. The divergent approach allows the coupling of aliphatic and aromatic amines and readily provides molecular diversity shedding light on the structure-fluorescence relationship of this emerging class of NIR fluorophores. [ABSTRACT FROM AUTHOR]

Primary arylamines are an important unit broadly found in synthetic, biological, and materials science. Herein we describe the development of a (NHC)Cu system that mediates a direct C--H amidation of (hetero)arenes by using Nchlorocarbamates or their sodio derivatives as the practical amino sources. A facile stoichiometric reaction of reactive copper-aryl intermediates with the amidating reagent led us to isolate key copper arylcarbamate species with the formation of a C--N bond. The use of 'BuONa base made this transformation catalytic under mild conditions. The present (NHC)Cu-catalyzed C--H amidation works efficiently and selectively on a large scale over a range of arenes including polyfluorobenzenes, azoles, and quinoline N-oxides. Deprotection of the newly installed carbamate groups such as Boc and Cbz was readily performed to afford the corresponding primary arylamines. [ABSTRACT FROM AUTHOR]

Charge transfer (CT) transitions are relevant in the fields of solar energy conversion and nonlinear optical materials. Herein, a series of complexes with an alkynyl linkage between an aryl amine donor and a TiIV (titanocene) acceptor is reported. Each complex displays a strong (15000 > ε > 24,000 M-1cm-1), low-energy (520 > λ > 560 nm) absorption ascribed to an amine to TiIV ligand-to-metal CT. This characterization is supported by UV-vis spectroscopy, cyclic voltammetry, and TD-DFT calculations. These complexes are not photostable; therefore, an alternate architecture, wherein the amine donor is appended to the titanocene cyclopentadienyl ligand, has been designed. The molar absorptivity of the amine to TiIV CT in this latter architecture is lower (2100 M-1 cm-1), indicating weaker donor-acceptor coupling. This architecture is indeed much more photostable. [ABSTRACT FROM AUTHOR]

One of the most significant aspects in the development of dye-sensitized solar cells is the exploration and design of high-efficiency and low-cost dyes. This paper reports the theoretical design of various triphenylamine analogues, wherein the central nitrogen moiety establishes an sp2-hybridization, which endows a significant participation in the charge-transfer properties. Density functional theory (DFT) and time-dependent DFT methodologies were utilized to investigate the geometry, electronic structure, photochemical properties, and electrochemical properties of these dyes. Different exchange-correlation functionals were initially evaluated to establish a proper methodology for calculating the excited-state energy of the reference dye, known as DIA3. Consequently, TD-LC-ωPBE with a damping parameter of 0.175 Bohr-1 best correlates with the experimental value. Four new dyes, namely, Dhk1, Dhk2, Dhk3, and Dhk4, were designed by modifying the rigidity of the donor moiety. According to the results, altering the type and position of binding in the donor group leads to distinct planarity of the dyes, which significantly affects their properties. The designed Dhk4 dye showed more red-shifted and broadened absorption spectra owing to the enhanced coplanarity between its donor and π-bridge moiety, which brings an advantage for its potential use as sensitizer for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Efficient alkylations of amines by alcohols catalyzed by well-defined Co(II) complexes are described that are stabilized by a PCP ligand (N,N′-bis(diisopropylphosphino)-N,N′-dimethyl-1,3-diaminobenzene) based on the 1,3-diaminobenzene scaffold. This reaction is an environmentally benign process implementing inexpensive, earth-abundant nonprecious metal catalysts and is based on the acceptorless alcohol dehydrogenation concept. A range of primary alcohols and aromatic amines were efficiently converted into mono-N-alkylated amines in good to excellent isolated yields. [ABSTRACT FROM AUTHOR]

The design of enzyme-like complexity within metal–organic frameworks (MOFs) requires multiple reactions to be performed on a MOF crystal without losing access to its interior. Here, we show that seven post-synthetic reactions can be successfully achieved within the pores of a multivariate MOF, MTV-IRMOF-74-III, to covalently incorporate tripeptides that resemble the active sites of enzymes in their spatial arrangement and compositional heterogeneity. These reactions build up H2N-Pro-Gly-Ala-CONHL and H2N-Cys-His-Asp-CONHL (where L = organic struts) amino acid sequences by covalently attaching them to the organic struts in the MOFs, without losing porosity or crystallinity. An enabling feature of this chemistry is that the primary amine functionality (−CH2NHBoc) of the original MOF is more reactive than the commonly examined aromatic amines (−NH2), and this allowed for the multi-step reactions to be carried out in tandem within the MOF. Preliminary findings indicate that the complexity thus achieved can affect reactions that were previously accomplished only in the presence of enzymes. [ABSTRACT FROM AUTHOR]

The cationic ruthenium-hydride complex catalyzes the dehydrative C-H coupling reaction of arylamines with 1,2-diols to form the indole products. The analogous coupling of arylamines with 1,3-diols afforded the substituted quinolines. The catalytic method directly forms these coupling products in a highly regioselective manner without generating any toxic byproducts. [ABSTRACT FROM AUTHOR]

Using five Schiff base ligands (E)-N-(pyridine-2-yl) (CH=NPhR) (where R = 4-CH3, L¹; 2,6-(CH3)2, L²; 2,4,6-(CH3)3, L³; 2,6-(C2H5)2, L4; 2,6-(i-C3H7)2, L5), nine Zn(II)/Cd(II) complexes, namely, Zn1-Zn3, Cd1, Cd2, Cd3a, Cd3b, Cd4, and Cd5, have been successfully synthesized. The structures of the Zn(II)/Cd(II) complexes have been established by single crystal X-ray diffraction and further physically characterized by ¹H NMR, FT-IR, and elemental analysis. The crystal structures of these complexes indicate that the structures of ligand and anions can directly influence the formation of 1D → 3D supramolecular metal-organic frameworks (SMOFs) via C-H⋯O/C-H⋯Cl hydrogen bonds and π⋯π interactions. Upon irradiation with UV light, the nine Zn(II)/Cd(II) complexes display deep blue emissions of 401-436 nm in acetonitrile solution and light blue or bluish green emissions of 485-575 nm in the solid state, respectively. The photoluminescence properties of nine Zn(II)/Cd(II) complexes can be finely and predictably tuned over a wide range of wavelengths by small and easily implemented changes to ligand structure. It is worth noting that Zn1 and Cd1 exhibit obvious aggregation-induced emission enhancement (AIEE) properties in the CH3CN-H2O mixture solutions. [ABSTRACT FROM AUTHOR]