Generation Of Anion Radical Research Articles

Supramolecular Radical Anions Triggered by Bacteria In Situ for Selective Photothermal Therapy.

A supramolecular complex that can be selectively reduced to radical anions in situ by facultative anaerobic bacteria is reported. To this end, a water-soluble bifunctional monomer bearing perylene diimide was synthesized, and its supramolecular complex with cucurbit[7]uril was fabricated on the basis of host-guest complexation, which could be reduced to forming radical anions in the presence of E. coli. It was found that this supramolecular complex could display different ability of generating radical anions by facultative anaerobic and aerobic bacteria in terms of their various reductive abilities. The selective antibacterial activity of the supramolecular complex could be realized by the photothermal performance of the radical anions under near-infrared irradiation. It is anticipated that this method may lead to a novel bacteria-responsive photothermal therapy to regulate balance of bacterial flora.

The Participation of calcium ions and reactive oxygen species in the induction of antioxidant enzymes and heat resistance in plant cells by hydrogen sulfide donor

The effect of hydrogen sulfide (H2S) donor sodium hydrosulfide (NaHS) on the heat resistance of wheat (Triticum aestivum L.) coleoptile cells, the formation of reactive oxygen species (ROS), and the activity of the antioxidant enzymes in them was investigated. The treatment of coleoptiles with 100 µM NaHS caused transient enhancement of the generation of the superoxide anion radical (O2 •) and an increased hydrogen peroxide content. The activities of antioxidant enzymes—superoxide dismutase, catalase, and guaiacol peroxidase— and coleoptile resistance to damaging heat was later found to have increased. The biochemical and physiological effects of the hydrogen sulfide donor described above were inhibited by the treatment of wheat coleoptiles with the hydrogen peroxide scavenger dimethylthiourea, the NADPH oxidase inhibitor imidazole, the extracellular calcium chelator EGTA, and the phosphatidylinositol-specific phospholipase C inhibitor neomycin. A conclusion was made on the role of ROS generation, which is dependent on the activity of NADPH oxidase and calcium homeostasis, in the transduction of the H2S signal, which induces antioxidant enzymes and the development of plant cell heat resistance.

Real-time monitoring of superoxide anion radical generation in response to wounding: electrochemical study.

BackgroundThe growth and development of plants is deleteriously affected by various biotic and abiotic stress factors. Wounding in plants is caused by exposure to environmental stress, mechanical stress, and via herbivory. Typically, oxidative burst in response to wounding is associated with the formation of reactive oxygen species, such as the superoxide anion radical (O2•−), hydrogen peroxide (H2O2) and singlet oxygen; however, few experimental studies have provided direct evidence of their detection in plants. Detection of O2•− formation in plant tissues have been performed using various techniques including electron paramagnetic resonance spin-trap spectroscopy, epinephrine-adrenochrome acceptor methods, staining with dyes such as tetrazolium dye and nitro blue tetrazolium (NBT); however, kinetic measurements have not been performed. In the current study, we provide evidence of O2•− generation and its kinetics in the leaves of spinach (Spinacia oleracea) subjected to wounding.MethodsReal-time monitoring of O2•− generation was performed using catalytic amperometry. Changes in oxidation current for O2•− was monitored using polymeric iron-porphyrin-based modified carbon electrodes (φ = 1 mm) as working electrode with Ag/AgCl as the reference electrode.ResultThe results obtained show continuous generation of O2•− for minutes after wounding, followed by a decline. The exogenous addition of superoxide dismutase, which is known to dismutate O2•− to H2O2, significantly suppressed the oxidation current.ConclusionCatalytic amperometric measurements were performed using polymeric iron-porphyrin based modified carbon electrode. We claim it to be a useful tool and a direct method for real-time monitoring and precise detection of O2•− in biological samples, with the potential for wide application in plant research for specific and sensitive detection of O2•−.

IR study on the electrochemical generation of a nitro radical anion by a hepatotoxic N,N′-disubstituted benzimidazole-2-thione

In the course of our study on the hepatotoxicity of 1,3-disubstituted-1H-benzo[d]imidazole-2(3H)-thiones, we generated and characterized the radical anion of methyl 3-[3-(3-methoxy-3-oxopropyl)-5-nitro-2-thioxo-2,3-dihydro-1H-benzimidazol-1-yl]propanoate which shows the highest toxicity within the studied series. The reduction of the title compound was carried out electrochemically and the spectral and structural changes arising from the conversion were described based on IR spectra and DFT calculations. Repeated monitoring of IR spectra over time demonstrated successful generation of the radical anion accompanied by strong frequency decrease of NO stretching vibrations and increase of CN stretching vibration. The neutral compounds and the radical anion are characterized by coplanar orientation of the nitro group towards the aromatic system which most likely contributes to the observed toxicity. The structure of the radical anion shows extended electronic conjugation compared to the neutral compound. The NBO spin population analysis of the radical anion indicated that 0.707 of the odd electron is localized over the nitro group, while 0.293 is spread over the benzimidazole-2-thione fragment. Based on calculated energy of the lowest unoccupied molecular orbital (ELUMO) for the neutral compound, energy difference between the lowest unoccupied and the highest occupied molecular orbital (ΔEL−H), and adiabatic electron affinity (EA), it was estimated that the propensity of methyl 3-[3-(3-methoxy-3-oxopropyl)-5-nitro-2-thioxo-2,3-dihydro-1H-benzimidazol-1-yl]propanoate to generate a radical anion in biological systems would be comparable to that of nitrobenzene and nimesulide and much lower than those of nitrofurantoin.

Systematically Studying the Effect of Fluoride on the Properties of Cyclophanes Bearing Naphthalene Diimide and Dialkoxyaryl Groups.

Anion-π interactions between the Lewis basic anion fluoride and π-acidic naphthalene diimide was systematically studied in a series of cyclophanes in which the properties are modulated through the influence of a second, electron-rich aromatic unit. The systems and subsequently generated radical anions, upon addition of fluoride, were studied by absorption spectroscopic and EPR techniques. The results infer a modulation as a result of the nature and strength of the π-π interaction in the macrocyclic structure.

Photosensitizing anthraquinones from Heterophyllaea lycioides (Rubiaceae)

Seven anthraquinones were isolated from aerial parts of Heterophyllaea lycioides (Rusby) Sandwith (Rubiaceae), including three derivatives that have not been described before: a hetero-bianthraquinone identified as (R)-2-hydroxymethyl-2′methyl-1,1′,6,6′-tetrahydroxy-5,5′ bianthraquinone (lycionine), and two mono-chlorinated derivatives related to soranjidiol. One of them is a homo-bianthraquinone: (R)-7-chloro-2,2′-dimethyl-1,1′,6,6′-tetrahydroxy-5,5′ bianthraquinone (7-chlorobisoranjidiol), whereas the second halogenated derivative corresponds to a monomeric structure: 5-chloro-1,6-dihydroxy-2-methyl anthraquinone (5-chlorosoranjidiol). The four known compounds were already isolated from another species of this genus, H. pustulata, and they were identified as 5,5′-bisoranjidiol, soranjidiol, pustuline and heterophylline. Structural elucidation was performed by means of an extensive spectroscopic analysis, including 1D and 2D NMR data as well as by HRMS analysis. Chemical structures of 7-chlorobisoranjidiol and 5-chlorosoranjidiol were confirmed by their synthesis from 5,5′-bisoranjidiol and soranjidiol, respectively. Type I photosensitizing properties (superoxide anion radical generation, O2−) were assessed by using the nitroblue tetrazolium assay. When lycionine and chlorinated derivatives were irradiated, they enhanced the O2− production with respect to the control; 7-chlorobisoranjidiol stood out by generating an increase of 20%, whereas the other anthraquinones only produced a slight increase of 7%.

Ferulic acid prevents methylglyoxal-induced protein glycation, DNA damage, and apoptosis in pancreatic β-cells.

Methylglyoxal (MG) can react with amino acids of proteins to induce protein glycation and consequently the formation of advanced glycation end-products (AGEs). Previous studies reported that ferulic acid (FA) prevented glucose-, fructose-, and ribose-induced protein glycation. In this study, FA (0.1-1mM) inhibited MG-induced protein glycation and oxidative protein damage in bovine serum albumin (BSA). Furthermore, FA (0.0125-0.2mM) protected against lysine/MG-mediated oxidative DNA damage, thereby inhibiting superoxide anion and hydroxyl radical generation during lysine and MG reaction. In addition, FA did not have the ability to trap MG. Finally, FA (0.1mM) pretreatment attenuated MG-induced decrease in cell viability and prevented MG-induced cell apoptosis in pancreatic β-cells. The results suggest that FA is capable of protecting β-cells from MG-induced cell damage during diabetes.

Brachycorynella asparagi (Mordv.) Induced-Oxidative Stress and Antioxidative Defenses of Asparagus officinalis L.

The aim of this study was to investigate whether and to what extent oxidative stress is induced in leaves of one- and two-month-old plants of Asparagus officinalis L. cv. Argenteuil infested by Brachycorynella asparagi (Mordvilko) at a varied population size. The pest B. asparagi has been described as the most damaging species feeding on asparagus. Analyses using electron paramagnetic resonance (EPR) demonstrated generally higher concentrations of semiquinone radicals with g-values of 2.0045 ± 0.0005 and 2.0026 ± 0.0005 in Asparagus officinalis (A. officinalis) leaves after Brachycorynella asparagi (B. asparagi) infestation than in the control. Observations of leaves under a confocal microscope showed a post-infestation enhanced generation of the superoxide anion radical (O2•−) and hydrogen peroxide (H2O2) in comparison to the control. Strong fluctuations in Mn2+ ion levels detected by EPR spectroscopy versus time were detected in leaves infested by aphids, which may indicate the involvement of these ions in the control of O2•− production. An enhanced superoxide dismutase activity is an important element in leaf defense against oxidative stress. Visible symptoms were found in aphid-infested A. officinalis. Damage to leaves of one- and two-month-old A. officinalis plants by the aphid B. asparagi was dependent on the intensity, duration of infestation and plant age.

Synthesis, Electrochemical Characterization, and Linear Free Energy Relationship of 1,3-Diphenyl-6-alkyl/arylfulvenes

A series of 1,3-diphenyl-6-alkyl/arylfulvenes was prepared, and the electrochemical properties were investigated. The addition of phenyl groups about the fulvene raised the reduction potential and helped to stabilize the electrochemically generated radical anion. The addition of various functional groups onto the phenyl ring at the 6-position of 1,3,6-triphenylfulvene results in a linear free energy relationship between reduction potential and the Hammett substituent constant, σ. Further extending the conjugation at the 6-position of 1,3-diphenyl-6-arylfulvenes increases the reversibility of the redox reactions, but does not appear to further stabilize the generated radical anion. This in-depth investigation provides evidence that the compounds studied may have utility in light-harvesting applications.

Protective effect of cyanidin against glucose- and methylglyoxal-induced protein glycation and oxidative DNA damage

Cyanidin, a natural anthocyanin abundant in fruits and vegetables, has shown the health benefits due to its pharmacological properties. However, there was no evidence regarding anti-glycation activity of cyanidin. The aim of the study was to investigate the inhibitory effect of cyanidin on methylglyoxal (MG)- and glucose-induced protein glycation in bovine serum albumin (BSA) as well as oxidative DNA damage. Free radical scavenging activity and the MG-trapping ability of cyanidin were also investigated. The results demonstrated that cyanidin (0.125–1mM) significantly inhibited the formation of fluorescent and non-fluorescent AGEs in BSA/MG and BSA/glucose systems. There was a significantly improved protein thiol in BSA/MG and BSA/glucose when incubated with cyanidin. Correspondingly, cyanidin decreased the level of protein carbonyl content in BSA/glucose system. Moreover, cyanidin (0.5–1mM) prevented lysine/MG-mediated oxidative DNA damage in the absence or presence of copper ion. The results demonstrated that cyanidin showed the MG-trapping ability in a concentration-dependent manner. Cyanidin also reduced superoxide anion and hydroxyl radical generation in lysine/MG system. The mechanism by which cyanidin inhibited protein glycation was the MG-trapping ability and the free radical scavenging activity. The present study suggests that cyanidin might be a promising antiglycation agent for preventing or ameliorating AGEs-mediated diabetic complications.

Protective effects of polyvinylpyrrolidone-wrapped fullerene against intermittent ultraviolet-A irradiation-induced cell injury in HaCaT cells

To identify compounds that suppress UV irradiation-induced oxidative stress in the skin, various types of antioxidants have been studied. Polyvinylpyrrolidone-entrapped fullerene (C60/PVP) is known as a powerful antioxidant that exerts a cytoprotective effect against UV irradiation-induced cell injury in human skin cells and skin models. However, the effects of the alternate attractive C60/PVP feature, persistent antioxidant ability, on cytoprotection have rarely been ascertained. In this study we therefore investigated the efficacies of C60/PVP using an intermittently repeated UVA irradiation model wherein human keratinocytes were repeatedly exposed to UVA five times every 1h and compared the cytoprotective effects with those provided by ascorbic acid-2-O-phosphate-disodium salt (APS) and α-tocopherol (α-Toc). Our results demonstrated that C60/PVP yielded prominent cytoprotective effects against intermittently repeated UVA irradiation-induced injuries in a dose-dependent manner and suppressed intracellular superoxide anion radical (O2−) generation both during and after the repeated UVA irradiation. Additionally, C60/PVP also repressed the intermittent UVA irradiation-induced apoptosis via suppression of chromatin condensation and caspase-3/7 activation. Furthermore, the observed cytoprotective effects were superior to the effects of the typical antioxidants APS and α-Toc. These data suggest that C60/PVP might function as a potent cosmetic antioxidant against the effects of repeated and prolonged UVA irradiation through its persistent antioxidative property.

Erratum to: Expression of SOD and production of reactive oxygen species in Acinetobacter calcoaceticus caused by hydrocarbon oxidation

Expression of antioxidant enzymes [superoxide dismutase (SOD) and catalase] and generation of reactive oxygen species (ROS) in the presence of various hydrocarbons were investigated in two strains of hydrocarbon-degrading microorganism Acinetobacter calcoaceticus isolated from water (VKPM B-10353) and bottom sediment (EMBM-06). Upon biotransformation of hydrocarbons by the studied strains, superoxide generation strengthening by bacterial cells and accumulation of peroxides in the cultivation medium were observed. The strongest superoxide anion radical generation occurred during the incubation of microorganisms with diesel fuel (increasing 12 times and 2 times), cyclohexane (1.8 times and 1.75 times), a mix of benzene and anthracene (4.4 times and 3.7 times), naphthalene (8 times and 1.9 times) and benz(a)pyrene (2 times and 2.3 times) in strains VKPM B-10353 and EMBM-06 respectively, and anthracene (2.8 times) in strain VKPM B-10353. The accumulation of peroxides in the medium took place upon biotransformation of diesel fuel by both strains. Activity of SOD increased considerably and activity of catalase decreased in cells in the medium with hydrocarbons. Decane and crude oil had the maximum impact on SOD expression. Decane increased SOD expression in strains VKPM B-10353 and EMBM-06 24.4 times and 28.5 times, respectively. Crude oil increased SOD expression in strain VKPM B-10353 19 times, and in strain EMBM-06 16 times. The authors assumed that increased ROS generation and oxidizing stress development in bacteria during the biotransformation of various hydrocarbons can have an adaptive character.

Peculiarities of the free radical processes in rat liver mitochondria under toxic hepatitis on the background of alimentary protein deficiency.

The rate of superoxide anion radical, hydroxyl radical and hydrogen peroxide generation, the level of oxidative modification of mitochondrial proteins in the liver of rats with toxic hepatitis was investigated on the background of alimentary protein deficiency. We did not find significant increases of the intensity of free radical processes in liver mitochondria of rats maintained on the protein-deficient ration. The most significant intensification of free radical processes in liver mitochondria is observed under the conditions of toxic hepatitis, induced on the background of alimentary protein deprivation. Under these conditions the aggravation of all studied forms of reactive oxygen species generation was observed in liver mitochondria. The generation rates were increased as follows: O2 – by 1.7 times, Н2О2 – by 1.5 times, •ОН – practically double on the background of accumulation of oxidized mitochondria-derived proteins. The established changes in thiol groups’ redox status of respiratory chain proteins insoluble in 0.05 M sodium-phosphate buffer (pH 11.5), and changes of their carbonyl derivatives content may be considered as one of the regulatory factors of mitochondrial energy-generating function.

Real-Time Monitoring of Superoxide Anion Radical and Hydrogen Peroxide Generation in Higher Plants in Response to Wounding: In-Vivo Electrochemical Study

The growth and development in plants are deleteriously affected by various biotic and abiotic stress factors. Wounding in plants occurs with exposure to environmental mechanical stresses or via herbivory. The response of plants towards wounding have been categorized based on the response time; the fast response includes oxidative burst accompanied by generation of reactive oxygen species (ROS) or delayed response which includes transcriptional activation of wound-induced genes, deposition of callose, accumulation of proteinase inhibitors and hydrolytic enzymes etc. The oxidative burst in response to wounding is known to be associated with the formation of various ROS such superoxide anion radical (O2 •−), singlet oxygen and hydrogen peroxide (H2O2). In the current study, we provide experimental evidences and real time monitoring of O2 •− and H2O2 generation following wounding in leaves of spinach (Spinacia oleracea). Real-time monitoring of ROS generation was achieved using amperometric method utilizing different electrodes. Non-specific real-time measurements of ROS were done by monitoring the changes in reduction current using carbon electrode while qualitative and quantitative measurement of O2 •− and H2O2 generationwere done using newly developed iron-porphyrin based modified carbon electrodes and osmium-horseradish peroxidase (Os-HRP) based modified carbon electrodes, respectively. The results obtained showed continuous generation of O2 •− and H2O2 for minutes after injury followed by a decline. The activation of lipoxygenase after wounding; its involvements in the production of H2O2 and the contribution of H2O2 in generation of local response in injured plant tissue besides the initiation of systemic response caused by hormones such as jasmonic acid, ethylene, salicylic acid, and abscisic acid will be disscussed.

Lipid peroxidation in cardiac mitochondrial fraction of rats exposed to different supplementation with polyunsaturated fatty acids

The effect of diet supplementation with polyunsaturated fatty acids (PUFAs) used at different ratios of w-6/w-3 was studied on the content of primary (diene conjugates, DC; triene conjugates, TC), secondary (ketodienes, CD; coupled trienes, CT; TBA-active products) and terminal (Schiff bases) lipid peroxidation products (LPO) and generation of superoxide anion-radical in rat heart mitochondrial fraction. It was shown that diet supplementation with high doses of w-6 or w-3 PUFAs increased the content of primary, secondary and terminal LPO in rat heart mitochondrial fraction. Llipid peroxidation was accompanied by the intensification of superoxide anion-radical generation in rat heart mitochondrial fraction. During diet consumption with the PUFAs leading factor affecting the intensity of lipoperoxidation in rat heart mitochondria is fatty acid composition, rather than the level of their saturation.

Antioxidant Effects of Herbal Tea Leaves from Yacon (Smallanthus sonchifolius) on Multiple Free Radical and Reducing Power Assays, Especially on Different Superoxide Anion Radical Generation Systems.

Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot-water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot-water extract was similarly demonstrated among these extracts. Varying concentrations of the hot-water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC50 28.1 μg/mL), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical (EC50 23.7 μg/mL), galvinoxyl radical (EC50 3.06 μg/mL), and chlorpromazine cation radical (EC50 475 μg/mL). The yacon tea-leaf extract further demonstrated superoxide anion (O2(-)) radical scavenging effects in the phenazine methosulfate-NADH-nitroblue tetrazolium (EC50 64.5 μg/mL) and xanthine oxidase assay systems (EC50 20.7 μg/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea-leaf extract could suppress the cellular O2(-) radical generation (IC50 65.7 μg/mL) in a phorbol 12-myristate 13-acetate-activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders. Yacon has been considered to be a potent alternative food source for patients who require a dietary cure in regional area, while the leaf part has been provided and consumed as an herbal tea in local markets. We demonstrated here potent antioxidative effects of the tea leaves from yacon in different free radical assays, reducing power assay, and cellular superoxide anion radical generation assay. Results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders.

Isoferulic acid prevents methylglyoxal-induced protein glycation and DNA damage by free radical scavenging activity.

BackgroundIsoferulic acid (IFA), a naturally occurring cinnamic acid derivative, is a main active ingredient of the rhizoma of Cimicifuga dahurica. It has been shown various pharmacological activities. The aim of the study was to investigate the effect of IFA against MG-induced protein glycation and oxidative DNA damage. Free radical scavenging activity and the MGO-trapping abilities of IFA were also investigated.MethodsThe fluorescent MG-derived AGEs and non-fluorescent Nε-(carboxymethyl) lysine (Nε-CML) was measured using a spectrofluorometer and an enzyme linked immunosorbant assay (ELISA). Protein carbonyl content was used to detect protein oxidation. Gel electrophoresis was used to determine DNA damage. Superoxide anion radicals and hydroxyl radicals were determined using cytochrome c reduction assay and thiobarbituric acid reactive 2-deoxy-D-ribose oxidation products, respectively. The MG-trapping capacity was performed by HPLC.ResultsIFA (1.25–5 mM) inhibited the formation of fluorescent MG-derived AGEs, and Nε-CML, and protein carbonyl in bovine serum albumin. In addition, IFA (0.1–1 mM) also prevented MG/lysine-mediated oxidative DNA damage in the presence and absence of copper ion. The protective ability of IFA was directly correlated to inhibition of hydroxyl and superoxide anion radical generation during the reaction of MG and lysine. Most notably, IFA had no the directly trapping ability to MG.ConclusionsThe present results highlighted that free radical scavenging activity, but not the MG-trapping ability, is the mechanism of IFA for preventing MG-induced protein glycation and DNA damage.

EPR and UV–vis spectroelectrochemical studies of diketopyrrolopyrroles disubstituted with alkylated thiophenes

EPR and UV–vis spectroelectrochemical behavior of a series of ambipolar donor–acceptor–donor (DAD) compounds, consisting of a diketopyrrolopyrrole (DPP) central unit symmetrically disubstituted with mono-, bi- and terthiophene, is reported. All derivatives studied undergo a reversible reduction to radical anions at E ca. −1.55V to ca. −1.65V vs Fc/Fc+. Electrochemically generated radical anions are sufficiently stable to be detected at RT. Two-step oxidation of these compounds involves the formation of radical cations in the first step followed by their transformation into spinless dications in the second one. The formed radical cations are detectable at RT, however, contrary to the case of radical anions they yield unresolved EPR spectra. The potential of their formation depends on the length of D segment decreasing from ca. 0.50V vs Fc/Fc+ for monothiophene disubstituted DPP to ca. 0.25V in the case of the terthiophene derivative. Combining differential pulse voltammetry with EPR and UV–vis spectroelectrochemistry allows for unequivocal identification of all new, electrochemically induced UV–vis bands to particular forms of the studied molecules (radical anions, radical cations or dications). Both electrochemical reduction and electrochemical oxidation processes involve profound and distinctly different spectral changes in the visible range of the spectrum. Since they are reversible, the studied compounds can be considered as promising multicolor electrochromophores.

Development of Anolyte Materials for All-Organic Redox Flow Batteries

Energy storage systems for solar and wind power are expected to play a central role in addressing the global energy crisis and climate change concerns. Among the various strategies deployed, redox flow batteries (RFBs) are regarded as one of the most promising technologies for integration of intermittent and capricious energy resources. Unlike the traditional secondary batteries, the energy and power of RFBs are decoupled which offers remarkable flexibility as both of them can be independently scaled for different applications by controlling the size of the storage tank and/or the cell stack. Material development of redox active molecules, especially redox active organic molecules is crucial to enable the extensive deployment of this energy storage technology. Unlike the catholyte (high potential) materials that have been extensively investigated, the anolyte (low potential) molecules are still less tapped. In this presentation, our approach to the development of aromatic heterocycle based anolyte materials will be reported. The radical anion generation, the supporting electrolyte effect on the ion-pairing of the radical anion and its corresponding stability, as well as its coupling with catholyte material for an all-organic redox flow battery will be covered.

Synthesis of 2‐X‐, 3‐X‐4,4′‐Dicyanobiphenyls (X = CH3, OCH3, F) by Cross‐Coupling of the Terephthalonitrile Dianion with Substituted Benzonitriles

AbstractA concise noncatalytic synthetic approach to 2‐ and 3‐substituted 4,4′‐dicyanobiphenyls by applying terephthalonitrile dianion 12– as para‐cyanophenylating reagent for neutral benzonitriles is described. Neutral participants are varied to reveal the scope of applicable substrates and to evaluate the electronic and structural factors governing the regioselectivity and efficiency of the cross‐coupling. Benzonitriles substituted with Me, OMe and F provide the corresponding dicyanobiphenyls in good yields. The regularities in the reactivities are interpreted in terms of a reaction scheme involving the intermediacy of a charge‐transfer complex between 12– and benzonitrile, which transforms into a dimeric dianion either through a heterolytic pathway and/or by successive single electron transfer and recombination of the primary generated radical anions. Quantum chemical calculations of the structure and energy of the principal reaction intermediates match the experimental data. CV measurements of the new dicyanobiphenyls are also included.