Aromatic Amines Research Articles

Mechanism and Origins of Nucleophile‐Controlled Regioselectivity of Palladium‐Catalyzed Allylic C−H Amination of 1,4‐Dienes: A Computational Study

AbstractDensity functional theory calculations have been conducted to investigate the palladium‐catalyzed allylic C−H amination of 1,4‐dienes with commonly available amines. The computations indicate that the reaction begins with the allylic C−H bond cleavage through the concerted proton and two‐electron transfer process to forge the η3‐allyl Pd(II) species. The ensuing C−N bond formation was found to be highly dependent on the basicity of the nucleophile, enabling the regioselectivity switch upon change of the nucleophile. With the weakly basic aromatic amine, the reaction occurs through the hydrogen‐bonding enabled inner‐sphere nucleophilic attack pathway. The distance between the reacting carbon atom and the terminal carbon atom is responsible for the Z/E‐selectivity. The regioselectivity is primarily due to steric repulsion between the allyl group and the ligand. On the other hand, the outer‐sphere nucleophilic attack pathway is favored for the reaction with the more basic aliphatic cyclic amine. The change of the coordinating mode of the allylic moiety was found to play a crucial role in determining the regioselectivity.

A new perspective on contaminants as "activators": Aromatic amine groups promoted degradation of tetracycline by ferrate(VI)

Occasionally, our group found that the degradation of tetracycline by ferrate(VI) could be promoted by four co-exist contaminants, containing aromatic amines (ofloxacin, diatrizoic acid, sulfadiazine and alachlor). This study investigated the promotion of aromatic amine groups on tetracycline degradation by ferrate(VI) by using aniline as a model compound. The results implied that the presence of aniline increased the degradation rate of tetracycline by 2.76 times, and the enhancement was weakened gradually with the decrease of pH from 10 to 7.5. The generation of Fe(IV) and·OH by the reaction between ferrate(VI) and aniline was proposed to enhance the degradation of tetracycline, supported by quenching experiments, electron paramagnetic resonance (EPR) and theoretical calculations. A positive correlation was found between the rate constant of tetracycline degradation and the electron-donating ability of the substituted amines (quantified by the Hammett substituent constants). In addition, the degradation of tetracycline was remarkably inhibited by HA and some inorganic ions such as NO3-, SO42-, Cl-, Ca2+, and Mg2+, and the inhibition also happened in the Songhua River water and the secondary effluent. The present study provided an insight into the complex oxidation process for the degradation of micropollutants containing aromatic amine by ferrate in water treatment.

One-step solvothermal synthesis of nitrogen-doped carbon dots with efficient red emission from conjugated perylene for multiple applications

Despite its significance for applications related to plant growth, the development of carbon dots (CDs) with bright red emissions still faces multiple obstacles. Herein, red emission hydrophobic carbon dots (RH-CDs) featuring one emission peak centered at 594 nm and a shoulder emission peak at 630 nm with a quantum yield of 34 % and a wide full width at half maximum (FWHM) of 100 nm (580 nm–680 nm) were synthesized by adopting large conjugated perylene anhydride and aromatic amine precursors under solvothermal conditions. Density functional theory calculations support the method of using larger conjugated systems and higher graphite N doping to increase red emissions from CDs. With a post-surface functionalization strategy, polyvinylpyrrolidone (PVP)-modified RH-CDs (QY = 12 %) were utilized as an anti-counterfeiting ink for information printing. Moreover, both blue-red light-emitting diodes (LEDs) and light conversion poly (methyl methacrylate) (PMMA)-CDs film were fabricated with emission spectra that are consistent with the absorption spectra of plants, suggesting that the prepared RH-CDs may have widespread application potential as a stable fluorescent material in plant growth.

Electrodeposition of Au Nanowires via Amine Ligand-Induced Active Surface Growth.

Amine ligands have been widely applied as morphology-directing reagents in nanostructure synthesis. In this work, we explored the application of the amine ligands in the active surface growth mechanism in place of the strong thiolated ligands. Despite being weaker compared to the thiols, amine ligands such as aniline were also shown to be capable of facilitating the template-less electrodeposition of Au nanowires (NWs) on the substrate via the active surface growth mechanism. Given the close binding difference between the amine-grafted substrate and the ligands, substrate functionalization becomes critically important for effective construction of the active surface and the growth of the nanowires. Additionally, the growth with the amine ligands took place at more positive reduction potentials and is less prone to splitting and bundle formation. A systematic generality study revealed that besides the aromatic amines, long-chain aliphatic amines were also capable of facilitating nanowire growth. Given the weak binding affinity of the amine ligands, the Au NWs are readily accessible for further processing to generate sophisticated one-dimensional structures. As a demonstration, tandem electrodeposition was performed to directly obtain coaxial core-shell Au@Pt NWs with adjustable length, diameter, and shell thickness.

Biosynthesis of Ag‐CuO Nanocomposites: Efficient Catalyst for the Synthesis of Schiff Bases, Photodegradation of Congo Red Dye and Their Cytotoxicity Evaluation on MCF‐7 Cell Line

ABSTRACTAmid growing environmental concerns and the need for a sustainable future, green synthetic methodologies are gaining popularity for their simplicity and nontoxicity. In pursuit of the eco‐friendly synthesis of nanomaterials, the study reports an innovative synthesis of Ag‐CuO nanocomposites via the coprecipitation method utilizing Citrus limetta fruit juice extract as the bioreductant and stabilizing agent. The morphological and structural characteristics of the fabricated nanocomposites were evaluated by ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), transmission electron microscopy (TEM), X‐ray diffraction (XRD), Raman and Brunauer–Emmett–Teller (BET) analyses. The nanocomposites were crystalline with particle sizes ranging from 15 to 24 nm and exhibited spherical and rod‐like shapes. The band gap value and specific surface area of the nanocomposites were found to be 1.5 eV and 25.50 m2/g, respectively. The photoluminescence (PL) analysis and electrochemical studies revealed significant charge separation and effective charge migration behaviour of the nanocomposites, respectively. The nanocomposites effectively catalysed the synthesis of Schiff bases from aryl aldehydes and aromatic amines at room temperature and without solvents. The reactions proceeded in a brief time with excellent product yields, and the nanocatalyst retained its activity for five consecutive cycles. The nanocomposites also efficiently catalysed the photodegradation of Congo red dye under visible light. A significant degradation of 94.33% was attained in 55 min, and the nanocatalyst maintained its efficacy over four consecutive reaction cycles. Moreover, the nanocomposites exhibited notable anticancer properties against the MCF‐7 (human breast) cell line, demonstrating a remarkable cytotoxicity rate of 87.79%. The findings highlight the efficacy of the biosynthesized nanocomposites in catalysis, environmental remediation and biological applications.

Spectroscopic and Electrochemical Studies of Interaction of Cu(II) Ion with Different Aliphatic and Aromatic Amine Based Ligands in Aqueous Solutions

The composition and stability constant of the complexes of copper(II) with the ligands 2,2 –bipyridine, 1,10-phenanthroline, saccharin, and ethylenediamine tetraacetic acid (EDTA),were determined, as well as the effect of temperature on the thermodynamic parameters were studied. The metal-to-ligand ratio in the EDTA complex is found 1:1 and in the rest of the cases, the ratio is 1:2. The redox behavior of the Cu (II) / Cu (0) system in the Cu-ligand complex has been studied in KCl solution as a supporting electrolyte. The redox process of the Cu (II) / Cu (0) system in the Cu-sac complex is almost similar to that of the Cu (II) solution in the absence of any ligand. In other cases, the redox process is a single-step 2-electron transfer process. The electron transfer process in all the cases is diffusion-controlled. The values of peak current ratio and peak potential separation are the evidence that the redox processes are quasi-reversible. Dhaka Univ. J. Sci. 72(2): 61-67, 2024 (July)

Phosphomolybdic Acid‐Catalyzed One‐Pot Multicomponent Synthesis of 1,2,5,6‐Tetrahydropyridine Derivatives

AbstractWe report the synthesis of alkyl 1,2,6‐triaryl‐4‐arylaminopiperidine‐3‐ene‐3‐carboxylates in acceptable yields (42%–71%) and high trans‐diastereoselectivity (69:31 to 100:0) through a one‐pot multicomponent reaction of aromatic aldehydes, aromatic amines, and β‐ketoesters catalyzed by phosphomolybdic acid in methanol at room temperature. The structure and stereochemistry of tetrahydropyridines were confirmed by X‐ray crystallography. This protocol stands out for its operational simplicity, the use of an inexpensive and commercially available heteropolyacid catalyst, low catalyst loading, and purification via simple filtration, resulting in acceptable yields and high diastereoselectivity.

Laccase-assisted Bioremediation of Pesticides: Scope and Challenges

Abstract: Laccase (Benzenediol: oxygen oxidoreductase; E.C.1.10.3.2), a multicopper oxidase that is a known lignin-degrading enzyme, can catalyse an ample array of substrates, from phenolic, nonphenolic compounds, aromatic amines, diamines, heterocyclic compounds to organic/inorganic metal compounds, etc., bestowed they have not too high redox potentials. Despite many laccase-producing organisms like bacteria, insects, plants, and animals, white rot filamentous fungi are the best producers of this enzyme. In the presence of laccase, pesticides (fungicides, herbicides, insecticides, etc.) of various chemical compositions (organophosphates, organochlorines, carbamates, pyrethrin & pyrethroids, etc.) are oxidized into the water with collateral reduction of four electrons of molecular oxygen with various efficiencies. Bioremediation efficiency can be increased in the presence of various natural or synthetic mediators, viz. ABTS, violuric acid, 1- hydroxy benzotriazole, vanillin, syringaldehyde, PEG, etc. Immobilized laccase on various supporting materials increased the enzyme's stability, reliability, and reusability for continuous application, particularly for industrial processes. The present review discusses the structure, catalytic cycle, general mechanism of oxidation, and various scopes and challenges of pesticide degradation by this multifaceted biocatalyst which could lead to a green sustainable environment.

Effect of sintering temperature on magnetic, catalytic and photocatalytic properties of Cu-Co-Mn ferrite catalyst

Wastewater pollution is a pressing environmental issue, necessitating effective remediation strategies to mitigate its impact. This study investigates the use of an efficient catalyst for degrading nitrophenols by converting them into useful aromatic amines, which are crucial building blocks for many pharma industries, and photodegradation of various dyes in their unitary solution as well as in mixture. The Cu-Co-Mn ferrite was synthesized using the sol-gel process and sintered at different temperatures. Structural analysis using XRD and Rietveld refinement revealed a crystal structure corresponding to the Fd3‾m space group having high purity in all the samples. Additionally, the impact of sintering temperature on the magnetic features of the phases were also studied and the findings suggest that all the phases exhibit ferromagnetic behaviour, which means they can be easily separated from reaction mixtures using an external magnetic field. It was also found that higher sintering temperatures lead to a rise in saturation magnetization and magnetic moment with decrease in coercivity (Hc). Further, it was observed that Curie temperature (Tc) increases with increase in sintering temperature with the exception of CFM400. The catalytic performance of all the catalysts, including CFM400, CFM500, CFM600, CFM800, and CFM1000, was evaluated and the results indicate that CFM400 exhibits the highest catalytic activity for nitrophenols reduction and photodegradation of dyes, which could be accredited to its larger BET surface area and lower PL intensity. Overall, the structural and magnetic features of the catalyst’s sheds light on the underlying mechanisms governing their catalytic activity. These insights offer valuable guidance in the designing and development of effective catalysts for sustainable wastewater treatment practices, emphasizing the importance of considering both structural and magnetic features in catalyst design.

Sustainable and versatile Aza-Michael additions promoted by acidic ionic liquids

Acidic ionic liquids are a subset of ionic liquids where the cation or anion possess acidic properties with huge applications in various fields. Here we describe environmentally safe and highly efficient conjugate addition of aromatic and aliphatic amines to α, β-unsaturated compounds in the presence of novel acidic ionic liquids. The acidic ionic liquid catalyst was prepared by combining benzyl chloride with 2-(dimethylamino) ethanol and SnCl2 in a simpler manner. The resulting acidic ionic liquid was characterized using SEM, EDS and FTIR spectroscopy. In the presence of ionic liquids, a wide variety of amines undergo facile conjugate addition to α, β-unsaturated compounds affording the corresponding β-amino compounds in good to excellent yields (72–97 %), shorter reaction times (1–4 h) and mild reaction conditions (60 °C). Furthermore, the study demonstrated the sustainability of the process by showcasing that the acidic ionic liquids could be reclaimed and reused for up to five cycles without compromising their catalytic effectiveness.

Facile Ring Opening of Novel Bisoxazolone with Substituted Aromatic Amines: Synthesis, Antimicrobial, Antioxidant Potential, In Silico ADME Profile and Molecular Docking Study

AbstractThis article describes the controlled synthesis and characterization of an olefin‐linked oxazolone scaffold compound containing multifunctional groups, including the carbonyl group, imine, and carbon‐carbon double bond. The reaction of the bisoxazolone with aromatic amines led to the ring‐opening of the bisoxazolone into the corresponding bisdiamide derivatives in a short time (average 10 min), resulting in a high yield (>90 %). The compounds were characterized by FT‐IR, 1H‐NMR, 13C‐NMR, and MS. Besides, screened against Escherichia coli, Staphylococcus aureus, and Candida albicans using ciprofloxacin as a standard. All compounds exhibited significant inhibition potency against E. coli, with a lower potency against S. aureus. Compounds 3 a, 3 b, and 3 d showed more reactivity against E. coli, while compound 3 i has the highest activity against S. aureus (MIC=128 μg/mL). Additionally, the antioxidant activity was performed utilizing DPPH radical scavenging activity. The findings indicated that some compounds possessed moderate antioxidant activity in comparison to ascorbic acid as a control. A molecular docking study demonstrated a positive interaction between synthesized compounds and the bacterial DNA gyrase target (PDB ID: 1KZN) in S. aureus. Subsequently, in silico ADME simulations were conducted for all the synthesized compounds, indicating favorable properties in comparison to the established antibiotic ciprofloxacin.

Exploration of the prediction and generation patterns of heterocyclic aromatic amines in roast beef based on Genetic Algorithm combined with Support Vector Regression

Heterocyclic aromatic amines (HAAs) are harmful byproducts in food heating. Therefore, exploring the prediction and generation patterns of HAAs is of great significance. In this study, genetic algorithm (GA) and support vector regression (SVR) are used to establish a prediction model of HAAs based on heating conditions, reveal the influence of heating temperature and time on the precursor and formation of HAAs in roast beef, and study the formation rules of HAAs under different processing conditions. Principal component analysis (PCA) showed that the effect on HAAs generation increases with the increase of heating temperature and time. The GA-SVR model exhibited near-zero absolute errors and regression correlation coefficients (R) close to 1 when predicting HAAs contents. The GA-SVR model can be applied for real-time monitoring of HAAs in grilled beef, providing technical support for controlling hazardous substances and intelligent processing of heat-processed meat products.

B(C6F5)3·H2O-Catalyzed N-H and C-H Functionalization of Aromatic Amines with Sulfoxonium Ylides under Metal-Free Conditions.

Hydrogen-bonded aggregates of B(C6F5)3 and water are proven as strong Brønsted acid catalysts, which have the advantages of low toxicity and broad compatibility. Sulfoxonium ylides are stable surrogates of diazo compounds, which participate in various reactions due to their versatile reactivity. Based on these characteristics, a strategy for C-N bond or C-C bond construction of aromatic amines with sulfoxonium ylides under metal-free catalytic conditions was established. This method has advantages of mild conditions and excellent yield, which is suitable for the N-H or C-H functionalization of various aromatic amine compounds.

Synthesis and comparative anticancer studies of Novel amide functoinalised thienopyridine and pyridothienopyrimidinone derivatives

Amide functionalized trifluoromethyl thieno[2,3-b] pyridine derivatives as a series were prepared starting from reaction between 1,3 di-ketone and thiocyanoacetamide. Compound 3 reacts with bromoethyl acetate to give compound 4. Compound 4 on reaction with diverse substituted aromatic and aliphatic amines gives amide derivatives 5a-f and these amide derivatives on reaction with triethylorthoformate give pyridothienopyrimidinone derivatives 6a-f. All the final compounds were evaluated for anti cancer activity against four human cancer cell lines such as A549—Lung cancer (CCL-185), MCF7—Breast cancer (HTB-22), DU145—Prostate cancer (HTB-81) and HeLa—Cervical cancer (CCL-2) by using MTT assay. Promising compound 5d was identified.

Heterobimetallic Cu(I)/Fe(II) azomethine bridged coordination-organometallic hybrid complexes: Synthesis, luminescence, electrochemical and catalytic properties

A new series of heterobimetallic complexes of the type [Cu(L)(PPh3)2]X (1–4) [where L = trans-4-(ferrocenylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one; PPh3 = triphenylphosphine, X = NO3−(1), ClO4− (2), BF4− (3) , PF6− (4)] were prepared by reaction of L with [Cu(MeCN)2(PPh3)2]X and characterized by elemental analysis, FTIR, 1H NMR, 31P NMR and UV–visible spectral studies. The thermal stability of (1–4) has been investigated by using thermogravimetric analysis (TGA). X-ray powder diffraction of the representative complex 1 used to clarify the crystal structure of the complex. The electrochemical behaviour of complexes (1–4) displayed quasireversible redox behaviour corresponding to Cu(I)/Cu(II) and Fe(II)/Fe(III) couples. All complexes show red emission as a result of ligand-ligand charge transfer (LLCT) and metal-ligand charge transfer (MLCT) or admixture of them. The catalytic efficiency of the complexes (1–4) was tested and it was found that the complex 4 worked as an effective catalyst for the C-N coupling reaction of aromatic amines and aryl halides.

Synthesis of rGO/CuBi2O4 nanocomposite as an effective photocatalyst in the reduction of nitroaromatic compounds to corresponding amines under visible light

AbstractBACKGROUNDChemical pollutants, such as nitroaromatic compounds, have been a significant challenge in recent decades of human societies as they contribute to environmental pollution and pose serious health risks due to their high toxicity. One promising and green method to address this issue is the photocatalytic reduction of nitroaromatic compounds to their corresponding amino aromatic compounds. In this study, an rGO/CuBi2O4 nanocomposite was synthesized using the hydrothermal method, involving the simultaneous reduction of graphene oxide and the coupling of CuBi2O4 nanoparticles in its layers. The resulting heterogeneous structure was characterized using various techniques including FTIR, Raman, XPS, XRD, FESEM, TEM, EDAX, UV–Vis DRS, BET, PL spectroscopy, and EIS. Subsequently, the photocatalytic efficiency of the nanocomposite in reducing nitroaromatic compounds to the corresponding aromatic amines under visible light was evaluated.RESULTSThe results indicated that graphene oxide was effectively reduced and coupled with CuBi2O4 nanoparticles in the reduced graphene oxide sheets. The rGO/CuBi2O4 heterogeneous nanocomposite successfully reduced nitroaromatic compounds to the corresponding aromatic amines under visible light. Hydrazine monohydrate was used to supply the necessary hydrogen for the reaction.CONCLUSIONThis study confirmed the high photocatalytic activity of the rGO/CuBi2O4 heterogeneous nanocomposite. Our nanocomposite was more effective than others, reported in similar studies, at reducing nitroaromatic compounds to the corresponding amino aromatic compounds. Additionally, it demonstrated high recycling and reuse properties, as there was no significant change in reaction conversion percentage and nanocomposite amount after 16 reuses. © 2024 Society of Chemical Industry (SCI).

A new catalyst Cu(I)@TpFO-PA with high activities to C-N coupling reactions

TpFO-PA, a novel spherical hollow mesoporous polyamide, was firstly synthesized by the reaction among 1,3,5-tris(4-aminophenyl)benzene (TAPB), furylamine and oxalyl chloride in using silica-gel nanoparticle as hard template, and the composite Cu(I)@TpFO-PA with high catalytic activities in C-N coupling reactions between (hetero)aryl bromide and (hetero)aryl amines under mild conditions was prepared basing on presence of N in the framework. A maximum activity of the catalyst with yield of C-N coupling product were about 311.9 g(product)/molCu(I)·h and 95 % respectively, and the activity could be maintained at least 5 times after the catalyst was reused. The composite Cu(I)@TpFO-PA is a few heterogeneous catalysts reported in catalyzing coupling reaction between aromatic amines and brominated aromatic compounds.

Comparative analysis of free and bound heterocyclic aromatic amines in fried chicken drumsticks affected by various vegetable oils

The study explored the impact of different vegetable oils, including soybean oil, rice bran oil, and safflower oil, on the generation of free and protein-bound heterocyclic aromatic amines (HAAs) in fried chicken drumsticks. All fried samples showed increased pH values, a*-values (the redness), and b*-values (the yellowness), while decreased L*-values (the brightness) and water content than the control sample (P < 0.05). Fried chicken drumsticks contained a total of 10 HAAs, including five types of free HAAs (MeIQ, MeIQx, PhIP, Harman, and Norharman), as well as five types of protein-bound HAAs (4,8-DiMeIQx, 7,8-DiMeIQx, AαC, Harman, and Norharman). Drumsticks prepared with safflower oil exhibited the highest levels of free HAAs (248.23 ng/g) and protein-bound HAAs (116.14 ng/g). In contrast, those fried in rice bran oil showed the lowest levels of free HAAs (172.92 ng/g) and protein-bound HAAs (99.13 ng/g) (P < 0.05). In conclusion, rice bran oil is an appropriate choice for frying chicken drumsticks due to its ability to reduce HAAs, which provides a scientific foundation for the production of fried chicken drumsticks.

Occurrence and eco‐toxicological risk assessment of primary aromatic amines in hookah wastewater

AbstractThis study was conducted for the first time to discern the levels of primary aromatic amines (PAAs) in hookah wastewater resulting from the consumption of fruit‐flavored and traditional tobacco. The ecological risk of PAAs laden hookah wastewater and its toxic effects on crustaceans and fish have also been evaluated. The mean concentrations of PAAs in hookah wastewater resulting from consumption of Al‐Mahmoud, Al‐Ayan, Al‐Fakher, and Mazaya brands were 1075.56, 1033.25, 986.94, and 946.58 ng/L, respectively, while it was determined as 355.91 ng/L in traditional tobacco. The concentration of PAAs in the hookah wastewater of fruit‐flavored tobacco was significantly higher than the traditional one (p &lt; 0.05). Aniline (ANL) had the maximum level in hookah wastewater from fruit‐flavored (679.83–802.50 ng/L) and traditional (316.53 ng/L) tobacco consumption. The RQ value of the mean concentration of PAAs in hookah wastewater for all samples was in the range of medium to low‐risk (RQ &lt; 1). In addition to PAAs, other dangerous chemicals in hookah wastewater can increase its ecological and health risk, so it is necessary to manage such wastewater before discharging it into the environment.

FSO2N3-Mediated On-DNA Diazo-Transfer Chemistry.

DNA-encoded library (DEL) is a powerful hit selection technique in both basic science and innovative drug discovery. In this study, we report a robust and straightforward DNA-compatible diazo-transfer reaction utilizing FSO2N3 as the diazo-transfer reagent in solution. This reaction demonstrates high conversions and facile operation while being metal-free and maintaining high levels of DNA fidelity. It is also compatible with a wide range of substrates, allowing for convenient access to both aliphatic and aromatic amines. Consequently, it will further enrich the DEL chemistry toolbox.