Electronic Structures of Halogenated Porphyrins: Spectroscopic Properties of ZnTFPPX8 (TFPPX8 = Octa-.beta.-halotetrakis(pentafluorophenyl)porphyrin; X = Cl, Br)

Takeuchi, Toshihiko; Gray, Harry B.; Goddard, William A.

doi:10.1021/ja00100a043

Cited by 104 publications

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“…Introducing ␤-electron-withdrawing substituents and modifying meso substituents of water soluble porphyrins can have a major impact on the redox and electrostatic properties of manganese porphyrins (1)(2)(3)(4)(5)(6)(7). Such substitution allows the redox potential to approach the potential of SOD itself, E1 ⁄2 ϳ ϩ0.…”

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confidence: 99%

The Ortho Effect Makes Manganese(III)Meso-Tetrakis(N-Methylpyridinium-2-yl)Porphyrin a Powerful and Potentially Useful Superoxide Dismutase Mimic

Batinić‐Haberle¹,

Benov²,

Spasojević³

et al. 1998

Journal of Biological Chemistry

254

300

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The ortho, meta, and para isomers of manganese(III) 5,10,15,20-tetrakis(N-methylpyridyl)porphyrin, MnTM-2-PyP 5؉ , MnTM-3-PyP 5؉, and MnTM-4-PyP 5؉ , respectively, were analyzed in terms of their superoxide dismutase (SOD) activity in vitro and in vivo. The impact of their interaction with DNA and RNA on the SOD activity in vivo and in vitro has also been analyzed. Differences in their behavior are due to the combined steric and electrostatic factors. In vitro catalytic activities are closely related to their redox potentials. The half-wave potentials (E1 ⁄2 ) are ؉0.220 mV, ؉0.052 mV, and ؉0.060 V versus normal hydrogen electrode, whereas the rates of dismutation (k cat ) are 6.0 ؋ 10 7 , 4.1 ؋ 10 6 , and 3.8 ؋ 10 6 M ؊1 s ؊1 for the ortho, meta, and para isomers, respectively. However, the in vitro activity is not a sufficient predictor of in vivo efficacy. The ortho and meta isomers, although of significantly different in vitro SOD activities, have fairly close in vivo SOD efficacy due to their similarly weak interactions with DNA. In contrast, due to a higher degree of interaction with DNA, the para isomer inhibited growth of SOD-deficient Escherichia coli.Due to their high stability and chemical versatility, manganese porphyrins are a promising group of compounds for development as SOD 1 mimics. Introducing ␤-electron-withdrawing substituents and modifying meso substituents of water soluble porphyrins can have a major impact on the redox and electrostatic properties of manganese porphyrins (1-7). Such substitution allows the redox potential to approach the potential of SOD itself, E1 ⁄2 ϳ ϩ0.26 V (8). This is approximately midway between the redox potentials of the two half-reactions of the dismutation process (9, 10). While maintaining the redox potential at a value close to that of SOD, it is important to also ensure electrostatic facilitation. We have already shown that ␤-bromination (11, 12) of the manganese(III) 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (13) and of manganese(III) 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin increases their SOD-like activities (13).2 However, the large positive redox potential of the former, E1 ⁄2 ϭ ϩ0.480 mV versus NHE, (13) stabilizes manganese in its 2ϩ state and diminishes stability, and the latter compound had only modest activity, probably due to lack of electrostatic facilitation (13).It has been shown that ortho substitution on the meso phenyl ring exhibits an ortho effect that is as strong as if the same substituent were placed directly on the meso position (14). Thus, meso-tetrakis(2-methylphenyl)porphyrin behaves similar to the meso tetramethylporphyrin (14). The same was found for other porphyrins in which meso phenyl groups have different ortho substituents, as well as when meso groups are ortho pyridyls, such as 5,10,15,20-tetrakis-(N-methylpyridinium-2-yl) (H 2 TM-2-PyP 4ϩ ) and its zinc complex, ZnTMP-2-PyP 4ϩ (15)(16)(17)(18)(19). Such a profound impact on the properties of the ortho isomers, known as the ortho effect, is due to the combi...

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confidence: 99%

The Ortho Effect Makes Manganese(III)Meso-Tetrakis(N-Methylpyridinium-2-yl)Porphyrin a Powerful and Potentially Useful Superoxide Dismutase Mimic

Batinić‐Haberle¹,

Benov²,

Spasojević³

et al. 1998

Journal of Biological Chemistry

254

300

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“…22 In fact, distortions in the porphyrin skeleton can destabilize the macrocycle π systems, thereby modulating their oxidation potentials. [79][80][81][82][83][84][85][86][87] Hence, distinct structural configurations could also determine the catalytic outcome. 78,79 The catalytic results achieved with the solid FeP-LDHME were also better than those reported by Halma et al 41 for FeP-LDHM (Table 1, run 8).…”

Section: Catalytic Oxidation Reactionsmentioning

confidence: 99%

Anionic Iron(III) Porphyrin Immobilized on/into Exfoliated Macroporous Layered Double Hydroxides as Catalyst for Oxidation Reactions

Nakagaki¹,

Castro²,

Ucoski³

et al. 2014

Journal of the Brazilian Chemical Society

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A oxidação de substratos orgânicos é uma importante classe de reações explorada visando a produção de insumos industriais tais como epóxidos, álcoois e cetonas. As metaloporfirinas são compostos com reconhecida atividade catalítica que mimetizam processos de oxidação que ocorrem em seres vivos. A sua imobilização em diferentes sólidos robustos e inertes permite a recuperação e reuso do catalisador em processos catalíticos heterogêneos. Hidróxidos duplos lamelares (LDHs) são materiais inorgânicos constituídos de hidróxidos de metais di e trivalentes, resultando em lamelas bidimensionais carregadas positivamente. Neste trabalho reportamos a preparação de catalisadores baseados na imobilização de ferroporfirina (FeP) em LDH macroporoso (LDHM) obtido pelo método de co-precipitação usando poliestireno como template, reconstrução de óxidos e esfoliação (LDHME). A imobilização da FeP no LDH intercalado com ânions nitrato obtido pelo método de co-precipitação também é reportada. Os sólidos obtidos foram caracterizados e investigados como catalisadores na oxidação do cicloocteno e cicloexano.The oxidation of organic substrates via catalytic routes is an important class of reactions to produce industrial input materials such as epoxides, alcohols, and ketones. Metalloporphyrins display recognized catalytic activity that mimics oxidation processes in living organisms. Their immobilization in different inert supports allows their recovery and reuse in heterogeneous catalytic processes. Layered double hydroxides (LDHs) are inorganic materials consisting of di-and trivalent metal hydroxides that afford bidimensional positively charged layers. This work reports on the preparation of the solid based on macroporous LDHs (LDHMs) by the co-precipitation method, which involved the use of polystyrene as template, oxides reconstruction, and exfoliation, to furnish LDHME. We also describe the immobilization of an iron(III) porphyrin (FeP) in LDHME and in LDH intercalated with nitrate anions, obtained by the co-precipitation method. Application of the immobilized catalysts in (Z)-cyclooctene and cyclohexane oxidation will help to assess their catalytic activity. Keywords: porphyrin, macroporous LDH, oxidation, biomimetic reaction, heterogeneous catalysis IntroductionThe family of enzymes collectively known as cytochrome P450 monooxygenases bear a heme prosthetic group and participate in different catalytic processes, mainly oxidative metabolism of endogenous/exogenous products in mammals. [1][2][3][4][5] Over the last years, researchers have made great efforts to develop routes that can generate robust synthetic metalloporphyrins (MPs), 6-10 aiming to mimic biological enzymes such as cytochrome P450 (biomimetic approach). Indeed, MPs can efficiently and selectively catalyze hydrocarbon oxidation.11 Some of these MPs are based on the structure of meso-tetraphenylporphyrin [H 2 (TPP)].The high efficiency and selectivity of MPs have motivated the proposition of technological catalytic systems based on this versatile family of oxidation ca...

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“…Recentemente, uma vasta literatura vem sendo publicada abordando as conformações do anel porfirínico, as relações com a configuração de spin eletrônico do centro férrico, suas implicações físico-químicas como reatividade e potencial redox e repercussões espectroscópicas nas várias técnicas empregadas. 137,146,[154][155][156][157][158] Dentre estas técnicas, vale mencionar o emprego amplamente difundido da ressonância magnética nuclear (RMN), fazendo uso, no caso do centro férrico (Fe(III)), do acoplamento hiperfino para sondar a conformação e as circunvizinhanças do anel porfirínico. O emprego desta técnica espectroscópica para avaliar a interação hiperfina abrange os núcleos dos ligantes axiais, os núcleos do anel porfirínico e também a interação com o spin nuclear dos núcleos pertencentes aos resíduos de aminoácidos formadores dos limites da cavidade do bolsão hidrofóbico do heme.…”

Section: A Configuração Eletrônica Dos Grupos Heme Férricos Para Os Sunclassified

Hemoglobina extracelular gigante de Glossoscolex paulistus: um extraordinário sistema supramolecular hemoproteico

et al. 2011

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Recebido em 26/1/10; aceito em 1/6/10; publicado na web em 22/9/10 GIANT EXTRACELLULAR HEMOGLOBIN OF Glossoscolex paulistus: AN EXTRAORDINARY SUPRAMOLECULAR HEMOPROTEIN SYSTEM. Giant extracellular hemoglobins are considered the summit of complexity in systems that carry oxygen, constituting an extraordinary model system to the study of hemoproteins. This class includes the hemoglobin of the annelid Glossoscolex paulistus that presents high cooperativity, great oligomeric and redox stabilities and ability of oligomeric reassociation. These properties have motivated evaluations about its utilization as prototype of artificial blood and biosensor. Kinetic studies involving autoxidation and detailed spectroscopic characterizations of its ferrous and ferric species have propitiated information about the structure-activity relationship of this macromolecule. The present review analyzes several biochemical issues, evaluating the state-of-art of this subject.Keywords: hemoglobin; ligand exchange; autoxidation. INTRODUÇÃOA hemoglobina extracelular gigante de Glossoscolex paulistus (HbGp) é uma hemoproteína que constitui um sistema carregador de oxigênio in vivo e, consequentemente, credenciado pela seleção natural, apresentando características extremamente interessantes em termos de evolução como, por exemplo, sua possível adaptação a meios ricos em sulfetos.1 Esta hemeproteína apresenta uma extraordinária massa molecular, em torno de 3,1 MDa, 2 com uma unidade estrutural básica altamente organizada, contendo 144 cadeias que apresentam o grupo heme, além da presença de aproximadamente 36 cadeias que não apresentam este grupamento prostético.Os sistemas hemoglobínicos gigantes extracelulares, também conhecidos por eritrocruorinas, 3 constituem arranjos supramoleculares proteicos tão elaborados do ponto de vista da sua relação estrutura/ atividade, que são considerados, segundo Vinogradov, 4,5 o ápice de complexidade em se tratando de hemoproteínas que ligam oxigênio.Além disso, este grupo de hemoglobinas é conhecido por ligações de oxigênio altamente cooperativas.6-8 Entre elas, destaca-se a hemoglobina de Lumbricus terrestris, que vem sendo amplamente estudada por diversos grupos e que apresenta similaridade macromolecular com a hemoglobina de Glossoscolex paulistus. Cálculos por homologia envolvendo o monômero d de Glossoscolex paulistus constataram uma identidade estrutural de 54% em relação ao monômero d de Lumbricus terrestris.A título de ilustração, é interessante mencionar que a hemoglobina de Lumbricus terrestris vem sendo aplicada em pesquisas sobre sangue artifical, 7,9,10 devido à sua natureza extracelular, grande tamanho e resistência à oxidação. Em relação a este último tópico, vale citar os trabalhos de Dorman e colaboradores 9 e Madura e colaboradores 8 que, por meio de estudos espectroeletroquímicos, têm determinado que a hemoglobina de Lumbricus terrestris exibe potenciais redox altamente positivos (de +112 até +61 mV) quando comparados aos potenciais negativos das hemoglobinas tetraméricas e mioglobinas ...

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Electronic Structures of Halogenated Porphyrins: Spectroscopic Properties of ZnTFPPX8 (TFPPX8 = Octa-.beta.-halotetrakis(pentafluorophenyl)porphyrin; X = Cl, Br)

Cited by 104 publications

References 0 publications

The Ortho Effect Makes Manganese(III)Meso-Tetrakis(N-Methylpyridinium-2-yl)Porphyrin a Powerful and Potentially Useful Superoxide Dismutase Mimic

The Ortho Effect Makes Manganese(III)Meso-Tetrakis(N-Methylpyridinium-2-yl)Porphyrin a Powerful and Potentially Useful Superoxide Dismutase Mimic

Anionic Iron(III) Porphyrin Immobilized on/into Exfoliated Macroporous Layered Double Hydroxides as Catalyst for Oxidation Reactions

Hemoglobina extracelular gigante de Glossoscolex paulistus: um extraordinário sistema supramolecular hemoproteico

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