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The present work was focused on the corrosion properties and contact resistance behavior of poly(orthophenlyenediamine) (PoPD) coating on 316L SS bipolar plates. To reduce the corrosion rate and increase the interfacial conductivity of 316L SS bipolar plates, PoPD coating was deposited using an electropolymerization technique by the various monomer concentration of orthophenlyenediamine (oPD) on its surface. The presence of 1, 2, 4, 5- tetra substituted benzene nuclei of phenazine units in the polymer coating was confirmed by infrared spectroscopy. X-ray photoelectron spectroscopy analysis has confirmed the (%) of chemical composition in PoPD coating. The results of scanning electron microscopy analysis revealed that the uniform and compact coating with complete cover on 316L SS. The corrosion properties were investigated in 0.5 M H 2 SO 4 and 2 ppm HF solution at 80 °C. The polarization test results showed that the PoPD coating reduced the corrosion current density both in the PEMFC anode and cathode environments. The charge transfer resistance values were in the order of 316L SS ˂ 0.02 M PoPD ˂ 0.06 M PoPD ˂ 0.04 M PoPD. A very low interfacial contact resistance and good adhesion strength was observed for 0.04 M PoPD coating. The higher contact angle of 0.04 M PoPD coating explained the hydrophobic property and more benefit of water management in the PEMFC environment. The results of the analysis of total metal ion releases clearly explained that the low level of metal ions released for 0.04 M PoPD coating. The overall studies revealed the PoPD coating with optimized 0.04 M oPD concentration showed best performance and provided more anodic protection to 316L SS bipolar plates. • Anticorrosive performance of PoPD coated 316L SS was significantly increased. • PoPD coating withstands the physical barrier during long term immersion. • Lower contact resistance of PoPD coated 316L SS was greatly achieved. [ABSTRACT FROM AUTHOR]

A single‐step process has been demonstrated for the synthesis of core‐shell hybrid of poly(o‐phenylenediamine) functionalized with uniformly distributed silver nanoparticles. The silver nanoparticles as core were formed by the thermal reduction of the amine complexes of silver mono‐positive cation. The interfacial functionalization of silver nanoparticles by the =NH was characterized using Fourier transform infrared spectroscopy and ultraviolet‐visible spectroscopy. The uniform size of particles in core‐shell hybrid and the amount of metal nanoparticle ingrained in polymer matrix were confirmed from the characterizations, viz. dynamic light scattering, inductively coupled plasma‐optical emission spectrometry and field‐emission scanning electron microscopy. The hybrid with ∼12 % silver loading was found to have the highest DC‐conductivity of 10−4 S cm−1 range, even without the usage of any other dopant. The induced doping of silver nanoparticles through the functional groups of the polymer was considered to explain the conducting properties of the prepared core‐shell hybrid. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the relationship between the professional environment and hypersensitivity reactions to various contact allergens, the features of the clinical course, and the type of allergic contact dermatitis (ACD) in 35 hairdressers. The analysis was based on data on length of professional experience, localization of rashes, clinical diagnosis and allergens, and the cause of positive reactions in patch testing. Skin changes most often affect the hands, palms, face, and neck. The frequency of ACD diagnosed was 46%, followed by dyshidrotic eczema (DE) - 34%. The highest percentage of contact dermatitis (68%) was seen in the upper extremities, followed by dermatitis of the face and hands (26%). Of the patients investigated, 34% had a history of illness up to 3 years. A negative correlation was found between professional experience and "hand eczema" (p=0.005). Patch tests showed that the most frequent positive reactions were to Nickel (II) sulfate hexahydrate (Nickel, 15 times) and p-Phenylenediamine (PPD, 14 times). These contact allergens are directly correlated with hand eczema. We compared the results with those published in the literature. [ABSTRACT FROM AUTHOR]

A significant group of compounds arise from substituted s-triazine derivatives that have tripodal heterocyclic compound. Compounds classified as heterocyclic possible created the largest and most diverse family of organic compounds. In this study, we reported that a new template has been syntheses from a cyanuric chloride and its diamine derivative. The desired triamine a tripodal 2, 4, 6-tris (p-aminoaanilino)-1, 3, 5-triazine (C21H21N9), called to be TRIPOD, has been obtained from cyanuric chloride with 3 eq of p-phenylenediamine reaction in acetone. After synthesis, TRIPOD sample which was polycrystal form was irradiated by cobalt-gamma source. The electron paramagnetic resonance spectra of TRIPOD were recorded using X-band EPR spectrometer at room temperature in three axes (x, y, z) which are perpendicular at 10° intervals. The EPR spectrum was simulated using computer program and by using the spectrum. The radical structure was determined in the sample. [ABSTRACT FROM AUTHOR]

In this paper, the tuning of the thermopower with single‐molecule junctions of fullerene (C60), 4,4′‐bipyridine (BPY), and p‐phenylenediamine (PPD) using scanning tunneling microscopy (STM)‐based break junction technique is demonstrated. Single‐molecule junctions are prepared in a nanogap between a Au‐STM tip and a Au(111) electrode. Upon applying a temperature difference across the junction, a thermoelectric voltage is generated across it. By mechanically controlling the tip–electrode separation distance, the thermoelectric voltage of the junction is tuned. The absolute value of the thermopower decreases with decreasing tip–electrode separation distance for BPY and PPD, while it increases for C60. Atomistic simulations of the junction illustrate how this arises from shifts in the conduction orbital energies induced by the mechanical compression of the junctions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ratiometric detection of o-phenylenediamine (OPD) was successfully realized by combinatorial principles of in-situ fluorogenic reaction and in-situ generation of metal nanoparticles. • OPD can react with AA to produce blue fluorescent quinoxaline (OXD) in the presence of Cu2+. • The unreacted Cu2+ can react with dithiothreitol (DTT) to yield red-emitting DTT-copper nanoparticles (DTT-CuNPs). Herein, a novel ratiometric strategy for ultra-sensitive detection of o-phenylenediamine (OPD) was proposed based on combinatorial reactions of in-situ fluorogenic reaction and in-situ formation of red fluorescent dithiothreitol-copper nanoparticles (DTT-CuNPs). Here, Cu2+ is used both as an oxidant and as a precursor. Dehydroascorbic acid (DHAA) is formed via redox reaction of AA and Cu2+. Then, DHAA reacts with OPD to yield blue fluorescent quinoxaline (OXD) with emission peak at 434 nm through in-situ fluorogenic reaction. Red emitting DTT-CuNPs with emission peak at 666 nm is instantly generated due to the coordination reaction between DTT and the residual Cu2+ which is not consumed by AA. The fluorescence intensity (FI) of OXD at 434 nm is closely relied on the concentration of OPD, which can be used as a response signal for OPD detection. Meanwhile, FI of DTT-CuNPs at 666 nm has no significant change, which can be used as a reference signal for OPD detection. Thus, the ratio (F 434 /F 666) of the Cu2+/AA/DTT sensing system is successfully employed to quantify OPD, exhibiting a wide linear range from 0.2 µM to 60 µM, with LOD of 0.09 µM. [ABSTRACT FROM AUTHOR]

• Curing-agent reactivity controlled graphene dispersion in epoxy composites. • The application of a magnetic field induced effective graphene orientation. • Affinity between biphenyl epoxy and graphene gave high-thermal-conductivity materials. Epoxy/multilayer graphene (ML-graphene) composites were prepared using different curing agents to control the graphene dispersion by changing the curing reactivity. With increasing initial reactivity, the aggregation size of the ML-graphene decreased and their thermal conductivity increased. In particular, the thermal conductivity of the composite prepared with p -phenylenediamine showed a maximum value of 1.46 W/(m·K) at 25 wt% ML-graphene loading because of the highest initial curing reactivity. The application of a magnetic field led to graphene alignment along the applied field, resulting in two times higher thermal conductivity than that of the corresponding system without magnetic field. The relationship between the interfacial affinity for epoxy/graphene and thermal conductivity was also investigated. As a result, resulting in a biphenyl epoxy composite showed higher thermal conductivity (6.17 W/(m·K)) than that of the bisphenol-A epoxy composite. This is derived that the π-conjugated and planar structure of biphenyl epoxy can easily interact with the surface of graphene. [ABSTRACT FROM AUTHOR]

A new photoelectrochemical sensor has been developed using a metal–organic framework-derived oxide and covalent organic framework heterostructure material, which demonstrated highly sensitive and selective detection of dopamine in real samples. [Display omitted] • A novel ZnO/TpPa-1 heterostructure composite was successfully synthesized by an in situ synthesis strategy. • The synergies between ZnO and TpPa-1 effectively improved the photoelectric activity and the addition of more reactive sites. • The resultant ZnO/TpPa-1 heterojunction exhibits the enhancement of photoelectrochemical response toward dopamine detection. • Wide linear range, low detection limit and excellent stability and selectivity were obtained. This study used ZIF-8 metal–organic framework as a precursor to create a N-doped ZnO. Subsequently, covalent organic framework named TpPa-1 (Tp, 1,3,5-triformylphloroglucinol; Pa-1, p-phenylenediamine) with a ZnO heterostructure composite (ZnO/TpPa-1) was created through an in-situ synthesis approach. Due to its superior band structure and outstanding photocatalytic performance, the ZnO/TpPa-1 composite is a good candidate for the development of a new type of photoelectrochemical (PEC) sensor for the detection of dopamine (DA). According to experimental data, ZnO/TpPa-1/ITO had a photocurrent that was roughly 1.5 times higher than TpPa-1/ITO and 4.5 times higher than ZnO/ITO. The primary reason for this improvement was the synergistic effects brought about by effective light usage and charge transfer at the interface between the TpPa-1 π-conjugated backbone and ZnO porous structure. The determination ranges for DA demonstrated two linear ranges, 0.005–0.25 μmol/L and 0.25–1.00 μmol/L, and the detection limit was as low as 1.3 nmol/L. Moreover, the PEC sensor exhibited good stability, selectivity, repeatability, and suitability for real-world samples. This work provides important new understandings for covalent organic framework (COF)-based heterostructure design, which can be used to improve PEC sensor performance. [ABSTRACT FROM AUTHOR]

The misuse of chloramphenicol (CAP) has jeopardized environmental safety. It is critical to create an effective and sensitive CAP detection technique. In this paper, a composite of chitosan (CS)-derived carbon material modified hollow spherical hydroxylated poly(3,4-propylenedioxythiophene) (PProDOT-2CH 2 OH) was designed, which innovatively used o -phenylenediamine and p-aminobenzoic acid as bi-functional monomers to prepare molecular imprinting polymer (MIP) sensors for highly sensitive analysis and determination of CAP. It was found that the hollow spherical structure of PProDOT-2CH 2 OH significantly enhanced the rapid electron migration. When combined with the CS-derived carbon material, which has multi-functional sites, it improved the electrical activity and stability of the sensor. It also provided more active centers for the MIP layer to specifically recognize CAP. Therefore, this MIP sensor had a wide linear response (0.0001 ∼ 125 μM), a low limit of detection (LOD, 6.6 pM), excellent selectivity and stability. In addition, studies showed that the sensor has potential practical value. Chloramphenicol (CAP) is one of the most widely used antibiotics with the highest dosage due to its low price and broad-spectrum antimicrobial properties. Due to its incomplete metabolism in living organisms and its difficulty in degrading in the environment, contamination caused by it can pose a threat to public health. In this study, a novel molecularly imprinted sensor (MIP/PC2C1/GCE) was designed to provide a new idea for rapid and precise removal of CAP by adsorption. The detection of CAP in pharmaceutical, water quality, and food fields was realized. [Display omitted] • Hollow spherical PProDOT-2CH 2 OH significantly improves sensitivity and selectivity. • Dual utilization of chitosan to synthesize N-doped carbon materials. • Bifunctional monomers with diverse active sites for efficient detection of chloramphenicol. • This MIP sensor has good sensitivity, stability, and selectivity for chloramphenicol. [ABSTRACT FROM AUTHOR]

Pesticide residues in agricultural products pose a significant threat to human health. Herein, a sensitive fluorescence method employing upconversion nanoparticles was developed for detecting organophosphorus pesticides (OPs) based on the principle of enzyme inhibition and copper-triggered o -phenylenediamine (OPD) oxidation. Copper ions (Cu2+) oxidized the colorless OPD to a yellow 2,3-diaminophenazine (oxOPD). The yellow solution oxOPD quenched the fluorescence of upconversion nanoparticles due to the fluorescence resonance energy transfer. The high affinity of Cu2+ for thiocholine reduced the level of oxOPD, resulting in almost no fluorescence quenching. The addition of dimethoate led to the inhibition of acetylcholinesterase activity and thus prevented the formation of thiocholine. Subsequently, Cu2+ oxidized OPD to form oxOPD, which attenuated the fluorescence signal of the system. The detection system has a good linear range of 0.01 ng/mL to 50 ng/mL with a detection limit of 0.008 ng/mL, providing promising applications for rapid detection of dimethoate. • An AChE-modulated UCNPs-oxOPD sensor for the detection of dimethoate was first proposed. • More than 80% quenching efficiency. • The proposed nanosensor has a low detection limit of 0.008 ng/mL. • A broader detection linear range with nearly 4 orders of magnitude. [ABSTRACT FROM AUTHOR]

• A new and efficient LDH@PpPDA@CuI nanocatalyst was designed and created. • Several derivatives of dihydropyranochromenes were synthesized using the catalyst. • The new catalyst showed excellent reactivity under soft and green conditions. • Products were synthesized with high efficiency and short time. • The catalyst was recycled for four cycles without loss of efficiency. A new catalyst, poly(p -phenylenediamine) functionalized with copper nanoparticles stabilized on layered double hydroxide (LDH@poly(p -phenylenediamine)@CuI), was prepared. The structure of the new catalyst was identified and confirmed using different analyzes such as FESEM, EDX, XRD, TGA and elemental mapping. The efficiency of the mentioned catalyst was confirmed in the three-component one-pot synthesis of various derivatives of dihydropyrano[3,2-c]chromene in aqueous ethanol solvent. The structure of the synthesized products was confirmed using infrared spectrometry (FT-IR), nuclear magnetic resonance (1H NMR and 13C NMR) and Mass techniques. High yield of products, short reaction time, easy purification, reuse of catalyst, and the use of a soft reaction method can be considered as the main advantages of this method. Additionally, this catalyst was recycled four times without a significant loss of catalytic power. [Display omitted] [ABSTRACT FROM AUTHOR]

The photoluminescence properties of novel bis- N -carboxamide ligand and its Cu(II) complex were studied. Molecular docking was utilized to describe the interactions between the ligand and the EGFR tyrosine kinase enzyme. Moreover, all compounds were investigated cytotoxic activity on HTB-54 and BEAS-2B lung cell lines. [Display omitted] A new bis- N -carboxamide ligand (H 2 L) was synthesized from reaction of dibenzoylaceticacid- N -carboxyethylamide with p -phenylenediamine. The binuclear metal complex of the new ligand was prepared from Cu(II) salt. The structures of the synthesized compounds were confirmed using elemental analysis, UV–Vis, IR, 1H NMR, 13C NMR, TGA, and LC-MS/MS spectroscopy. The stoichiometric ratio of H 2 L-Cu2+ was found to be 2:2 (L:M) by the use of Job's graph. The photoluminescence properties of the ligand and Cu(II) complex was investigated in DMF solution. The ligand is highly emissive upon excitation at 291 nm. The coordination of the ligand to the Cu(II) ion caused quenching of the emission band along with the red shift. The Cu complex did not affect healthy cells at the dose administered, but showed toxic effects at concentrations close to the ligand, suggesting that the Cu complex may be a potential anticancer drug. In addition, molecular docking results indicate that amino acids Asp776 and Met742 generated π-Anionic and π-Sulfur interactions with the phenolic portions of the molecule. There was a π-sigma connection between the ligand and the amino acid Leu820, and a π-alkyl interaction between the ligand and the amino acids Val702 and Ala719. [ABSTRACT FROM AUTHOR]

The strong excitonic effect is widely prevalent in covalent organic frameworks (COFs)-based catalysts, while the high exciton binding energies (E b) of COFs seriously limit their photocatalytic performance. Herein, theoretical calculations are conducted to evaluate the E b values of potential COFs derived from benzo[1,2-b:3,4-b'-b'']trithiophene-2,5,8-tricarbaldehyde (BTT) and 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Bp) as aldehyde monomers. Diverse aromatic amine linkers including dipyridine diamine (BPy), biphenyl diamine (BPh), and p -phenylenediamine (MPh) with different molecular lengths and N-sites are used as linker models to regulate the excitonic effect. The obtained BTT-BPy-COF with a long BPy linker and the lowest calculated E b value possesses the best photocatalytic performance for benzylamine coupling, with conversion and selectivity up to 99% accompanied by a high oxidation rate, outperforming most of the reported works. Further mechanistic investigation reveals that the bipyridine-N sites in BTT-BPy-COF exhibit strong electron transfer as well as enhanced O 2 adsorption and activation that is beneficial to photocatalytic benzylamine coupling. [Display omitted] • Different aromatic amine linkers are used to regulate the excitonic effect of COFs. • Photocatalytic performance of the obtained COFs closely relates to their E b values. • BTT-BPy-COF with low E b value and pyridine-N linker shows best catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • New approach to beer analysis using the precepts of green analytical chemistry. • Use of microdistillation to determine total vicinal diketones (VDK) • Determination of VDK in different types and styles of industrial and craft beers. Vicinal diketones (VDK) strongly affect the quality of beers, as they are responsible for off-flavors and deterioration markers, which are recognized as safe for humans when ingested but are toxic when inhaled. Thus, their determination is required in both the production process and the final beverage. A novel approach for determining the total VDK content in beers using microdistillation as a simple approach for sample pretreatment is proposed. The lab-made microdistillation apparatus consists of a capped Falcon® tube with the sample at the bottom and the acceptor solution inside a suspended Eppendorf® tube. The sample is heated (90 °C, 20 min) to volatilize the analytes, which are collected from the headspace by an acceptor-derivatizing solution (o-phenylenediamine in acid medium), and the product is determined by ultraviolet spectrophotometry. Under conditions optimized by experimental design, a linear response was achieved from 0.05 to 1.00 mg L-1 diacetyl, with a coefficient of variation (n = 11) and limit of detection (95 % confidence level) estimated at 4.3 % and 0.01 mg L-1 diacetyl, respectively. The procedure requires as low as 40 μg of o-phenylenediamine, 1.7 μL of 37 % (v/v) hydrochloric acid, and 5000 μL of sample, generating only 5400 μL of waste per determination. It allows for the simultaneous analysis of 10 samples, a capability not previously reported in the literature. Results obtained for Ale and Lager beers using the proposed and reference procedures agreed at a 95 % confidence level. Therefore, the current proposal is a reliable and environmentally friendly alternative for the rapid determination of VDKs in beer, contributing to improved quality control in both the process and final products of the brewing industry. [ABSTRACT FROM AUTHOR]

The current designs of ratiometric fluorescence sensing strategies primarily make use of the opposite responses of analyte target to two fluorescence probes, often overlooking their potential capabilities for signal amplification. Herein, a novel ratiometric fluorescence sensor was constructed for sensitive detection of glutathione (GSH) by combining CeO 2 /CuO nanozymes with poly[2,7-(9,9′-dioctylfluorene)-alt-4,7-bis(thiophen-2-yl) benzo-2,1,3-thiadiazole] (PFO-DBT)-based polymer dots (Pdots). The CeO 2 /CuO nanozymes with high oxidase-like activity were prepared via a deep eutectic solvent (DES) strategy and used for catalytic oxidization of o -phenylenediamine to produce fluorescent 2,3-diaminophenazine (DAP), which concurrently quenched the fluorescence of Pdots through photoinduced electron transfer (PET), thus amplifying the ratiometric signal. Upon addition of target GSH, the oxidase-like activity of CeO 2 /CuO were inhibited due to its blocking to metal active sites and scavenging superoxide anion (O 2 ‧−), which responsively decreased the amount of produced DAP, and thus increased the fluorescence of Pdots. The designed CeO 2 /CuO-OPD-Pdots system showed a linear ratiometric response to GSH concentration within the range of 2 μM to 20 μM, with a limit of detection (LOD) determined as 1.24 μM. The proposed method could be used for selective detection of GSH in serum samples, and thus possessed potential application in clinic analysis. • CeO 2 /CuO nanozymes are synthesized via a deep eutectic solvent strategy with L -proline as a ligand. • The high catalysis activity of CeO 2 /CuO is integrated with Pdots for ratiometric fluorescence detection. • The ratiometric fluorescence mechanism is based on the interaction of formed DAP and Pdots. • The catalytic oxidation of OPD by CeO 2 /CuO can be inhibited by GSH and thus leads to its sensitive detection. [ABSTRACT FROM AUTHOR]

Epilepsy has been treated for centuries with herbal remedies, including leaves of the African shrub Mallotus oppositifolius, yet the underlying molecular mechanisms have remained unclear. Voltage-gated potassium channel isoforms KCNQ2-5, predominantly KCNQ2/3 heteromers, underlie the neuronal M-current, which suppresses neuronal excitability, protecting against seizures. Here, in silico docking, mutagenesis and cellular electrophysiology reveal that two components of M. oppositifolius leaf extract, mallotoxin (MTX) and isovaleric acid (IVA), act synergistically to open neuronal KCNQs, including KCNQ2/3 channels. Correspondingly, MTX and IVA combine to suppress pentylene tetrazole-induced tonic seizures in mice, whereas individually they are ineffective. Co-administering MTX and IVA with the modern, synthetic anticonvulsant retigabine creates a further synergy that voltage independently locks KCNQ2/3 open. Leveraging this synergy, which harnesses ancient and modern medicines to exploit differential KCNQ isoform preferences, presents an approach to developing safe yet effective anticonvulsants.

Bimetallic catalysts have been investigated as the most efficient materials to accelerate the chemical transformations at the anode in Direct Ethanol Fuel Cells. A comparative study is presented here to synthesize Ni–Cu bimetallic nanoparticles for the ethanol oxidation reaction on three conducting polymers: poly-ortho-phenylenediamine, poly-meta-phenylenediamine, and poly-para-phenylenediamine. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Electrochemical Impedance Spectroscopy (EIS) were used to analyze the modified electrodes. A series of bimetallic Ni–Cu nanoparticles with tunable ratios were successfully synthesized by simply changing the concentrations of Nickel and Copper. It has been confirmed that the best Ni/Cu molar ratio was 25% in the aspect of catalytic performance. The electrocatalyst exhibited an excellent catalytic activity with an anodic current of 70.5 mA cm−2 at the lowest onset potential of 0.39 V with impressive stability. Ni 4 Cu 1 /PpPD should be considered as a good alternative to noble metal anode catalyst. [Display omitted] • Ni 4 Cu 1 /PpPD a novel cost-effective and eco-friendly electrocatalyst was designed. • Ni 4 Cu 1 bimetallic nanoparticles were electrochemically synthesized on PpPD. • The catalyst exhibits high-electrocatalytic performance towards ethanol oxidation. • An impressive stability and anodic current of 70.5 mA cm−2 at low onset potential 0.39 V was achieved. [ABSTRACT FROM AUTHOR]

The absorption spectra of polymers derived from ortho, meta and para phenylenediamines (o-PDA, m-PDA and p-PDA) have been simulated combining periodic density functional theory (DFT) calculations with time-dependent DFT simulations. These latter have been carried out on finite clusters embedded in a set of point charges devised to exactly reproduce the electrostatic potential of the periodic chains. The results are compared with those obtained for solvated o-PDA, m-PDA and p-PDA oligomers of increasing sizes extracted from the periodic structures. The electronic transitions involved have been investigated by a qualitative analysis based on isodensity maps completed by a quantitative analysis based on the density-based index (DCT). For poly-(o)- and poly-(p)- phenylenediamines the agreement with the experimental data is achieved already by modeling solvated dimers whereas the inclusion of long-range electrostatic effects is mandatory for poly-(m)-phenylenediamine highlighting the importance of an accurate treatment of the electrostatic environment when a finite cluster approach is considered. [ABSTRACT FROM AUTHOR]

In this work, we developed a simple route to synthesize green fluorescence carbon nanoparticles (FCPs) at room temperature with dopamine and p-phenylenediamine as raw materials. The FCPs exhibited a salient fluorescence emission peak at 525 nm and well stability in the intricate surroundings. Only Cu2+ ions could significantly inhibited the fluorescence of FCPs and could be successfully detected in the concentration scope of 0–200 µmol·L−1 based on the fluorescence quenching of FCPs. The Cu2+ ion-quenched fluorescence of FCPs system can be further recovered by the addition of dipicolinic acid (DPA) and could be utilized for DPA detection within the dynamic scope of 10–150 µmol·L−1. [ABSTRACT FROM AUTHOR]

Three‐component acid‐catalyzed cyclocondensation of isomeric phenylenediamines with aldehydes and cyclopentadiene (CPD) was studied. In the M06‐2X//B3LYP/6–311 + G(d,p) + IEFPCM(SMD) approximation, a quantum chemical model was developed, energies of the PES stationary points were determined, and activation barriers were found for the CPD addition to the protonated Schiff base (rate‐limiting step) and for electrophilic carbocation cyclization to give endo, endo (syn)‐ or endo, exo (anti)‐cyclopentene‐annulated octahydropyridoquinoline‐ and octahydrophenanthroline‐based cycloadducts. The calculation results are in full agreement with the experimental data, which indicate that the cyclocondensation involving p‐phenylenediamine affords both types of cycloadducts, whereas the reactions of o‐ or m‐phenylenediamine lead to regioselective formation of octahydro‐1,10‐phenanthroline‐ or octahydropyridoquinoline‐based product, respectively. According to homo‐ and heteronuclear correlation 1Н and 13С NMR experiments and X‐ray diffraction data, the newly formed asymmetric centers of the cyclopentene‐annulated tetrahydroquinoline moiety in the polycyclic products have exo (endo)‐cis‐orientation. [ABSTRACT FROM AUTHOR]

Nasopharyngeal carcinoma (NPC) is an invasive cancer with particularly high incidence in Southeast Asia and Southern China. The pathogenic mechanisms of NPC, particularly those involving epigenetic dysregulation, remain largely elusive, hampering clinical management of this malignancy. To identify novel druggable targets, we carried out an unbiased high-throughput chemical screening and observed that NPC cells were highly sensitive to inhibitors of cyclin-dependent kinases (CDK), especially THZ1, a covalent inhibitor of CDK7. THZ1 demonstrated pronounced antineoplastic activities both in vitro and in vivo An integrative analysis using both whole-transcriptome sequencing and chromatin immunoprecipitation sequencing pinpointed oncogenic transcriptional amplification mediated by super-enhancers (SE) as a key mechanism underlying the vulnerability of NPC cells to THZ1 treatment. Further characterization of SE-mediated networks identified many novel SE-associated oncogenic transcripts, such as BCAR1, F3, LDLR, TBC1D2, and the long noncoding RNA TP53TG1. These transcripts were highly and specifically expressed in NPC and functionally promoted NPC malignant phenotypes. Moreover, DNA-binding motif analysis within the SE segments suggest that several transcription factors (including ETS2, MAFK, and TEAD1) may help establish and maintain SE activity across the genome. Taken together, our data establish the landscape of SE-associated oncogenic transcriptional network in NPC, which can be exploited for the development of more effective therapeutic regimens for this disease. Cancer Res; 77(23); 6614-26. ©2017 AACR.

Dehydroacetic acid and triacetic acid lactone are known to be versatile substrates for the synthesis of a variety of azaheterocycles. However, their fluorinated analogs were poorly described in the literature. In the present work, we have investigated reactions of trifluorotriacetic acid lactone and hexafluorodehydroacetic acid with primary amines, phenylenediamine, and phenylhydrazine. While hexafluorodehydroacetic acid reacted the same way as non-fluorinated analog giving 2,6-bis(trifluoromethyl)-4-pyridones, trifluorotriacetic acid lactone had different regioselectivity of nucleophilic attack compared to the parent structure, and corresponding 3-amino-6,6,6-trifluoro-5-oxohex-3-eneamides were formed as the products. In the case of binucleophiles, further cyclization took place, forming corresponding benzodiazepine and pyrazoles. The obtained 2,6-bis(trifluoromethyl)-4-pyridones were able to react with active methylene compounds giving fluorinated merocyanine dyes. [ABSTRACT FROM AUTHOR]

New oligo- and polyenaminones with Mw ~ 7–50 KDa were prepared in high yields by transaminative amino-enaminone polymerization of regioisomeric bis[(dimethylamino)methylidene]cyclohexanediones with alkylene and phenylenediamines. The polymers obtained are practically insoluble in aqueous and organic solvents and exhibit film-forming properties, UV light absorption at wavelengths below 500 nm, and redox activity. These properties indicate a promising application potential of these polymers, which could find use in optical and optoelectronic applications and in energy storage devices. [ABSTRACT FROM AUTHOR]

Phosphorus removal from effluents is vital to avoid eutrophication. The subject study presents the development and performance of poly(phenylenediamine) isometric adsorbents produced through oxidation using (NH4)2S2O8 and K2Cr2O7 oxidants. K2Cr2O7 synthesized polymers showed better adsorption capacities. The presence of Cr Lewis acid on the surface endorsed phosphate interaction through inner-sphere complex mechanism. The maximum adsorption capacities for K2Cr2O7 synthesized polymers were 143, 217 and 69.0 mg/L for poly(o-phenylenediamine), poly(m-phenylenediamine) and poly(p-phenylenediamine) adsorbents, respectively. The superior performance of poly(m-phenylenediamine) was associated with minimal symmetrical arrangement, hence it was more amorphous as indicated by XRD patterns. Kinetic model fitted pseudo-second-order and isotherm favoured Langmuir. Adsorption process was also controlled by pore diffusion and external mass transfer in the sorbent. Poly(m-phenylenediamine) displayed high affinity in the presence of competing anions and was amenable to recycling. [ABSTRACT FROM AUTHOR]

Copper peroxide/zeolitic imidazolate framework/polydopamine nanoparticles (CP/ZIF-8/PDA)-based fluorescence-linked immunosorbent assay (FLISA) was designed for the sensitive and high-throughput determination of carcinoembryonic antigen (CEA) by self-supplied H2O2 generation. Specifically, the CEA aptamer was modified on the surface of CP/ZIF-8/PDA to form an immunoprobe. The structures of CP and ZIF-8 could be broken under acidic conditions, and produced the Cu2+ and H2O2 due to the dissociation the CP. A subsequent Fenton-type reaction of Cu2+ and H2O2 generated hydroxyl radical (·OH). o-phenylenediamine (OPD) was oxidized by the ·OH to form 2, 3-diaminophenazine (DPA) with a significant fluorescence signal. CP/ZIF-8/PDA could be used as an efficient Fenton-type reactant to generate a large amount of ·OH to promote OPD oxidation. The sensitive detection of CEA could be realized. Under optimal conditions, the FLISA platform displayed a linear detection range from 0.01 to 20 ng mL−1 with a detection limit of 7.6 pg mL−1 for CEA. This strategy has great application potential for sensitive and high-throughput determination for other biomarkers in the field of biomedicine. [ABSTRACT FROM AUTHOR]

An electrochemical sensor based on a molecularly imprinted polymer membrane (MIP) was developed. The electrochemical sensor was prepared by electropolymerization of o-phenylenediamine (O-PD) on the surface of glassy carbon electrode (GCE), modified by AuNPs@covalent organic framework (COF) microspheres with ascorbic acid (AA) as template molecule. First, ultrasmall polyvinylpyrrolidone (PVP)-coated AuNPs were prepared by a chemical reduction method. Then, 1,3,5-tri(p-formylphenyl)benzene (TFPB) and N-boc-1,4-phenylene diamine (NBPDA) underwent an ammonaldehyde condensation reaction on PVP-coated AuNPs to form AuNPs@COFTFPB-NBPDA microspheres. The porous spherical structure of AuNPs@ COFTFPB-NBPDA could accelerate the mass transfer, enlarge the specific surface area, and enhance the catalytic activity of PVP-coated AuNPs. The electrochemical sensors, based on AuNPs@ COFTFPB-NBPDA/GCE and nMIPs/AuNPs@COFTFPB-NBPDA/GCE, were applied for the detection of AA, with a detection limit of 1.69 and 2.57 μM, as well as linear ranges of 5.07 to 60 mM and 7.81 to 60 mM. The nMIPs/AuNPs@COFTFPB-NBPDA sensor had satisfactory stability, selectivity, and reproducibility for AA detection. [ABSTRACT FROM AUTHOR]

This study includes the design, synthesis and characterization of 1,2-phenylenediamine (o-PDA) functionalized maleic anhydride (MA)-vinyl acetate (VA) copolymer-based conjugate to develop a new formulation. The phenylenediamine molecule is a fluorescent dye that allows designing new chemotherapeutic polymeric molecules. Poly(maleic anhydride-alt-vinyl acetate) [Poly(MA-alt-VA)] was obtained via charge transfer complex (CTC) radical polymerization presence of methyl ethyl ketone (MEK), utilizing benzoyl peroxide (BPO) free-radical initiator at 80 °C, as a potential functional polymeric carrier. Structural characterization of the surface functionalized poly(MA-alt-VA)/1,2-PDA conjugate was performed by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and Nuclear Magnetic Resonance (1H-NMR). Spectroscopic methods and water solubility results confirmed that the conjugation took place successfully after the ring opening reaction by the amide mechanism. [ABSTRACT FROM AUTHOR]

It is necessary to decrease the application cost of luminescent Ln-MOF sensors to develop multiple functionalities. The ingenious design of ligands and the rational doping of Ln3+ ions are the main approaches to endowing Ln-MOFs with more functionalities. "V" shaped ligands can cause diamond pore channels commonly. "O＝C–NH" groups as hydrogen bonding sites not only can participate in supramolecular self-assembly but also can achieve molecular recognition. Based on the above considerations, a "V" shaped ligand, H2L, with a suitable triplet state and "O＝C–NH" groups was designed and synthesized firstly. And the Ln-MOFs (Ln = Eu, Gd, Tb) were obtained by solvothermal reactions. Single crystal X-ray diffraction showed that Ln-MOFs had two types of diamond pore channels where "O＝C–NH" groups adhered to the surface. "O＝C–NH" groups not only played an important role in the stacking process of 2D coordinated layers but also can reduce the non-radiative transition resulting from molecular vibration. The Eu-MOF and Tb-MOF not only can emit strong "f–f" transitions characteristic of luminescence but also can detect o-phenylenediamine (OPD) and p-phenylenediamine (PPD) by luminescence quenching. Besides, EuxTb1−x-MOFs (x = 0.02, 0.05, 0.1) were synthesized and can be used as ratio luminescence thermometers whose maximum relative sensitivities were 1.19% K−1 at 400 K. It is pointed out specifically that the relationship between the relative sensitivities and the Eu3+ content was studied. What's more, our work not only developed a series of Ln-MOF luminescent sensors by designing functional ligands and doping Ln3+ rationally but also provided valuable knowledge for the following work. [ABSTRACT FROM AUTHOR]

Four aluminum, zinc, and aluminum/zinc heterometallic complexes 1–4 stabilized by o‐phenylenediamine bridged poly (phenolato) ligands were synthesized and characterized. It was found that the reaction sequence has significant influence on the formation of the Al‐Zn heterometallic complex AlZnL1Me (4), which was prepared through successive complexation of poly (phenol) with ZnEt2 and AlMe3. The catalytic behaviors of complexes 1–4 for the ring‐opening polymerization of cyclohexene oxide (CHO) were investigated, and the heterometallic complex 4 showed significantly enhanced activity (TOF up to 410 min−1). Kinetic study was conducted; the activation energy (Ea) for formation of PCHO using 4 was determined to be 58.0 ± 6.5 kJ mol−1. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a new type of metal-free porous architecture with a well-designed pore structure and high stability. Here an efficient electrochemical sensing platform was demonstrated based on COFs TpPa-1 constructed by 1,3,5-triformylphloroglucinol (Tp) with p-phenylenediamine (Pa-1), which possesses abundant nitrogen and oxo-functionalities. COFs TpPa-1 exhibited good water dispersibility and strong adsorption affinities for Pd2+ and thus was used as loading support to modify Pd2+. The Pd2+-modified COFs TpPa-1 electrode (Pd2+/COFs) showed high electrocatalytic activity for both hydrazine oxidation reaction and nitrophenol reduction reaction. In addition, TpPa-1-derived nitrogen-doped carbon presented high activity for the electro-oxidation of reduced glutathione (GSH), and sensitive electrochemical detection of GSH was achieved. The presented COFs TpPa-1 can be utilized as a precursor as well as support for anchoring electro-active molecules and nanoparticles, which will be useful for electrochemical sensing and electrocatalysis. [ABSTRACT FROM AUTHOR]

A novel double‐crosslinked 3D network hydrogel, poly(aniline‐co‐p‐phenylenediamine‐co‐melamine) (PD2M4) is synthesized through the chemical oxidative copolymerization of aniline, melamine, and p‐phenylenediamine, and its properties are compared with those of polyaniline (PANI), poly(aniline‐co‐p‐phenylenediamine) (PPDA2), and poly(aniline‐co‐melamine) (PMA4) hydrogels. The morphologies, mechanical properties, and chemical compositions of the hydrogels are investigated by nitrogen physisorption, rheological test, microscopic measurements, and spectroscopic techniques, while electrochemical techniques are used to evaluate their electrochemical performances. In accordance with PANI, PPDA2, and PMA4 hydrogels, the PD2M4 hydrogel exhibited an interconnected long nanofiber structure that encouraged the diffusion of electrolyte ions. Its double‐crosslinked 3D network and high nitrogen‐doping content (6.3 at. %) offered synergistic effects that generated an impressive pseudocapacitance of 657 F g −1 at 0.2 A g−1, a superior rate capability of 72% retention at a high current density of 30 A g−1, and good cyclic stability of 62% after 2000 charge/discharge cycles. The present work, therefore, provides a novel copolymerization strategy for N‐doping and hierarchical network structure to enhance the electrochemical performances of PANI hydrogel electrodes in supercapacitor applications. [ABSTRACT FROM AUTHOR]

The imination of a cage‐opened fullerene C60 derivative was examined using N,N‐dimethyl‐1,4‐phenylenediamine. The desired imine derivative showed a remarkably intense near‐infrared (NIR) absorption band (λedge=1050 nm). According to theoretical calculations, the longest wavelength absorption is assignable to the HOMO→LUMO transition with a strong charge‐transfer character, in which the HOMO localizes on the introduced imine moiety while the high LUMO coefficients can be seen over the entire C60 skeleton. It should be noted that the two reduced compounds bearing an amine or methylene group were also formed in the reaction producing the imine derivative, the former of which again showed NIR absorption tailing to 1200 nm. In this reduction, the hydride source is considered to be α‐hydrogen of the diamine so that the use of N,N,N',N'‐tetramethyl‐1,4‐phenylenediamine increased the yield of the methylene derivative up to 20%. [ABSTRACT FROM AUTHOR]

25-hydroxycholesterol (25HC) is an oxysterol derived from cholesterol and plays a role in various cellular processes, such as lipid metabolism, inflammatory responses, and cell survival. Extravillous trophoblasts (EVTs) are a major cell type found in the placenta, which are highly energetic cells with proliferative and invasive properties. EVT dysfunction can lead to pregnancy complications, including preeclampsia and intrauterine growth restriction. This study investigated the effects and underlying mechanisms of action of 25HC on EVT proliferation. Swan 71 cells, an EVT cell line, were treated with different concentrations of 25HC. Next, cell proliferation was assessed. The mitochondrial reactive oxygen species (mtROS), mitochondrial membrane potentials (MMPs), lipid peroxidation (LPO), and glutathione (GSH) levels were measured. Apoptosis, ferroptosis, and autophagy were evaluated by western blotting and flow cytometry. The results revealed that 25HC significantly inhibited proliferation and decreased the metabolic activity of EVTs. Moreover, 25HC caused oxidative stress by altering mtROS, LPO, MMPs, and GSH levels. Additionally, 25HC induces apoptosis, ferroptosis, and autophagy through the modulation of relevant protein levels. Interestingly, pretreatment with Z-VAD-FMK, an apoptosis inhibitor, and ferrostatin-1, a ferroptosis inhibitor, partially restored the effects of 25HC on cell proliferation, oxidative stress, and cell death. In summary, our findings suggest that 25HC treatment inhibits EVT proliferation and triggers apoptosis, ferroptosis, and autophagy, which are attributable to oxidative stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

In recent decades, researchers have focused on developing less toxic and more precise cancer therapies. Carbon nanodots (CDs) are among the most promising technologies due to their high biocompatibility, tunable fluorescence, and ability to facilitate photothermal and photodynamic therapy. This study explores the synthesis and characterization of two CDs conjugated with Salphen metal complexes, namely, CDs-PEG-M1 and CDs-PEG-M2 , through Sonogashira coupling. Their interaction with G-quadruplex DNA structures (G4s), motifs largely involved in cancer development, was evaluated using various spectroscopic techniques. The results indicate that CDs-PEG-M1 exhibits greater effectiveness in stabilizing G4 structures compared to the metal complex alone or nonfunctionalized CDs. This enhanced stabilization suggests that CDs-PEG-M1 could reduce the concentration of the metal complex needed for potential antitumor applications, thereby minimizing side effects on nontarget tissues. When tested on breast cancer models (MDA-MB-231 as a triple-negative model and MCF-7 as a HER-2 positive model) and on a healthy cell line (HDFa), the CDs-PEG-M1 conjugate reduced cell viability in a concentration- and time-dependent manner, showing greater potency and selectivity against cancer cells compared to virgin CDs and the free M1 complex. This synergistic anticancer effect, driven by the interaction with G4 structures and reactive oxygen species production, underscores the potential of CDs-PEG-M1 as a targeted nanotheranostic tool.

Objective: We aimed to explore the influence of ferroptosis on an oxygen-glucose deprivation/reoxygenation (OGD/R) model in primary rat microglia., Methods: Primary microglia were extracted from rats and cultured in vitro. The cells were subjected to a hypoxic environment for 6 h in a glucose-free medium, and then re-oxygenated for 24 h in DMEM/F12. Rat microglia were pretreated with the ferroptosis activator erastin and the ferroptosis inhibitor ferrostatin 1 for 24 h, followed by detection of cell cycle progression and apoptosis by flow cytometry. Intracellular total iron levels were measured. In addition, the relative levels of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were determined using enzyme-linked immunosorbent assay. The protein levels of 15-lox2, GPX4, SLC7A11, ACSL4, and TFR1 were examined by western blotting., Results: Compared with rat microglia subjected to OGD/R, pretreatment with erastin did not influence cell apoptosis but significantly enhanced total iron levels, MDA, and ROS levels, whereas it reduced SOD levels. Moreover, it upregulated ACSL4, TFR1, and 15-lox2 and downregulated GPX4 and SLC7A11. Pretreatment with ferrostatin 1 significantly inhibited cell apoptosis and cell cycle arrest in the G0/G1 phase. It significantly reduced total iron levels, MDA, and ROS levels and enhanced SOD levels, which also downregulated ACSL4, TFR1, and 15-lox2, and upregulated GPX4 and SLC7A11., Conclusion: Our study showed that inhibition of ferroptosis is favorable against potential OGD/R-induced damage in rat microglia.

In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m - and p -phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications.

With increasing concerns about N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and 6PPD-quinone (6PPD-Q), relevant environmental investigations and toxicological research have sprung up in recent years. However, limited information could be found for human body burden assessment. This work collected and analyzed 200 samples consisting of paired urine and plasma samples from participants (50 male and 50 female) in Tianjin, China. Low detection frequencies (DF, <15 %) were found except for urinary 6PPD-Q (86 %), which suggested the poor residue tendency of 6PPD and 6PPD-Q in blood. The low DFs also lead to no substantial association between two chemicals. Data analysis based on urinary 6PPD-Q showed a significant difference between males and females (p < 0.05). No significant correlation was found for other demographic factors (Body Mass Index (BMI), age, drinking, and smoking). The mean values of daily excretion (ng/kg bw/day) calculated using urinary 6PPD-Q for females and males were 7.381 ng/kg bw/day (female) and 3.360 ng/kg bw/day (male), and apparently female suffered higher daily exposure. Further analysis with daily excretion and ALT (alanine aminotransferase)/TSH (thyroid stimulating hormone)/ blood cell analysis indicators found a potential correlation with 6PPD-Q daily excretion and liver/immune functions. Considering this preliminary assessment, systematic research targeting the potential organs at relevant concentrations is required., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The development of functional neurons is a complex orchestration of multiple signaling pathways controlling cell proliferation and differentiation. Because the balance of antioxidants is important for neuronal survival and development, we hypothesized that ferroptosis must be suppressed to gain neurons. We find that removal of antioxidants diminishes neuronal development and laminar organization of cortical organoids, which is fully restored when ferroptosis is inhibited by ferrostatin-1 or when neuronal differentiation occurs in the presence of vitamin A. Furthermore, iron-overload-induced developmental growth defects in C. elegans are ameliorated by vitamin E and A. We determine that all-trans retinoic acid activates the Retinoic Acid Receptor, which orchestrates the expression of anti-ferroptotic genes. In contrast, retinal and retinol show radical-trapping antioxidant activity. Together, our study reveals an unexpected function of vitamin A in coordinating the expression of essential cellular gatekeepers of ferroptosis, and demonstrates that suppression of ferroptosis by radical-trapping antioxidants or by vitamin A is required to obtain mature neurons and proper laminar organization in cortical organoids., (© 2024. The Author(s).)

Background: Gentamicin is a commonly used aminoglycoside antibiotic, with ototoxicity as a significant side effect. Ferroptosis, an iron-dependent form of cell death, has been implicated in a variety of disorders. Whether ferroptosis impacts gentamicin ototoxicity is not yet known. The current work used an in-vitro model to examine the influence of gentamicin-induced ferroptosis on cochlear hair cell damage and probable molecular biological pathways., Methods: House Ear Institute-Organ of Corti 1 (HEI-OC1) cells were treated with different concentrations of gentamicin for 24 hours, with or without ferrostatin-1 pretreatment, to observe gentamicin-induced ferroptosis. The role of p53/solute carrier family 7 member 11 (SLC7A11)/glutathione peroxidase 4 (GPX4) signaling in gentamicin-induced ferroptosis was explored by pretreating cells with the p53 inhibitor pifithrin-α (PFT-α). We investigated the effect of gentamicin on cells by assessing cell viability. Cellular proteins were isolated and Western blots were performed to detect changes in the expression of p53, SLC7A11, and GPX4. Fluorescence staining was used to assess levels of reactive oxygen species. An enzymatic detection kit was used to detect glutathione, Fe, and malondialdehyde markers., Results: Gentamicin reduced cell viability, glutathione content, and SLC7A11 and GPX4 protein levels, and increased levels of p53 protein, reactive oxygen species, malondialdehyde, and Fe. These effects were largely blocked by pretreatment with ferrostatin-1. Pretreatment with the p53 inhibitor PFT-α prevented the gentamicin-induced reduction in SLC7A11 and GPX4, which alleviated several features of ferroptosis including glutathione depletion, iron overload, and lipid peroxidation build-up., Conclusion: Gentamicin induces ferroptosis in the HEI-OC1 cell line, and the mechanism may be related to the p53/SLC7A11/GPX4 signaling pathway., Competing Interests: Conflict of interest statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of Otology & Neurotology, Inc.)

Water flux is one of the most important performance parameters of the reverse osmosis (RO) membrane. The higher water flux means lower energy cost when treating the same volume of feed solution with membrane separation technology. However, the increase of membrane water flux always corresponds to the decrease of solvent rejection, known as the "trade-off" effect. In addition, the surface fouling of membranes is often a serious problem, as frequent cleaning not only increases the operating cost but also shortens the life of the membranes. Recently, various hydrophilic nanomaterials have been used to improve the performance of membranes. To fabricate thin film nanocomposite (TFN) RO membrane with high flux and antifouling performance, maleic anhydride-grafted graphene oxide (MG) was successfully synthesized and incorporated into the polyamide (PA) layer via the interfacial polymerization (IP) method. We performed the IP reaction with m-phenylenediamine (MPD) and trimesoyl chloride (TMC) as reactive monomers on a polysulfone (PSF) substrate, and acid absorbent (TEA) and surfactant (SDS) were added to improve the separation performance of the membrane. The effects of MG incorporation on the membrane morphology and separation performance were investigated. SEM and AFM results show that the surface of the MG membrane is rougher than that of the membrane without MG. In addition, excessive loading of MG will lead to aggregation of MG nanosheets. FT-IR spectra indicate that the interaction between MG and PA layers results in an increase of hydrophilic groups on the surface of the TFN membrane, which is further confirmed by the results of the contact angle. The optimal MG doping concentration in the aqueous solution is 0.004 wt%, the water flux of the resultant TFN membrane is significantly increased to 51 L·m-2·h-1, 150% higher than the blank control membrane, which also performs a higher NaCI rejection (97.5% vs. 96.6%). Furthermore, the MG-incorporated RO membrane exhibits superior antifouling performance compared with the blank control membrane. [ABSTRACT FROM AUTHOR]

While elemental sulfur has been largely used as oxidant or sulfurating agent, its role as a catalyst has not been developed. We report here its catalytic activity in the oxidative condensation of o‐phenylenediamines with acetophenones in DMSO to provide quinoxalines. The method was also extended to α‐tetralones, propiophenones (R=Me) as well as higher homologues (R=Et, n‐Pr) in place of acetophenones, leading to a wide range of naphthoquinoxalines and 3‐substituted 2‐arylquinoxalines. [ABSTRACT FROM AUTHOR]

The Ni(II) complex of N2,N6-bis(3-(triethoxysilyl)propyl)pyridine-2,6-dicarboxamide (PDCA) has been prepared in situ and immobilized on MCM-41 to prepare a heterogeneous catalyst. Techniques such as FT-IR, low angle powder XRD, TGA, SEM, TEM, MP-AES, and N2 sorption studies were used for characterization of the isolated heterogeneous catalyst, MCM-41@PDCA-Ni. MCM-41@PDCA-Ni was used for the synthesis of benzimidazoles and quinazolinones in coupling reaction of substituted benzaldehyde with o-phenylenediamine and anthranilamide, respectively. The new catalyst showed tolerance towards both electron-withdrawing and electron-donating functional groups present in benzaldehyde. The high yield, easy recovery, and reusability for five times without significant loss in catalytic efficiency are the main advantages of MCM-41@PDCA-Ni. [ABSTRACT FROM AUTHOR]

Photoredox catalysis has emerged as a robust tool for chemical synthesis. However, it remains challenging to implement photoredox catalysis under physiological conditions due to the complex microenvironment and the quenching of photocatalyst by biologically relevant molecules such as oxygen. Here, we report that UV‐absorbing N,N′‐dinitroso‐1,4‐phenylenediamine derivatives can be selectively activated by fac‐Ir(ppy)3 photocatalyst within micellar nanoparticles under visible light irradiation (e.g. 500 nm) through photoredox catalysis in aerated aqueous solutions to form quinonediimine (QDI) residues with concomitant release of NO. Notably, the formation of QDI derivatives can actively scavenge the reactive oxygen species generated by fac‐Ir(ppy)3, thus avoiding oxygen quenching of the photocatalyst. Further, we exemplify that the oxygen‐tolerant photoredox catalysis‐mediated NO release can not only kill planktonic bacteria in vitro but also efficiently treat MRSA infections in vivo. [ABSTRACT FROM AUTHOR]

Metal/carbon composite materials are highly promising electrocatalysts for water electrolysis. In this work, three composites of metal cobalt nanoparticles highly dispersed in N-doped carbon materials were facilely constructed by pyrolysis of different phenylenediamine based Schiff base-Co complexes (PDBs). Interestingly, the composites derived from PDBs based on different phenylenediamine exhibited different morphologies. The superior case is that rodlike composite catalyst was derived from o -phenylenediamine based PDBs. The obtained catalyst exhibited remarkable performances for both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), as well as overall water electrolysis. Only 172 and 289 mV of overpotentials and 1.57 V of cell voltage were exhibited at 10 mA cm−2 for HER, OER and water splitting in 1.0 M KOH, respectively. The catalyst also displayed robust stability and high Faraday efficiency, and thus are potential high-performance catalyst for commercial water electrolysis. [Display omitted] • PhenylenediamineSchiff base-Co complexes were used as precursors. • Catalysts derived from different phenylenediamine with different morphologies. • Metal dispersity, N doping level and morphology were simultaneously improved. • The catalysts exhibited high N-dopant level and defect density. • The optimum catalyst exhibits high electrocatalytic activity for water splitting. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is a ubiquitous signaling molecule, and thus a variety of methods have been developed for its detection and quantification. Fluorometric analyses using a fluorescent NO probe harboring an o -phenylenediamine (OPD) structure are widely used for NO analyses in various organisms, including yeast. Here, we discovered that an NO-independent fluorophore (UNK436) was generated from a fluorescent NO probe 4-amino-5-methylamino-2′,7′-difluorofluorescein (DAF-FM), which has an OPD structure, in yeast cells. The molecules responsible for this undesirable fluorescence and their reaction mechanisms were analyzed. Our mass spectrometric analysis showed that two carbon atoms from glucose were incorporated into UNK436. Subsequent analyses indicated that a non-proteinous small compound leads to the synthesis of UNK436 through an oxidative reaction. Furthermore, our LC/MS/MS analysis of the reaction mixture of DAF-FM with acetaldehyde in combination with stable isotope labeling demonstrated that acetaldehyde reacts with DAF-FM oxidatively, generating UNK436. Another NO probe with an OPD structure, diaminorhodamine-4M, reacted with acetaldehyde in the same way to emit fluorescence. Based on our findings, we recommend that in researches using OPD-based fluorescent NO probes, alternative analyses also be performed to identify the reaction products of the probes with NO to avoid false-positives. [Display omitted] • A fluorescent NO probe DAF-FM generates an NO-independent fluorophore UNK436. • Acetaldehyde reacts with DAF-FM oxidatively leading to the formation of UNK436. • Another NO probe with o -phenylenediamine moiety reacts with acetaldehyde similarly. [ABSTRACT FROM AUTHOR]

A chromogenic and fluorogenic active coumarin-based chemodosimeter (DP21) has been synthesized. The probe shows remarkable fluorescent intensity with phenylenediamine isomers (PDA) such as ortho-phenylenediamine (OPD) and para-phenylenediamine (PPD) in the presence of competitive species. The probe changes from light yellow to reddish brown and dark yellow with OPD and PPD, respectively, through naked eye. The interaction of lone pair electrons in carbonyl group present in DP21 with amino group of OPD and PPD shows the intermolecular hydrogen bonding. The PDA isomers can be detected selectively in the presence of other interfering organic and inorganic amines by the DP21. It shows excellent low detection limit (LOD) for OPD and PPD is 0.19 nM and 0.4 nM respectively. [ABSTRACT FROM AUTHOR]

α-Phenylglyoxylic acid is a novel cyclization reagent. In this study, three cyclization products were synthesized by the reaction of α-phenylglyoxylic acids with ortho -functionalized anilines in deep eutectic solvents (DES). The five-membered-ring-formation products, the 2-arylbenzothiazoles, with a highest yield of 88%, were obtained by the reaction between 0.30 mmol of an o -aminothiophenol and 0.30 mmol of an α-phenylglyoxylic acid in choline chloride (ChCl)/ d -(–)-tartaric acid DES at 60 °C for 0.5 h. The six-membered-ring-formation products, 3-aryl-2 H -benzo[ b ][1,4]oxazin-2-one derivatives, were obtained in yields up to 99% by the reaction between 0.30 mmol of an o -aminophenol and 0.60 mmol of an α-phenylglyoxylic acid in ChCl/urea DES at 80 °C for 2.0 h. In the reaction between 0.30 mmol of o -phenylenediamine and 0.45 mmol of an α-phenylglyoxylic acid in ChCl/anhydrous tin(II) chloride DES at 70 °C for 1.5 h, the six-membered-ring-formation products, 3-arylquinoxalin-2(1 H)-one derivatives, were synthesized, with a highest yield of 96%. This cyclization reaction occurred without the addition of other catalysts, and the title compounds were obtained with good yields under mild conditions. [ABSTRACT FROM AUTHOR]

Herein, a versatile electrochemical platform is constructed based on Cu(II) coordination by pyrophosphatase (PPase)-guided triggered-release system. The unique design of “homogeneous bio-enzyme catalytic reaction, but simple electrochemical interface modification” is involved. Firstly, we prepare a nucleic acid-like coenzyme A-Cu(II) coordination polymer (CoA-Cu(II) CP), which displays unique electrocatalytic oxidation to o-phenylenediamine (OPD). Secondly, the complex of pyrophosphate (PPi) and Cu(II) (PPi-Cu(II) complex) is formed well, which has a huge influence on the formation of CoA-Cu(II) CP. Next, PPi-Cu(II) complex can be broken along with the addition of PPase, which can catalyze the hydrolysis of PPi into Pi to release Cu(II), but NaF can also reverse the result. Under optimal conditions, the SWV response is virtually proportional to the content of PPi and the activity of the PPase, and the detection of limit is 30 nM and 0.65 mU/L, respectively (S/N = 3). Furthermore, the biosensor is successfully applied for the quantitative detection of PPase in complex samples with recoveries ranging from 98.8% to 102.0% with acceptable RSDs. This proposed method is sensitive, selective, stable and convenient without any labels or complicated operations, which provides a significant reference for PPi/PPase-based biological process and clinical determination. [ABSTRACT FROM AUTHOR]