Bimolecular electron transfer reactions of the excited states of transition metal complexes

Balzani, Vincenzo; Bolletta, Fabrizio; Gandolfi, Maria Teresa; Maestri, Matteo

doi:10.1007/bfb0048835

Cited by 431 publications

(188 citation statements)

References 250 publications

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“…4D+ + 2H20 >*4D + 02+4H+ (3) is receiving scrutiny [1][2][3][4][5] all over the world. Partial success has been achieved with photosensitizers such as Ru(bpy)3 2+ [2], acridine dyes [3] and porphyrins [4].…”

Section: Introductionmentioning

confidence: 99%

“…Since we were interested in exploring the utility of porphyrins as photoredox sensitizers in water, we decided to investigate the one and two-electron oxidations directly in water. Earlier, we have demonstrated [4 a] that water-soluble zinc porphyrins serve very well as photosensitizers for H2-evolution from water via reactions (1) and (2). Towards further exploration of their utility in reaction (3), herein, we de-scribe our studies on one and two-electron oxidation of these porphyrins in water.…”

Section: Introductionmentioning

confidence: 99%

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On the One and Two-Electron Oxidations of Water-Soluble Zinc Porphyrins in Aqueous Media

Neumann‐Spallart

Kalyanasundaram

1981

Zeitschrift Für Naturforschung B

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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 Π-cations and Π-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 β-substituents. While the one-electron oxidations for all these porphyrins are reversible, the dication formation leads to labile isoporphyrins as intermediates

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the One and Two-Electron Oxidations of Water-Soluble Zinc Porphyrins in Aqueous Media

Neumann‐Spallart

Kalyanasundaram

1981

Zeitschrift Für Naturforschung B

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“…Until a few years ago, the photochemical studies in this field were mostly confined to unimolecular photochemical processes, such as homolytic and heterolytic metal-ligand bond breaking or isomerization reactions (1,2). In the last few years, however, the interest has moved towards bimolecular processes (3) with particular emphasis on electron transfer reactions (4). This last class of photochemical reactions is very interesting for at least three reasons: (i) they are very promising for the conversion of light energy (including solar energy) into chemical energy; (ii) they can lead to camplaxes having unusual oxidation states and thus unusual chemical (catalytic) properties; (iii) they allow us to check the theories of outersphere electron transfer reactions (5-7) over a broad range of free energy change.…”

Section: Introductionmentioning

confidence: 99%

Excited state electron-transfer reactions of transition metal complexes

Balzani

Bolletta

Scandola

et al. 1979

Pure and Applied Chemistry

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-The properties of excited states of transition metal complexes are briefly reviewed. The outer-sphere electron transfer reactions of the excited states of complexes containing 2,2'-bipyridine or 1,10-phenanthroline ligands are discussed in detail, with particular reference to electron ~ energy transfer quenching and conversion of light into chemical energy. The kinetic aspects of outer-sphere electron transfer reactions involving excited states are examined with particular reference to the so-called "Marcus inverted behavior" which is not obser:ved in most of the systems studied. The extension of the kinetic formalism used for electron transfer reactions to energy transfer processes yields a unified view of "classical" and " nonclassical" energy transfer behavior.

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“…Therefore, the electronically excited state is expected to be both a better reductant and a better oxidant than the ground state. By assuming that differences in shape, size, solution, and entropy of the ground and excited states are small, the redox potentials of the excited state are fairly well approximated by equations 5 and 6 (43). (27,34) which can result in variations of k' of more than a factor of 10 when below the diffusion-controlled plateau (45).…”

Section: Formation Of Separated Charge Carriersmentioning

confidence: 99%

Photochemical Determinants of the Efficiency of Photogalvanic Conversion of Solar Energy

Hoffman

Lichtin

1979

Solar Energy

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A photogalvanic cell is a battery in which the cell solution absorbs light directly to generate species which, upon back reaction through an external circuit with the aid of suitable electrodes, produces electric power; photoactivation of the electrodes is 'not involved. The charge-carrying species have storage capacity if they are long-lived and can be prevented from engaging in degradativc back reactions in bulk solution. The efficiency of a photogalvanic cell for the conversion of photon energy into electrical energy is determined by photochemical and electrochemical factors. Among the latter are the choice of electrode materials and the kinetics of electron transfer at the heterogeneous surfaces. In this paper we examine '"the photochemical determinants of the efficiency of photogalvanic eel] operation: the absorption spectral characteristics of the cell solution, the efficiency of formation of separated charge carriers, and the lifetimes of the carriers toward back electron transfer. Modulation of bulk solution dynamics can be achieved by variation of the solution medium. The photochemical determinants are discussed with particular reference to the use of thionine or Ru(bpy)2+ as the light absorbing species.

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Bimolecular electron transfer reactions of the excited states of transition metal complexes

Cited by 431 publications

References 250 publications

On the One and Two-Electron Oxidations of Water-Soluble Zinc Porphyrins in Aqueous Media

On the One and Two-Electron Oxidations of Water-Soluble Zinc Porphyrins in Aqueous Media

Excited state electron-transfer reactions of transition metal complexes

Photochemical Determinants of the Efficiency of Photogalvanic Conversion of Solar Energy

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