| 2 | Author
| Michael Neumann-Spallart, K. Kalyanasundaram | Requires cookie* | | Title
| On the One and Two-Electron Oxidations of Water-Soluble Zinc Porphyrins in Aqueous Media  | | | Abstract
| The one and two-electron oxidations of water soluble ionic zinc porphyrins (Zinctetra-methylpyridylporphyrin, ZnTMPyP, Zinc-tetra-p-sulfonato-phenyl-porphyrin, ZnTPPS, and Zinc-tetra-p-carboxy-phenylporphyrin, ZnTPPC) leading to the porphyrin /7-cations and /7-dications have been investigated in water by electrochemical (cyclic voltammetry and controlled potential electrolysis) and chemical methods. The half-wave potentials for the oxidation are shown to be markedly dependent on the charge on the /?-substituents. While the one-electron oxidations for all these porphyrins are reversible, the dication formation leads to labile isoporphyrins as intermediates. | | |
Reference
| Z. Naturforsch. 36b, 596—600 (1981); received December 1 1980/February 19 1981 | | |
Published
| 1981 | | |
Keywords
| Redox Potentials, yr-Cation Radicals, Electrochemistry | | |
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| default:Reihe_B/36/ZNB-1981-36b-0596.pdf | | | Identifier
| ZNB-1981-36b-0596 | | | Volume
| 36 | |
3 | Author
| Berthold Kiefer, Helmut Sapper, WolfgangL. Ohm Ann | Requires cookie* | | Title
| The Influence of Amino Acid Ligands and Vitamin C on the Reduction Potential of Fe(III): Polarographie and Electron Spin Resonance Investigations  | | | Abstract
| The pH dependence o f Fe(III)-am ino acid com plexes has been studied polarographically and by means o f ESR spectroscopy. It could be shown that, at least, two com plexes exist: one with a low m olecular weight, ESR detectable at acid pH. and one with a high molecular w eight at alkaline pH, ESR non detectable. The half wave potential o f Fe (III) is lowered by am ino acid ligands. The redox interaction o f the Fe(III)-amino acid com plexes with vitam in C results in a decrease o f the ascorbyl radical concentration. Ascorbic acid also forms a com plex with Fe(III) as in dicated by a polarographic half wave potential near -0.55 V vs. S.C.E. at pH 7. | | |
Reference
| Z. Naturforsch. 39c, 102—106 (1984); received September 22 1983 | | |
Published
| 1984 | | |
Keywords
| Ferrous Ions Ascorbic Acid, Redox-Potential, Polarography, ESR -Spectroscopy | | |
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| default:Reihe_C/39/ZNC-1984-39c-0102.pdf | | | Identifier
| ZNC-1984-39c-0102 | | | Volume
| 39 | |
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