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Ludger Beerhues - One of the best experts on this subject based on the ideXlab platform.
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Phytoalexins of the Pyrinae: Biphenyls and Dibenzofurans.
Beilstein journal of organic chemistry, 2012Co-Authors: Cornelia Chizzali, Ludger BeerhuesAbstract:Biphenyls and Dibenzofurans are the phytoalexins of the Pyrinae, a subtribe of the plant family Rosaceae. The Pyrinae correspond to the long-recognized Maloideae. Economically valuable species of the Pyrinae are apples and pears. Biphenyls and Dibenzofurans are formed de novo in response to infection by bacterial and fungal pathogens. The inducible defense compounds were also produced in cell suspension cultures after treatment with biotic and abiotic elicitors. The antimicrobial activity of the phytoalexins was demonstrated. To date, 10 biphenyls and 17 Dibenzofurans were isolated from 14 of the 30 Pyrinae genera. The most widely distributed compounds are the biphenyl aucuparin and the Dibenzofuran γ-cotonefuran. The biosynthesis of the two classes of defense compounds is not well understood, despite the importance of the fruit crops. More recent studies have revealed simultaneous accumulation of biphenyls and Dibenzofurans, suggesting sequential, rather than the previously proposed parallel, biosynthetic pathways. Elicitor-treated cell cultures of Sorbus aucuparia served as a model system for studying phytoalexin metabolism. The key enzyme that forms the carbon skeleton is biphenyl synthase. The starter substrate for this type-III polyketide synthase is benzoyl-CoA. In apples, biphenyl synthase is encoded by a gene family, members of which are differentially regulated. Metabolism of the phytoalexins may provide new tools for designing disease control strategies for fruit trees of the Pyrinae subtribe.
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differential effect of elicitors on biphenyl and Dibenzofuran formation in sorbus aucuparia cell cultures
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Cornelia Huttner, Helge Scharnhop, Till Beuerle, Ludger Ernst, Ludger BeerhuesAbstract:The Rosaceous subtribe Pyrinae (formerly subfamily Maloideae) is well-known for its economically important fruit trees, such as apple and pear, and also includes Sorbus aucuparia. Elicitor-treated S. aucuparia cell cultures are used to study the biosynthesis of the Pyrinae-specific phytoalexins, biphenyls and Dibenzofurans. Three biphenyls (aucuparin, noraucuparin, 2′-hydroxyaucuparin) and a Dibenzofuran (eriobofuran) were isolated and structure elucidated using GC-MS and NMR. A second Dibenzofuran of low abundance was tentatively assigned as noreriobofuran. Treatment of S. aucuparia cell cultures with yeast extract induced the formation of aucuparin as the major phytoalexin. In contrast, addition of preparations from the fire blight bacterium, Erwinia amylovora, and the scab-causing fungus, Venturia inaequalis, resulted in accumulation of eriobofuran as the major inducible constituent. Methyl jasmonate was a poor elicitor. The observations are suggestive of a biogenic relationship between biphenyls and d...
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differential effect of elicitors on biphenyl and Dibenzofuran formation in sorbus aucuparia cell cultures
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Cornelia Huttner, Helge Scharnhop, Till Beuerle, Ludger Ernst, Ludger BeerhuesAbstract:The Rosaceous subtribe Pyrinae (formerly subfamily Maloideae) is well-known for its economically important fruit trees, such as apple and pear, and also includes Sorbus aucuparia. Elicitor-treated S. aucuparia cell cultures are used to study the biosynthesis of the Pyrinae-specific phytoalexins, biphenyls and Dibenzofurans. Three biphenyls (aucuparin, noraucuparin, 2'-hydroxyaucuparin) and a Dibenzofuran (eriobofuran) were isolated and structure elucidated using GC-MS and NMR. A second Dibenzofuran of low abundance was tentatively assigned as noreriobofuran. Treatment of S. aucuparia cell cultures with yeast extract induced the formation of aucuparin as the major phytoalexin. In contrast, addition of preparations from the fire blight bacterium, Erwinia amylovora, and the scab-causing fungus, Venturia inaequalis, resulted in accumulation of eriobofuran as the major inducible constituent. Methyl jasmonate was a poor elicitor. The observations are suggestive of a biogenic relationship between biphenyls and Dibenzofurans. Elicitor-treated S. aucuparia cell cultures provide an interesting in vitro system for studying biphenyl and Dibenzofuran metabolism in the economically valuable Pyrinae.
Jun Yeob Lee - One of the best experts on this subject based on the ideXlab platform.
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a novel molecular design employing a backbone freezing linker for improved efficiency sharpened emission and long lifetime in thermally activated delayed fluorescence emitters
Journal of Materials Chemistry C, 2019Co-Authors: Si Hyun Han, Ha Lim Lee, Wan Pyo Hong, Jun Yeob LeeAbstract:A novel molecular design employing a backbone structure freezing linker was developed to improve the external quantum efficiency, lifetime and emission profile of thermally activated delayed fluorescence (TADF) emitters. The backbone structure freezing linker was introduced in the TADF emitters having diphenyltriazine as an acceptor and bicarbazole, triscarbazole, and indolocarbazole as donors. A Dibenzofuran moiety was the backbone structure freezing unit between the donor and acceptor units, which are positioned at the 3 and 4 positions of Dibenzofuran. The Dibenzofuran linker worked as a rigid freezing unit compared with the common phenyl linker, which yielded an improved efficiency, sharpened emission spectrum and extended lifetime. The Dibenzofuran mediated TADF emitter exhibited a high external quantum efficiency of 23.5% and lifetimes surpassing those of the state of the art green TADF emitters. This is the first work simultaneously reporting both a high efficiency over 20% and lifetime longer than other state of the art TADF emitters.
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Lifetime enhancement of blue thermally activated delayed fluorescent devices by separated carrier channels using Dibenzofuran-triazine type hosts
Journal of Industrial and Engineering Chemistry, 2018Co-Authors: Yu Jin Kang, Si Hyun Han, Jun Yeob LeeAbstract:Abstract Lifetime enhancement of blue thermally activated delayed fluorescent (TADF) devices was achieved using a carrier separating host structure which was developed using Dibenzofuran-triazine type electron-transporting type host materials. Two host materials built on a chemical platform of Dibenzofuran-triazine were synthesized as high triplet energy host materials for a blue TADF emitter and were mixed with a common hole-transporting type host. The separation of the carrier channel in the emitting layer lead to voltage reduction, external quantum efficiency increase, and lifetime extension of blue TADF devices.
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structure property relationship of pyridoindole type host materials for high efficiency blue phosphorescent organic light emitting diodes
Chemistry of Materials, 2014Co-Authors: Chil Won Lee, Jun Yeob LeeAbstract:The structure–property relationship of pyridoindole-type host materials for blue phosphorescent organic light-emitting diodes (PHOLEDs) was investigated by synthesizing three pyridoindole derivatives modified with Dibenzofuran, dibenzothiophene, and 9-phenylcarbazole. The 9-phenylcarbazole moiety was better than Dibenzofuran or dibenzothiophene to manage the energy levels and charge-transport properties of the pyridoindole-derived host materials. The PCb-PCz host with the 9-phenylcarbazole moiety showed balanced charge density in the emitting layer and exhibited a high external quantum efficiency of 29.7% in blue PHOLEDs.
Maria Jose Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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elution pattern of planar chlorinated biphenyls and 2 3 7 8 polychlorinated dibenzo p dioxins Dibenzofurans on chromatographic adsorbents and factors affecting the mechanism of retention possibilities of selective separation of both families
Journal of Chromatography A, 1997Co-Authors: Lourdes Ramos, L M Hernandez, Maria Jose GonzalezAbstract:Abstract A possible retention mechanism for planar chlorinated biphenyls and 2,3,7,8-polychlorinated dibenzo-p-dioxins/Dibenzofurans on alumina and Florisil columns is proposed. The influence of factos such as the surface activity of the adsorbents as well as the volume, selectivity and polarity of the solvents has been studied. A very similar elution pattern was found for alumina and Florisil. These results suggested that retention of the compounds on the surface of the adsorbent depends on the planarity of the molecule, on the localisation of the π-electron cloud and, less clearly, on the extended π-electron cloud of the congener. The best separation between both families with the highest recoveries of individual polychlorinated biphenyl and polychlorinated dibenzo-p-dioxins/Dibenzofuran congeners was obtained by using 6 g of Florisil activated at 450°C for 24 h.
Jiping Chen - One of the best experts on this subject based on the ideXlab platform.
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electrophilic chlorination of dibenzo p dioxin and Dibenzofuran over composite copper and iron chlorides and oxides in combustion flue gas
Chemosphere, 2020Co-Authors: Meihui Ren, Dan Wang, Yun Fan, Yuan Gao, Jiping ChenAbstract:Abstract Dibenzo-p-dioxin (DD) and Dibenzofuran (DF) chlorination mediated by Cu and Fe chlorides can make a direct contribution to the formation of polychlorinated dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) in combustion flue gas. In this study, a kind of composite Cu and Fe chlorides and oxides (CuFe9O9.5Cl10) was prepared by impregnating oxides with HCl solution to imitate the coexistence status of Cu and Fe species in combustion flue gas. Composite CuFe9O9.5Cl10 was active in promoting the electrophilic chlorination of DD/DF at 150–300 °C, with the highest activity at 200 °C. DD/DF chlorination could occur under inert atmosphere, and 5% O2 atmosphere was most favorable for DD/DF chlorination. Electrophilic chlorination of DD/DF primarily favored at 2,3,7,8 positions. Hybridization of Cu and Fe chlorides and oxides not only decreased the starting temperature and activation energy of DD/DF chlorination, but also induced a synergistic effect for accelerating the chlorination of DD/DF. The measured activities of composite CuFe9O9.5Cl10 for promoting the chlorination of DD/DF were near to those of composite Cu chloride and oxide (CuO0.2Cl1.6), whereas 2 orders of magnitude higher than those of composite Fe chloride and oxide (FeO0.3Cl2.4). Comparison of PCDD/F congener distribution patterns indicated that DD/DF chlorination should be a main source of Cl1−3DFs and Cl1−2DDs in combustion flue gases.
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mechanistic aspects of polychlorinated dibenzo p dioxins and Dibenzofurans pcdd fs formation from chlorine bleaching of non wood pulp
Journal of Hazardous Materials, 2020Co-Authors: Yuwen Ni, Faqiang Zhan, Boyu Song, Yichi Zhang, Jiping ChenAbstract:Abstract Chlorine bleaching of non-wood pulp can produce and release polychlorinated dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) into environment. In this study, a series of chlorination experiments were conducted to explore the source, formation pathway and formation kinetics of Cl1−8DD/Fs during the chlorine bleaching of wheat straw pulp. The 13C isotope-labeling experiment verified that PCDD/Fs could not be formed from the chlorination of phenols in pulp. Above 80% of the observed PCDFs originated from the direct chlorination of Dibenzofuran (DBF) in unbleached wheat straw pulp, while approximately 60% of the observed PCDDs came from the chlorination of nonextractable precursors in the pulp. The yield of total PCDFs was 2 orders of magnitude higher than that of total PCDDs. The kinetic study indicated that DBF was more easily chlorinated than dibenzo-p-dioxin (DBD) in the pulp solution. Pseudo-first-order reaction kinetic equations fitted the formation and degradation of PCDD/Fs well. The direct chlorination of DBD/F primarily preferred a selective pattern at the 2 position, followed by the 8, 7 and 3 positions. A higher content of DBF in unbleached pulp led to a higher yield of 2,3,7,8-Cl4DF. Finally, the practical implication for dioxin formation control was discussed.
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polychlorinated dibenzo p dioxin and Dibenzofuran precursors and formation mechanisms during non woodpulp chlorine bleaching process
Chemosphere, 2018Co-Authors: Xueli Wang, Jiping ChenAbstract:Abstract There is great concern about decreasing the amounts of polychlorinated dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) that are formed and emitted during the chlorine bleaching of pulp. The formation of PCDD/Fs during non-woodpulp chlorine bleaching was investigated in the study described here. Wheat straw was separated into three components, cellulose, hemicellulose, and lignin. Chlorination experiments were performed, and lignin and hemicellulose contributed more than cellulose to PCDD/F formation when the pulp was bleached using chlorine. The chemical components of lignin were identified by gas chromatography mass spectrometry, and nine possible PCDD/F precursors were quantified by gas chromatography tandem mass spectrometry. Spiked chlorination experiments were performed to investigate the effects of these compounds on PCDD/F formation. 4-Ethyl-2-methoxyphenol had the strongest effect on PCDD/F formation, followed by p-chlorophenol, and guaiacol. All the test compounds promoted polychlorinated Dibenzofuran formation but had limited effects on polychlorinated dibenzo-p-dioxin formation. The results allowed mechanisms for the formation of PCDD/Fs from phenol, chlorophenol, catechol, and guaiacol to be proposed.
Cornelia Huttner - One of the best experts on this subject based on the ideXlab platform.
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differential effect of elicitors on biphenyl and Dibenzofuran formation in sorbus aucuparia cell cultures
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Cornelia Huttner, Helge Scharnhop, Till Beuerle, Ludger Ernst, Ludger BeerhuesAbstract:The Rosaceous subtribe Pyrinae (formerly subfamily Maloideae) is well-known for its economically important fruit trees, such as apple and pear, and also includes Sorbus aucuparia. Elicitor-treated S. aucuparia cell cultures are used to study the biosynthesis of the Pyrinae-specific phytoalexins, biphenyls and Dibenzofurans. Three biphenyls (aucuparin, noraucuparin, 2′-hydroxyaucuparin) and a Dibenzofuran (eriobofuran) were isolated and structure elucidated using GC-MS and NMR. A second Dibenzofuran of low abundance was tentatively assigned as noreriobofuran. Treatment of S. aucuparia cell cultures with yeast extract induced the formation of aucuparin as the major phytoalexin. In contrast, addition of preparations from the fire blight bacterium, Erwinia amylovora, and the scab-causing fungus, Venturia inaequalis, resulted in accumulation of eriobofuran as the major inducible constituent. Methyl jasmonate was a poor elicitor. The observations are suggestive of a biogenic relationship between biphenyls and d...
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differential effect of elicitors on biphenyl and Dibenzofuran formation in sorbus aucuparia cell cultures
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Cornelia Huttner, Helge Scharnhop, Till Beuerle, Ludger Ernst, Ludger BeerhuesAbstract:The Rosaceous subtribe Pyrinae (formerly subfamily Maloideae) is well-known for its economically important fruit trees, such as apple and pear, and also includes Sorbus aucuparia. Elicitor-treated S. aucuparia cell cultures are used to study the biosynthesis of the Pyrinae-specific phytoalexins, biphenyls and Dibenzofurans. Three biphenyls (aucuparin, noraucuparin, 2'-hydroxyaucuparin) and a Dibenzofuran (eriobofuran) were isolated and structure elucidated using GC-MS and NMR. A second Dibenzofuran of low abundance was tentatively assigned as noreriobofuran. Treatment of S. aucuparia cell cultures with yeast extract induced the formation of aucuparin as the major phytoalexin. In contrast, addition of preparations from the fire blight bacterium, Erwinia amylovora, and the scab-causing fungus, Venturia inaequalis, resulted in accumulation of eriobofuran as the major inducible constituent. Methyl jasmonate was a poor elicitor. The observations are suggestive of a biogenic relationship between biphenyls and Dibenzofurans. Elicitor-treated S. aucuparia cell cultures provide an interesting in vitro system for studying biphenyl and Dibenzofuran metabolism in the economically valuable Pyrinae.