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Titolo:
Heterodimers and -trimers of meso-tetra-(isophthalicacid)-porphyrin octaanions with meso- and beta-tetramethylpyridinium-porphyrin tetracations and their manganese complexes in water. Electrochemistry, spectroelectrochemistry and fluorescence quenching
Autore:
Ruhlmann, L; Zimmermann, J; Fudickar, W; Siggel, U; Fuhrhop, JH;
Indirizzi:
Free Univ Berlin, Inst Chem Organ Chem, D-14195 Berlin, Germany Free Univ Berlin Berlin Germany D-14195 an Chem, D-14195 Berlin, Germany Univ Paris 11, Chim Phys Lab, Equipe Electrochim & Photoelectrochim, F-91105 Orsay, France Univ Paris 11 Orsay France F-91105 otoelectrochim, F-91105 Orsay, France Humboldt Univ, Inst Phys, Lehrstuhl Photobiophys, D-10115 Berlin, Germany Humboldt Univ Berlin Germany D-10115 otobiophys, D-10115 Berlin, Germany Tech Univ Berlin, Max Volmer Inst Phys Chem, D-10623 Berlin, Germany Tech Univ Berlin Berlin Germany D-10623 ys Chem, D-10623 Berlin, Germany
Titolo Testata:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
fascicolo: 1-2, volume: 503, anno: 2001,
pagine: 1 - 14
Fonte:
ISI
Lingua:
ENG
Soggetto:
OXYGEN-EVOLVING COMPLEX; PHOTOSYSTEM-II; OLEFIN EPOXIDATION; COORDINATED WATER; AQUEOUS-SOLUTION; SOLUBLE IRON; PHOTOSYNTHESIS; OXIDATION; MODEL; PHOTOCHEMISTRY;
Keywords:
spectroelectrochemistry; cyclic voltammetry; fluorescence quenching; multivalent manganese porphyrin trimer; equilibrium constants;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
56
Recensione:
Indirizzi per estratti:
Indirizzo: Fuhrhop, JH Free Univ Berlin, Inst Chem Organ Chem, Takustr 3, D-14195 Berlin, Germany Free Univ Berlin Takustr 3 Berlin Germany D-14195 in, Germany
Citazione:
L. Ruhlmann et al., "Heterodimers and -trimers of meso-tetra-(isophthalicacid)-porphyrin octaanions with meso- and beta-tetramethylpyridinium-porphyrin tetracations and their manganese complexes in water. Electrochemistry, spectroelectrochemistry and fluorescence quenching", J ELEC CHEM, 503(1-2), 2001, pp. 1-14

Abstract

Non-covalent cofacial heterodimers and -trimers between meso-tetraphenyl-octacarboxylate-porphyrin and beta -tetracationic porphyrins have been prepared in bulk water. They are held together by Coulomb interactions between four or eight beta -methylpyridinium and meso-phenylcarboxylate ion pairs. The observation of the UV-vis absorption titration indicated quantitative trimerization at concentrations >10(-6) M. The equilibrium constants in waterwere 2.3 x 10(6) M-1 for the dimerization and 1.7 x 10(7) M-1 for the conversion of the dimer to the trimer in water. Fluorescence of free base or zinc porphyrins was strongly diminished on heterodimerization and -trimerization by redox quenching. In the case of Mn(III) heterotrimer, electrochemistry and spectroelectrochemistry showed that all three Mn(III) ions were oxidized simultaneously to Mn(IV) at a potential close to 0.20 V versus Ag \ AgCl at pH 12. Electroreduction of the peripheral cationic Mn(III) porphyrinswas achieved at - 0.20 V versus Ag \ AgCl and gave the first multivalent trimers, namely Mn(II)P-Mn(III)P-Mn(II)P. The reduction of the central manganese porphyrin finally occurred at -0.60 V yielding Mn(II)P-Mn(II)P-Mn(II)Ptrimers. Heterotrimers Mn(III)P-H2P-Mn(III)P and H2P-Mn(III)P-H2P were also studied as reference compounds for electrochemical measurements. (C) 2001Elsevier Science B.V. All rights reserved.

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Documento generato il 09/04/20 alle ore 18:54:37