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Copper oxide (CuO) nanoparticles were synthesized through the thermal decomposition of a copper(II) Schiff-base complex. The complex was formed by reacting cupric acetate with a Schiff base in a 2:1 metal-to-ligand ratio. The Schiff base itself was synthesized via the condensation of benzidine and 2-hydroxybenzaldehyde in the presence of glacial acetic acid. This newly synthesized symmetric Schiff base served as the ligand for the Cu(II) metal ion complex. The ligand and its complex were characterized using several spectroscopic methods, including FTIR, UV-vis, 1H-NMR, 13C-NMR, CHNS, and AAS, along with TGA, molar conductivity and magnetic susceptibility measurements. The CuO nanoparticles were produced by thermally decomposing the complex at 800 °C. These nanoparticles and other metal oxides are highly valued in various industries for their optical, magnetic, and electrical properties. The experiment highlighted the synthesis of CuO nanoparticles through the thermal breakdown of copper(II) ions, starting with copper acetate, which reacted with the ligand to form the complex. The characterization results of CuO nanoparticles reveal a highly pure crystalline structure with an average size of 70–90 nm.

The bottom perovskite with the hole transport layer (HTL) in inverted perovskite solar cells (PSCs) interface has received little attention due to challenges like interlayer dissolution during perovskite deposition. And voids at the perovskite/HTL interface can degrade cell performance. This work introduces a two‐dimensional (2D) perovskite layer between the perovskite and poly (N, N′‐bis‐4‐butylphenyl‐N, N′‐bisphenyl) benzidine (Poly‐TPD) HTL using a mixed solution of 4‐methylphenethylammonium chloride (4M‐PEA‐Cl), methylammonium iodide (MA‐I), and Poly(9,9‐bis(3′‐(N,N‐dimethyl)‐N‐ethylammoinium‐propyl‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene))dibromide (PFN‐Br). The amine functional groups in the organic salts improved HTL wettability, resulting in a void‐free interface. 4M‐PEA‐Cl, with its strong electron‐withdrawing benzene ring, outperformed other amine‐containing salts in passivating undercoordinated Pb2+ ions. Incorporating this hybrid passivation layer in PSCs resulted in a 1.8% absolute increase in power conversion efficiency (PCE) to 19.1% with 1.68 eV perovskite bandgap. Additionally, the passivated PSCs demonstrated enhanced operational stability, retaining 91% of their initial efficiency after 800 hours of continuous 1‐sun illumination, compared to 84.7% for the control sample. [ABSTRACT FROM AUTHOR]

This work describes the development of new spectrophotometric techniques for 3-aminophenol assessment. The first technique involves using benzidine in an alkaline solution to convert 3-aminophenol into a colored complex. The produced complex has a red color with an absorbance of 462 nm. Between the concentration range 5–14 μg mL−1, Beer's law is obeyed with a correlation coefficient (R2) of 0.99781, a limit of detection (LOD) of 0.0423 μg mL−1, and a limit of quantification (LOQ) of 0.1411 μg mL−1. The recovery was between 87.2–95.43%, the relative standard deviation (%RSD) was 2.40–3.31% and the molar absorptivity was 3.545 × 103 L mol−1 cm−1. Secondly, cloud point extraction (CPE) was used to determine a trace amount of the colored product in the first method, followed by measuring with a UV-vis spectrophotometer. The linearity of the calibration curve was above the range of 5–14 μg mL−1, and the R2 was 0.9988. The LOD and LOQ were found to be 0.0318 and 0.1059 μg mL−1, respectively. The recovery was between 99.49–99.82%, the %RSD was 0.67–2.00% and the molar absorptivity was 4.724 × 103 L mol−1 cm−1. This method was successfully employed for 3-aminophenol detection in several wastewater samples from Rustamiya, under the Al Doura and Diyala bridge.

Novel benzidine bis azo (BBA) complexes with Fe(III), Co(III), Ni(II), Cu(II), and Zn(II) were created and analyzed using a variety of analytical methods. The B3LYP/6-311G(d,p) and LANL2DZ basis sets were used in quantum chemical simulations with the DFT approach to analyze the structures of the BBA and its complexes. The compounds' strong NLO properties can be easily polarized, as indicated by the narrow HOMO-LUMO energy gap. The polarizability and hyperpolarizabilities of the chelates indicate that they are good candidates for NLO materials. The electronic spectra were computed using the polarizable continuous solvation method PCM, TD-DFT/PCM. Additionally, the infrared spectra obtained were compared to the anticipated harmonic vibrations of the azo dye ligand and its complexes. Utilizing molecular docking and virtual screening technologies, binding energy studies of the bis azo dye ligand and its complexes with the human coronavirus Nl63 nucleocapsid protein (PDB ID: 5epw) and SARS-CoV spike protein (PDB ID: 5wrg) were anticipated. The results demonstrated promising binding. The outcomes demonstrated the efficiency of the ligand and its complexes as COVID-19 and SARS virus inhibitors. Zn was shown to be the only metal that connected to the 5epw-Viral protein. [ABSTRACT FROM AUTHOR]

In this study, Some new Compounds have been Synthesized including the preparation of some Schiff bases (P1,P2,R4) from the reaction Benzdine, 2-aminoanthracine-9,10-dione compounds with two moles of various aldehydes The second stage includes preparation of new heterocyclic compounds seven membered rings ( Oxazepine, Oxazepane)(P1C1,P1C2,P1C3,P2C1,P2C2,P2C3,R4C1,R4C2,R4C3) using the microwave method . The prepared compounds were characterized by FT-IR, 1H-NMR, and 13C-NMR spectra in addition melting points were measured for all compounds and reactions was followed by TLC (Thin Layer Chromatography).Finally, the synthesized compounds are tested against Gram-positive(Staphylococcus aureus) and Gram-negative bacteria (Escherichia Coli) to study their biological activity, the results showed high biological effectiveness of some derivatives (P1,P2,R4,P1C1,P1C2,P1C3,P2C1,P2C2,R4C1) compared with Ciprofloxacin drug and study anti-oxidant for the R4C2 compound which gave good results. . [ABSTRACT FROM AUTHOR]

Benzidine-N,N,N',N'-tetraacetic acid (TAB) and its binuclear CuII complex were synthesized by condensation of benzidine and monochloroacetic acid in a 1:4 molar ratio. The composition and structure of the obtained compounds were studied by IR, electron spectroscopy, EPR, derivatography and elemental analysis. The surface morphology of the synthesized compounds was studied using a NeoScope Jeol JCM-5000 scanning electron microscope. The magnetic moment of the binuclear CuII complex of benzidine-N,N,N',N'-tetraacetic acid is µeff = 2.46 B.M. The electronic exchange interaction between Cu2+ ions in the binuclear copper complex is very small. In the electronic spectrum of the CuII complex of benzidine-N,N,N',N'-tetraacetic acid, the peaks at wavelengths of 230, 290, and 405 nm can be attributed to electronic transitions of metal ions. Thermogravimetric analysis showed that the CuII complex of benzidine-N,N,N',N'-tetraacetic acid is stable up to temperatures above 600°C. [ABSTRACT FROM AUTHOR]

This manuscript presents research on the optoelectronic and energy transfer properties of conjugated polymer poly (N,N′-bis-4-butylphenyl-N,N'-bisphenyl)benzidine (poly-TPD) and laser dye Fluorol 7GA (F7GA) hybrid thin films prepared via solution blending technique. Various weight ratios of F7GA were added to a fixed concentration of poly-TPD to form homogeneous hybrids. The hybrid thin films were characterized using absorption and photoluminescence spectroscopy. The results showed enhanced absorption, widened optical bandgaps, slight blue-shifted emission, and decreased refractive index in the hybrid films compared to pristine poly-TPD. The significant spectral overlap between the emission spectrum of poly-TPD and the absorption spectrum of F7GA, allowing for efficient Förster resonance energy transfer. Parameters including efficiency, distance, lifetime, and probability of energy transfer were calculated to quantitatively analyze energy transfer. Modulation of F7GA content led to tunable emission colors across the visible spectrum. Overall, the successful energy transfer demonstrated in this study paves the way for exciting future directions in the field of poly-TPD/F7GA hybrid materials for advanced optoelectronic applications. [ABSTRACT FROM AUTHOR]

Colorless polyimide (CPI), a heat‐resistant polymer being widely used in optoelectrical devices, has attracted worldwide attention. Polyamide‐imides due to the incorporation of amide groups into the CPI chains enhance the polymer performance by improving the thermal dimensional stability and excellent mechanical properties without sacrificing the optical transparency. In this article, CPI films PI‐(1‐3) are synthesized from one‐step polymerization of 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and cyclopentanone bis‐spironorbornane tetracarboxylic dianhydride (CpODA) with amide‐containing diamine N,N′‐(2,2′‐bis(trifluoromethyl)‐[1,1′‐biphenyl]‐4,4′‐diyl)bis(4‐aminobenzamide) (AB‐TFDB) and bis(trifluoromethyl)benzidine (TFDB). In comparison, by adjusting the ratio of imide and amide groups in the repeating unit, PI‐(4‐5) are prepared from copolymerization of terephthaloyl chloride (TPC), 6FDA, and CpODA with TFDB diamine. PI‐(1‐5) with 90% transmittance in the visible region tailored the excellent thermal and mechanical properties. Particularly, PI‐3 exhibited a high glass transition temperature of 412°C, a coefficient of thermal expansion of 20.8 ppm/K, a tensile strength of 128 MPa, and an elastic modulus of 5.4 GPa. The results also concluded that irrespective of the polyamide‐imide synthesis strategy, CPI films with similar amide‐to‐imide ratio in polymer chain demonstrated comparable optical, thermal, and mechanical properties. [ABSTRACT FROM AUTHOR]

A series of poly(ester imide) (PEsI) copolymers were synthesized using 3,3',4,4'-biphenyltetracarboxylic dianhydride (4,4'-BPDA), 2,2'-bis(trifluoromethyl) benzidine (TFMB), and 4-aminophenyl-4'-aminobenzoate (APAB) as the monomers. Wide-angle x-ray diffraction results revealed that the average interchain distances of these polymers ranged from 4.6 to 5.7 Å, increasing with the increase of TFMB contents. PEsI-0.3 and PEsI-0.4 exhibited a glass transition temperature (Tg) of 445 and 455°C, respectively, while no distinctive Tg was observed for the PEsI copolymers when the APAB content was >50 mol%. The coefficients of thermal expansion (CTE) of these PEsI copolymers ranged from 3.8 to 24.2 ppm K-1, increasing with the increase of TFMB contents. The PEsI copolymers exhibited a modulus of 5.7-7.8 GPa, a tensile strength of 282-332 MPa, and an elongation-at-break of 10.2%-23.3%. Furthermore, these copolymers exhibited a dielectric constant of 2.53-2.76, and a low dissipation factor (Df) of 0.0026-0.0032 at 10 GHz in dry state. Because of their excellent combined properties, these PEsI copolymers are promising candidates as dielectric substrate materials for the applications in next generation flexible printed circuit boards operating at high frequencies. [ABSTRACT FROM AUTHOR]

Polyimides (PI) are considered as one of the most used materials for flexible printed circuit board substrates because of their excellent thermal stabilities, outstanding mechanical properties, and great dielectric properties. Dielectric constants (Dk) of common commercial PIs, however, are still above 3.0 (at 10 GHz), which is still substandard for high‐frequency applications. In this study, we develop thermally stable PIs with enhanced dielectric properties by structural design and crosslinking. Stiff aromatic 2,2′‐bis(trifluoromethyl)benzidine (TFMB) and soft aliphatic dimer diamines (DDA, priamine), including priamine 1074 (DDA‐1) and priamine 1071 (DDA‐2), are used as the diamines, and cyclobutanetetracarboxylic dianhydride (CBDA) is used as the dianhydride. By adjusting the ratio of the diamines, a series of PIs (PI‐1–PI‐5) with high thermal stabilities and low‐Dk values are synthesized. Among these PIs, PI‐4 synthesized by diamines with the ratio of TFMB:DDA‐1:DDA‐2 = 85:10:5, possesses relatively good performances. Therefore, PI‐4 is further chosen to be thermally crosslinked. By changing the contents of the crosslinker, triallyl isocyanurate (TAIC), crosslinked PIs (CPIs) are synthesized. The resulting CPIs have a significant improvement in thermal properties, dielectric properties, and mechanical strengths. Especially, for the CPI‐4‐30, in which 30% of TAIC is used, the glass transition temperature (Tg) increases by 20°C, the Dk decreases from 2.62 to 2.41, and the ultimate tensile strength boosts from 91.65 to 115.16 MPa. The CPIs with low Dk and high Tg values may have great potential as substrate materials for broad applications, such as microelectronics and integrated circuit packages. [ABSTRACT FROM AUTHOR]

Polymer composites based on poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (poly-TPD) with PCBM and copper(II) pyropheophorbide derivative (Cu-PP) were developed. In thin films of the poly-TPD and Cu-PP composites, the charge carrier mobility was investigated for the first time. In the ternary poly-TPD:PCBM:Cu-PP composite, the electron and hole mobilities are the most balanced compared to binary composites and the photoconductivity is enhanced due to the sensitization by Cu-PP in blue and red spectral ranges. The new composites are promising for use in the development of photodetectors. [ABSTRACT FROM AUTHOR]

Metal complexes of Co(II), Cu(II) and Ni(II) with the Schiff base ligand, 6,6ʹ-(([1,1ʹ-biphenyl]-4,4ʹ diylbis(azaneylylidene))bis(methaneylylidene))bis(2,4-dichlorophenol) (H2L) were synthesised. All synthesised compounds were identified and characterised. The conductivity measurements showed the non-electrolytic nature of all the complexes. The decomposition of all complexes ended with metal oxide. Octahedral geometries were proposed for all complexes. Photocatalytic degradation of methylene blue dye (MB) in the presence and absence of hydrogen peroxide was studied by using Co(II), Cu(II) and Ni(II) complexes as catalysts. Fluorescence studies have shown that the reported compounds can act as photoactive materials. Density functional theory was used to investigate the geometries of the ligand and its complexes. The adsorption of Co2+, Ni2+ and Cu2+ in an aqueous solution on H2L ligand under various conditions was studied. The optical properties of all complexes were studied. Antimicrobial activities of the ligand and its transition metal complexes were studied. The in-vitro cytotoxicity of ligand and its cobalt(II), nickel(II) and copper(II) complexes were evaluated towards the human Liver Carcinoma (HepG2) cell line and compared with standard cisplatin. [ABSTRACT FROM AUTHOR]

Alkaline phosphatase (ALP) is a phosphomonoester hydrolase and serves as a biomarker in various diseases. However, current detection methods for ALP rely on bulky instruments, extended time, and complex operations, which are particularly challenging in resource-limited regions. Herein, we synthesized a MOF-derived Fe-N-C nanozyme to create biosensors for the coulometric and visual detection of ALP. Specifically, we found the Fe-N-C nanozyme can efficiently oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to generate blue-colored tetramethyl benzidine (TMBox) without the need for H2O2. To construct the biosensor, we incorporated the ALP enzymatic catalytic reaction to inhibit the oxidation of TMB by Fe-N-C oxidase nanozyme. This biosensor showed rapid and highly sensitive detection of ALP in both buffer and clinical samples. The limit of detection (LOD) of our approach could be achieved at 3.38 U L−1, and the linear range was from 5 to 60 U L−1. Moreover, we also developed a visual detection for ALP by using a smartphone-based assay and facilitated practical and accessible point-and-care testing (POCT) in resource-limited areas. The visual detection method also achieved a similar LOD of 2.12 U L−1 and a linear range of 5–60 U L−1. Our approach presents potential applications for other biomarker detections by using ALP-based ELISA methods. [ABSTRACT FROM AUTHOR]

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The development of water‐soluble redox‐active molecules with high potentials is one of the effective ways to enhance the energy density of aqueous organic flow batteries (AOFBs). Herein, a series of promising N‐substituted benzidine analogues as water‐soluble catholyte candidates with controllable redox potentials (0.78–1.01 V vs. standard hydrogen electrode (SHE)) were obtained by the molecular engineering of aqueous irreversible benzidines. Theoretical calculations reveal that the redox potentials of these benzidine derivatives in acidic solution are determined by their electronic structure and alkalinity. Among these benzidine derivatives, N,N,N′,N′‐tetraethylbenzidine(TEB) shows both high redox potential (0.82 V vs. SHE) and good solubility (1.1 M). Pairing with H4[Si(W3O10)4] anolyte, the cell displayed discharge capacity retention of 99.4 % per cycle and a high coulombic efficiency (CE) of ~100 % over 1200 cycles. The stable discharge capacity of 41.8 Ah L−1 was achieved at the 1.0 M TEB catholyte with a CE of 97.2 % and energy efficiency (EE) of 91.2 %, demonstrating that N‐substituted benzidines could be promising for AOFBs. [ABSTRACT FROM AUTHOR]

A novel triazine‐based covalent organic framework (TFPT‐Bz COF) has been constructed by the condensation of 2,4,6‐tris(5‐formyl‐2‐pyridinoxy)‐1,3,5‐triazine (TFPT) and benzidine (BZ) with deep eutectic solvent (DES) as the reaction medium. After the introduction of Pd ions through strong coordination to TFPT‐Bz COF matrix, the constructed TFPT‐Bz COF/Pd composite exhibited excellent catalytic activity for C−H arylation of azoles with aryl halides in 2‐methyltetrahydrofuran. The protocol allows the arylation of a variety of substituted azoles with diverse aryl halides in high to excellent yield. Moreover, the TFPT‐Bz COF/Pd catalyst can be recycled several times without significantly reducing its activity. [ABSTRACT FROM AUTHOR]

Carbazole‐ and fluorene‐substituted benzidine blocks have been functionalized with two different solubilizing pendant groups, in order to enhance the material's solubility in greener solvents. Preserving the optical and electrochemical properties, the aromatic function and substitution showed an important influence on the solvent affinity, achieving concentrations up to 150 mg/mL in o‐xylenes for the glycol‐containing materials and decent solubility in alcohols for the compounds functionalized with ionic chains. The latter solution proved to be ideal for the preparation of luminescence slot‐die coating film on top of flexible‐substrates up to 33 cm×2 cm. As a proof of concept, the materials have been implemented in different organic electronic devices, highlighting the low turn‐on voltage (4 V) presented by organic light‐emitting diodes (OLEDs), which is comparable with vacuum‐processed devices. A structure‐solubility relationship and a synthetic strategy are disentangled in this manuscript to tailor organic semiconductors and adapt their solubility towards the desired solvent and application. [ABSTRACT FROM AUTHOR]

Functionally graded materials (FGM) have attracted considerable attention in the field of composite materials and rekindled interest in research on composite materials due to their unique mechanical response achieved through material design and optimization. Compared to conventional composites, FGMs offer several advantages and exceptional properties, including improved deformation resistance, improved toughness, lightness properties, and excellent recoverability. This study focused on the production of functionally graded (FG) polymer materials by the additive manufacturing (AM) method. FG structures were produced by the fused deposition modeling (FDM) method using acrylonitrile benzidine styrene (ABS) and polylactic acid (PLA) materials, and tensile tests were performed according to ASTM D638. The effects of different layer thicknesses, volume ratios, and total thicknesses on mechanical behavior were investigated. The tensile standard of materials produced by additive manufacturing introduces geometric differences. Another motivation in this study is to reveal the differences between the results according to the ASTM standard. In addition, tensile tests were carried out by producing single-layer samples at certain volume ratios to create a numerical model with the finite element method to verify the experimental data. As a result of this study, it is presented that the FG structure produced with FDM improves mechanical behavior. [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]

Benzidine undergoes N-acetylation and following CYP1A2-catalyzed N-hydroxylation undergoes O-acetylation catalyzed by N-acetyltransferase 1 (NAT1). Benzidine exposure is associated with urinary bladder cancer but the effect of NAT1 genetic polymorphism on individual risk remains unclear. We used Chinese hamster ovary (CHO) cells transfected with human CYP1A2 and NAT1*4 allele (reference) or NAT1*14B (variant) to investigate the effects of dose and NAT1 polymorphism on benzidine metabolism and genotoxicity. Rates of benzidine N-acetylation in vitro were higher in CHO cells transfected with NAT1*4 compared to NAT1*14B. CHO cells transfected with NAT1*14B exhibited greater N-acetylation rates in situ than cells transfected with NAT1*4 at low doses of benzidine expected with environmental exposures but not at higher doses. NAT1*14B exhibited over tenfold lower apparent KM which resulted in higher intrinsic clearance for benzidine N-acetylation compared to CHO cells transfected with NAT1*4. Benzidine-induced hypoxanthine phosphoribosyl transferase (HPRT) mutations were higher in CHO cells transfected with NAT1*14B than with NAT1*4 (p < 0.001). Benzidine caused concentration-dependent increase in γ-H2AX signal (indicative of DNA double-strand breaks) in CHO cells transfected with NAT1*4 or NAT1*14B. CHO cells transfected with NAT1*14B exhibited significantly higher level of DNA damage than with NAT1*4 (p < 0.0001). Benzidine-induced ROS did not differ significantly (p > 0.05) between CHO cells transfected with NAT1*4 or NAT1*14B except at 50 μM. Levels of benzidine-induced DNA damage and reactive oxygen species (ROS) showed strong dose-dependent correlation. Our findings support human studies associating NAT1*14B with increased incidence or severity of urinary bladder cancer in workers exposed to benzidine. [ABSTRACT FROM AUTHOR]

A cycloaliphatic tetracarboxylic dianhydride, octahydro-2,3,6,7-anthracenetetracarboxylic dianhydride (OHADA) was synthesized to obtain novel colorless polyimides (PIs). Herein, approaches for decolorizing an OHADA prototype and simplifying the entire process are described, and a plausible steric structure for OHADA is proposed. The polyaddition of OHADA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) was unsuccessful; specifically, the reaction mixture remained inhomogeneous even after prolonged stirring. However, the modified one-pot process was applicable to the OHADA/TFMB system. The isolated PI powder form, as well as those for the other OHADA-based PIs, was highly soluble in numerous solvents and afforded a homogeneous and stable solution with a high solid content (20–30 wt%). Solution casting produced a colorless and ductile PI film with a very high glass transition temperature (Tg~300 °C). Furthermore, the OHADA/TFMB system exhibited remarkable thermal stability compared with those of the other related TFMB-derived semi-cycloaliphatic PIs. However, contrary to our expectations, this PI film did not exhibit a low linear coefficient of thermal expansion (CTE). This PI film also possessed excellent thermoplasticity, probably reflecting its peculiar steric structure. The use of an amide-containing diamine significantly enhanced the Tg (355 °C) and somewhat reduced the CTE (41.5 ppm K−1) while maintaining high optical transparency and excellent solubility. [ABSTRACT FROM AUTHOR]

Benzidine was coupled with ethyl cyanoacetate, and malononitrile, to give azo-hydrazo products which in turn were cyclized by using hydrazine and phenyl hydrazine to give 4,4'-([1,1'-biphenyl]-4,4'-diylbis(hydrazin-2-yl-1-ylidene))bis pyrazole derivatives 5–7. These compounds were identified by various spectral analysis. The examination of 0.1 M NaOH and 0.1 M HCl in DMF revealed that the λmax of the synthesized dyes are quite sensitive to pH variation and slightly affected by the coupler moieties. Utilizing the dispersion agent DYEWELL-002, polyester fabric (PE-F) was dyed in water. The color strength (K/S), its summation (K/Ssum), dye exhaustion (%E) and reflectance values were measured and discussed. The DFT method estimates the chemical descriptor parameters of the titled dyes, using B3LYP/6-31G(d,p) level to investigate the performance of dyes as well as to postulate a mechanism of dyeing process. [ABSTRACT FROM AUTHOR]

The reaction of the oxygen‐bridged frustrated Lewis pairs (FLPs) tBu2P−O−Si(C2F5)3 (1) and tBu2P−O−AlBis2 (2) with azobenzene, promoted by UV irradiation, led to a selective complexation of the cis‐isomer. The addition product of 2 is stable, while the adduct of 1 isomerizes in solution in an ortho‐benzidine‐like [3,3]‐rearrangement by cleavage of the N−N bond, saturation of the nitrogen atoms with hydrogen atoms and formation of a new bond between two phenyl ortho‐carbon atoms. Similar rearrangements take place with different para‐substituted azobenzenes (R=Me, OMe, Cl) and di(2‐naphthyl)diazene, while ortho‐methylated azo compounds do not form adducts with 1. All adducts were characterized by multinuclear NMR spectroscopy and elemental analyses and the mechanism of the rearrangement was explored by quantum‐chemical calculations. [ABSTRACT FROM AUTHOR]

The use of dyes is widespread across almost all industries. Consequently, these dyes are found in various sources of water and food that humans, animals, and plants consume directly or indirectly. Most of these dyes are comprised of complex aromatic structures that have proven harmful. Congo red dye, a complex aromatic azo dye based on benzidine, is most commonly used in these dyes; its metabolites (benzidine and analogs) can be toxic, but Congo red dye itself is not always harmful. The present review summarizes the toxicity of Congo red dye towards different living forms. Herein, the primary emphasis has been given to the mutagenic, teratogenic, and carcinogenic consequences of Congo red and its metabolites. The mechanisms of azo dyes' carcinogenicity have also been discussed. This review will undoubtedly be beneficial for researchers to understand the harmful effects of Congo red in genotoxic, teratogenic, mutagenic, and carcinogenic factors. [ABSTRACT FROM AUTHOR]

Risk level of benzidine residue to the environment and food safety urges surface enhanced Raman scattering (SERS) substrates to develop with high sensitivity and rapid enrichment. Herein, a hybrid of Au NPs decorated crystalline carbon nitride nano-walls (Au/CCN NWs) is fabricated on Al sheet and employed as a SERS substrate for the first time. An electro-enhanced adsorption strategy is employed to endow as-prepared Au/CCN NWs/Al chip with rapid assay capability. Crystalline phase transition and nano-wall morphology respectively bestows high charge transfer efficiency and favorable enrichment activity upon Au/CCN NWs/Al chip, and the hybrid substrate owns a considerable enhancement factor of 1.76 × 106 under static adsorption mode. Moreover, Au/CCN NWs/Al substrate can achieve the saturation enrichment of benzidine in 120 s with the help of electro-enhanced adsorption, and gains a significantly enhanced signal response compared to static adsorption. Likewise, the highly sensitive response (1 μg L−1), superior reproducibility (RSD = 9.11 %, n = 100) and reliable accuracy (recovery rate of 95.55 %–109.46 %) jointly demonstrate that Au/CCN NWs/Al substrate may be applicable for detecting benzidine residue in actual application. This work offers an integrated solution to both enhance charge transfer efficiency and enrichment activity based on collaborative crystalline phase transition and electro-enhanced adsorption, and may inspire the design of novel noble metal/semiconductor hybrid SERS substrates. [Display omitted] • Crystalline carbon nitride nano-walls (CCN NWs) was constructed via combined molten salt template and hydrothermal assembly. • Electro-enhanced adsorption endowed SERS chip with rapid analysis capability within 120s. • Crystallization transition and nano-wall morphology synergistically improved SERS activity. • Au/CCN NWs/Al chip could rapidly and sensitively detect benzidine in laundry wastewater. [ABSTRACT FROM AUTHOR]

Bi2WO6 with enhanced photocatlytic degradation performance was successfully synthesized by a facile O3 etching method. The photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, and ultraviolet-visible diffuse reflectance spectra. Characterization results revealed that the O3 treated Bi2WO6 photocatalyst has abundant of oxygen vacancies, which could effectively restrain recombination of photon-generated carriers, broaden light absorption region, serve as photocatalytic reaction center. Moreover, the photocatalytic activities of the prepared photocatalysts were evaluated by the photocatalytic degradation of benzidine under a xenon lamp irradiation. The photocatalytic activity of treated Bi2WO6 photocatalyst samples with O3 pose a greater improvement. Among that, the O3-Bi2WO6-3-4 modifying with ozone flux of 3.0 L/min for 4 h photocatalytic degradation of benzidine wastewater reached ~76.0% in 180 min under the irradiation of xenon lamp light (λ = 420 nm), which is about ~2.1 times higher than that of pure Bi2WO6. Moreover, the photocatalytic activities of the modified Bi2WO6 via O3 exhibit without significantly decrease after four cycles, indicating that the photocatalyst has a favourable application prospect. [ABSTRACT FROM AUTHOR]

The leakage of aromatic amines will pose a great threat to human health and the ecological environment. Therefore, there is an urgent need to achieve rapid and high-sensitivity detection of such substances. In this study, a simple surface-enhanced Raman scattering (SERS) method based on gold nanostars-modified silver nanorods (AuNSs@AgNRs) was established for the detection of benzidine and 4-aminobiphenyl (4-ABP). The enhancement factors of the substrate towards rhodamine 6G (R6G) and crystal violet (CV) were 4.67 × 108 and 1.11 × 108, respectively. Combined with density functional theory (DFT), the AuNSs@AgNR substrate achieved the rapid detection of benzidine and 4-ABP and obtained low detection limits (LODbenzidine = 7.09 × 10−9 M; LOD4-ABP = 1.20 × 10−9 M). Furthermore, the AuNSs@AgNR substrate can realize the high-sensitivity detection of benzidine and 4-ABP in the spiked river water samples within 3 min, which means that the AuNSs@AgNR-based SERS method can be used as a portable platform to realize the on-site rapid detection of environmental pollutants. [ABSTRACT FROM AUTHOR]

A series of bisazo reactive dyes have been synthesized via efficient methodology. In this paper we report the synthesis of a series of reactive dyes by coupling of tetrazotized 3, 3'-dichloro benzidine with various 2-amino 5(4'-nitro phenyl) 1,3,4-thiadiazole cyanurated coupling component viz, H-acid, J-acid, N-methyl J-acid, N-phenyl J-acid, sulpho tobias acid, tobias acid, peri acid, S-acid, K-acid, N-benzoyl H-acid, sulfo C-acid, N-phenyl peri acid, laurent acid and Chicago acid dyeing performance of these dyes was evaluated on cotton, wool and silk fabric. The purity of dyes was checked by thin layer chromatography (TLC). All synthesized dyes were characterized by FTIR and 1H NMR spectra, fastness properties and antimicrobial activity of these dyes were evaluated. [ABSTRACT FROM AUTHOR]

A series of four binuclear complexes [Cr2(CO)2L2] (1), [Mo2O4(L)2] (2), and [W2O4(L)2] (3) [Mo2O5(CO)L].H2O (4) were synthesized from the reaction of [M(CO)6] (M = Cr, Mo and W) with 6,6'-(([1,1'-biphenyl]-4,4' diylbis(azaneylylidene)) bis(methaneylylidene)) bis(2,4-dichlorophenol) H2L in THF. The structures of the ligand and its complexes were characterized using elemental studies, IR, mass, UV-vis and 1H NMR spectroscopy. Magnetic measurements showed diamagnetic properties for molybdenum and tungsten complexes and paramagnetic character for chromium complex. The thermal analyses for all metal complexes were also determined by the thermogravimetry technique. The thermodynamics parameters of complexes were calculated. Spectroscopic data revealed that H2L was coordinated as a tetradentate ligand through two imine nitrogen and two deprotonated phenolic oxygen atoms. The Schiff base ligand (H2L) and its complexes displayed fluorescence properties and can potentially serve as photoactive materials. The values of optical band gap energy (Eg) of the prepared complexes suggested that these compounds could be used as semiconductors.

In this work, a copolyimide (Co-PI) film with high transparency was prepared by the copolymerization of hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 2,2′-Bis(trifluoromethyl)benzidine (TFMB) and adamantane-1,3-diamine (DAA). The effects of DAA monomers on the optical, thermal, and mechanical properties of the co-PIs were discussed in detail. We found that the preparation of polyimide (PI) based on the combination of two dianhydrides and two diamines could obtain the co-PI film with excellent comprehensive performance due to the synergy between the -CF3 group, the aliphatic ring and the aromatic structure. Through the structure and composition optimization, the co-PI film with 1.30% DAA (Q3) has a T g of 374oC, T 5 higher than 530oC, T 430 of 82% and the tensile strength higher than 145 MPa. These results indicate that the Co-PI films can be successfully utilized in the development of novel heat-resistant plastic substrates for the optoelectronic engineering applications. Graphical Abstract [ABSTRACT FROM AUTHOR]

By blending semiconducting polymers with the cross-linkable matrix ethoxylated-(4)-bisphenol-a- dimethacrylate (SR540), an insoluble layer is acquired after UV-illumination. Following this approach, a trilayer polymer light-emitting diode (PLED) consisting of a blend of poly[N,N'-bis(4- butylphenyl)-N,N'-bis(phenyl)-benzidine] (poly-TPD) and SR540 as an electron-blocking layer, Super Yellow-Poly(p-phenylene vinylene) (SY-PPV) blended with SR540 as an emissive layer, and poly(9,9-di-n-octylfluorenyl-2,7-diyl) as a hole-blocking layer is fabricated from solution. The trilayer PLED shows a 23% increase in efficiency at low voltage as compared to a single layer SY- PPV PLED. However, at higher voltage, the advantage in current efficiency gradually decreases. A combined experimental and modelling study shows that the increased efficiency is not only due to the elimination of exciton quenching at the electrodes but also due to suppressed nonradiative trap-assisted recombination due to carrier confinement. At high voltages, holes can overcome the hole-blocking barrier, which explains the efficiency roll-off. [ABSTRACT FROM AUTHOR]

• A novel compound comprising an acyl-thiourea and amide functional in a single molecular architecture (VII) was successfully prepared in high yield. • SC-XRD, Molecular Docking (MD) study against jack bean urease enzyme, DFT and Hirshfeld analyses were carried out. • Electrostatic interactions, dispersion effects, and total energy components proposes that the primary factor driving crystal stabilization is the electrostatic energy contribution. • The MD studies reveal notable H-bonding, C H π interactions with the active site of urease signifying a potent inhibitor. The new compound 3-methyl- N -((4′-(3-methylbenzamido)-[1,1′-biphenyl]-4-yl)carbamothioyl) benzamide (VII) was prepared with a room temperature procedure. It was synthesized in situ in three steps with an excellent yield of 85 %. The chemical structure of VII was confirmed spectroscopically. Its molecular structure was determined by X-ray structural analysis and then used for a docking study with jack bean urease enzyme. The obtained coordinates were further used for comprehensive DFT and Hirshfeld analyses. Evaluation of the combination of electrostatic interactions, dispersion effects, and total energy components suggests that the primary factor driving crystal stabilization is the electrostatic energy contribution. The molecular docking studies of VII reveal that the combination of acyl-thiourea with an amide functional group (known for their importance in artificial drug design) facilitated a good docking score of -8.7 Kcal/mol. Notable hydrogen bonding and C H π interactions were found. The presence of very efficient hydrogen bonding interactions with the active site of jack bean urease emphasizes that the molecule might serve as a rather potent actual inhibitor for urease enzymes. [Display omitted] [ABSTRACT FROM AUTHOR]

Melamine formaldehyde fiber is widely used in various fields because of its excellent heat resistance and flame‐retardant properties. In this study, melamine and paraformaldehyde are used as the main raw materials, 2,2′‐bis(trifluoromethyl)benzidine (TFMB) is successfully introduced into the molecular chain. The TFMB modified spinning solutions (MF‐TFMB) are obtained by one‐step copolymerization, the TFMB‐modified melamine‐formaldehyde fibers (MFF‐TFMB) are prepared by dry spinning. The surface contact angle and surface energy are measured by a contact angle measuring instrument. The thermal stability and mechanical properties of the fibers are measured by a thermogravimetric analyzer and a single‐fiber strength tester. The results show that the introduction of the TFMB group reduces the surface free energy of the polymer and effectively improves the heat resistance and mechanical properties of the fiber. When the addition amount of TFMB is 3%, the MFF‐TFMB‐3% fiber has smooth surface and bubble‐free inside, the breaking strength is 2.25 cN/dtex and the elongation at break is 11.85%. The limiting oxygen index is 32.5%, and the mass loss rate is decreased from 63.88% to 51.36% at 400°C. The fiber has excellent thermal stability and flame‐retardant properties. [ABSTRACT FROM AUTHOR]

A new four series of 2,2′-([1,1′- phenyl or biphenyl]-4,4′-diylbis(azanediyl)) bis(N′-((E)-1-(4-alkoxyphenyl) ethylidene) acetohydrazide) [V-XI]a,b and 1,1′-(2,2′-([1,1′- phenyl or biphenyl]-4,4′-diyl bis(azanediyl)) bis- (acetyl)) bis(3-(4-ethoxyphenyl)-1H-pyrazole-4-carbalde hyde) [XII-XVIII]a,b have been synthesized by varying terminal lateral alkoxy chain length (n = 1–3, 5–8), central linkage group (phenyl or biphenyl) and induced pyrazole heterocyclic ring in the main chain. The last two series were synthesized by the cyclization of substituted acetophenone hydrazones with Vilsmeier–Haack reagent (DMF/POCl3) to produce 4-formylpyrazole derivatives. The chemical structures of the synthesized compounds were examined by elemental analysis, FTIR and 1H-NMR. The results are in agreement with the considered molecular structure. The liquid crystalline behaviors were studied by using hot-stage optical polarizing microscopy (OPM) and differential scanning calorimetry (DSC). The correlation between the molecular structures and mesomorphic behavior and transition temperatures was discussed. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles are important materials for synthesizing multifunctional nanozymes. A technique for preparing gold-platinum nanoparticles (NPs) on a silica core template (SiO2@Au@Pt) using seed-mediated growth is reported in this study. The SiO2@Au@Pt exhibits peroxidase-like nanozyme activity has several advantages over gold assembled silica core templates (SiO2@Au@Au), such as stability and catalytic performance. The maximum reaction velocity (Vmax) and the Michaelis–Menten constants (Km) were and 2.1 × 10−10 M−1∙s−1 and 417 µM, respectively. Factors affecting the peroxidase activity, including the quantity of NPs, solution pH, reaction time, and concentration of tetramethyl benzidine, are also investigated in this study. The optimization of SiO2@Au@Pt NPs for H2O2 detection obtained in 0.5 mM TMB; using 5 µg SiO2@Au@Pt, at pH 4.0 for 15 min incubation. H2O2 can be detected in the dynamic liner range of 1.0 to 100 mM with the detection limit of 1.0 mM. This study presents a novel method for controlling the properties of bimetallic NPs assembled on a silica template and increases the understanding of the activity and potential applications of highly efficient multifunctional NP-based nanozymes. [ABSTRACT FROM AUTHOR]

A huge amount of azo-dye wastewater is generated annually by the textile industry. At present, the improper disposal of azo dyes to water bodies causes considerable concern as it can disrupt the ecosystem and, because of their toxicity and carcinogenicity, constitutes a possible environmental and health problem. Because of its cheap, environmentally safe, and sustainable properties, chemical, physical, and biological methods have been used to treat azo-dye wastewater, and biological technology has been recognized as a promising technique. Azo dyes are one of the most pollutant synthetic dyes to the environment. Azo dyes can be transmitted through a food chain and may be associated with problems of toxicity, carcinogenicity, and mutagenesis. In this study, contaminated soil with two Azo dyes, Reactive Blue (RB) and Reactive Red (RR) was used in sorghum planting (Sorghum bicolor L. Moench) using different dye concentrations (0, 0.05, 0.1, 0.2 g Kg-1 soil). Increased concentration of the dye caused significant alterations in the morphological characteristics of sorghum, such as steam length, leaves number and leaf area. There was a slight decrease in the plant content of total chlorophyll and carotenoids, while a significant variation in CAT and SOD enzyme activities was observed by increased dye concentration in the soil for both dyes compared to the control group. In addition, a significant increase in proline content was found at higher dye concentrations.

The best‐recorded performance of perovskite‐based solar cells (PSCs) in regular mesoscopic architecture is generally associated with the use of the common 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (Spiro‐OMeTAD). However, the need for lithium‐based hygroscopic dopants hinders the chemical and environmental stability of the devices. This work presents a passivated stable PSC device based on a dopant‐free poly(3‐hexylthiophene) (P3HT) hole transport layer. By introducing a poly(N,N′‐bis‐4‐butylphenyl‐N,N′‐biphenyl)benzidine (polyTPD) interlayer at the perovskite/P3HT interface, the parameters of the low‐performance pristine P3HT‐based cells are improved. This introduction leads to optimizing the P3HT film morphology, interfacial defects, and charge extraction, along with a significant suppression of interfacial recombination and enhancement of the cell power conversion efficiency (PCE) from 7% to 10.65%. Further, an improvement is observed in open‐circuit voltage and the fill factor, increasing from 0.912 to 0.95 V and from 59.2% to 61.1%, respectively. Moreover, the noncapsulated passivated PSC devices exhibit higher operational stability. Examinations show that devices in a dark controlled environment (10–15% humidity) can retain 82% of their initial PCE for 450 h, and 73% of their initial PCE when thermally stressed at 60 °C temperature under ambient conditions (25–35% humidity) for 264 h. [ABSTRACT FROM AUTHOR]

In this study, practically useful colorless polyimides (PIs) with low coefficients of thermal expansion (CTEs) and other desirable properties were prepared from hydrogenated pyromellitic dianhydride (1-exo,2-exo,4-exo,5-exo-cyclohexanetetracarboxylic dianhydride, H-PMDA). A modified one-pot polymerization method afforded a high-molecular-weight PI with sufficient film-forming ability from 2,2′-bis(trifluoromethyl)benzidine (TFMB) with a rod-like structure and H-PMDA. However, the PI film cast from its homogeneous solution did not have low CTEs, similar to the analogous system using meta-tolidine. To solve this problem, a series of amide- and amide-imide-containing diamines were designed and synthesized. The modified one-pot polymerization of H-PMDA and the diamines in γ-butyrolactone produced homogeneous, viscous, and stable solutions of high-molecular-weight PIs with high solid contents. The cast films of certain systems examined in this study simultaneously achieved low CTEs, high optical transparency, considerably high glass transition temperatures (Tgs), and sufficient ductility. A possible mechanism for the generation of low CTEs, which is closely related to the spontaneous in-plane orientation behavior during solution casting, was proposed. Certain H-PMDA-based PIs developed in this study are promising colorless heat-resistant plastic substrates for use in image display devices and other optical applications. [ABSTRACT FROM AUTHOR]

The carcinogenic effects of benzidine (BZ) on bladder cancer are well documented, but its potential for promoting upper urinary tract urothelial carcinoma (UTUC) remains unclear. The ability of emodin, a natural pharmaceutical compound, to prevent BZ‑associated UTUC has not been previously explored. To the best of our knowledge, the present study is the first to reveal that BZ significantly enhanced the survival and migration of UTUC cell lines in vitro . Furthermore, in vivo experiments demonstrated that BZ promoted an increase in the size of subcutaneous tumors in nude mice. Further investigation revealed that BZ upregulated the expression of protein kinase A (PKA) and cyclooxygenase 2 (COX2), along with downstream matrix metalloproteinase 9 (MMP9) and vascular endothelial growth factor (VEGF), in UTUC cells. Moreover, BZ increased the levels of cyclic adenosine monophosphate (cAMP) and prostaglandin E2 (PGE2) in cell lysates. By contrast, emodin reduced the PKA and COX2 expression levels compared with the BZ‑treated group. Similarly, the in vivo experiments demonstrated that emodin significantly inhibited tumor growth in BZ‑pretreated nude mice, accompanied by reductions in the cAMP, PGE2, MMP9 and VEGF levels. These findings elucidated the role of BZ in promoting UTUC progression. Additionally, emodin has emerged as a novel inhibitor of BZ‑induced UTUC development through PKA/COX2 inhibition, suggesting its potential as a natural therapeutic agent against BZ‑associated UTUC.

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Enhanced kinetic stability of vapor-deposited glasses has been established for a variety of glass organic formers. Several recent reports indicate that vapor-deposited glasses can be orientationally anisotropic. In this work, we present results of extensive molecular simulations that mimic a number of features of the experimental vapor deposition process. The simulations are performed on a generic coarse-grained model and an all-atom representation of N,N'-bis(3-methylphenyl)-N,N'- diphenylbenzidine (TPD), a small organic molecule whose vapor-deposited glasses exhibit considerable orientational anisotropy. The coarse-grained model adopted here is found to reproduce several key aspects reported in experiments. In particular, the molecular orientation of vapor-deposited glasses is observed to depend on substrate temperature during deposition. For a fixed deposition rate, the molecular orientation in the glasses changes from isotropic, at the glass transition temperature, Tg, to slightly normal to the substrate at temperatures just below Tg. Well below Tg, molecular orientation becomes predominantly parallel to the substrate. The all-atom model is used to confirm some of the equilibrium structural features of TPD interfaces that arise above the glass transition temperature. We discuss a mechanism based on distinct orientations observed at equilibrium near the surface of the film, which get trapped within the film during the non-equilibrium process of vapor deposition. [ABSTRACT FROM AUTHOR]

Vapor-deposited organic glasses can show enhanced kinetic stability relative to liquid-cooled glasses. When such stable glasses of model glassformers are annealed above the glass transition temperature Tg, they lose their thermal stability and transform into the supercooled liquid via constant velocity propagating fronts. In this work, we show that vapor-deposited glasses of an organic semiconductor, N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), also transform via propagating fronts. Using spectroscopic ellipsometry and a new high-throughput annealing protocol, we measure transformation front velocities for TPD glasses prepared with substrate temperatures (TSubstrate) from 0.63 to 0.96 Tg, at many different annealing temperatures. We observe that the front velocity varies by over an order of magnitude with TSubstrate, while the activation energy remains constant. Using dielectric spectroscopy, we measure the structural relaxation time of supercooled TPD. We find that the mobility of the liquid and the structure of the glass are independent factors in controlling the thermal stability of TPD films. In comparison to model glassformers, the transformation fronts of TPD have similar velocities and a similar dependence on TSubstrate, suggesting universal behavior. These results may aid in designing active layers in organic electronic devices with improved thermal stability. [ABSTRACT FROM AUTHOR]

• A 99.9 % probability of carcinogenicity was estimated for 8 benzidine-related-dyes. • A 98.9 % probability of carcinogenicity was forecast for other 251 BZ-related-colorants. • Bayesian forecasting exhibited the potential to enhance predictive toxicology. • Bayesian forecasting showed the potential to increase the impact of nonclinical toxicology. The preclinical identification of health hazards relies on the performance (the historic concordance to the respective gold standard) of regulatorily recommended bioassays. However, any testing with less than 100% sensitivity (or 100% specificity) can deliver false results (outcomes discordant to the respective gold standard). Conversely, the predictive values approach (a.k.a. Bayesian forecasting) weighs (1) the performance of the predictive bioassay (battery, or framework) with (2) the prevalence of -positivity to the respective gold standard- in the most representative category to which the test substance can be allocated. Thus, the predictive values approach (PVA) provides the numeric probability for the toxicity to humans of chemicals that, circumstantially, are evaluable only through nonclinical data. Consequently, the PVA improves the predictivity of nonclinical toxicology, and increases the impact of hazard identifications entirely based on preclinical data. This article aimed to introduce the PVA through a worked example. Due to their toxicological homogeneity and public health relevance, the superfamily of colorants synthesized from benzidine (BZ) or some mutagenic congeners was selected (colorings hereafter mentioned as BZ-related-colorants). Through the PVA, the numeric probability of innate carcinogenicity to humans of 259 BZ-related-colorants was either estimated from rodent carcinogenesis bioassays (RCBs) or predicted from methods alternative to the RCB. A discussion was provided on (1) some limitations and implications of the PVA, and (2) the probable significance of the predictive values figured here for 259 BZ-related-colorings. [ABSTRACT FROM AUTHOR]

Detailed quantum‐chemical investigation of competing routes of substituted diphenylamines oxidation was performed. Chemoselectivity as well regioselectivity of the phenazine and benzidine skeletons formation were elucidated and confirmed by experimental testing on the model diphenylamines containing CF3, But, α‐methylcyclopropyl substituents. It was shown that the oxidation of 4,4'‐disubstituted donor‐acceptor amines leads to dihydrophenazines chemo‐ and regioselectively. For 2,4'‐disubstituted donor‐acceptor diphenylamines, the reaction rates for the competing reactions differ ca. 25 times in favor of the benzidine formation. Oxidation of 2,4'‐disubstituted diphenylamines with electron‐rich phenyl rings is much less selective; both benzidines and dihydrophenazines are formed. It was shown that the activation energy for the benzidines formation is strongly dependent on the electronic properties of the substituents in the starting amine, in contrast to the competing formation of the phenazines, which is more sensitive to sterical bulkiness of substituents. [ABSTRACT FROM AUTHOR]