Manganese Tetraphenylporphyrin Research Articles

Interaction of artemisinin (qinghaosu) with the tetraphenylporphyrinato-manganese(II) complex

The reaction of artemisinin with manganese tetraphenylporphyrin was studied in the presence of a reducing agent by UV-visible spectroscopy and 1H NMR. The observed data suggested an initial electron transfer from the reduced complex towards artemisinin, followed by a fast modification of the metalloporphyrin. A covalent adduct between artemisinin and the tetrapyrrolic derivative has been isolated.

Paramagnetic metalloporphyrins: infarct avid contrast agents for diagnosis of acute myocardial infarction by MRI.

In previous experiments in tumors we demonstrated that metalloporphyrins are particularly avid for nonviable tumor components. This study was performed to find out whether these agents can be used as MRI contrast agents for the visualization of acute myocardial infarction (MI). A total of 44 rats, 6 normal controls and 38 with occlusive MI (2-24 h old), were used. Gadolinium mesoporphyrin (Gd-MP) or manganese tetraphenylporphyrin (Mn-TPP) was intravenously injected at doses of 0.1, 0.05, and 0.01 mmol/kg. Three to 24 h after injection, axial and coronal T1-weighted (TR/TE 300/15 ms) spin-echo MR images were obtained before and after killing the animals and correlated with triphenyl tetrazolium chloride (TTC) histochemical preparations. The Gd-MP content in infarcted and noninfarcted myocardium was measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). MRI without contrast media could not discern the MI. However, 3-24 h after injection of either Gd-MP or Mn-TPP, the infarcted area was positively stained on MR images. This area matched well with the negatively TTC-stained area on the heart slices (r = 0.97). The contrast ratios between the infarcted necrotic myocardium and the noninfarcted regions varied from 150 to 300% depending on the type of agents and doses used. Neither false-positive nor false-negative findings were encountered. The metalloporphyrin concentration was more than 10 times higher in the infarcted than in the noninfarcted heart. Metalloporphyrins appear to be promising MRI contrast agents for detection and quantification of necrosis in MI. These preclinical results may open new perspectives in cardiac imaging.

Effect of nafion on geometry and axial ligation in manganese (III) tetraphenylporphyrins

AbstractManganese(III) porphyrins were successfully incorporated into Nafion, wherein they are located in the ionic pockets of the polymer. The result of UV—visible spectroscopy indicate that at least one solvent molecule and the anion accompany the macrocycle into the membrane. The anion is only loosely associated with the porphyrin, but strongly coordinating solvents such as pyridine remain in the axial coordination sites. Dramatic changes which were observed in the electronic and resonance Raman spectra when THF and dioxane were used as incorporation solvents indicate that the geometry of the macrocyle also changes when in Nafion. Puckering of the porphyrin ring apparently occurs as it interacts with the restrictive environment in Nafion.

ChemInform Abstract: Mechanisms of Reaction of Hypervalent Oxochromium, Iron, and Manganese Tetraphenylporphyrins with Alkenes

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Localization of metalloporphyrin-induced “specific” enhancement in experimental liver tumors: Comparison of magnetic resonance imaging, microangiographic, and histologic findings

We investigated the tumor specificity of gadolinium mesoporphyrin (Gd-MP) and manganese tetraphenylporphyrin (Mn-TPP) as magnetic resonance (MR) imaging contrast agents. Fifteen rats with multiple hepatocellular carcinomas and eight rats with implanted Novikoff hepatomas were given intravenous injections of either Gd-MP or Mn-TPP at 0.05 mmol/kg, which was compared with nonspecific gadopentetate dimeglumine (0.3 mmol/kg). T1-weighted spin-echo images were obtained before and up to 48 hr after injection and compared with corresponding microangiograms and histologic specimens. The relative enhancement of organs and tumors was plotted as a function of time. Initially, both metalloporphyrins behaved as nonspecific agents, similar to gadopentetate dimeglumine, and enhanced the tumor by perfusion and diffusion. However, metalloporphyrins, but not gadopentetate dimeglumine, caused a delayed (> or = 3 hr) enhancement in some compartments of certain lesions. The MR imaging-microangiography-histology matching technique revealed that those compartments were actually nonviable components, including necrosis (n = 10), thrombosis (n = 7), and cystic secretion (n = 3), but not viable tumor tissue. Metalloporphyrins did not prove to be tumor specific. However, the observed affinity for nonviable tissue has elicited other potential applications for these agents.

Controlled Orientation of Metalloporphyrins and Regioselective Epoxidations in Thermotropic Liquid Crystals

Abstract The orientation of a porphyrin molecule in a thermotropic nematic liquid crystal can be controlled by molecular design. Thus, the porphyrin plane of tetraphenylporphyrin (TPP) is aligned parallel to the director of a liquid crystal whereas a porphyrin with orthogonal substitution of mesogenic 4-n-butoxybiphenyl appendages (MesogenP) is oriented in a perpendicular conformation. The alignment was determined by time resolved EPR spectroscopy of the triplet state of the free base porphyrin. Manganese TPP and MesogenP porphyrins then were used as catalysts for the epoxidation of alkenes using iodosobenze as oxidant. Reaction yields and regioselectivity for enlongated substrates such as cis-stilbene and 4-vinylbiphenyl were dependent on the alignment of the alkene and its carbon-carbon double bond relative to the director and metalloporphyrin catalyst.

Metalloporphyrin-catalysed rearrangement of oxaziridines: an efficient and regioselective synthesis of lactams using ring-enlargement of N-phenyl-spirooxaziridines

Manganese(III) tetraphenylporphyrin, Mn(tpp)Cl, is a new and specific catalyst for stereo- and regio-selective rearrangement of N-phenyl-spirooxaziridines into lactams.

Poly(pyrrole-manganese porphyrin): A catalytic electrode material as a model system for olefin epoxidation and drug metabolism with molecular oxygen

The oxidative electropolymerization of three pyrrole-substituted manganese tetraphenylporphyrins can be used to coat Pt or C electrodes with polymeric films able to catalyse the epoxidation of cyclo-octene and stilbene with molecular oxygen. Cross-linked polymers prepared from monomers containing two or three pyrrole groups, and thus having a better polymerizability, present a lower activity than the polymeric films synthesized from the monomer containing only one pyrrole moiety. Confinement of the catalyst on the electrode surface markedly improves its stability compared with that of homogeneous electrocatalytic systems. This catalytic electrode material has been successfully applied to the preparation of oxidized metabolites of a drug.

Efficient catalytic epoxidation of alkenes by a manganese porphyrin and periodate in the presence of imidazole

Different alkenes are epoxidized with high selectivity in the presence of manganese(III) tetraphenylporphyrin–imidazole–sodium periodate–tetrabutylammonium bromide system in CH2Cl2–H2O media, with high yields (80–100%) at room temperature.

Two unusual formate-bridged manganese(III) tetraphenylporphyrin complexes

Two unusual formate-bridged manganese(III) tetraphenylporphyrin complexes

Electrochemistry and the dependence of potentials on pH of iron and manganese tetraphenylporphyrins in aqueous solution

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemistry and the dependence of potentials on pH of iron and manganese tetraphenylporphyrins in aqueous solutionThomas W. Kaaret, Guo Hua Zhang, and Thomas C. BruiceCite this: J. Am. Chem. Soc. 1991, 113, 12, 4652–4656Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June 1991https://doi.org/10.1021/ja00012a038RIGHTS & PERMISSIONSArticle Views340Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (562 KB) Get e-Alerts Get e-Alerts

Oxidation of dyes by manganese tetraphenyl porphyrin activated peroxy bleach

The oxidation of a number of dyes in predominantly aqueous systems by tetraphenylporphyrinato manganese(III) imidazole, MnTPP(Im), activated peroxy bleach has been studied in the context of application in detergent systems. Dyes with an olefinic linkage in the chromophoric group are readily oxidized by perborate even in the absence of the activator. On the other hand, dyes with an azo linkage are resistant to oxidation and are bleached only to a limited extent (25%) even by MnTPP(Im) activated perborate. In the presence of a surfactant, alkylbenzene sulphonate, bleaching is further inhibited by micellar solubilization of the dyes. Sulphonation of MnTPP(Im) only marginally improves the bleaching efficiency in presence of the surfactant. MnTPP(Im) is also destroyed by perborate in the absence of the substrate. In view of these limitations, the metalloporphyrin activated peroxy bleach system is not promising for application in detergent systems. Attempts have also been made to explain the difference in the behaviour of different substrates on structural consideration.

Spontaneous formation of reactive oxometal porphyrins by oxygen atom transfer from dioxirane

Oxygen atom transfer to manganese(II) tetraphenylporphyrin (tpp) and iron(II) tetramesitylporphyrin (tmp) is readily effected at < –10 °C with dimethyldioxirane in anhydrous acetone to afford the labile oxometal species OMnIV(tpp) and OFeIV(tmp) in quantitative yields.

ChemInform Abstract: Hydroxylation of Alkanes Catalyzed by Manganese Tetraphenylporphyrin Immobilized on Imidazole‐Modified Silica Gel.

Abstract Manganese tetraphenylphorphyrin complex fixed on imidazole-modified silica exhibits fair catalytic activity for cyclohexane oxidation by hydrogen peroxide. Immobilization of the porphyrin complex could result in the prevention of the formation of μ-oxo dimers, increasing the catalytic capability. Turnover numbers for cyclohexane oxidation are greatly improved by decreasing metal loadings, suggesting the importance of site isolation of the metal complexes. Rather high loading of imidazolyl group is required since its ligation to Mn was fully effected when imidazolyl group in large excess of Mn is present, as shown in the change in the diffuse reflectance spectra with imidazolyl/Mn ratio.

Hydroxylation of alkanes catalyzed by manganese tetraphenylporphyrin immobilized on imidazole-modified silica gel

Manganese tetraphenylphorphyrin complex fixed on imidazole-modified silica exhibits fair catalytic activity for cyclohexane oxidation by hydrogen peroxide. Immobilization of the porphyrin complex could result in the prevention of the formation of μ-oxo dimers, increasing the catalytic capability. Turnover numbers for cyclohexane oxidation are greatly improved by decreasing metal loadings, suggesting the importance of site isolation of the metal complexes. Rather high loading of imidazolyl group is required since its ligation to Mn was fully effected when imidazolyl group in large excess of Mn is present, as shown in the change in the diffuse reflectance spectra with imidazolyl/Mn ratio.

Hydroxylation of Alkanes Catalyzed by Manganese Tetraphenylporphyrin Immobilized on Imidazole-modified Silica Gel

Abstract Immobilization of Mn(TPP)Cl (TPP = tetraphenylporphyrin) onto 3-imidazolylpropyl-modified SiO2 resulted in enhancement of its activity for hydroxylation of cyclohexane; the support prevented the complex from forming a dimer leading to oxidative destruction.

Can µ-imidazolate mediate strong antiferromagnetic coupling?

A re-examination of antiferromagnetic coupling via imidazolate bridging ligands in manganese(II) tetraphenylporphyrin complexes suggests that previous reports of strong antiferromagnetic coupling in MnII(imidazolate)CuII systems may be in error.

ChemInform Abstract: Facile Preparation of Manganese(II) Tetraphenylporphyrin by the Pyrolysis of Dimethoxomanganese(IV) Tetraphenylporphyrin.

Manganese(II) tetraphenylporphyrin, MnII (tpp) (tpp = meso-tetraphenylporphinato), was afforded by the pyrolysis of MnIV(tpp)(OCH3)2 at ≈180 °C under 10−4–10−5 Torr (1 Torr ≅ 133.3 Pa). The pyrolysis of MoVO(tpp)OR (R = CH3, C2H5) in the solid state yielded MoIVO(tpp).

ChemInform Abstract: Temperature‐Dependent Valence Isomerization in a Manganese Tetraphenylporphyrin

The preparation and properties of a manganese tetraphenylporphyrin compound, MnTTP(CF/sub 3/SO/sub 3/)/sub 2/, are described. This compound is believed to undergo temperature-dependent valence isomerization from a manganese(III) pi cation radical at higher temperature to a manganese (IV) porphyrin at reduced temperatures. The compound is produced by a one-electron oxidation from the starting material MnTPP(Cl) containing a trivalent Mn. The data reported support the hypothesized temperature-dependent oxidation-state change. 12 references, 3 figures, 1 table.

Observations and comments on the mechanism of epoxidation of alkenes by manganese(III) porphyrins with hypochlorite.

The kinetics of olefin epoxidation in a methylene chloride/water biphase containing a phase-transfer agent with hypochlorite as oxygen transfer reagent and manganese(III) tetraphenylporphyrin catalysts has been reinvestigated. The results do not support the accumulation of an intermediate composed of an alkene and a hypervalent metaloxo porphyrin. Second-order rate constants for oxygen transfer from hypochlorite to the manganese porphyrin, comproprotionation of the hypervalent manganese-oxo porphyrin with manganese(III) porphyrin, and olefin epoxidation by the hypervalent manganese-oxo porphyrin were obtained from experiments in a wet organic monophase.