Dissertations / Theses on the topic 'Cobalt porphyrin'
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1
Medforth, C. J. "Cobalt (III) porphyrin N.M.R. shift reagents." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384368.
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Joshua, Warren A. C. "Reactions of some cobalt and rhodium complexes of macrocyclic N-donor ligands." Thesis, Kingston University, 1991. http://eprints.kingston.ac.uk/20551/.
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This thesis is principally concerned with the interaction of cobalt porphyrin complexes with halocarbons. There have been no previous studies of these, despite the afct that the ability to readily introduce substituents into the porphyrin ligand makes it ideal for inducing subtle electronic and steric changes into the complexes. The reactions of various substituted cobalt tetraphenylporphyrins with halocazbons was studied. Three series of experiments were performed involving activation by heat, visible light and ultraviolet light. Products were characterized by electronic, nmr and mass spectrometry. The five coordinate complexes, [CoX (Por)] , obtained from thermally activated reactions and those performed with uv irradiation under nitrogen, proved particularly difficult to characterize since they are subject to disproportionation giving paramagnetic products. This aspect is discussed in detail and the results obtained allow clarification of conflicting reports in the literature. A qualitative investigation of relative reaction rates has led to the tentative suggestion that thermal reactions proceed by an electron transfer mechanism, whereas an atom abstraction mechanism applies to reactions involving activation by ultraviolet light. No reaction took place between cobalt porphyrins and the substrates in the presence of visible light. Aerobic ultraviolet radiation results in the formation of cobalt porphyrin [pi]-cation radicals with either a1u or azU. ground states, depending on the substituent pattern of the porphyrin. The cobalt porphyrins were all shown to possess catalytic activity for halocarbon-alkene addition reactions. Furthermore, studies in this area suggest that the catalytic activity could be correlated wíth the substituent pattern on the porphyrin ligand and, thus, complements the studies described above. A related rhodium complex was also synthesized and examined but was shown to have a disappointingly low catalytic activity. Products of [RuC1[sub]2z(PPh[sub]3)[sub]3] -catalysed additions of halocarbons to cyclohexa-1,3-diene were investigated by chromatographic and spectroscopic analyses to ascertain the stereochemistry of the products. The ratio of the two isomeric products was found to depend on steric effects of the addend groups, CX[sub]3 (X = Cl, Br) and X (X = Cl, Br).
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Wang, Weilong. "Application of a cobalt porphyrin as catalyst in microbial fuel cells." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398947294.
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Tao, Jingran. "Asymmetric Nitrene Transfer Reactions with Azides via Co(II)-Based Metalloradical Catalysis (MRC)." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4590.
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Asymmetric nitrene transfer reactions via metalloradical catalysis (MRC) with
azides has attracted research interest because of its fundamental and practical importance.
The resulting nitrogen-containing units are recurrent motifs in biologically important
molecules and can serve as versatile precursors in organic synthesis.
The [Co(D2-Por*)] have emerged as a new class of catalysts for asymmetric
aziridination and C-H amination. These metalloradical catalysts have been shown to be
highly effective for the asymmetric intermolecular aziridination of a broad scope of
substrates with different classes of azides with excellent to good enantioselectivity. The
intramolecular C-H amination utilizing various azides can allow for the construction of
diverse nitrogen containing heterocyclic compounds.
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Lizardi, Christopher Lee. "Aldehydic C-H Amination Reactions via Co(II)-Based Metalloradical Catalysis and Construction of Novel Chiral meso-Amidoporphyrin Ligands." Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5526.
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Medium-sized organic ring synthesis poses a seemingly insurmountable challenge, and because of this it is a field under immense investigation. Heterocyclic containing medium-sized rings are common structural motifs in nature, which has caused researchers to investigate their potential biological activity and properties as materials. This research focused on the grand challenge of medium-sized heterocyclic ring synthesis, providing the synthesis community with new tools to generate these highly evasive products, while elucidating energetic and geometric properties of one of Nature's least understood organic ring systems.
Cobalt(II)-Amidoporphyrins, [Co(D2-Por)], are an emerging class of metalloradical catalysts (MRC) which can facilitate a wide range of atom and group transfer reactions. A strategy was employed using [Co(D2-Por)] to carry out an intramolecular C-H amination reaction using sulfamoyl azides as the radical nitrene source to aminate the highly reactive aldehydic C-H bond. This newfound reaction allowed for the generation of previously unobtainable medium-sized heterocycles, which surprisingly provided a racemic mixture of chiral medium-sized rings.
A wide array of chiral amidoporphyrins including meso-heteroatom containing porphyrins were synthesized as well during the course of research to probe their potential as new chiral ligands for the emerging field of cobalt(II)-amidoporphyrin catalyzed MRC system. A practical synthetic scheme was discovered employing the highly selective Zn(II)-bromoporphyrin synthon to generate a new library of chiral amidoporphyrin ligands for the MRC system through well-established cross-coupling methodologies.
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Houwaart, Torsten. "Cobalt porphyrins on coinage metal surfaces - adsorption and template properties." Thesis, Lyon, École normale supérieure, 2014. http://www.theses.fr/2014ENSL0927.
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Cette thèse est une étude théorique sur la interface de porphyrine de cobalt avec des surfaces métalliques avec le code VASP DFT. Le cadre DFT nécessaire a été introduit dans le chapitre 1. La structure de la jBardeen, une programme ecrit en Java, pour la simulation de la STM est expliqué dans le chapitre 2 et le code source est jointe en annexe. Une étude de l'adsorption de CoTPP sur les surfaces métalliques a été entrepris dans le chapitre 3. Différents paramètres de calcul ont été évalués: Le site d'adsorption et de la géométrie à la fois la molécule et la surface ont été étudiés par rapport à la xc-fonctionnel et correction de la dispersion utilisée. Une adsorption site le plus stable est identifié. Par conséquent, ce site plus stable a été étudiée pour sa structure électronique. Calculés images STM avec le code jBardeen ont été comparés avec une experimentation de CoTPP Cu sur une surface (111) avec une couverture sous monocouche. Dans le chapitre 4, un adatome Fe a été présenté à la CoTPP sur Ag système (111). Trois sites de liaison symétrique différentes pour l'atome Fe ont été identifiés sur le macrocycle, marqué les , bi-, brd- et bru-positions. Un moment magnétique pouvait être attestée qui a été principalement situé sur l'atome Fe. Voies possibles entre les quatre, symétriquement équivalentes, sites bi- ont été étudiées avec des méthodes différentes. Simples calculs dans le vacuum et calculs de la “Nudged Elastic Band” (NEB) de l'ensemble du système a révélé une hauteur de barrière légèrement au-dessus de 0,2 eV allant de position bi à la posititon brd. Une analyse de vibration a montré que la commutation de l'atome Fe est susceptible, lorsqu'il est perturbé hors d'équilibre dans les positions brd et bruThis thesis is a theoretical study on the cobalt porphyrin - coinage metal surface interface with the DFT code VASP. The necessary DFT framework has been introduced in chapter 1. The structure of the Java program jBardeen for STM simulation is explained in chapter 2 and the source code is attached as Appendix. A study of the adsorption of CoTPP on coinage metal surfaces has been undertaken in chapter 3. Different parameters of the calculation have been evaluated: the adsorption site and the geometry of both the molecule and surface have been investigated with respect to the xc-functional and dispersion correction used. A most stable adsorption site -bridge down- is identified. Consequently, this most stable site was investigated for its electronic structure. Calculated STM images with the jBardeen code were compared with an experiment of CoTPP on a Cu(111) surface with sub monolayer coverage. In chapter 4 an Fe adatom was introduced to the CoTPP on Ag(111) system. Three symmetrically different binding sites for the Fe atom were identified on the macrocycle, labelled the bi-, brd- and bru-positions for bisector, bridge down and bridge up respectively. A magnetic moment could be evidenced which was mainly located on the Fe atom. Possible pathways between the four symmetrically equivalent bisector sites were investigated with different methods. Single point calculations in vacuum and Nudged Elastic Band (NEB) of the whole system revealed a barrier height of slightly above 0.2 eV going from bi- to the brd-position. A vibrational analysis showed that switching of the Fe atom is likely, when perturbed out of equilibrium in the brd- and bru- positions
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Xu, Xue. "Asymmetric Intra- and Intermolecular Cyclopropanation by Co(II)- Based Metalloradical Catalysis." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4262.
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Metal-catalyzed cyclopropanation of olefins with diazo reagents has attracted research interest because of its fundamental and practical importance. The resulting cyclopropyl units are recurrent motifs in biologically important molecules and can serve as versatile precursors in organic synthesis. Since they were first introduced in 2004, Co(II) complexes of D2-symmetric chiral amidoporphyrins [Co(D2-Por*)] have emerged as a new class of catalysts for asymmetric cyclopropanation. These metalloradical catalysts have been shown to be highly effective for asymmetric intermolecular cyclopropanation of a broad scope of substrates with different classes of carbene sources, particularly including electron-deficient olefins and acceptor/acceptor-substituted diazo reagents, with excellent diastereoselectivity and enantioselectivity.
This dissertation focuses on exploring the Co(II)-based metalloradical catalyzed enantioselective cyclization reactions. It includes expanding families of catalysts, types of reactions and classes of substrates. With the developed novel approach for chiral porphyrin ligands, a new family of catalysts bearing different electronic and steric characters was synthesized. They turned out to be better catalysts for metalloradical cyclization in many cases, for instance, enantioselectivity of intramolecular cyclopropanation reached up to 99% with new catalyst. Besides the catalyst synthesis, more challenging diazo reagents were successfully employed in both intra- and intermolecular cyclopropanation for direct synthesis of highly functionalized cyclopropanes. Moreover, a tandem radical cyclization process beyond cyclopropanation was discovered, dihydrofuran was generated in a highly selective manner. Last but not least, we developed some novel applications of cyclopropane products, which could potentially lead to more exciting works.
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Xia, Wei [Verfasser], Bernhard [Akademischer Betreuer] Rieger, and Thomas F. [Akademischer Betreuer] Fässler. "Cobalt Porphyrin Catalysts Utilised in the Copolymerisation of CO2 and Propylene Oxide / Wei Xia. Gutachter: Thomas F. Fässler ; Bernhard Rieger. Betreuer: Bernhard Rieger." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1071370049/34.
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Ledung, Greger. "Heterogenization of a Cobalt Porphyrin Catalyst Investigated by Scanning Probe Microscopy and X-Ray Photoelectron Spectroscopy: The Effect on Catalysis of Oxidation Reactions." Doctoral thesis, Västerås : School of sustainable Development of Society and technology, Mälardalen university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-492.
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Ladd, Richard Maurice. "Synthesis of the zinc and cobalt derivatives of meso-(4-sulphonatophenyl)-porphyrin for use as diamagnetic shift reagents in nuclear magnetic resonance studies." Thesis, Manchester Metropolitan University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238379.
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Gill, Joseph B. "Co(II) Based Metalloradical Catalysis| Carbene and Nitrene Transfer Reactions." Thesis, University of South Florida, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3666726.
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Radical chemistry has attracted a large amount of research interest over the last few decades and radical reactions have recently been recognized as powerful tools for organic synthesis. The synthetic applications of radicals have been demonstrated in many fields, including in the synthesis of complex natural products. Radical reactions have a number of inherent synthetic advantages over their ionic counterparts. For example, they typically proceed at fast reaction rates under mild and neutral conditions in a broad spectrum of solvents and show significantly greater functional group tolerance. Furthermore, radical processes have the capability of performing in a cascade fashion, allowing for the rapid construction of complex molecular structures with multiple stereogenic centers. To further enhance the synthetic applications of radical reactions, current efforts are devoted toward the development of effective approaches for the regioselective control of their reactivity as well as stereoselectivity, especially enantioselectivity, a challenging issue that is intrinsically challenged by the "free" nature of radical chemistry.
This research has identified a fundamentally new approach to radical reactions based on the concept of metalloradical catalysis (MRC) for controlling the stereoselectivity of both C- and N-centered radical reactions. Cobalt(II) porphyrins [Co(Por)], are stable metalloradicals, and have been shown to enable the activation of diazo reagents and azides to cleanly generate C- and N-centered radicals, respectively, with N2 as the only byproduct in a controlled and catalytic manner. In addition to the radical nature of [Co(Por)], the low bond dissociation energy of Co-C/Co-N bonds plays a key role in the successful turnover of the Co(II)-based catalytic carbene and nitrene transfers. Through the support of porphyrin ligands with tunable electronic, steric, and chiral environments, this general concept of Co(II)-based metalloradical catalysis (Co-MRC) has been successfully applied to the development of various radical processes that enable stereoselective carbene and nitrene transfers.
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Cromer, Rémy. "Porphyrines n-substituees : modelisation de l'inhibition d'hemoproteines." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13015.
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Migration cobalt-azote des groupements : phenyl et styryl. L'etude des reactions de migration dans les porphyrines de cobalt(iii) aryliques a justifie l'utilisation de ces dernieres pour modeliser l'hydrazinolyse des hemoproteines. Les porphyrines de cobalt(iii) aryliques ont un comportement analogue a celui des porphyrines de fer(iii) aryliques. Oxydation des styryl -co(iii) porphyrines. Mecanisme de reaction. Extension de cette reaction a la cyclisation en serie arylique qui permet la synthese de la premiere porphyrine n,n'-(phenylene-1,2) analogue du produit d'inhibition suicide obtenu apres activation de l'amino-1 benzotriazole par divers enzymes a cytochrome p-450
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Jérôme, François. "Synthèse et réactivité de dérivés bimacrocycliques face à face de type biscorrole et porphyrine-corrole." Dijon, 2000. http://www.theses.fr/2000DIJOS056.
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ACe manuscrit apporte une contribution dans le domaine de la synthèse et de la réactivité de systèmes homo ou hétérobimacrocycliques face à face à base du macrocycle corrole et/ou du macrocycle porphyrine. L'intérêt majeur de notre travail concerne les points suivants : la métallation d'un hétérobimacrocycle de type porphyrine-corrole par le cobalt conduit à la formation d'un système à valence mixte PCo(II)/Co(III) Cor. Ce système présente une très forte affinité pour le dioxygène et trouve directement son application dans le domaine du transport du dioxygène mais également dans le domaine des piles à combustible. La synthèse et la métallation par le cobalt d'un homobimacrocycle de type biscorrole montre la flexibilité du système. Sa métallation par le nickel conduit quant à elle a la formation d'une nouvelle famille de bimacrocycle : les bisoxocorroles. L'utilisation des dérivés de type (COD)MC1 x n (M = Ru, Rh) a permis l'accès aux premières liaisons métal-métal dans la chimie des corroles.
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Griveau, Sophie. "Analyse de l'activité électrocatalytique de matériaux moléculaires, à base de films de porphyrines et de phtalocyanines de cobalt électropolymérisés, vis-à-vis de l'oxydation de thiols : application à l'électroanalyse." Paris 6, 2002. http://www.theses.fr/2002PA066165.
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Takeuchi, Toshihiko Gray Harry B. Goddard William A. Meade Thomas J. "The electronic structure of distorted porphyins and cobalt schiff base derivatives as novel enzyme inhibitors." Diss., Pasadena, Calif. : California Institute of Technology, 1996. http://resolver.caltech.edu/CaltechTHESIS:11052009-085123252.
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Thesis (Ph. D.)--California Institute of Technology, 1996. UM #9617425.Advisor names found in the Acknowledgments pages of the thesis. Title from home page. Viewed 01/19/2010. Includes bibliographical references.
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Mikros, Emmanouil. "Analyse conformationnelle en solution aqueuse de complexes d'acides aminés avec des porphyrines de cobalt (III) hydrosolubles." Paris 11, 1988. http://www.theses.fr/1988PA112219.
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A 1H NMR spectroscopic study of intramolecular interactions has been made for the octahedral complexes of cobalt (III) Co (L) (P) in water solutions. P refers to 4-N-methylpyridyl por phyrine(TMPyP) and 4carboxylphenylporphyrine(TCPP)and L to amino acid. Spectra obtained in various pH confirms the equilibrium between different complexes existing. When L contains two atoms which con bind to Co. An equilibrium also exists between different species. The stability of the complex increases with the basicity of the ligand. The conformation of the complexed aminoacids in L2CoTMPyP has been deduced from the 3J coupling constants. It was shown that for all aminoacids: a) the conformation around the N-C bond appears to be a nearly eclipsed geometry b) a staggered rotamer is predominant around Ca-Cᵝ bond. The fractional populations of the three rotamers calculated from coupling constants indicated that the rotamer capable of intramolecular interactions between the side chain and the porphyrin ring is favored as compared to the free aminoacid. Proton coordinates were calculated from the induced shifts using a Johnson-Bovey type model of ring-current. The ring of the aromatic aminoacids lies parallel to the porphyrin nucleus at a distance of ca 3. 5 Å. The free energy gain due to the hydrophobie or electrostotic interactions has been calculated (from the constant K=PI/PII+PIII of the "closed form-opened form" equilibrium) for the free and for the bound aminoacid. The order observed is: indole> phenol>benzene>phenolote>imidazole>sobutyl. Variable temperature measurement reveal that the enthalpic change contributes to the hydrophobic interaction. The electrostatic interactions were shown to contribute from a comparison between complexes with CoTMPyP and CoTCPP. Only the conformation of polar aminoacids like Asp, Asn and Ser werefound to be differentOn rapporte l'analyse conformationnelle en solution aqueuse par RMN 1H de complexes octaédriques du cobalt, de formule générale [L2CoTMPyP]5+Cl- et [L2CoTCPP] où TMPyP=tétra-N-méthylpyri dylporphyrine, TCPP=tétracarboxylphénylporphyrine et L=acide aminé. L'équilibre entre les différents complexes formés par réactions de Co(III)TMPyP avec les acides aminés a été étudié en fonction du pH. Lorsque le ligand amino acide contient deux groupements susceptibles de se lier au cobalt, il existe aussi un équilibre entre différentes espèces. La stabilité de différents complexes est d'autant plus grande que la basicité du ligand augmente. La conformation des acides aminés complexés a été déterminée à partir les constantes de couplage 3J interprotoniques. Pour tous les acides aminés il a été démontré: a) une conformation unique éclipsée autour de la liaison NCa b) une conformation décalée prédominant autour de la liaison Ca-Cᵝ. Les populations relatives de ces conformations ont été calculées à l'aide des constantes 3J. La stabilisation importante d'une conformotion dons l'acide aminé complexé par rapport à l'acide aminé libre s'explique en termes d'interactions entre la chaîne latérale et le cycle porphyrinique. La géométrie de certains complexes a été déduite à partir des déplacements chimiques induits par le cycle porphyrinique ou moyen d'un modèle empirique de type Johnson-Bovey. Le plan du noyau aromatique pour les acides aminés aromatiques est parallèle au plan du cycle porphyrine à une distance 3,5 À. Le gain d'énergie libre, dû aux interactions hydrophobes ou électrostatiques a pu être calculé (à partir des constantes d'équilibre K=PI/PII+PIII) pour l'acide aminé complexé. L'ordre de stabilisation décroissante observé est: indole>phénol>benzène>phénolate>imidazole >isobutyle. Une étude en fonction de la température montre que le terme enthalpique contribue de manière significative. Les interactions électrostatiques ont été mises en évidence dans les complexes des acides aminés avec CoTCPP. Les seuls acides aminés dont la conformation est différente dans les deux types des complexes sont les complexes avec l'Asp, l'Asn et la Ser
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Mikros, Emmanouil. "Analyse conformationnelle en solution aqueuse de complexes d'acides aminés avec des porphyrines de cobalt (III) hydrosolubles." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376165321.
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Bolze, Frédéric. "Synthèse et caractérisation de complexes métalliques en série bismacrocyclique." Dijon, 2001. http://www.theses.fr/2001DIJOS029.
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Ce mémoire apporte une contribution à la synthèse de monocorroles, de biscorroles, de bisporphyrines face à face et à l'étude de leurs propriétés photophysiques. L'intérêt majeur de notre travail concerne les points suivants : - Synthèse de Pacman porphyrines libres ainsi que leurs complexes homo et hétérobimétalliques - Synthèse de biscorroles face à face - Synthèse de monocorroles alkyl et aryl substitués - Etude photophysique de Pacman porphyrines bases libres et de leurs complexes métalliques - Etude de la réactivité des corroles de cobalt vis à vis de la pyridine et du monoxyde de carbone.
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Chniti, Meherzia. "Propriétés optiques non linéaires des composés porphyriniques à base de cobalt et de zinc de type push-pull." Thesis, Angers, 2016. http://www.theses.fr/2016ANGE0030/document.
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Cette étude traite des propriétés optiques non linéaires (NL) du troisième ordre des tétraphénylporphyrines et de certains de ses dérivées métallisées (Zn, Co) dissoutes dans le chlorobenzène. Les solutions ont été exposées à un laser émettant à 1064 nm, 532 nm et 355 nm dans le régime picoseconde ( ≈ 10 ps) en utilisant la méthode D4σ-Z-scan dans un montage 4f ainsi qu’une nouvelle technique appelée Dark-Field Zscan. Cette dernière se révèle être très fiable pour la détermination directe du signal de réfraction non linéaire en présence d’une forte absorption linéaire et/ou non linéaire. Le comportement des coefficients non linéaires a été étudié en fonction de la concentration et de l’intensité laser. La réponse a été attribuée à une susceptibilité effective du 3eme ordre {χ} rsub {eff} rsup {(3)} = {χ} ^ {(1)} : {χ} ^ {(1)} , dominée par un processus en cascade. Il a été mis en évidence que le comportement optique non linéaire des porphyrines dépend fortement du métal incorporé et de la durée des impulsions par rapport aux durées de vie des états excités. Ces résultats démontrent aussi que l’extension des systèmes électroniques π -conjugués accroît les non linéarités du troisième ordre de ces complexes, ce qui devrait être utile à l’élaboration de nouveaux matériaux. Cette propriété se révèle être intéressante pour la synthèse de porphyrines plus complexes avec d’autres substituants. Les effets importants d'absorption et de réfaction NL donnent aux porphyrines un fort potentiel d’utilisation pour la limitation optique, la commutation optique et pour différents autres applications en optique non linéaireThis study deals with the third-order nonlinear optical properties (NL) of tetraphenylporphyrins and some of its metallic derivatives (Zn, Co) dissolved in chlorobenzene. The solutions were exposed to a laser emitting at 1064 nm, 532 nm and 355 nm in the picosecond regime ( ≈ 10 ps) using D4σ-Z-scan method in a 4f setup and a new technique called Dark-Field Zscan. The latter provides to be very reliable for the direct determination of the nonlinear refractive signal in the presence of a strong linear absorption and / or nonlinear one. The behavior of nonlinear coefficients has been studied as a function of the concentration and laser intensity. The response has been attributed to an effective 3rd order susceptibility, {χ} rsub {eff} rsup {(3)} = {χ} ^ {(1)} : {χ} ^ {(1)} , dominated by a cascading process. It has been demonstrated that the nonlinear optical behavior of porphyrins strongly depends on the metal incorporated and the pulse duration when compared to lifetimes of the excited states. These results also demonstrate that the extension of π- conjugated electronic systems increases the third order nonlinearities of these complexes, which should be useful in the development of new materials. This property appears to be interesting for the synthesis of more complex porphyrins with other substituents. The high impact on the coefficients related to the NL absorption and refraction gives porphyrins great potential of use for applications in optical limiting, optical switching
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Sbai, Mohammed. "Photoréactivité de complexes du ruthénium et du cobalt : dérivés polyruthéniés en solution homogène, phorphyrines dans des interfaces." Montpellier 2, 1991. http://www.theses.fr/1991MON20297.
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Ce travail est compose de deux parties differentes. La premiere concerne des complexes du ruthenium, moleculaires, a proprietes electroniques originales, la seconde etant orientee vers l'etude de porphyrines en milieux micellaires. Une nouvelle famille de complexes du ru obtenue par assemblage sequentiel de ligands doublement tridentates et termines par des terpyridines est etudiee par spectroscopie electronique d'adsorption et d'emission et par electrochimie. Les composes binucleaires possedent des formes a valence mixtes tres stables. Les emissions dans le visible ou le proche infra-rouge sont accompagnees d'emissions dans l'uv ou le violet. Ces emissions anormales sont dues a la presence de ligands tridentates complexes sur deux positions. La reaction de complexation de l'oxygene declenchee par une photodeligandation connue pour co tpp est etendue aux porphyrines de ruthenium mais la reversibilite est moins bonne pour ces dernieres. Il est aussi montre que la photodissociation de co a partir de la molecule rutpp(co) qui est efficace en solution homogene est totalement inhibee en milieux micellaires. Ce phenomene est analyse en detail et une interpretation basee sur un deplacement de la bande d'absorption photoactive est proposee. Les rendements quantiques de photodissociation et ceux de luminescence sont determines pour tous les composes emissifs etudies dans l'ensemble de ce travail
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Ngameni, Emmanuel. "Comportement électrochimique de biporphyrines adsorbées ou en solutions aqueuses acides : Etude du pouvoir catalytique de la biporphyrine de cobalt, CO::(2) FTF4, à l'égard de la réduction de l'oxygène." Brest, 1988. http://www.theses.fr/1988BRES2021.
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Xiang, Feifei [Verfasser], M. Alexander [Akademischer Betreuer] Schneider, M. Alexander [Gutachter] Schneider, and Hans-Peter [Gutachter] Steinrück. "Scanning Tunneling Microscopy Investigations of Porphyrins on Cu(111) and Cobalt Oxide Films: Adsorption, Self-Assembly and On-Surface Synthesis / Feifei Xiang ; Gutachter: M. Alexander Schneider, Hans-Peter Steinrück ; Betreuer: M.Alexander Schneider." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1206416823/34.
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Martins, Paulo Roberto. "Preparação de hidróxidos mistos nanoestruturados de níquel/cobalto e desenvolvimento de sensores FIA amperométricos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-06092012-093005/.
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Nesta tese foram desenvolvidos sensores amperométricos baseados em porfirinas supramoleculares e hidróxido de níquel nanoestruturado e estabilizado na fase alfa, bem como novos materiais baseados em hidróxidos mistos de níquel e cobalto nanoetruturados e estabilizados na fase alfa. Também, um analisador FIA amperométrico, foi desenvolvido em colaboração com o Laboratório de Instrumentação Analítica do IQ-USP, para a determinação e quantificação de SO2 livre em amostras reais, como vinhos, águas de coco e sucos de frutas. Os sensores amperométricos baseados em porfirinas supramoleculares foram empregados na determinação de SO2 livre, presente em sucos de frutas e águas de coco, utilizando um sistema FIA amperométrico. O sistema FIA amperométrico foi constituído de um injetor manual, uma cela amperométrica em fluxo integrada a uma unidade de difusão de gases e um fluxo de uma solução de ácido sulfúrico e de uma solução de eletrólito. Possíveis interferentes como ácido ascórbico, catecol, glicose e benzoato de sódio foram avaliados antes de iniciar as análises das amostras reais. Os resultados das análises foram comparados com o método oficial Monier-Williams. Os níveis de SO2 livre encontrados nas amostras estavam de acordo com o que é preconizado pela Legislação Brasileira. Os eletrodos de FTO, modificados com hidróxido de níquel estabilizado na fase alfa, foram utilizados como sensores amperométricos para a determinação de glicose, usando um sistema FIA amperométrico. Estes sensores apresentaram excelentes respostas lineares em concentrações inferiores a 100 µM. Ainda estes sensores têm apresentado uma sensibilidade específica muito elevada para a glicose, provavelmente associada com a sua natureza nanoestruturada, e consequêntemente sua área superficial aumentada. No entanto o eletrodo modificado apresentou uma tendência de mudar de fase, da fase meta-estável alfa para a fase termodinamicamente estável beta, com o aumento da concentração de glicose. Novos materiais baseados em hidróxidos mistos de níquel e cobalto estabilizados na fase alfa também foram desenvolvidos. A partir de técnicas como difratometria de raio-x e Microbalança Eletroquímica de Cristal de Quartzo (MECQ) foi possível determinar a fase polimórfica dos materiais. Técnicas como AFM e MEV demonstraram que estes materiais são formados por nanopartículas com tamanhos de 5 nm. Estes nanomateriais apresentaram uma maior quantidade de carga específica, em comparação com o hidróxido de níquel puro. E por último um analisador FIA amperométrico automatizado foi desenvolvido para a realização de análises de SO2 livre em amostras líquidas. Este analisador é composto por reservatórios de soluções, sistema de amostragem, sistema de propulsão das soluções, cela FIA amperométrica integrada a uma unidade de difusão de gases, um sensor amperométrico, além de placas controladoras, mini-potenciostato e um software para controlar o equipamento. Uma elevada reprodutibilidade foi alcançada para análises sequenciais de uma amostra, mas quando a amostra foi trocada a reprodutibilidade foi muito baixa, sendo necessário mais desenvolvimento do sistema FIA automatizado nesta área.New nanomaterials based on mixed nickel and cobalt hydroxides stabilized in the alpha phase, as well as amperometric sensors based on supramolecular porphyrins and stabilized alpha nickel hydroxide were developed in this thesis. An amperometric FIA sulfite analyzer was also developed in colaboration with of Group of Analytical Instrumentation of IQ-USP, for determination of free SO2 present in liquid samples such as wine, coconut water and fruit juices. The amperometric FIA system is constituted by manual injector, amperometric FIA cell with integrated gas diffusion unit and amperometric sensor based on supramolecular porphyrins, whereas sulfuric acid and electrolyte were used as reactive and carrier solution. Some species such as ascorbic acid, cathecol, glucose and sodium benzoate were evaluated as possible interferents before starting the analyses of real samples. The results were compared with those obtained with the official Monier-Williams method. The concentrations of free SO2 found in fruit juices and coconut water were in accordance with Brazilian law. The amperometric FIA sensors for determination of glucose were based on FTO electrodes modified stabilized alpha nickel hydroxide, which presented excellent linear responses at concentrations below 100 µM. These sensors have shown a very high specific sensitivity for glucose probably associated with their nanostructured nature, and consequent enhanced surface area. Nevertheless, the electrode material was shown to have an increasing tendency to change from alpha to the beta phase as function of the glucose concentration. New materials based on mixed nickel and cobalt hydroxides, stabilized in the alpha phase was prepared and characterized by techniques such as X-ray diffraction, thermogravimetric analysis and Electrochemical Quartz Crystal Microbalance to determine their polymorphic phase. The nanostructured nature of the mixed nickel and cobalt hydroxide materials was confirmed by microscopy techniques such as AFM and SEM. These new materials showed a high specific charge, in fact higher than of nanostructured stabilized alpha nickel hydroxide. An amperometric FIA sulfite analyzer system for liquid samples consisting of solution reservoirs, a sampling system, a solution propulsion system, an amperometric FIA cell with integrated gas diffusion unit, an amperometric sensor based on supramolecular porphyrins, in addition to controller boards, a mini-potentiostat and control software, was developed and tested for determination of free SO2. High reproducibility was achieved for sequential analyses of a sample but the reproducibility after exchange of samples was relatively low, needing further developments in the sampling system.
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Le, Mest Yves. "Etude des propriétés électrochimiques de biporphyrines de type "face-à-face" : réactivité des dérives du cobalt vis-à-vis de l'oxygène." Brest, 1988. http://www.theses.fr/1988BRES2013.
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Cartier, dit Moulin Christophe. "Structures fines d'absorption des rayons X de complexes moléculaires d'éléments de transition de la premiere période." Paris 11, 1988. http://www.theses.fr/1988PA112002.
Full textAbstract:
Ce travail est consacré à l'étude par spectroscopie d'absorption des rayons X de complexes moléculaires d'éléments de transition de la première période. Une première partie porte sur l'étude fondamentale des structures fines au seuil d'absorption : nous utilisons la flexibilité de la chimie de coordination pour étudier des complexes de stéréochimie et de structure électronique variées. Pour des molécules discrètes de structure connue, nous mettons en évidence l'influence sur le seuil du degré d'oxydation et de l'état de spin de l'élément de transition, de la symétrie du site, des distances métal-ligand et des différentes couches de voisins. Nous interprétons les transitions vers des états liés dans une approche orbitale moléculaire. Dans le domaine d'énergie où le photoélectron est éjecté, nous utilisons l'approche "diffusion multiple". L'intérêt et les limites des deux modèles sont discutés. Enfin, la présence de bandes d'intensité faible est attribuée à des transitions biélectroniques. La compréhension de l'influence des différents paramètres électroniques et structuraux qui déterminent les structures fines du seuil, et l'analyse EXAFS, sont ensuite utilisées pour l'étude structurale et stéréochimique de matériaux nouveaux intéressants pour leurs propriétés physiques, chimiques et catalytiques. Nous avons ainsi caractérisé :- les modifications structurales associées aux transitions de spin dans des complexes du fer(ll), du fer(lll) et du cobalt(ll). - la stéréochimie de complexes du titane(IV), actifs dans l'oxydation de sulfures en sulfoxydes : à toutes les étapes de la réaction, les espèces sont octaédriques et ne présentent pas d'arrangement di -oxo. - l'ordre local dans les porphyrines de fer à anse de panier, modèles de l'hémoglobine. Le spectre de la forme oxygénée permet de proposer une formulation Fe(ll)-02 plutôt que Fe(lll)-02 -. L'EXAFS résolu dans le temps permet de réaliser des cinétiques structurales et a été utilisé pour étudier l'environnement de l'ion fer au cours de la réaction d'oxydation d'une porphyrine de fer(ll) à anse de panierLn this work, molecular complexes of the first period transition elements are studied by X-ray absorption spectroscopy. The first point is devoted to a fundamental study of the absorption edge: we take advantage of the versatility of coordination chemistry, to study complexes, with different stereochemistries and electronic structures. Ln the case of isolated molecules with well-known structures, we point out the influence of oxidation and spin states of the metallic ion, symmetry, metal-ligand distances and remote neighbours shells upon the edge. We discuss the transitions towards bound states using a molecular orbital approach. As for the XANES part of the spectrum, we use multiple scattering theory. We discuss the interest and the limitations of the two models. Sorne weak bands can be attributed to bielectronic transitions. This knowledge of the influence of different structural and electronic parameters which impel the fine structures of the edge and EXAFS spectroscopy are then used to characterise the local structure and stereochemistry of new compounds, of interest for their physical, chemical and catalytic properties. Then we studied:- The structural changes occurring during thermal spin cross-over in iron(ll), iron(lll) and cobalt(ll) complexes. - The stereochemistry of titanium(IV) complexes active in oxidation of sulfides in sulfoxides :at each reaction step, species are octahedral and do not show di µ oxo geometry. - The local order in basket-handle iron porphyrins, model compounds of haemoglobin. The spectrum of the oxy species allows to propose a Fe(ll)-02 formulation rather than a Fe(lll)-02 -. We used the time resolved EXAFS spectrometer at LURE to record structural kinetics data and study iron surroundings during the oxidation of an iron(ll) basket-handle porphyrin
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Hantzer, Sylvain. "Nouveaux materiaux pour la reaction d'hydrodesulfuration (hds)." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13120.
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Nouveau modele de phase active obtenu par interpretation des resultats de rmn du **(59)co et de microscopie electronique haute resolution pour des catalyseurs d'hydrotraitement a base de sulfure de molybdene et de cobalt. Application a d'autres systemes : nire, core, rhre et rhmo. Etude de l'empoisonnement par la porphyrine de catalyseur nimo/al::(2)o::(3)
27
Bedioui, Fethi. "Etude électrochimique de complexes de métaux de transition (bases de Schiff et porphyrines) en solution et sous forme d'électrodes modifiées : application à la catalyse électroassistée de réactions organiques." Paris 6, 1986. http://www.theses.fr/1986PA066338.
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Les propriétés électrochimiques des complexes co-base de Schiff (phenylene-bis(salicylideneiminoto)-co, ou Co(II)saloph, et n-methylenepropylene-bis-(salicylideneiminoto)-co, ou co-selnmedpt) et de tetraphenylporphine-co, ou CoTPP, sont utilisées pour étudier la réduction électroassistée d'halogénures organiques, Rx, avec un catalyseur fixe sur support conducteur, en milieu organique. On étudie: 1) la réduction du chlorure de benzyle électrocatalysée par des électrodes de graphite modifiées par du co-saloph et 2) l'oxydation par l'oxygène moléculaire du di-tert-butylphenol, électrocatalysée par des films de polypyrrole contenant la porphyrine mntcpp.
28
Pérollier, Céline. "Synthèse de nouvelles métalloporhyrines chirales à substituants cyclopropaniques : applications en catalyse d'époxydation asymétrique et en reconnaissance moléculaire d'enantiomères." Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10191.
Full textAbstract:
Le biocartol ou acide (1r)-cis-hemicaronaldehydique, un compose cyclopropanique enantiopur provenant de la synthese industrielle d'insecticides pyrethroides, est utilise comme synthon pour la preparation de nouvelles porphyrines chirales. Nous decrivons la synthese d'amides du biocartol, puis la synthese des porphyrines correspondantes par condensation avec le pyrrole. Celles-ci sont obtenues exclusivement sous la forme de l'atropoisomere , avec un rendement variant de 7 a 60%. Une serie de complexes de manganese (iii) de ces chiroporphyrines, derivees d'amides et d'esters du biocartol, ont ete prepares. Ces complexes sont de bons catalyseurs pour l'epoxydation asymetrique d'olefines prochirales. Les substrats a structure rigide cyclique sont epoxydes avec la plus grande selectivite. Ainsi, des exces enantiometriques allant jusqu'a 86% ont ete obtenus pour l'epoxydation du 1,2-dihydronaphtalene en (1s, 2r)-epoxy-1,2,3,4-tetrahydronaphtalene. L'influence de differents facteurs (nature des substituants, solvant, ligand axial, metal) sur la reactivite et l'enantioselectivite ont ete etudies. Des etudes structurales par resonance magnetique nucleaire et par diffraction des rayons x ont permis d'etablir une correlation entre structure et induction asymetrique dans cette serie. Nous avons mis en evidence que l'encombrement sterique au niveau du centre metallique lors de l'epoxydation est le determinant principal de l'enantioselectivite. Ces resultats sont interpretes par un modele geometrique de l'approche de l'olefine vers le centre metallique. La complexation d'amines derivees d'olefines prochirales par les chiroporphyrines de cobalt (iii) a egalement ete etudiee.
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Simonato, Jean-Pierre. "Chimie de coordination de la tétraméthylchiroporphyrine avec le fer(III), le cobalt(III) et le rhodium(III) : applications à l'analyse d'énantiomères d'amines, à la complexation énantiosélective d'aminoalcools, et à la catalyse d'aziridination asymétrique." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10051.
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Des complexes metalliques de la tetramethylchiroporphyrine, de symetrie et possedant des groupements meso derives du biocartol, ont ete synthetises, caracterises, et utilises dans quatre axes de recherches. _la caracterisation du complexe bis-ethanol de la tetramethylchiroporphyrine de fer(iii), en solution et en phase solide, revele que ce compose presente un etat de spin inhabituel : le spin intermediaire pur (s = 3/2). _l'insertion d'un metal diamagnetique, le cobalt(iii), coordonnant les amines au cur de la porphyrine, a permis l'analyse qualitative et quantitative de la composition de derives d'amines par resonance magnetique nucleaire du proton. Cette methode s'est averee precise, fiable, rapide et tres facile d'utilisation. _l'addition de -aminoalcools sur cette meme molecule resulte en la complexation preferentielle d'un enantiomere. Les aspects cinetiques et thermodynamiques ont ete abordes, et une explication quant a l'enantioselectivite observee est avancee sur la base de liaisons hydrogene intramoleculaires de type c-h___o. _parmi differentes complexes de la tetramethylchiroporphyrine, ceux de fer(iii) et de manganese(iii) ont donne les meilleurs resultats pour la catalyse d'aziridination asymetrique, avec des exces enantiomeriques allant jusqu'a 57% pour le styrene. Un point remarquable est l'induction asymetrique opposee de ces deux catalyseurs, chacun favorisant la formation majoritaire d'un enantiomere.
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沈奕伶. "Six-coordinated, Nitric oxide Cobalt N-confused Porphyrin Complexes and Cocrystallization of Cobalt N-confused Porphyrin with [60]Fullerene." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/30839166322692584025.
Full textAbstract:
碩士國立彰化師範大學
化學系
94
Abstract In the derivatives of the porphyrin system, N-confused porphyrin(NCP) has attracted extensive attention in recent years. In this thesis, we prepared a series of cobalt complexes of N-confused porphyrin and devided the results into four parts including synthesis and oxidation reaction of four coordinated N-confused porphyrin cobalt complex, preparation of six-coordinated cobalt complexes, preparation of nitrosylated cobalt NCP complexes and cocrystallization of cobalt NCP complex with fullerene. We confirmed that four coordinated and planar starting Co(HCTPP) (1) has a Co+2 metal oxidation state. NMR spectra suggested that it is a high-spin, paramagnetic complex with electronic configuration of (dxy)2(dxz,dyz)3(dz2)1(dx2-y2)1. During the process of oxidation tracing, two steps processes were observed. The first step is the oxidation of Co(II) to Co(III) and the second step is the porphyrin ring oxygenation. Because CoII(HCTPP) is a four coordinated complex, it is easy to form five or six coordinating structure in the presence of coordinating base. Interestingly, in the CoIII(CTPP)(2-MeIm)2 (3), the NCP ring exhibits severe sadde shape distortion, most likely, originated from the steric constrain between the methyl group of 2-MeIm and porphyrin core. We confirmed that the metal centre in CoIII(CTPP)(2-MeIm)2 is low-spin diamagnetic Co(III) ion and the electronic configuration of the metal centre is (dxy)2(dxz,dyz)4. In the case of five-coordination cobalt NCP complex, we have found that CoII (HCTPP)NO (4) exhibits a bent M�{N�{O geometry and belongs to {M(NO)}8 electronic system with a planer porphyrin ring. The metal centre is most likely Co+2, low-spin, diamagnetic and the electronic configuration of the metal centre is (dxy)2(dxz,dyz)4(dz2)1. The oxidation of Co(HCTPP)NO gives CoIII(CTPPO)NO (5). The axial ligand for CoIII(CTPPO)NO is bent M�{N�{O and belongs to {M(NO)}7 electronic structure with a saddling nonplaner porphyrin ring. The metal centre is Co+3, low-spin, paramagnetic and the electronic configuration of the centre metal is (dxy)2 (dxz,dyz)4. The cocrystallization of cobalt N-confused metalloporphyrin complex and fullerene, utilize its different solubility, obtained two types of crystal structures. The structure with chemical formula of C60•CoII(HCTPP)•2C7H8•CH2Cl2 (6) has a zigzag linear chain orientation while C60•CoII(HCTPP)•2CH2Cl2 (7) exhibits a trigonal-cage structure. The structure of trigonal-cage is not yet appeared in the literature.
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Wang, Ssu-Ching, and 王思卿. "Electrocatalytic reduction reactions at cobalt porphyrin modified gold electrodes." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/36118882568641478488.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
96
We prepapred a cobalt porphyrin-modified electrode, showing characteristics of electrocatalytic reduction of oxygen and carbon tetrachloride in aqueous solution. The water-soluble cobalt(III) porphyrin was modified onto gold disk surface through 4-mercaptopyridine as a bridge. The modified electrode showed excellent catalytic activity for the oxygen reduction in phosphate buffer solutions at pH 2. The electrochemical behavior and stability of the modified electrode were investigated using cyclic voltammetry and rotating disk electrode methods. The heterogeneous rate constant for the reduction of O2 at the surface of the modified electrode and the diffusion coefficient of oxygen were determined. Organohalides are an important source of environmental pollutants. The obtained modified electrode was used for detection of carbon tetrachloride. Cyclic voltammetric results showed that the modified thin film can facilitate electron transfer, lower the overpotential required and improve electrochemical behavior of carbon tetrachloride reduction, as compared to the bare gold electrode. The modified electrode permitted the detection of carbon tetrachloride in mixed solvents or aqueous solution with ease and good reproducibility.
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"Part 1, serendipitous synthesis of cobalt(III) and rhodium(III) porphyrin-phosphoryls: part 2, synthesis of rhodium(III) porphyrin-silyls." Chinese University of Hong Kong, 1995. http://library.cuhk.edu.hk/record=b5888423.
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by Andy Kwong Shun Tse.Thesis (M.Phil.)--Chinese University of Hong Kong, 1995.
Includes bibliographical references (leaves 53-57).
ACKNOWLEDGMENTS --- p.i
ABBREVIATIONS --- p.ii
ABSTRACT --- p.iv
CONTENTS --- p.v
Chapter Part 1: --- Serendipitous Synthesis of Cobalt(III) and Rhodium (III) Porphyrin-phosphoryls
Chapter I. --- INTRODUCTION --- p.1
Chapter II. --- RESULTS AND DISCUSSIONS --- p.6
Chapter III. --- CONCLUSION --- p.28
Chapter Part 2: --- Synthesis of Rhodium(III) Porphyrin-silyls
Chapter I. --- INTRODUCTION --- p.29
Chapter II. --- RESULTS AND DISCUSSIONS --- p.32
Chapter III. --- CONCLUSION --- p.41
EXPERIMENTAL --- p.42
REFERENCES --- p.53
APPENDIX I-III --- p.58
LIST OF SPECTRA --- p.61
SPECTRA --- p.62
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Aron, Janine. "The coordination chemistry of some cobalt corrinoid and iron porphyrin complexes." Thesis, 2014. http://hdl.handle.net/10539/15738.
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Sheng-You, Shiue, and 薛勝有. "Preparations of Cobalt Porphyrin-Platinum Modified Electrodes and Their Electrocatalytic Reactions." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/11355771286004746101.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
95
The study investigates the preparation of water-soluble cobalt（III） tetrakis（N-methyl-4-pyridyl）porphyrin[ CoIII(4-TMPyP)5+ ] and platinum particle complexes-modified electrode through layer-by-layer self-assembly method. The electrochemical oxidation of sodium 4-aminobenzenesulfonate in potassium chloride aqueous solution leads to formation of amine cation radical, which subsequently formed 4-ABS-modified SPE. CoIII(4-TMPyP)5+ and K2PtCl6 were alternately deposited on a 4-ABS-modified SPE based on electrostatic interaction, and the multilayer films modified electrodes were fabricated. The CoIII(4-TMPyP)5+/Pt particle films was fabricated by electrochemical reduction. The complexes-modified electrode exhibits electrocatalytic activity for the oxidation of cysteine. At the electrooxidation of 10 mM cysteine in 0.5 M NaOH solution, reducing the overpotential by about 0.4 V, and the maximum catalytic current and the catalytic potential obtained from cyclic voltammetry were 66 μA and -0.08 V, respectively.
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"Characterization of cobalt porphyrin coordination polymer: Ab initio structure by DFT method." 2002. http://library.cuhk.edu.hk/record=b5891144.
Full textAbstract:
Fong Ching-yee.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 72-76).
Abstracts in English and Chinese.
ABSTRACT (English Version) --- p.iii
ABSTRACT (Chinese Version) --- p.v
ACKNOWLEGEMENT --- p.vi
TABLE OF CONTENTS --- p.vii
LIST OF TABLES --- p.ix
LIST OF FIGURES --- p.xi
LIST OF APPENDICES --- p.xiii
Chapter CHAPTER ONE --- Introduction
Chapter 1.1 --- Importance and Recent Development in Metalloporphyrin --- p.1
Chapter 1.2 --- Structure of Metalloporphyrin --- p.2
Chapter 1.3 --- General Properties of Metalloporphyrin --- p.4
Chapter 1.4 --- Linkage Patterns of Metalloporphyrin Polymers --- p.7
Chapter 1.5 --- Reasons for Studying Co-Por-Au Polymer --- p.10
Chapter CHAPTER TWO --- Cobalt Porphyrin Gold (Co-Por-Au) Polymer Model
Chapter 2.1 --- Synthetic Scheme --- p.13
Chapter 2.2 --- Experimental Results and Related Properties --- p.14
Chapter 2.3 --- The Structure of Co-Por-Au Polymer --- p.18
Chapter CHAPTER THREE --- Structure Characterization of Co-Por-Au Polymer by DFT Method
Chapter 3.1 --- Quantum Chemical Calculations --- p.21
Chapter 3.2 --- Density Functional Theory --- p.22
Chapter 3.3 --- Computational Details --- p.24
Chapter 3.4 --- Justification for using Gaussian 98 and VASP --- p.27
Chapter 3.5 --- Results and Discussions --- p.30
Chapter 3.5.1 --- Monomers of TPHP and TPCNP --- p.30
Chapter 3.5.1.1 --- The Geometry of the Monomer Structures of TPhP and TPCNP --- p.30
Chapter 3.5.1.2 --- The Axial Coordination Mode of Monomer in TPhP and TPCNP --- p.34
Chapter 3.5.1.3 --- Comparison between Hybrid DFT and Pure DFT method --- p.38
Chapter 3.5.1.4 --- Comparison with Other Porphyrin System --- p.40
Chapter 3.5.1.5 --- Summary --- p.43
Chapter 3.5.2 --- Polymers of TPhP and TPcnP --- p.44
Chapter 3.5.2.1 --- (μ-pyrazine)(octaethylporphyrinato)iron(II) {[Fe(OEP)pyz]}n --- p.44
Chapter 3.5.2.2 --- Energetic Comparison of TPHP and TPCNP with Different Axial Coordination Modes --- p.46
Chapter 3.5.2.3 --- Geometry of the Repeating Units in the Polymer of TPhP and TPCNP --- p.48
Chapter 3.5.2.4 --- Comparison with Other Porphyrin System --- p.52
Chapter 3.5.2.5 --- The Electronic Structures of TPHP and TPCNP --- p.55
Chapter 3.5.2.6 --- Summary --- p.58
Chapter CHAPTER FOUR --- Conclusion --- p.59
APPENDIX I-III --- p.61
REFERENCES --- p.72
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Li, Shin-Yi, and 李信毅. "Electrocatalytic oxidation of 2-mercaptoethanol at cobalt porphyrin-modified screen-printed carbon electrode." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/69411418081553890273.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
99
We report here the electrochemical determination of 2-mercaptoethanol (2-ME) in alkaline aqueous solution by using cobalt(III) porphyrin/Nafion screen printed carbon electrodes (SPCE). Bare SPCE were electro-activated by potential scans ranging from -0.6 to 1.0 V for 10 cycles in pH 7 buffer solution. Then, a Nafion solution containing cobalt porphyrin was dropped onto the pre-actived electrode surfaces. Cyclic voltammetrograms of 5.0 mM 2-ME was studied in various buffer solutions at the modified electrodes. It was observed that the modified electrodes showed good electrocatalytic activity toward the oxidation of 2-ME. Flow injection amperometry (FIA) was studied in pH 12 buffer solution at the optimized conditions. Good analytical features were obtained, including a wide linear range (1~1000 µM), a low detection limit(0.2 µM) and high sensitivity (0.0093 µAµM-1). In addition, the interferent species, such as uric acid, glutathione and caffeine showed insignificant effect on the detection signals.
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Fremond, Laurent. "Cobalt(III) Corroles as Electrocatalysts for O2 Reduction: Reactivity of a Monocorrole, Biscorroles, and Porphyrin–Corrole Dyads." Phd thesis, 2007. http://tel.archives-ouvertes.fr/tel-00340913.
Full textAbstract:
Le travail de recherche concerne l'électroreduction catalytique du dioxygène par des complexes de cobalt adsorbés à la surface d'électrodes de graphite. Les systèmes bismacrocycliques étudiés se composent soit d'un corrole de cobalt(III) lié à une porphyrine de cobalt(II) soit de deux corroles de cobalt(III) maintenus face-à-face par un espaceur aromatique. En employant des espaceurs rigides tels que l'anthracène (A), le biphenylène (B), le 9,9-dimethylxanthène (X) ou le dibenzofurane (O), il est possible de varier la distance cobalt-cobalt entre les deux unités macrocycliques. L'étude des propriétés catalytiques de ces complexes à l'aide d'une électrode tournante disque-anneau indique que les porphyrin-corroles (PCY)Co2 et les biscorroles (BCY)Co2 (avec Y = A, B, X ou O) catalysent la réduction du dioxygène en eau selon un processus à 4 électrons et 4 protons avec une sélectivité plus élevée par rapport au processus de réduction à 2 électrons conduisant à la formation de H2O2.
L'activité catalytique de systèmes face-à-face monométalliques (PCY)H2Co et hétérobimétalliques (PCY)MClCoCl (avec M = Fe(III), Mn(III)) contenant un corrole de cobalt(IV) lié à une porphyrine de fer ou de manganèse ont été également examinés. La comparaison des quatre séries de complexes, (PCY)Co2, (PCY)H2Co, (PCY)FeClCoCl et (PCY)MnClCoCl, montre que les complexes dicobalt de porphyrin–corrole catalysent la réduction du dioxygène à des potentiels plus cathodiques d'environ 110 mV par rapport aux complexes contenant un corrole de cobalt lié à une porphyrine libre ou à une métalloporphyrine de fer ou de manganèse. Les valeurs de potentiels de demi-vague E1/2 correspondant à la réduction catalytique du dioxygène par les complexes (PCY)Co2, (PCY)H2Co, (PCY)FeClCoCl et (PCY)MnClCoCl sont en relation avec les processus redox des ions cobalt. Dans le cas du système (PCY)Co2, la réduction du dioxygene est induite par l'ion Co(II) de la porphyrine alors que dans le cas des complexes (PCY)H2Co, (PCY)FeClCoCl et (PCY)MnClCoCl, l'ion Co(III) du corrole catalyse la réduction du dioxygène. L'ensemble des données électrochimiques indiquent que la forme active du catalyseur (PCY)Co2 contient une porphyrine de cobalt(II) et un corrole de cobalt(IV).
38
Pao, Yi-Chi, and 包翊琦. "Preparation of Self-Assembled Monolayer of Cobalt Porphyrin-modified Gold Electrodes and Their Applications in Electrocatalytic Oxidation of 2-Mercaptoethanol." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/16556171139919964475.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
97
We prepared a cobalt porphyrin-modified electrode, showing characteristics of electrocatalytic oxidation of 2-mercaptoethanol in aqueous solution.The water-soluble cobalt(III) porphyrin was modified onto gold disk surface through 4-mercaptopyridine as a bridge. The modified electrode showed excellent catalytic activity for the 2-mercaptoethanol oxidation in 0.1M NaOH solution. The electrochemical behavior and stability of the modified electrode were investigated using cyclic voltammetry, UV-Vis and rotating disk electrode methods. The heterogeneous rate constant for the oxidation of 2-mercaptoethanol at the surface of the modified electrode and the diffusion coefficient of 2-mercaptoethanol were determined. Detection of thiols has been an important research subject in the biological and industrial world. The obtained modified electrode in this work was used for detection 2-mercaptoethanol in alkaline solutions. Cyclic votammetric results showed that the modified thin fim can facilitate electron transfer, lower the overpotential required and improve electrochemical behavior of 2-mercaptoethanol oxidation, as compared to the bare gold electrode. The way for the assembly of electrodes was easy, fast and highly stable with enhanced performances toward the electrocatalytic oxidation of 2-mercaptoethanol.
39
Chiang, Meng-Ju, and 江孟儒. "Oxidation of Nonplanar cobalt porphyrins." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/71616136303634723410.
Full textAbstract:
碩士國立中興大學
化學系所
99
π cation radical of metalloporphyrins play an important role in oxidation catalysis or electron transport in many diverse biological system such as the intimate compound I of HRP, CPO and CAT which are all iron porphyrin derivatives. Although these biological mechanical processes related to the coupling between central metal and porphyrin cation radical still remain ambiguous, one intriguing occasion with respect to the deformation of macrocycle might get involved. To elucidate this difficult issue, we initiate the one electron oxidation of cobalt(II) porphyrin systems which are saddle-shaped deformation e.g. OMTPP and OETPP to facilitate the understanding in spin coupling between two individual electron spins localized in central cobalt (dz2 orbital) and macrocycle (a1u or a2u orbital) respectively. Aside from, the influence of axial ligands which are obtained after single electron oxidation was also discussed by means of varying the halogen oxidants (I2, Br2 and Cl2). Through a series of analyses of UV-Vis, EPR, NMR, X-ray and DFT calculations, these five-coordinate CoII(OETPP)+ •X (X=Cl, Br, I) complexes have strong antiferromagnetically coupled in room temperature associated with a dxy2dxz2dyz2dz21a2u1(S=0) and ferromagnetically coupled in liquid helium temperature associated with a dxy2dxz2dyz2dz21a1u1(S=0). In the two electron oxidation, the CoIII(OETPP)Br2 complex was obtained and a corresponding a1u type radical species proved by EPR interpret that five-coordinate CoII(OETPP)+ •X (X=Cl, Br, I) complexes approve dxy2dxz2dyz2dz21a1u1(S=1) as ground state more than dxy2dxz2dyz2dz21a2u1(S=0).
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Ghun, Cheng Hsu, and 鄭旭均. "Synthesis and Electrochemical Studies of Cobalt Porphyrins." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/44053869726165268902.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
94
We reported changing the electron-withdrawing groups or electron- donating group could affect the potential in oxidation and reduction. In the past references, the first oxidation is involved the reaction of CoII/ CoIII transition. We discover that the electron-withdrawing groups or electron-donating group could make the first oxidation of cobalt porphyrins occur on the porphyrin ring. We observe every compound in the cyclic voltammogram (CV). In the oxidation, we discover every compound (including CoT(OMe)3PP, CoT(p-OMe)PP, CoTMP, CoTTP, CoTDMPP,and CoTPP ) have three reversible .By using optically transfer thin-layer electrochemistry (OTTLE), we can confirm the mechanism and establish the absorbance spectra of CoIIP, CoIIIP and CoIIP+*.
41
洪敬倫. "Electrochemical Characterization and Electropolymerization of Cobalt Porphyrins." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/31186168709558470321.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
93
There are two sections in this study. In chapter 1, spectral and electrochemical studies for triphenylamino-substituted porphyrins are presented. We found both the meso-tetra-p-(di-p-phenylamino)phenyl porphyrin (H2TDPAPP) and Cobalt meso-tetra-p-(di-p-phenylamino) phenylporphyrin (CoTDPAPP) can be electropolymerized by the oxidative potential scans The structures and properties of the electropolymerized films are examined by cyclic voltammetry and spectroelectrochemistry. In Chapter 2, the ion-exchange properties of the electropolymerized film are presented. When we dipped the films in various pH buffer solutions containing K3Fe(CN)6 and Ru(NH3)6Cl3, respectively, the redox couple of K3Fe(CN)6 and Ru(NH3)6Cl3 can be observed. It is indicated that the electropolymerized films are capable of anion- and cation-exchange, respectively in various pH buffer solutions.
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Sannasy, Desigan. "Characterisation and Solution Chemistry of N-Acetyl-Cobalt(III)-Microperoxidase 8." Thesis, 2007. http://hdl.handle.net/10539/1988.
Full textAbstract:
Student Number : 0010064D -
MSc dissertation -
School of Chemistry -
Faculty of ScienceThis dissertation describes the synthesis, physical characterisation and solution chemistry of NAc-CoIIIMP8, a biomimetic model compound of vitamin B12a, synthesised from the haemoctapeptide derived from horse heart cytochrome c. Peptic and tryptic digestion of horse heart cytochrome c removes much of the globular protein encapsulating the iron porphyrin prosthetic group. The resulting haemoctapeptide fragment retains residues 14 to 21 of the parent cytochrome (MP8) via thioether linkages to Cys-14 and Cys-17. Reductive demetalation of MP8 yielded the metal free MP8. This was treated with cobaltous acetate in an aerated aqueous solution to produce CoIIIMP8. CoIIIMP8 was acetylated by treatment with acetic anhydride and yielded N-acetyl-Co(III)- microperoxidase 8 (NAc-CoIIIMP8). It is well established that acetylation reduces aggregation of these haempeptides. The starting materials and products of each step during synthesis were characterised by UV-visible absorption spectroscopy, high performance liquid chromatography (HPLC) and fast atom bombardment-mass spectroscopy (FAB-MS). MP8 free base and Co(III)-MP8 were also analysed using luminescence spectroscopy. The molar extinction coefficients of NAcCoIII-MP8 in aqueous and ionic medium were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and UV- visible absorption spectroscopy. The extinction coefficient, e, of NAcCoIIIMP8 (? = 420 nm, pH 7.00, 25 ºC) in distilled water and 1.0 M NaClO 4 was 1.80 + 0.01 x 105 M-1 cm-1 and 1.66 + 0.01 x 105 M-1 cm-1, respectively. Beer’s law studies show that NAc-CoIIIMP8 remains monomeric in aqueous solution up to concentrations of at least 35 μM. The spectroscopic changes observed for NAc-CoIIIMP8 during the course of a spectrophotometric titration are very similar to those observed for NAc-FeIIIMP8, with both being consistent with six successive ionisations. By analogy with NAc-FeIIIMP8, we attributed the first (pK1 = 2.0 + 0.3) to the coordination of the c-terminal carboxylate group (Glu-21) of the appended polypeptide. The second acid range transition (pK2 = 2.8 + 0.1) for NAcCoIIIMP8 involved the deprotonation of the cationic His-18 and concomitant replacement of the c-terminal carboxylate by the neutral heterocyclic base. The third and fourth pKa’s are attributed to the ionisation of the haem propanoic acid groups (pK3 = 3.9 + 0.03) and (pK4 = 7.5 + 0.03). Ionisation of the cobalt-bound water molecule above neutal pH was assigned to pK5 = 9.2 + 0.04. Finally, we attributed pK6 (12.1 + 0.03) to the ionisation of the coordinated histidine trans to the OH- to form the histidinate complex (His--CoIII-OH-). A principal aim of this work was to demonstrate that the kinetics and the thermodynamics of the ligand substitution reactions of NAc-CoIIIMP8 can be studied spectrophotometrically; a comprehensive investigation of these reactions will be undertaken by othe rs. Towards this end the formation constants between NAc-CoIIIMP8 and N- methylimidazole and pyridine were determined. We observed the formation of a bis-substituted complex in the reaction of NAc-CoIIIMP8 with the ligands, but only mono-substitution with NAc-FeIIIMP8 and B12a. We attribute this first ligand binding to the replacement of the axial water molecule, and the second replacement of the axial histidine residue. The absence of the second reaction with NAc-FeIIIMP8 and B12a suggest that the CoIII-N(His) bond in NAc-CoIIIMP8 is significantly weaker than the FeIIIN( His) and CoIII-N(dimethylbenzimidazole) bond, respectively. When comparing the formation constants of NAc-FeIIIMP8, NAc-CoIIIMP8 and B12a, we found that the value of log K1 for NAc-CoIIIMP8 for these ligands is significantly higher than that reported for NAc-FeIIIMP8 and B12a. Kinetics studies of NAc-CoIIIMP8 with N-methylimidazole and methylamine were investigated. The data obtained did not follow conventional pseudo-first order kinetics; instead there was some evidence for biphasic kinetics. In the reaction of Nmethylimidazole with NAc-CoIIIMP8, we observed that the rate of reaction is virtually independent of the concentration of the incoming ligand. The results can be explained if the mechanism proceeds through a purely dissociative mechanism, i.e., if the rate of the reaction is controlled by the rate at which, firstly, the water molecule dissociates from the CoIII centre and, secondly, the histidine dissociates from the metal. The second order rate constant, k2, could not be determined since the rate of reaction is independent of Nmethylimidazole concentration. In the reaction of methylamine with NAc-CoIIIMP8, we observed that the rate of reaction is dependent on the concentration and participation of the incoming ligand. We propose that the displacement of water and histidine by methylamine involves an interchange mechanism (Id), where the bond forming and bond breaking occur simultaneously, and thus the rate of reaction becomes dependent on the concentration of the incoming ligand. The results showed that the rate of reaction for methylamine with NAc-CoIIIMP8 was faster than with N-methylimidazole. We attributed these differences in rate constants to the size of the incoming ligands. N-methylimidazole is a secondary amine and is relatively more bulky than methylamine which is a primary amine; therefore it is easier for methylamine to attach to the metal centre compared to N- methylimidazole. For comparison, the rate of reaction of B12a with N-methylimidazole and methylamine was determined. The results show that the rate of the reaction between NAc-CoIIIMP8 and B12a with N-methylimidazole and methylamine are significantly different. Furthermore, we observe only mono -substitution in B12a and bisubstitution in NAc- CoIIIMP8. Overall, the results presented in this work do give a general indication on how thermodynamically stable a CoIII ion is in a porphyrin ring and also to a very limited extent show that a porphyrin does not confer the same kinetic lability on the CoIII ion as the corrin ring.
43
Hsu, Chen-Shou, and 許鎮守. "Cobalt Porphyrins Mediated Living Radical Polymerization of Vinyl Acetate." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/35365905326002415256.
Full textAbstract:
碩士國立清華大學
化學系
101
Cobalt porphyrins mediated vinyl acetate radical polymerization has been performed in different solvent environments and was found that a high monomer conversion (69%) with linear increased molecular weight versus conversion, narrow molecular weight distribution (Mw/Mn = 1.12 ~ 1.34), and little molecular weight deviation could be approached in bulk condition. However, different levels of molecular weight deviation occurred when polymerization was performed in solution, indicating that the control of vinyl acetate radical polymerization was affected by chain transfer to solvent. Besides, non-coordinating solvents caused a difference in polymerization rate mainly due to the different propagation rate constant (kp), but the coordinating solvents such as THF blocked the reaction site of cobalt porphyrins and interfered the whole polymerization behavior. The effect of radical concentration and the ratio of [VAc]0 / [CoII]0 have been also discussed. The higher radical concentration shortened the induction period, increased the polymerization rate and caused a slight deviation of molecular weight. But the control efficiency of cobalt porphyrins to vinyl acetate polymerization was not significantly affected by the ratio of [VAc]0 / [CoII]0. The coordinating effect of pyridine was demonstrated by the shift of equilibrium from dormant organo-cobalt(III) species to active cobalt(II) species. The equilibrium constant (Keq) was changed from < 10-12 to 5.2 × 10-8 when 25 equivalent of pyridine was added into the polymerization so that the major control process was switched from degenerate transfer to reversible termination. Polymerization of methyl acrylate mediated by cobalt porphyrins has been conducted in different solvents. The polymerization behaviors were similar in non-coordinating solvents. However, the induction period was shortened with coordinating solvents such as acetonitrile, anisole and THF which blocked the reaction site of cobalt porphyrins. When THF was used as an additive, the induction period was slightly decreased, but it showed no effect to the polymerization rate and the controlled efficiency.
44
"Part I, base-promoted aryl-bromine bond cleavage by cobalt(ii) porphyrins." 2013. http://library.cuhk.edu.hk/record=b5549304.
Full textAbstract:
本論文主要研究了鹼性添加劑促進二價鈷卟啉絡合物(Co{U+1D35}{U+1D35}(por))在苯溶劑中與溴代苯及其衍生物(ArX)的反應及鹼性條件下，該絡合物催化溴代苯及其衍生物的脫鹵反應。第一部分主要介紹了在KOH和{U+1D57}BuOH存在下，Co{U+1D35}{U+1D35}(por)斷裂碳-溴鍵（Ar-Br）形成各種三價鈷卟啉芳基絡合物（Co{U+1D35}{U+1D35}{U+1D35}(por)Ar）(eq. 1)。
機理研究顯示，Co{U+1D35}{U+1D35}(por)首先從ArBr中得到Br·形成芳基自由基（Ar·）及Co{U+1D35}{U+1D35}{U+1D35}(por)Br (Scheme 1, i). Ar 與另一個Co{U+1D35}{U+1D35}(por)反應得到Co{U+1D35}{U+1D35}{U+1D35}(por)Ar (Scheme 1, ii)。在鹼性條件中，Co{U+1D35}{U+1D35}{U+1D35}(por)Br 最終形成CoII(por)從而繼續反應 (Scheme 1, iii-iv)。
第二部份主要介紹了在200 ºC時， 鹼性條件下Co{U+1D35}{U+1D35}(por)催化鹵代苯及其衍生物脫鹵形成對應芳烴的反應 (eq. 2)。 該反應在四氫呋喃（THF）及異丙醇 ({U+2071}PrOH) 中都可以進行。
機理研究顯示， Co{U+1D35}{U+1D35}(ttp) 首先與ArBr反應得到Ar· 和Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br (Scheme 2, i)。 Ar 從溶劑（THF 或者 {U+2071}PrOH）得到一個氫原子從而形成芳烴 (ArH) (Scheme 2, ii)。 Ar 也可以與另一個Co{U+1D35}{U+1D35}(ttp) 反應得到Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar。 在鹼性條件下， Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar水解形成ArH 和 Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH (Scheme 2, iii)。 Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br 與KOH進行取代反應得到Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH, 并最終形成催化劑Co{U+1D35}{U+1D35}(ttp) (Scheme 1, iii-iv)。所以， 溶劑 （THF 或者 {U+2071}PrOH）及H₂O 都可以作為Co{U+1D35}{U+1D35}(ttp) 催化鹵代苯脫鹵形成芳烴的氫的來源。
This thesis focuses on (1) the base-promoted aryl bromine bond (Ar-Br) cleavages by cobalt(II) porphyrins and (2) catalytic hydrodehalogenation of aryl bromides by cobalt(II) porphyrin in alkaline conditions.
Part I describes the aryl bromine bond cleavage with cobalt(II) porphyrin (Co{U+1D35}{U+1D35}(por)) in the presence of KOH and {U+1D57}BuOH in benzene at 150ºC to give cobalt(III) porphyrin aryls (Co{U+1D35}{U+1D35}{U+1D35}(por)Ar) (eq. 1).
[With images]
Mechanistic studies suggest that CoII(por) first abstracts the bromine atom from the aryl bromide to form aryl radical (Ar) and Co{U+1D35}{U+1D35}{U+1D35}(por)Br (Scheme 1, i). Ar· further reacts with Co{U+1D35}{U+1D35}(por) to generate Co{U+1D35}{U+1D35}{U+1D35}(por)Ar (Scheme 1, ii). Co{U+1D35}{U+1D35}{U+1D35}(por)Br undergoes ligand substitution with KOH to form Co{U+1D35}{U+1D35}{U+1D35}(por)OH, which quickly gives Co{U+1D35}{U+1D35}(por) and H₂O₂ (Scheme 1, iii). H₂O₂ undergoes base-promoted decomposition to form H₂O and O₂ (Scheme 1, iv).
[With images]
Scheme 1 Reaction Mechanism of Base-promoted Ar-Br Cleavage with Co{U+1D35}{U+1D35}(por)
Part II describes the catalytic hydrodehalogenation of aryl bromides by Co{U+1D35}{U+1D35}(ttp) at 200 ºC in alkaline conditions to generate arenes (eq. 2). The reaction can occur in both THF and {U+2071}PrOH.
[With images]
Mechanistic studies suggest that Co{U+1D35}{U+1D35}(ttp) also first abstracts the bromine atom from the aryl bromide in the presence of KOH to form Ar· and Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br (Scheme 2, i). Ar· can abstract a hydrogen atom from the solvent (THF or {U+2071}PrOH) to form arenes (Scheme 2, ii). Ar also could be trapped by Co{U+1D35}{U+1D35}(ttp) to give Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar, which undergoes hydrolysis in the presence of OH⁻ to the arene (ArH) and Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH (Scheme 2, iii). Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br gives Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH by ligand substitution with KOH and Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH regenerates the catalyst Co{U+1D35}{U+1D35}(ttp) (Scheme 1, iii-iv). The solvent (THF or {U+2071}PrOH) and H₂O are the hydrogen sources for the catalytic dehalogenation of aryl bromides by Co{U+1D35}{U+1D35}(ttp).
Scheme 2 Mechanism of Catalytic Dehalogentaion of ArBr by CoII(ttp) in Alkaline Media
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Liu, Chunran.
"October 2012."
Thesis (M.Phil.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves ).
Abstracts also in Chinese.
Chapter Table of Contents --- p.i
Chapter Acknowledgements --- p.iv
Chapter Abbreviations --- p.v
Chapter Abstract --- p.vi
Chapter Part I --- The Base-promoted Aryl Bromine Bond Cleavage of Aryl Bromides by Cobalt(II) Porphyrins
Chapter Chapter 1 --- General Introduction --- p.1
Chapter 1.1 --- Introduction to Porphyrins and Group 9 metalloporphyrins --- p.1
Chapter 1.1.1 --- Porphyrin Ligand --- p.1
Chapter 1.1.2 --- Group 9 metalloporphyrins --- p.2
Chapter 1.1.3 --- Chemistry of Group 9 Metalloporphyrin --- p.3
Chapter 1.1.3.1 --- Chemsitry of M{U+1D35}(por) --- p.3
Chapter 1.1.3.2 --- Chemsitry of M{U+1D35}{U+1D35}(por) --- p.4
Chapter 1.1.3.3 --- Chemsitry of M{U+1D35}{U+1D35}{U+1D35}{U+1D35}(por) --- p.4
Chapter 1.1.3.4 --- Chemsitry of M{U+1D35}{U+1D35}{U+1D35}{U+1D35}(por)OH --- p.6
Chapter 1.2 --- Physical Properties of Aryl Halides --- p.9
Chapter 1.3 --- Synthesis of Metalloporphyrin Aryl --- p.10
Chapter 1.4 --- Modes of Reactivity of Aryl Carbon-Halogen Bond Cleavage by Transition Metal Complexes --- p.11
Chapter 1.4.1 --- Oxidative Addition (OA) --- p.11
Chapter 1.4.2 --- Nucleophilic Aromatic Substitution (SNA) --- p.14
Chapter 1.4.3 --- Halogen Atom Transfer (HXA) --- p.14
Chapter 1.4.4 --- Radical ipso-Substitution --- p.15
Chapter 1.5 --- Scope of Part I --- p.16
Chapter Chapter 2 --- Base-promoted Aryl Bromine Bond Cleavage of Aryl Bromides by Cobalt(II) Porphyrins
Chapter 2.1 --- Introduction --- p.17
Chapter 2.2 --- Objectives of the Work --- p.18
Chapter 2.3 --- Preparation of Starting Materials --- p.18
Chapter 2.3.1 --- Synthesis of Porphyrin --- p.18
Chapter 2.3.2 --- Synthesis of Cobalt(II) Porphyrin --- p.18
Chapter 2.3.3 --- Synthesis of Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br --- p.19
Chapter 2.4 --- Discovery of Ph-Br Bond Cleavage by Co{U+1D35}{U+1D35}(ttp) with KOH --- p.19
Chapter 2.5 --- Optimization of Reaction Conditions --- p.20
Chapter 2.5.1 --- {U+1D57}BuOH Effect --- p.20
Chapter 2.5.2 --- Solvent Effect --- p.21
Chapter 2.5.3 --- Temperature Effect --- p.21
Chapter 2.5.4 --- Base Loading Effect --- p.22
Chapter 2.6 --- Summary of Optimization of the Base-promoted Ph-Br Bond Cleavage by Co{U+1D35}{U+1D35}(ttp) --- p.22
Chapter 2.7 --- Porphyrin Ligand Effect --- p.23
Chapter 2.8 --- Substrate Scope of Aryl Bromides --- p.24
Chapter 2.9 --- Mechanistic Studies --- p.25
Chapter 2.9.1 --- Possible Pathways of Ar-Br Bond Cleavage --- p.25
Chapter 2.9.1.1 --- Oxidative Addition (OA) --- p.26
Chapter 2.9.1.2 --- Nucleophilic Aromatic Substitution (SNA) --- p.27
Chapter 2.9.1.3 --- Radical ipso-Substitution --- p.28
Chapter 2.9.1.4 --- Halogen Atom Transfer (HXA) --- p.28
Chapter 2.9.2 --- Electronic Effect of 4-Substituted ArBr by Hammett Plot --- p.29
Chapter 2.9.3 --- Proposed Mechanism --- p.32
Chapter 2.9.4 --- Evidence for Halogen Atom Transfer --- p.33
Chapter 2.10 --- Conclusion --- p.35
Chapter Chapter 3 --- Experimental Section --- p.36
Reference --- p.53
Chapter Part II --- Catalytic Hydrodehalogenation of Aryl Bromides by Cobalt(II) Porphyrin in Alkaline Conditions
Chapter Chapter 4 --- General Introduction --- p.58
Chapter 4.1 --- Introduction --- p.58
Chapter 4.1.1 --- Properties of Halogenated Aromatic Compounds --- p.58
Chapter 4.1.2 --- Reactivity of Aryl Carbon-Halogen Bond --- p.59
Chapter 4.2 --- Hydrodehalogenation of Aryl Halides by Transiton Metal Complexes --- p.59
Chapter 4.2.1 --- Molecular Hydrogen (H₂) --- p.60
Chapter 4.2.2 --- Alcohols and Metal Alkoxides --- p.61
Chapter 4.2.3 --- Dimethyformamide (DMF) --- p.64
Chapter 4.2.4 --- Hydrazine (NH₂-NH₂) --- p.65
Chapter 4.2.5 --- Metal Hydrides --- p.65
Chapter 4.2.6 --- Alkyl Grignard Reagents --- p.67
Chapter 4.2.7 --- Formic Acid and Its Salts --- p.67
Chapter 4.3 --- Common Reducing Agents --- p.69
Chapter 4.3 --- Scope of Part II --- p.69
Chapter Chapter 5 --- Catalytic Hydrodehalogenation of Aryl Bromides by Cobalt(II) Porphyrin in Alkaline Conditions
Chapter 5.1 --- Introduction --- p.70
Chapter 5.2 --- Objectives of the Work --- p.71
Chapter 5.3 --- Optimization of Reaction Conditions --- p.71
Chapter 5.3.1 --- Solvent Effect --- p.71
Chapter 5.3.2 --- Temperature Effect --- p.72
Chapter 5.3.3 --- Base Loading Effect --- p.73
Chapter 5.3.4 --- Porphyrin Loading Effect --- p.73
Chapter 5.3.5 --- Atmosphere Effect --- p.74
Chapter 5.4 --- Summary of Optimization of Hydrodehalogention of Aryl Bromides by Co{U+1D35}{U+1D35}(ttp) --- p.74
Chapter 5.5 --- Substrate Scope of Aryl Bromides --- p.75
Chapter 5.5.1 --- THF as the Solvent --- p.75
Chapter 5.5.2 --- {U+2071}PrOH as the Solvent --- p.76
Chapter 5.6 --- Catalytic Reactivity of Co{U+1D35}{U+1D35}(ttp) as the Catalyst --- p.77
Chapter 5.7 --- Mechanistic Studies --- p.78
Chapter 5.7.1 --- Proposed Mechanism of Hydrodehalogenation of Aryl Bromides by Co{U+1D35}{U+1D35}(ttp) --- p.78
Chapter 5.7.2 --- Hydrogen Source Investigation --- p.80
Chapter 5.8 --- Conclusion --- p.83
Chapter Chapter 6 --- Experimental Section --- p.84
Reference --- p.92
Chapter Appendix --- Appendix I --- p.101
Appendix II --- p.112
Appendix III --- p.118
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Wang, Chun-Yuan, and 王春元. "Macrocycle deformation mediated bonding characteristics between cobalt(II) porphyrins and axial ligands." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/65200879517788824468.
Full text
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"Base-promoted aryl carbon-iodine bond activation by cobalt(ii) porphyrins: scope and mechanism." 2012. http://library.cuhk.edu.hk/record=b5549052.
Full textAbstract:
本論文的研究包括Co(por)Ar的合成和對Ar-I鍵被Co(por)活化的机理研究。首先，一系列Co(por)Ar成功的由Co(por)和取代碘帶苯在150 ℃和氫氧化鉀的作用下合成并得到中等到高的产率。其次，自由能研究表明 Co(por)對Ar-I键的活化是通过碘原子轉移進行的。相对速率k[subscript rel]从取代碘代苯和碘代苯同Co(por)的競爭反應得出。自由能關係研究表明logk[subscript rel]同取代常數σp-的哈密特相关给出一斜率為1.02的直線，表明高度離域的负电荷在苯环的增加和碘原子的π電子同對位取代基在過渡態的共軛。基于这个事实和对其它机理的排除得出Co(por)對Ar-I键的活化的機理為碘原子轉移機理。因此， Co[superscript II](ttp)首先同ArI反應形成一個直線型過渡態[Co(ttp)---I---Ar]，而後生成Co(ttp)I同一個苯自由基(Ar·)。Ar同Co[superscript II](ttp)反應生成Co(ttp)Ar，Co(ttp)I同 KOH反應生成Co[superscript II](ttp)和H₂O₂，並且Co[superscript II](ttp)同ArI繼續反應。
This research includes the synthesis of cobalt porphyrin aryl complexes (Co(por)Ar) and mechanistic study of the aryl-iodine (Ar-I) bond activation by Co(por). First, a series of cobalt porphyrin aryl complexes, Co(por)Ar, were successfully synthesized from Co(por) and aryl iodides in moderate to high yield in the presence of potassium hydroxide at 150°C.
Second, the free energy relationship study demonstrates that Ar-I bonds are activated by cobalt porphyrin (Co(por)) through an iodine atom transfer pathway. The relative rates (k[subscript rel]) were derived from competition reactions of substituted aryl iodides and phenyl iodide with Co(por). The free energy relationship study illustrates that the krel against σp - yields linear behavior with positive slope (ρ = 1.02), suggesting that a highly delocalized negative charge builds on the aryl ring, and conjugation of π-electron density of iodine atom with para substituents occurs in the transition state. With this fact and the exclusion of other possible mechanisms, it is concluded that the mechanism of activation of Ar-I bond by Co(por) involves iodine atom transfer pathway. Thus, Co[superscript II](ttp) reacts with ArI to form a linear transition state [Co(ttp)---I---Ar], which then yields Co(ttp)I and an aryl radical (Ar·). Ar· reacts with Co(ttp) to give Co(ttp)Ar, Co(ttp)I reacts with KOH to give Co[superscript II](ttp) and H₂O₂, and Co(ttp) continues to react with ArI.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Li, Chen.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 50-55).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese.
Table of Contents --- p.i
Acknowledgements --- p.iv
Abbreviations --- p.v
Abstract --- p.vi
Structural Abbreviations for Porphyrins --- p.ix
Chapter Chapter 1 --- General Introduction --- p.1
Chapter 1.1 --- Application of Cobalt Porphyrin Complexes --- p.1
Chapter 1.2 --- Energy Level Diagram for Cobalt Porphyrin Complexes --- p.1
Chapter 1.3 --- Co(I) Porphyrin Chemistry --- p.2
Chapter 1.4 --- Co(II) Porphyrin Chemistry --- p.3
Chapter 1.5 --- Co(III) Porphyrin Chemistry --- p.5
Chapter 1.6 --- Activation of Aryl Carbon-Halogen bond by Cobalt Complexes --- p.5
Chapter 1.6.1 --- Definination of pathways of activation of aryl carbon-halogen bond by transition metals --- p.5
Chapter 1.6.2 --- Bond dissociation energy (BDE) of Aryl halides --- p.6
Chapter 1.6.3 --- Mechanism of aryl carbon-halogen bond activation by cobalt complex --- p.7
Chapter 1.6.3.1 --- Oxidative addition --- p.7
Chapter 1.6.3.2 --- Nucleophilic Aromatic Substitution --- p.8
Chapter 1.6.3.3 --- Radical pathway --- p.9
Chapter 1.7 --- Free energy relationship study of aryl-halide bond activation by transition metal complexes --- p.13
Chapter 1.7.1 --- Oxidative addition of aryl-halide bond by transition metal complexes --- p.13
Chapter 1.7.2 --- Aryl-halide bond acitvation by transition metal complexes via radical pathway --- p.18
Chapter 1.8 --- Objectives of the work --- p.21
Chapter Chapter 2 --- Mechanistic study of Bond Activation of Aryl Carbon-Iodide (C-I) Bonds by Cobalt(II) Porphyrin --- p.22
Chapter 2.1 --- Background --- p.22
Chapter 2.2 --- Aryl Carbon-iodide (C-I) bond Activation by Co(II) Porphyrins --- p.22
Chapter 2.3 --- Preparation of Starting Materials --- p.23
Chapter 2.3.1 --- Synthesis of Porphyrins --- p.23
Chapter 2.3.2 --- Synthesis of Cobalt(II) Porphyrins --- p.23
Chapter 2.4 --- Optimization of the reaction conditions --- p.24
Chapter 2.4.1 --- Optimization of Substrate, Base and Additive --- p.24
Chapter 2.4.2 --- Temperature Optimization --- p.24
Chapter 2.5 --- Halogen Atoms Effect on the Cleavage Rates of Ph-X (X = Br, Cl) Bonds --- p.25
Chapter 2.6 --- Substrate Scope of Base-Promoted Aryl C-I Activation by Co[superscript II](ttp) --- p.26
Chapter 2.7 --- Porphyrin Scope --- p.27
Chapter 2.8 --- X-Ray Data of Cobalt(III) Porphyrin Aryls --- p.28
Chapter 2.9 --- Mechanistic Study of Aryl C-I Bond Activation by Co[superscript II](ttp) --- p.29
Chapter 2.9.1 --- Possible Mechanistic Pathway --- p.29
Chapter 2.9.2 --- Competition Reactions --- p.30
Chapter 2.9.3 --- Free energy relationship study --- p.32
Chapter 2.9.4 --- Mechanism discussion --- p.33
Chapter 2.9.4.1 --- Nucleophilic Aromatic Substitution --- p.33
Chapter 2.9.4.2 --- Oxiative Addition --- p.33
Chapter 2.9.4.3 --- Radical ipso-Substitution --- p.34
Chapter 2.9.4.4 --- Electron Transfer and Iodine Atom Transfer pathways --- p.34
Chapter 2.10 --- Conclusions --- p.37
Chapter Chapter 3 --- Experimental Section --- p.38
References --- p.50
Appendix --- p.56
47
Takeuchi, Toshihiko. "The electronic structure of distorted porphyins and cobalt schiff base derivatives as novel enzyme inhibitors." Thesis, 1996. https://thesis.library.caltech.edu/5351/1/Takeuchi_t_1996.pdf.
Full textAbstract:
Halogenated porphyrins, which are catalysts for the oxidation of alkanes, were studied by semiempirical AM 1 calculations. The calculations predicted the effects of halogenation of the porphyrin ring on UV-visible absorption spectra and electrochemical data. Predictions regarding the stability of catalysts were made, and have been experimentally verified. INDO/S semiempirical calculations were performed on a series of porphyrins to understand the effects of a highly disfavored distortion that is conserved in cytochromes c. The highest occupied molecular orbitals were destabilized, and the orbital energy of the metal and the lowest unoccupied orbitals change, causing a shift in the redox potential of the heme and a change in the electron transfer properties of cytochromes c.
In order to delineate the anti-enzymatic properties of Co(acacen) derivatives, which are potent inhibitors of the herpes virus, carbonic anhydrase (CA), thermolysin (TL), and thrombin (TH) were chosen as targets Inhibition of CA occurs upon incubation with the novel water-soluble Co(II)hydroxypropylacacen (Co(II)hpr) but not with [Co(III)hpr(NH_3)_2 ^+(OAc)^- . The difference in reactivity of the species is a consequence of the steric limitations imposed by the axial ligands bound to the Co(III) complex. [Co(III)acacen(NH_3)_2^+ irreversibly inhibits TL, and this inhibition was prevented by binding a strong reversible inhibitor to the active site of the enzyme before addition of the cobalt species, suggesting that cobalt-acacen derivatives can inhibit enzymes by binding to active site histidines. In an effort to develop more potent and selective enzyme inhibitors, active site-directed peptides were coupled via a peptide bond through a carboxylic acid, which is part of the acacen ligand framework. The peptide coupled derivatives rapidly and irreversibly inhibited TH, and the potency of inhibition was over an order of magnitude better than the uncoupled components.
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De, Paz Héloïse. "Étude spectroélectrochimique de la réaction de réduction de l'oxygène sur une électrode de carbone modifiée avec une porphyrine de cobalt (CoTPP)." Mémoire, 2010. http://www.archipel.uqam.ca/3038/1/M11389.pdf.
Full textAbstract:
L'épuisement des combustibles fossiles et les problèmes environnementaux causés par la combustion de ceux-ci rendent urgent le développement de nouvelles énergies dites renouvelables. Dans le domaine des transports (autobus, automobiles...) la recherche porte notamment sur la pile à combustible. Un facteur limitant la commercialisation des piles à combustible est l'absence de catalyseurs efficaces et peu coûteux pour la réaction de réduction de l'oxygène (RRO) qui a lieu à la cathode. L'utilisation de métaux non nobles comme catalyseur pour cette réaction est en forte expansion. Le carbone est l'un des supports les plus intéressants dans ce domaine du fait de son bas prix. Cependant, il doit être modifié afin d'en faire une surface catalytique. Le greffage de macrocycles tels que des porphyrines sur une surface d'or est bien connu. Il est possible de contrôler l'orientation, l'assemblage et le taux de recouvrement des porphyrines sur une telle surface notamment en attachant les porphyrines via des monocouches de thiols. Notre projet vise dans un premier temps à chimisorber une monocouche de porphyrine de cobalt (CoTPP) sur une électrode de carbone vitreux via une monocouche de 4-aminothiophénol (4-ATP) et d'utiliser cette électrode pour examiner la réduction de l'oxygène en peroxyde afin de mieux comprendre le mécanisme de réduction. La caractérisation de l'électrode par spectroscopie de photoélectron X (XPS) et par des méthodes électrochimiques a montré un fort taux de recouvrement des porphyrines à la surface du carbone. Les mesures de voltampèrometrie cyclique et de chronocoulométrie ont démontré que l'électrode GC/4-ATP-CoTPP (chimisorbé) est un catalyseur aussi efficace que lorsqu'il est seulement physisorbé à la surface (GC/CoTPP) et que l'électrode Au/4ATP-CoTPP. Lorsqu'elle est chimisorbée, la porphyrine donne des résultats beaucoup plus reproductibles et ne subit aucune désorption de la surface. Les spectres UV-visible montrent qu'une pentacoordination du cobalt et un état d'oxydation +lI sont nécessaires pour une complexation avec l'oxygène. La présence d'un intermédiaire (LCo(II) TPP-O₂) très stable a été identifié à la fois en solution et lorsque la porphyrine est chimisorbée sur le support de carbone. La spectroscopie UV -visible par réflectance (UVDRS) en fonction du potentiel révèle la relation entre la formation de l'intermédiaire LCoTPP-O₂ et la réduction en peroxyde. Ces mesures donnent des informations sur les différentes constantes cinétiques et indiquent que la formation du complexe est plus rapide que sa réduction en peroxyde, le mécanisme n'est donc pas limité par la réaction avec l'oxygène mais par le transfert d'électrons. À partir des ces informations un mécanisme catalytique est proposé. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Électroréduction de l'oxygène, Catalyseur, Modification de carbone, Porphyrine.
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Chuang, Chuan-Hung, and 莊川弘. "Chemistry of Cobalt−Nitrosyl N-confused Porphyrins and Studies on Reduction of Nitric Oxide to Nitrous Oxide or Hydrogen Evolution Reaction." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/80277984344697361843.
Full textAbstract:
博士國立清華大學
化學系
104
Complexes [Co(CTPPMe)(NO)] (1) and [Co(HCTPP)(NO)] (2) with an {Co(NO)}8, the Enemark−Feltham notation of the total number of electrons in the metal d and π*(NO) orbitals, electronic configuration were prepared and thoroughly characterized by IR, UV-Vis, 1H and 15N NMR spectra as well as single-crystal X-ray diffraction. Cyclic voltammetry (CV) and the combined infrared or UV-Vis spectroelectrochemistry (IR or UV-Vis SEC) were also applied to understand the redox chemistry of complexes 1 and 2. IR and UV-Vis SEC studies revealed a porphyrin-based and a CoNO-centered oxidations for 1^0/+ and 2^0/+, respectively. The investigations also indicated a porphyrin-based reduction for 1^0/− and a CoNO-centered reduction for 2^0/−. IR and UV-Vis SEC spectra also demonstrated such good CoNO-centered redox reversibility of 1^0/−/0 or 2^0/+/0 observed in the cyclic voltammogram. It is noteworthy that the reduction of complex 1 or 2 resulted in no facile denitrosylation that commonly occurs in the reduction of {Co(NO)}8 cobalt−nitrosyl porphyrins. Moreover, CV and IR SEC studies on the known {Co(NO)}7 [Co(CTPPO)(NO)] (3) showed a porphyin-based 1st oxidation and a CoNO-centered 1st reduction. Concluded IR SEC results of the cobalt−nitrosyl N-confused porphyrins suggested Δν(NO) ≈ 100 and 35 cm−1 for the CoNO-centered and the porphyrin-based redox processes, respectively. Significantly, the reduction of 1 caused the shift of ν(NO) as large as 95 cm−1 that was first observed in the reduction of {Co(NO)}8 cobalt−nitrosyl porphyrinoid compounds. Suggestive evidences of IR SEC intrigued us to isolate the products reduced by Co(Cp*)2 and examine the subsequent reactivity of the reduced products. Only the product [Co(CTPPMe)(NO)][Co(Cp*)2] (4) of the reduction reaction of 1 to was quantitatively (89.7%) isolated and successfully characterized. Complex 4, to our knowledge, is the first isolated {Co(NO)}9 cobalt−nitrosyl porphyrinoid complex. In the presence of a proton source (NH4PF6), H2(g) evolution occurred with the oxidation of complex 4 to 1. The parallel reaction to evolve H2(g) was also active as conducting NH4+ into the reduction reaction of complex 2 by Co(Cp*)2. We then serendipitously observed that the addition of methanol, ethanol, or water to the THF solution of 4 (protic solvent/THF, 1:1, v/v) stimulated the NO-to-N2O conversion. The strategy of using MeOH to trigger the conversion of NO-to-N2O, however, was not effective as using the reduced product of complex 2. Furthermore, reducing complex 3 to its {Co(NO)}8 state generated neither H2(g) nor N2O(g) in the presence of NH4+ and MeOH, suggesting not only the reduction site but also the electron-richness were demanded for converting the coordinating NO to N2O. Mechanistic insight into the N2O formation was provided by monitoring the whole reaction process of complex 4 and MeOH using IR spectroscopy and ESI(−) mass spectrometry. Complex 4 was NO-reduction-silent in neat THF, but was partially activated to a hydrogen-bonded species 4···MeOH in THF/MeOH (1:1, v/v). This species coupling with 4 transformed NO into N2O, which was fragmented from an [N2O2]-bridging intermediate. An intensified IR peak at 1622 cm−1 was ascribed to ν(NO) due to the formation of an [N2O2]-containing intermediate. Time-course ESI(−) mass spectra supported the presence of the dimeric [Co(NCP)]2(N2O2) intermediate. The observation that the mass signals of the corresponding dimeric fragments exhibited maximum intensity after the reaction had proceeded for approximately 30 min is consistent with the result that the intensity of the peak at 1622 cm−1 in the IR spectrum reached its plateau at 30 min. Five complete NO-to-N2O conversion cycles have been achieved without significant decreasing on the amount of N2O produced.