Bibliografías temáticas / Organic electron donors

Índice

Artículos de revistas
Tesis
Libros
Capítulos de libros
Actas de conferencias
Informes

Literatura académica sobre el tema "Organic electron donors"

Autor: Grafiati

Publicado: 25 de mayo de 2024

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros

Elija tipo de fuente:

Consulte las listas temáticas de artículos, libros, tesis, actas de conferencias y otras fuentes académicas sobre el tema "Organic electron donors".

Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.

También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.

Artículos de revistas sobre el tema "Organic electron donors"

Lowe, Grace A. "Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors". Beilstein Journal of Organic Chemistry 19 (8 de agosto de 2023): 1198–215. http://dx.doi.org/10.3762/bjoc.19.88.

Texto completo

Resumen

This review surveys advances in the literature that impact organic sacrificial electron donor recycling in artificial photosynthesis. Systems for photocatalytic carbon dioxide reduction are optimized using sacrificial electron donors. One strategy for coupling carbon dioxide reduction and water oxidation to achieve artificial photosynthesis is to use a redox mediator, or recyclable electron donor. This review highlights photo- and electrochemical methods for recycling amines and NADH analogues that can be used as electron donors in artificial photosynthesis. Important properties of sacrificial donors and recycling strategies are also discussed. Compounds from other fields, such as redox flow batteries and decoupled water splitting research, are introduced as alternative recyclable sacrificial electron donors and their oxidation potentials are compared to the redox potentials of some model photosensitizers. The aim of this review is to act as a reference for researchers developing photocatalytic systems with sacrificial electron donors, and for researchers interested in designing new redox mediator and recyclable electron donor species.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Murphy, John A. "ChemInform Abstract: Organic Electron Donors". ChemInform 43, n.º 37 (16 de agosto de 2012): no. http://dx.doi.org/10.1002/chin.201237244.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Garnier, Jean, Douglas W. Thomson, Shengze Zhou, Phillip I. Jolly, Leonard E. A. Berlouis y John A. Murphy. "Hybrid super electron donors – preparation and reactivity". Beilstein Journal of Organic Chemistry 8 (3 de julio de 2012): 994–1002. http://dx.doi.org/10.3762/bjoc.8.112.

Texto completo

Resumen

Neutral organic electron donors, featuring pyridinylidene–imidazolylidene, pyridinylidene–benzimidazolylidene and imidazolylidene–benzimidazolylidene linkages are reported. The pyridinylidene–benzimidazolylidene and imidazolylidene–benzimidazolylidene hybrid systems were designed to be the first super electron donors to convert iodoarenes to aryl radicals at room temperature, and indeed both show evidence for significant aryl radical formation at room temperature. The stronger pyridinylidene–imidazolylidene donor converts iodoarenes to aryl anions efficiently under appropriate conditions (3 equiv of donor). The presence of excess sodium hydride base has a very important and selective effect on some of these electron-transfer reactions, and a rationale for this is proposed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Broggi, Julie, Marion Rollet, Jean-Louis Clément, Gabriel Canard, Thierry Terme, Didier Gigmes y Patrice Vanelle. "Polymerization Initiated by Organic Electron Donors". Angewandte Chemie International Edition 55, n.º 20 (8 de abril de 2016): 5994–99. http://dx.doi.org/10.1002/anie.201600327.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Broggi, Julie, Marion Rollet, Jean-Louis Clément, Gabriel Canard, Thierry Terme, Didier Gigmes y Patrice Vanelle. "Polymerization Initiated by Organic Electron Donors". Angewandte Chemie 128, n.º 20 (8 de abril de 2016): 6098–103. http://dx.doi.org/10.1002/ange.201600327.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Martin, Julien D. y C. Adam Dyker. "Facile preparation and isolation of neutral organic electron donors based on 4-dimethylaminopyridine". Canadian Journal of Chemistry 96, n.º 6 (junio de 2018): 522–25. http://dx.doi.org/10.1139/cjc-2017-0526.

Texto completo

Resumen

A number of new neutral bis-2-(4-dimethylamino)pyridinylidene electron donors featuring N-akyl groups of varying lengths (propyl, butyl, hexyl, dodecyl) have been prepared from 4-dimethylaminopyridine by means of a simple two-step procedure. Each derivative could be isolated in high yield and could be stored indefinitely under inert atmosphere. The electron donors were chemically oxidized to the corresponding bipyridinium ions, and all compounds were characterized by NMR spectroscopy and cyclic voltammetry. As an emerging class of electron transfer agents, the availability of the isolated neutral bispyridinylidenes should be beneficial for cases that are incompatible with generating the electron donor in situ.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Broggi, Julie, Thierry Terme y Patrice Vanelle. "Organic Electron Donors as Powerful Single-Electron Reducing Agents in Organic Synthesis". Angewandte Chemie International Edition 53, n.º 2 (24 de noviembre de 2013): 384–413. http://dx.doi.org/10.1002/anie.201209060.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Zhou, Feng, Jing-Hui He, Quan Liu, Pei-Yang Gu, Hua Li, Guo-Qin Xu, Qing-Feng Xu y Jian-Mei Lu. "Tuning memory performances from WORM to flash or DRAM by structural tailoring with different donor moieties". J. Mater. Chem. C 2, n.º 36 (2014): 7674–80. http://dx.doi.org/10.1039/c4tc00943f.

Texto completo

Resumen

Four donor–acceptor organic molecules (HATT, HDTT, HETT and HRTT) consisting of different electron donors (phenol, triphenylamine, benzene and carbazole) and the same electron acceptor (triazole) were used as the active layer in NVM (nonvolatile memory) devices.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Xu, Tongle, Yuying Chang, Cenqi Yan, Qianguang Yang, Zhipeng Kan, Ranbir Singh, Manish Kumar, Gang Li, Shirong Lu y Tainan Duan. "Fluorinated oligothiophene donors for high-performance nonfullerene small-molecule organic solar cells". Sustainable Energy & Fuels 4, n.º 6 (2020): 2680–85. http://dx.doi.org/10.1039/d0se00335b.

Texto completo

Resumen

Two oligothiophenes were synthesized and used as electron donors in organic solar cells. The devices with a fluorinated donor (2FDC5T) achieved power conversion efficiencies of up to ca. 9.02% (vs. ca. 7.03% for the non-halogenated donor DC5T).

Los estilos APA, Harvard, Vancouver, ISO, etc.

Zhou, Shengze, Hardeep Farwaha y John A. Murphy. "The Development of Organic Super Electron Donors". CHIMIA International Journal for Chemistry 66, n.º 6 (27 de junio de 2012): 418–24. http://dx.doi.org/10.2533/chimia.2012.418.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Más fuentes

Tesis sobre el tema "Organic electron donors"

Schonebeck, Franziska. "Super electron donors powerful reductions performed by neutral organic molecules". Thesis, University of Strathclyde, 2007. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21732.

Texto completo

Resumen

This project aims to explore the ability of organic molecules to transfer electrons and is based on the recent development within the Murphy group of a novel organic molecule, called Super-S.E.T. reagent 1, that allows the reduction of unactivated aryl and alkyl iodides. My study investigates the scope of donor 1 as a reducing agent and extends the study to a more powerful donor 2. Chapter One provides an introduction to the world of electron transfer. After giving a theoretical background, synthetic applications of electron transfer are highlighted, in particular using metal chemistry, electrochemical and photochemical methods. This chapter also discusses the use of sulfones and sulfonamides as challenging substrates for electron transfer. Finally the field of neutral organic electron-donors, which form the basis of my studies, is introduced. Chapters Two to Seven then summarise my work. Chapter Two and the second part of Chapter Six highlight my adventures in investigating the chemistry of donor 1. Until now, donor 1 is known to reduce efficiently only specific aryl and alkyl iodides. This report (i) highlights the scope and limitations of donor 1 in the reduction of different aryl iodide substrates and of aryl halides other than iodides and (ii) discusses the application of donor 1 in the selective reduction of an ortho- over an analogous para-aryl iodide in substrate 3 and (iii) recounts the successful isolation of the first adduct of the donor, i.e. 4. Chapter Three to Six deal with the exploration of the power of Super-S.E.T. reagent 2. This donor was successfully applied as a powerful reducing agent in the reductive cleavages of a number of activated sulfones and sulfonamides, giving the reduced counterparts in excellent yields. Further, strong evidence for the first example of a Julia olefination using a neutral organic electron donor has been given. It was also shown that the reagent has remarkable reducing power, being the first neutral organic reagent to generate highly reactive aryl anion intermediates in the reduction of aryl 3 bromides and iodides. Ester substrates 5,6 and 7 were synthesised and investigated as mechanistic probes in that context. The chemistry of donor 2 with aliphatic halides was investigated, leading to the formation of aldehydes in DMF or DMA. It was found that the proportion of aldehyde can be increased with more equivalents of donor 2, ultimately leading to the aldehyde being the exclusive product. Using non-polar solvents, such as diethyl ether, donor 2 was transformed into a powerful reducing agent for alkyl bromides, reacting at room temperature and showing radical chemistry. Selective reduction of an alkyl over aryl bromide was achieved also. Intriguing reactivity was observed with anthracene esters, giving the dihydroester as one of the major products, if a carbene is added, and dihydroanthracene if not. After a summary of results in Chapter Seven, Chapter Eight presents the experimental procedures and analytical data for the compounds discussed in Chapters Two to Six.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Cumine, Florimond. "Studies on organic electron donors and their applications in chemistry". Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=29432.

Texto completo

Resumen

Electron transfer reactions using organic donors have been and are still successfully applied in the Murphy group to perform reductions usually requiring heavy metals. This thesis focuses on several organic electron donors used to: (i) promote the cross-coupling reaction between aryl halides and benzene, which was also studied with computational experiments, (ii) cleave carbon-oxygen bonds and (iii) reduce nitrobenzenes and azobenzenes. In addition, computational analysis of controversial literature proposals for a radical/electron transfer mechanism for ring-forming reactions of alkoxide allenes and amide allenes is reported and supports an anionic rather than a radical process. Chapter Two highlights the ability of diketopiperazines 1-4 to promote the cross-coupling reactions of aryl halides 5-16 with benzene in the presence of potassium tert-butoxide 17 to form biaryls 18-24 via electron transfer [graphic of electron transfer process]. It also investigates the different outcomes of the reaction when a diketopiperazine is used or not, providing evidence for formation of a benzyne intermediate which can lead to both the coupling product with benzene (when aryl iodides are used) and to tert-butoxybenzenes. Chapter Three explores electron transfer reactions that lead to alkyl aryl ether deprotection. It highlights that tert-butyllithium 25 performs this deprotection and shows the series of reactions that led to evidence of an anionic addition of phenyllithium 26 to benzene and also of tert-butyllithium 25 to benzene [graphic of base-induced process and additions to Benzene with oxidative termination]. Chapter Four focuses on a 4-DMAP-derived organic electron donor 32, commonly referred to as 'DMAP donor', that reduces nitrobenzene 34 and azobenzene 36, amongst others, under UV activation or thermal conditions, via successive single electron transfers. This chapter also discusses the unlikely possibility of an electron transfer from the DMAP donor 32 to the 1,2-diphenylhydrazine dianion 38 leading to the formation of aniline dianion 39. More rational mechanistic considerations involving the reduced diphenylhydrazine and dication 33 will be described to explain the formation of aniline 35 [graphic of DMAP electron donor]. Chapter Five is a computational study of the 5-endo-trig cyclisation of alkoxideallenes and amide-allenes, discussing the process involved (electron transfer or direct intramolecular anionic cyclisation) and comparing it with the, non-experimentally observed, 4-exo-dig cyclisation [DMSO graphic]. Chapter Six provides the detailed experimental procedures and data for the compounds that were synthesised and reported in this thesis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Buker, Nicholas D. "Guanidine donors in nonlinear optical chromophores /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8669.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Chua, Jonathan. "Exploring new reactions with Organic Electron Donors and the complexities of the Birch reduction". Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=26437.

Texto completo

Resumen

Reductive σ-bond cleavages of challenging substrates under metal-free, mild conditions have recently been achieved with photoactivated super-electron donor (SED). These include (but are not limited to) C-O bonds of benzylic ethers and esters, C-N bonds of benzylic sulfonamides and aromatic amides. This work has successfully widened the substrate scope of reduction by SED to include i) the C-O bond cleavages of phenolic esters and aryl ethers and ii) the C-S bond cleavages of aromatic sulfides, sulfoxides and sulfones. Previously it was also discovered that the X-N bond of several amides were reductively cleaved via intramolecular electron-shuttling instead of the more conventional through-bond electron transfer. This mode of reduction by SED is not well-explored. To this end, several ester and amide-based substrates were synthesised in an attempt to expand the scope of this electron-shuttling mechanism induced by SED. This study has also been successful, with the electron-shuttling effect thought to be responsible for the C-C bond cleavage of 14 [illustration not shown], resulting in the production of 15 [illustration not shown]. Perhaps the most powerful reducing agent in the synthetic industry is the "solvated electron" which is conveniently prepared during the Birch reduction. In this work, the Birch reduction conditions were successfuly applied, in an unprecedented way, to the C-S bond cleavage of methyl-coenzyme M (MeCoM). The experimental results have the potential to contribute significantly towards our current understanding of MeCoM reductase activity. This study has also highlighted the complex nature of the Birch reduction; by simply switching from sodium to lithium, reactivity and regioselectivity could be significantly altered. Presently, some details of the mechanism for the observed reduction(s) remain unsolved.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Anderson, Greg. "Towards the rational development of organic super electron donors for transition metal-free biaryl coupling". Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27424.

Texto completo

Resumen

Within both the industrial and academic laboratory, the coupling of two aryl moieties is a process of significant synthetic use. To achieve such transformations typically requires the use of expensive transition metal catalysts that cannot always be recovered from the reaction mixtures. Consequently, the investigation of biaryl coupling reactions without the requirement for any such catalysts has been of key interest amongst chemists. Throughout the literature, a variety of simple organic molecules have been incorrectly termed as “ligands” or “catalysts” with respect to their role in transition metal-free biaryl coupling reactions. We have discovered that these molecules in fact undergo reaction with a strong base to form an organic electron donor in situ, capable of reducing aryl iodides to their respective radical anions. This reduction can then initiate a cyclic radical reaction mechanism, furnishing the desired biaryl product. A number of key structures, identified through experimental studies, have helped to guide the early theoretical investigations. These allowed the feasibility of the formation of organic electron donors in situ, based on their free energy profiles, to be investigated. The mechanistic understanding gained from these calculations was then applied to rationalise the reactivity of other molecules shown to effectively promote this chemistry. To fully understand the reactivity in this chemistry, the computational application of Marcus Theory was called upon to predict the relative reducing ability of the proposed donor species. Shortcomings of the present protocol for the computational application of Marcus Theory prompted the development of a novel reaction model utilising electron transfer complexes. These complexes more accurately capture the internal reorganisation energy associated with the electron transfer reaction, affording calculated reaction energetics in stronger agreement with experiment. The foundations for the predictive application of this model to identify novel electron donors have been laid. Synthetic routes towards novel electron donor precursors have been identified for future work on this research.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tyree, William Stuart. "Correlation of Structure and Magnetic Properties in Charge-Transfer Salt Molecular Magnets Composed of Decamethylmetallocene Electron Donors and Organic Electron Acceptors". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34436.

Texto completo

Resumen

Di-n-propyl dicyanofumarate (DnPrDCF) and di-isopropyl dicyanofumarate (DiPrDCF) have been used as one-electron acceptors in the synthesis of charge-transfer salt magnets with decamethylmetallocenes, MCp*2 (M = Mn, Cr). Salts of each acceptor with each metallocene have been characterized and the structures of the chromium analogues have been solved. The two acceptors are structurally similar to dimethyl dicyanofumarate (DMeDCF) and diethyl dicyanofumarate (DEtDCF), which have been previously studied and found to form charge-transfer salt magnets with the aforementioned decamethylmetallocenes. A typical structural motif is present in these types of charge-transfer salts which allows for the comparison of magnetic properties based on the length or size of the alkyl group of the dialkyl dicyanofumarate. Some trends were established based on the magnetic properties of the homologous series including ordering temperature/bulkiness of the alkyl group and intrastack distances/theta values. Correlation of magnetic and structural properties may give some insight into "through-space" magnetic coupling, of which little is understood.
Master of Science

Los estilos APA, Harvard, Vancouver, ISO, etc.

Xu, Yunhua. "Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems". Doctoral thesis, Stockholm : Department of Organic Chemistry, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-411.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Zhao, Yuxi. "Synthèse de donneurs d’électrons organiques : application en synthèse organique et chimie des polymères". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0156.

Texto completo

Resumen

Les donneurs d'électrons organiques (DEO), aux potentiels redox exceptionnellement négatifs, ont montré un intérêt particulier en synthèse organique du fait de leurs fortes propriétés réductrices. Ils sont capables de transférer spontanément un ou deux électrons à des substrats organiques, formant ainsi des intermédiaires radicalaires ou anioniques. Néanmoins, la diversité structurale des DEO est limitée et leur champ d'application assez restreint.Dans cette thèse, nous avons tout d'abord développé de nouvelles bibliothèques de DEO afin d'identifier de nouvelles familles de réducteurs organiques, d'élargir la gamme de potentiels redox et d'accéder à de nouvelles réactivités. Des modulations structurales appropriées sur sept catégories de sels d'iminium ont donné accès à de puissants DEO avec diverses capacités réductrices. Cette étude a également permis de rationaliser les facteurs régissant le transfert d’un ou deux électrons en fonction de la structure du DEO et des conditions réactionnelles. Une enquête mécanistique plus approfondie a confirmé les structures des espèces donneuses d'électrons formellement actives. Enfin, les DEO se sont également avérés être de remarquables systèmes redox organiques pour l’amorçage de réactions de polymérisation radicalaire et anionique. Alors que la propagation anionique est initiée par réduction directe du monomère, la simple addition d'un oxydant compétitif, avec un potentiel de réduction plus élevé, permet de passer à un processus de propagation radicalaire. Ces stratégies de polymérisation ont montré une excellente applicabilité pour la préparation d'une large gamme de (co-)polymères à haute valeur ajoutée
Organic electron donors (OEDs) with exceptionally negative redox potentials have attracted considerable attention in organic synthesis as powerful reducers. They enable the spontaneous transfer of one or two electrons to organic substrates, to form radical or anionic intermediates. Nevertheless, the structural diversity of OEDs is limited and their application scope quite narrow. In this thesis, we first developed novel libraries of OEDs in order to identify new families of organic reducers, broaden the range of redox potentials and access new reducing reactivities. Appropriate structural modulations on seven categories of iminium salts gave access to powerful OED with various reducing abilities. It also allowed to rationalize the factors governing single- or double-electron transfers according to the OED structures and the reaction conditions. A more thorough mechanistic investigation was conducted to formally confirm the active electron donor species at work.Finally, OEDs also appeared to be remarkable organic redox initiating systems for both free radical and anionic polymerization reactions. While the anionic propagation was promoted by direct reduction of the monomer, simple addition of a competing oxidant with a higher reduction potential allowed to switch to a clean free radical propagation process. Scope investigation exhibited excellent applicability of these self-initiating polymerization strategies, which enabled the preparation of a large array of (co-)polymers with high added values

Los estilos APA, Harvard, Vancouver, ISO, etc.

Fall, Arona. "Donneurs d’électrons organiques : développement d’un nouveau système catalytique photoredox". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0607.

Texto completo

Resumen

Durant ces dernières décennies, la réactivité des donneurs d’électrons organiques de type énamine (DEO) a été largement exploitée dans des réactions de réduction par transfert électronique. De part leurs forts pouvoir réducteur avec des potentiels redox exceptionellement négatifs, les DEOs sont capables de transférer spontanément un ou deux électrons à des substrats organiques, formant ainsi des intermédiaires radicalaires ou anioniques. Cependant, ces DEOs sont toujours utilisés en quantité stœchiométrique, ce qui limite leur compétivité face aux catalyseurs organométalliques et organiques.Les travaux de cette thèse consistent à répondre à cette problématique en développant un nouveau système catalytique avec ces DEOs. Pour cela, plusieurs stratégies ont été envisagées. Dans une première méthode, une quantité catalytique du DEO serait utilisée pour amorcer le transfert d’électron pour la réduction du substrat. L’oxydation d’intermédiaires radicalaires générés, permettrait alors de régénérer le DEO. Cette stratégie n’a malheureusement pas donné de résultat. Une seconde méthode consisterait à régénérer le DEO à partir de la forme oxydée DEO2+, stable à l’air et d’un donneur d’électron sacrificiel (amine tertiaire, dithionite de sodium ou Rongalite®) sous photoactivation. Plusieurs étapes d’optimisation ont permis d’aboutir à un système catalytique photoredox efficace avec la forme oxydée comme photocatalyseur et la Rongalite® en tant que donneur sacrificiel. Ce nouveau système catalytique photoredox a été appliqué à la réduction de divers groupements fonctionnels (sulfone, halogénure d’aryle, triflate) par transfert mono et biélectronique
During this last decade, the reactivity of enamine-based organic electron donor (OED) has been widely explored in electron transfer processes. With exceptionally negative redox potentials, OEDs spontaneously promote single (SET) or double electron transfer (DET) to an organic substrate, to form radical or anionic intermediates. However, the use of stoichiometric amount of OEDs limits their competitivity compared to their organometallic and organic catalysts. This thesis project consisted in developing a new catalytic system with OEDs. Different strategies were envisaged. In a first method a catalytic amount of OED would initiate the electron transfer to reduce the substrate. The oxidation of the generated radical intermediate would allow the regeneration of OED. Unfortunately, this strategy was unsuccessful. The second strategy would consist in regenerating the OED from its air-stable oxidized form OED2+ and a sacrificial electron donor (tertiary amine, sodium dithionite or Rongalite®) under photoactivation. Several optimizing steps allowed the development of a new efficient catalytic photoredox system with the oxidized form as photocatalyst and Rongalite® as sacrificial electron donor. This new photoredox catalytic system was applied to the reduction of various functionals groups (sulfone, aryl halide and triflate) by single electron transfer (SET) and double electron transfer (DET). The reactivity of the photocatalytic system was also explored in radical addition reactions

Los estilos APA, Harvard, Vancouver, ISO, etc.

Turek, Amanda Katherine. "Activation of Electron-Deficient Quinones Through Hydrogen-Bond-Donor-Coupled Electron Transfer". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845499.

Texto completo

Resumen

Quinones are organic oxidants that play important roles in biological contexts and find wide application in organic synthesis. They are known to be activated toward electron transfer through hydrogen bonding, which has largely been observed for Lewis basic, weakly oxidizing quinones. Comparable activation through H-bonding is more difficult to achieve when more reactive, electron-deficient quinones are used, as these intrinsically weaker Lewis bases are less prone to engage in H-bonding interactions. Herein, we describe the successful application of HBD-coupled electron transfer as a strategy to activate electron-deficient quinones. A systematic investigation of several small-molecule HBDs allowed examination of the effects of H-bonding on electron transfer to o-chloranil, an electron-deficient quinone that lacks the intrinsic reactivity necessary to oxidize many organic substrates of synthetic interest. This study has led to the discovery that dicationic HBDs have an exceptionally large effect on the rate and thermodynamics of these electron transfer reactions. Favorable modulation of the thermodynamics occurs as a result of the stabilization provided to the reduced quinone (Q•–) by the HBD. Electrochemical experiments have allowed quantification of the binding affinity for Q•– to each of the HBDs, as well as elucidation of the binding stoichiometry of the resulting ground-state complex. Monocationic HBDs bind to Q•– with 2:1 stoichiometry, whereas dicationic HBDs bind in a 1:1 complex. Dicationic bis-amidinium salts exhibit significantly improved binding to Q•–, offering more thermodynamic stabilization to this reduced state. The effects of HBDs on the kinetics of electron transfer have also been evaluated under homogenous conditions. Reactions between o-chloranil and ferrocene derivatives exhibit pronounced HBD-dependent rate enhancements, with dicationic HBDs displaying the greatest effect. Relative to neutral dual HBDs, the bis-amidinium salts accelerate the rate of electron transfer by > 1012. Binding stoichiometries within the rate-limiting transition states corroborate the results determined electrochemically, and binding affinity correlates with rate enhancement was observed across the series of HBDs evaluated. Application of HBD-coupled electron transfer in an oxidative lactonization illustrates that this strategy is applicable to catalysis of organic reactions. A dicationic HBD catalyst affords the lactone product in nearly quantitative yield within 24 h, whereas o-chloranil alone was ineffective (< 5% yield). The rates of lactonization with several HBD catalysts correlate well with the thermodynamic and kinetic trends described above. This trend indicates that the rate of the oxidative lactonization is related to the ability of the HBD to promote an electron transfer step. Potential strategies for application in enantioselective transformations and possibilities for future mechanistic investigation are presented.
Chemistry and Chemical Biology

Los estilos APA, Harvard, Vancouver, ISO, etc.

Más fuentes

Libros sobre el tema "Organic electron donors"

Kapinus, E. I. Fotonika molekuli͡a︡rnykh kompleksov. Kiev: Nauk. dumka, 1988.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Ogura, F. y Y. Aso. Design of Novel Chalcogen-Containing Organic Metals: Extensively Conjugated Electron Donors and Acceptors with Reduced On-site Coulomb Repulsion. Taylor & Francis Group, 1992.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Solymar, L., D. Walsh y R. R. A. Syms. Semiconductors. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198829942.003.0008.

Texto completo

Resumen

Both intrinsic and extrinsic semiconductors are discussed in terms of their band structure. The acceptor and donor energy levels are introduced. Scattering is discussed, from which the conductivity of semiconductors is derived. Some mathematical relations between electron and hole densities are derived. The mobilities of III–V and II–VI compounds and their dependence on impurity concentrations are discussed. Band structures of real and idealized semiconductors are contrasted. Measurements of semiconductor properties are reviewed. Various possibilities for optical excitation of electrons are discussed. The technology of crystal growth and purification are reviewed, in particular, molecular beam epitaxy and metal-organic chemical vapour deposition.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Kirchman, David L. Processes in anoxic environments. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0011.

Texto completo

Resumen

During organic material degradation in oxic environments, electrons from organic material, the electron donor, are transferred to oxygen, the electron acceptor, during aerobic respiration. Other compounds, such as nitrate, iron, sulfate, and carbon dioxide, take the place of oxygen during anaerobic respiration in anoxic environments. The order in which these compounds are used by bacteria and archaea (only a few eukaryotes are capable of anaerobic respiration) is set by thermodynamics. However, concentrations and chemical state also determine the relative importance of electron acceptors in organic carbon oxidation. Oxygen is most important in the biosphere, while sulfate dominates in marine systems, and carbon dioxide in environments with low sulfate concentrations. Nitrate respiration is important in the nitrogen cycle but not in organic material degradation because of low nitrate concentrations. Organic material is degraded and oxidized by a complex consortium of organisms, the anaerobic food chain, in which the by-products from physiological types of organisms becomes the starting material of another. The consortium consists of biopolymer hydrolysis, fermentation, hydrogen gas production, and the reduction of either sulfate or carbon dioxide. The by-product of sulfate reduction, sulfide and other reduced sulfur compounds, is oxidized back eventually to sulfate by either non-phototrophic, chemolithotrophic organisms or by phototrophic microbes. The by-product of another main form of anaerobic respiration, carbon dioxide reduction, is methane, which is produced only by specific archaea. Methane is degraded aerobically by bacteria and anaerobically by some archaea, sometimes in a consortium with sulfate-reducing bacteria. Cultivation-independent approaches focusing on 16S rRNA genes and a methane-related gene (mcrA) have been instrumental in understanding these consortia because the microbes remain uncultivated to date. The chapter ends with some discussion about the few eukaryotes able to reproduce without oxygen. In addition to their ecological roles, anaerobic protists provide clues about the evolution of primitive eukaryotes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Clarke, Andrew. Metabolism. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199551668.003.0008.

Texto completo

Resumen

Metabolism is driven by redox reactions, in which part of the difference in potential energy between the electron donor and acceptor is used by the organism for its life processes (with the remainder being dissipated as heat). The key process is intermediary metabolism, by which the energy stored in reserves (glycogen, starch, lipid, protein) is transferred to ATP. In aerobic respiration the electrons released from reserves are passed to oxygen, which is thereby reduced to water. Not all ATP regeneration involves oxygen as the final electron acceptor, and not all oxygen is used for ATP regeneration, but oxygen consumption is often the simplest and most practical way to measure the rate of intermediary metabolism and the errors in doing so are believed to be small. The costs of existence, as estimated by resting metabolism, represent only a part (~ 25%) of the daily energy expenditure of organisms. The costs of the organism’s ecology (growth, reproduction, movement and so on) are additional to existence costs. Resting metabolic rate increases with cell temperature, indicating that it costs more energy to maintain a warm cell than it does a cool or cold cell. The temperature sensitivity of resting metabolism is highly conserved across organisms.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Raven, John. Phytoplankton Productivity. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199233267.003.0003.

Texto completo

Resumen

This chapter describes the productivity of phytoplankton, from the initial energy and chemical requirements for photosynthesis to the rate of production of heterotrophic organisms. Phytoplankton are the planktonic organisms which account for most of the primary production in the ocean. Their characteristic trophic mode is the production of organic compounds using energy from light and chemical elements from inorganic compounds, known as phototrophy, or more strictly photolithotrophy. This process uses water as the electron donor and the reduction of inorganic carbon producing sugars, from which all other cell components are made using inorganic forms of nitrogen, phosphorus, and all the other chemical elements needed to produce cells.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Bronson, Vincent. Guide to DIY Homemade Yoghurt: Fermentation Is an Enzyme-Catalyzed, Energy-generating Process in Which Organic Compounds Act As Both Donors and Acceptors of Electrons. Independently Published, 2021.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Capítulos de libros sobre el tema "Organic electron donors"

Graja, A., V. N. Semkin, N. G. Spitsina y S. Król. "Electron Donor-Acceptor Interactions of C60 with Tetraphenylphosphonium and Tetraphenylarsonium Halides". En Electrical and Related Properties of Organic Solids, 259–78. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5790-2_15.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Wróbel, Danuta y Bolesław Barszcz. "Quantum Dot and Fullerene with Organic Chromophores as Electron-Donor-Acceptor Systems". En Challenges and Advances in Computational Chemistry and Physics, 97–122. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-01355-4_3.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Newton, Marshall D. "Electronic Coupling of Donor—Acceptor Sites Mediated by Homologous Unsaturated Organic Bridges". En ACS Symposium Series, 196–218. Washington, DC: American Chemical Society, 2003. http://dx.doi.org/10.1021/bk-2003-0844.ch015.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Schubert, Marcel, Johannes Frisch, Sybille Allard, Eduard Preis, Ullrich Scherf, Norbert Koch y Dieter Neher. "Tuning Side Chain and Main Chain Order in a Prototypical Donor–Acceptor Copolymer: Implications for Optical, Electronic, and Photovoltaic Characteristics". En Elementary Processes in Organic Photovoltaics, 243–65. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-28338-8_10.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Williams, Jack M., K. Douglas Carlson, Aravinda M. Kini, H. Hau Wang, Urs Geiser, John A. Schlueter, Arthur J. Schultz et al. "Structure-Property Relationships in Radical-Cation (Electron-Donor Molecule) and Anion-Based (Including Fullerides) Organic Superconductors and their Use in the Design of New Materials". En Materials and Crystallographic Aspects of HTc-Superconductivity, 539–51. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1064-8_26.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Clark, K. F., D. Dimitrova y J. A. Murphy. "2.1 Organic Electron Donors in Electron-Transfer Reactions". En Free Radicals: Fundamentals and Applications in Organic Synthesis 2. Stuttgart: Georg Thieme Verlag KG, 2021. http://dx.doi.org/10.1055/sos-sd-233-00233.

Texto completo

Resumen

AbstractThe field of organic electron donors is large and diverse, both in terms of the structures of the donors and the structures of the acceptors. In the past 15 years, organic donors have been developed that show remarkable strength, with ground-state or excited-state oxidation potentials rivalling even the most reactive metals. At the other end of the scale of reactivity, highly reactive oxidizing agents are now available upon photoactivation of a number of organic structures. The first part of this chapter reviews organic electron donors that are based upon an alkene that is activated by strongly electron-releasing substituents; these donors can be active in the ground and/or excited states. The chapter also covers anionic organic donors that emerged in the field of SRN1 and base-induced homolytic aromatic substitution (BHAS) reactions, as well as substrate-based anionic donors including borates and silicates. The use of photoexcited organic dyes as electron donors is described and, finally, some of the recent research with very weak organic donors is highlighted.

Los estilos APA, Harvard, Vancouver, ISO, etc.

"Conjugated Polymers as Electron Donors in Organic Solar Cells". En Organic Solar Cells, 24–39. CRC Press, 2017. http://dx.doi.org/10.1201/b18072-5.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Cook, Michael y Philippa Cranwell. "Nucleophilic substitution". En Organic Chemistry, editado por Elizabeth Page. Oxford University Press, 2017. http://dx.doi.org/10.1093/hesc/9780198729518.003.0003.

Texto completo

Resumen

This chapter examines nucleophilic substitution. It begins by defining electrophiles and nucleophiles. An electrophile is a neutral or positively charged species with an empty orbital (or an energetically accessible anti-bonding orbital) which can accept electrons. Lewis acids can also be considered electrophiles as they have an empty orbital that can accept an electron pair. Meanwhile, a nucleophile contains a pair of electrons that can be used to form a new chemical bond. Nucleophiles thus act as electron donors. The chapter then looks at Lewis acids/bases.. The chapter then looks at Lewis acids/bases. It also considers S_N1 and S^N2, which are two classes of reaction that describe the nucleophilic substitution, or replacement, of one functional group at a saturated carbon centre by another. Finally, the chapter studies the impact of pK _a on leaving group ability.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Ogura, Fumio y Kazuo Takimiya. "Preparation of organic conductors". En Organoselenium Chemistry, 257–78. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198501411.003.0014.

Texto completo

Resumen

Abstract Since the striking discovery of the charge-transfer (CT) complex of tetrathiafulvalene (TTF, 1) and 7,7,8,8-tetracyanoquinodimethane (TCNQ, 2) as the first synthetic metal, the development of novel electron donors and acceptors and the synthesis of organic metals and superconductors from them have aroused great interest among not only organic chemists but also scientists in many other interdisciplinary areas.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Leonties, Anca R., Ludmila Aricov y Adina Raducan. "Electron Transfer". En Fundamental and Biomedical Aspects of Redox Processes, 344–68. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-7198-2.ch016.

Texto completo

Resumen

Oxidoreductases are a special class of enzymes that use the redox mechanism for the efficient transformation of organic substrates. Most oxidoreductases contain metals in the active site and, for optimal functioning, require the participation of a small co-substrate with the ability to donate electrons. From the multitude of enzymes with economic and applicable potential, the authors focused their attention on three particular classes: catalases, peroxidases, and laccases. Catalases and peroxidases contain heme iron in their active sites and most often require electron donors such as oxygen or hydrogen peroxide while laccase contains copper and demands special co-substrates such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) or syringaldehyde. The theoretical aspects regarding the mechanism in which the electron transfer of the three enzymes is involved as well as the practical applications of the selected enzymes in the field of environmental remediation will be the subject of this chapter.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Actas de conferencias sobre el tema "Organic electron donors"

Gu, Qinying y Dan Credgington. "Organic Photovoltaics Incorporating Electron Donors with Small Exchange Energy". En 1st International Conference on Advances in Organic and Hybrid Electronic Materials. València: Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.aohm.2019.040.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Sheats, John E., Andrew Jones, Albert Lang, Felicia Bland y Elizabeth Hernandez. "Organotransition Metal Complexes as π Acceptors in Non-linear Optical Materials". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/otfa.1993.wd.22.

Texto completo

Resumen

Previous investigators 1-4 have employed ferrocenyl derivatives as strong π-electron donors in the preparation of highly conjugated organic molecules such as Ia-c with high values of the second order hyperpolarizability, β.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tian, Mingzhen, Baozhu Luo, Wenlian Li, Shihua Huang y Jiaqi Yu. "Persistent Photon-gated Spectral Holeburning In A New Donor-Acceptor Electron Transfer System". En Persistent Spectral Hole Burning: Science and Applications. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/pshb.1991.fa7.

Texto completo

Resumen

Due to the interest in the frequency-domain optical storage application, recent researches on spectral holeburning concentrated on the two-colour photon-gated persistent holeburning[1,2]. Some organic systems have been investigated [3-7]. A representative one is TZT as a donor and CHCl3 as an acceptor in PMMA film undergoing donor-acceptor electron transfer, which offered a significant mechanism for persistent holeburning in organic system [4,5]. But there is an insurmountable problem in the system. As CHCl3 is volatile at room temperature, its concentration can not be controlled and the sample is difficult to further study. Here we report the holeburning system composed of metal-tetrabenzoporphyrin derivatives (MTBP) as the donors and a solid electron acceptor, p-hydroxybenzaldhyde (PHBA), which can easily be made into a stable "dry" film and in which the concentration of each component can be modified easily.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Ehrlich, J., A. Heikal, Z. Y. Hu, I. Y. S. Lee, S. R. Marder, J. W. Perry, H. Röckel y X. L. Wu. "Nonlinear Spectroscopy and Applications of Two-Photon Absorbing Molecules". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.tha.3.

Texto completo

Resumen

Molecules exhibiting strong two-photon absorption hold great potential for a wide range of applications including: two-photon fluorescence microscopy, three-dimensional (3D) optical data storage, 3D microfabrication, and optical limiting. (1-4) From a fundamental point of view, knowledge of molecular two-photon spectra and structure/property relationships are also important for a more complete understanding of the third order polarizabilities of conjugated molecules. However, very little is known or understood about two-photon states and spectra of conjugated molecules or how they correlate with structure. We have observed large two-photon absorptivities in bis-donor diphenylpolyene derivatives, that appears to be correlated to simultaneous charge transfer from the end groups to the pi-conjugated bridge in the molecule. These molecules are also excellent photoexcitable electron donors that can initiate charge-transfer reactions. In initial applications of these materials we have demonstrated their use in two-photon initiation of polymerization and optical limiting.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Jiang, Min-hua, Xu-tang Tao, Duo-rong Yuan, Nan Zhang y Dong Xu. "The Exploration of New Organic Crystals for Semiconductor Laser Second-Harmonic Generation". En Nonlinear Optics. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/nlo.1992.md31.

Texto completo

Resumen

The demand for miniature blue and violet laser applications has stimulated the research on nonlinear optical crystals for semiconductor laser (800-1000nm) second-harmonic generation (SHG).This paper summarized our recent development on the exploration of new organic nonlinear optical (NLO) materials for such purposes. Based on the features of organic crystals and the requirements of semiconductor lasers to the corresponding SHG materials. The relations between the crystal sturcture and the spectral characteristics as well as the NLO properties of the organic corjugated molecules were investigated. The electron spectra of the donors and acceptors and their influence on the NLO properties were analyzed. According to these results. We have made an approach for solving the contradiction existed between the UV transmission range and the nonlinear conversion efficiency of the crystals i. e. Substituting the medium and weak donor-acceptor radicals into benzene- the organic conjugated matrix, to form benjene derivatives. Which may possess both large NLO coefficients and good UV transmission property, and satisfy the requirement for diode laser SHG applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Ahrens, Michael J., Michael J. Fuller y Michael R. Wasielewski. "Aminated and cyanated perylene mono- and diimides: Liquid crystalline electron donors and acceptors for organic photonics and electronics". En Frontiers in Optics. Washington, D.C.: OSA, 2003. http://dx.doi.org/10.1364/fio.2003.tuj5.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Rovira, C., J. Veciana, J. Tarres, N. SantaIo, E. Molins, M. Mas, D. O. Cowan, S. Yang y E. Canadell. "Towards tridimensional organic metals. synthesis and study of mlrlti sulfur /spl pi/-electron donors and their charge transfer complexes and salts". En International Conference on Science and Technology of Synthetic Metals. IEEE, 1994. http://dx.doi.org/10.1109/stsm.1994.835659.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Patel, J. "Role of Plasma-Induced Liquid Chemistry for the Reduction Mechanism of Silver Ions to form Silver Nanostructures". En Functional Materials and Applied Physics. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901878-7.

Texto completo

Resumen

Abstract. There exists a variety of reports on the synthesis of silver nanostructures by plasma-liquid interactions; however seldom are those that discusses the underlying reaction kinetics. The present study focuses in such direction where the role of plasma-induced chemistry has been analysed in detail with the reports on the influence of radicals on the formation of silver nanostructures. The silver nanostructures are synthesized from various precursor concentrations of silver and characterized byultraviolet-visible spectroscopy and transmission electron microscopy analysis. Further, experiments have been carried out to clarify the role of reductants in silver nanostructures synthesis. It is found that hydrogen peroxide is unable to reduce the silver ions to silver atoms which is a necessary step to produce silver nanostructures. The addition of organic solvents such as methanol and ethanol has been found to enhance the production rate of silver nanostructures which indicates that methanol and ethanol are strong electron donors affecting the reduction process of silver ions. In order to probe the exact reaction mechanism for silver nanostructures synthesis, iodine has been used as hydrogen radical scavenger along with silver precursor solutions; however, it has been observed that addition of iodine ions generates a favourable condition for the reduction of silver ions. The ultraviolet-visible spectroscopy results indicate the existence of small clusters of silver ions and silver iodide and further transmission electron microscopy characterization suggests that a well-dispersed silver nanoparticles of less than 30 nm in size have been formed. The lattice spacing calculation from transmission electron microscopy images suggests the presence of crystallinity of the particles. Overall, it is found that there are two possible ways for the reduction mechanism of silver nanostructures: either via hydrated electrons or hydrogen radicals or both.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Cha, Myoungsik, Akira Otomo, William E. Torruellas, George I. Stegeman, David Beljonne, Jean Luc Brédas, Winfried H. G. Horsthuis y Guus R. Möhlmann. "Nonlinear Spectroscopy of DANS Side Chain Polymers". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.ma.5.

Texto completo

Resumen

Molecular systems, in particular polymers, with π-electron donor-acceptor groups are becoming potential candidates in applications where large bandwidth and low costs are desired for electro-optical modulation of optical information. Di-Phenyl molecules including Disperse-Red-1 and Di-Amino-Nitro-Stilbene (DANS) embody most of the requirements in stability, high loading, processability and very large electro-optical figures of merit1. However little is known about their electronic structure represented by their excited state spectrum and responsible for their nonlinear optical response, for both second and third order. We present a complete spectroscopic study of the DANS molecular system and compare our theoretical predictions to the second order nonlinear spectrum and four third order nonlinear optical spectra of amorphous DANS side-chain polymers. In particular we can successfully explain shifts of the nonlinear spectrum compared to the linear absorption one by properly accounting for Frank-Condon type displacements2.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Zyss, Joseph, Ifor Samuel, Céline FIORINI, Fabrice Charra y Jean-Michel Nunzi. "Permanent All Optical Poling of An Octupolar Dye". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.tue.1.

Texto completo

Resumen

The predominant class of molecular systems considered so-far towards applications in the realm of quadratic nonlinear optics has been derived from the all-pervading "molecular diode" template as exemplified by paranitroaniline-like molecules. The underlying basic paradigm consists in the dipolar anchoring of an interacting couple of electron donor and acceptor groups to a conjugated π electron linkage(1). The virtue of such a configuration is to provide a significant electronic charge displacement in the ground state which is further enhanced upon directional optical excitation towards the charge-transfer level. This basic mechanism has been confirmed by nearly two decades of experiments in solutions, crystals and polymer media with the two-level quantum model providing solid theoretical support(2). Both the Electric Field Induced Second Harmonic (EFISH) experiment and the current poled polymer technology essentially depend on the existence and magnitude of a strong ground state dipole μ contributing to the μ.E coupling potential between individual molecules and the externally applied de poling field E.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Informes sobre el tema "Organic electron donors"

Rittman, Bruce. Biotic Transformations of Organic Contaminants. The Groundwater Project, 2023. http://dx.doi.org/10.21083/ousn4116.

Texto completo

Resumen

Biodegradation—the breakdown of organic matter by microorganisms—is an important groundwater process that occurs naturally and is especially important for the in situ cleanup of contaminated groundwater. Pollutant biodegradation follows well-established principles that are summarized in this book. The first principle is that the microorganisms must grow and sustain themselves by oxidizing an electron-donor substrate (food) and transferring the electrons to an electron-acceptor substrate (respiration). This electron flow generates energy that the microorganisms use to fuel biomass synthesis. Most pollutants are either an electron acceptor or an electron donor, which means that their biotransformation can grow and sustain the microorganisms. Accordingly, it is critical to understand whether a pollutant is an electron donor or electron acceptor. This book systematically describes the biodegradation mechanisms for common organic pollutants in groundwater: The author identifies if the pollutant behaves as an electron donor or acceptor, and points out when special activation reactions are necessary to initiate biodegradation and put the pollutant into a chemical form that allows it to be an energy-yielding electron donor or acceptor. Special attention is given to organics derived from petroleum and those that have chlorine, fluorine, and nitro substituents.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Forsythe, Eric, Jianmin Shi y David Morton. Next Generation Highly Conducting Organic Films Using Novel Donor-Acceptor Molecules for Opto-Electronic Applications. Fort Belvoir, VA: Defense Technical Information Center, junio de 2009. http://dx.doi.org/10.21236/ada499643.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova y Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, enero de 2016. http://dx.doi.org/10.32747/2016.7604286.bard.

Texto completo

Resumen

The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Ofrecemos descuentos en todos los planes premium para autores cuyas obras están incluidas en selecciones literarias temáticas. ¡Contáctenos para obtener un código promocional único!