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Title: Study of intermediates from transition metal excited-state electron- transfer reactions

Abstract

Progress on 6 projects is reported: excited state absorption spectrum of Ru(bpy)[sub 3][sup 2+], solvent cage model for electron transfer quenching, reductive quenching of [sup *]Cr(III) complexes, solution medium effects in oxidative quenching of [sup *]Ru(II) complexes, photosensitized oxidation of phenol in aqueous solution, and quenching of Ru(II) complexes by oxygen.

Authors:
Publication Date:
Research Org.:
Boston Univ., MA (United States). Dept. of Chemistry
Sponsoring Org.:
DOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6735328
Alternate Identifier(s):
OSTI ID: 6735328; Legacy ID: DE93010904
Report Number(s):
DOE/ER/13603-7
ON: DE93010904
DOE Contract Number:
FG02-86ER13603
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHROMIUM COMPLEXES; PHOTOCHEMICAL REACTIONS; ELECTRON TRANSFER; RUTHENIUM COMPLEXES; ABSORPTION SPECTRA; BIPYRIDINES; EXCITED STATES; OXYGEN; PHENOL; PHOTOLYSIS; PROGRESS REPORT; REACTION INTERMEDIATES; SCINTILLATION QUENCHING; AROMATICS; AZINES; CHEMICAL REACTIONS; COMPLEXES; DECOMPOSITION; DOCUMENT TYPES; ELEMENTS; ENERGY LEVELS; HETEROCYCLIC COMPOUNDS; HYDROXY COMPOUNDS; NONMETALS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PHENOLS; PYRIDINES; SPECTRA; TRANSITION ELEMENT COMPLEXES 400500* -- Photochemistry

Citation Formats

Hoffman, M.Z. Study of intermediates from transition metal excited-state electron- transfer reactions. United States: N. p., 1993. Web. doi:10.2172/6735328.
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Hoffman, M.Z. Study of intermediates from transition metal excited-state electron- transfer reactions. United States. doi:10.2172/6735328.
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Hoffman, M.Z. Wed . "Study of intermediates from transition metal excited-state electron- transfer reactions". United States. doi:10.2172/6735328. https://www.osti.gov/servlets/purl/6735328.
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@article{osti_6735328,
title = {Study of intermediates from transition metal excited-state electron- transfer reactions},
author = {Hoffman, M.Z.},
abstractNote = {Progress on 6 projects is reported: excited state absorption spectrum of Ru(bpy)[sub 3][sup 2+], solvent cage model for electron transfer quenching, reductive quenching of [sup *]Cr(III) complexes, solution medium effects in oxidative quenching of [sup *]Ru(II) complexes, photosensitized oxidation of phenol in aqueous solution, and quenching of Ru(II) complexes by oxygen.},
doi = {10.2172/6735328},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 31 00:00:00 EST 1993},
month = {Wed Mar 31 00:00:00 EST 1993}
}
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Technical Report:
View Technical Report (0.40 MB)
DOI:  10.2172/6735328
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  • Objective of this research program, which utilizes the techniques of continuous and pulsed photolysis and radiolysis, is the acquiring of an understanding of the photophysical and photochemical pathways that dictate the efficiencies and rates of population and depopulation of the excited states; the quantitative effect of solution medium and ion-pairing on the dynamics of the reactions; and the properties and reactivities of the reduced and oxidized species.

  • In our study of intermediates from excited-state electron-transfer reactions, we have focused our attention during the past year on MV/sup +/., the reduced methyl viologen radical cation, which is a precursor to the formation of H/sub 2/ in the photosensitized reduction of water. Through the use of photochemical and radiation chemical techniques, we have examined the efficiency of interaction of MV/sup +/. with colloidal Pt, the stability of MV/sup +/. as a function of pH, the quantum yield of formation of MV/sup +/. in the Ru(bpy)/sub 3//sup 2 +//MV/sup 2 +//EDTA system, and the formation of photoactive charge-transfer complexes betweenmore » MV/sup 2 +/ and sacrificial electron donors.« less

  • Our research, which has utilized the techniques of continuous and pulsed photolysis and radiolysis, has focused on the following aspects of excited-state electron transfer reactions involving coordination complexes and ion-pair donor-acceptor complexes in an attempt to understand the parameters that govern the reaction pathways in the photochemical processes: (1) ion-pairing and aggregation among reactive species; (2) control of the yields of redox products; (3) chemistry of reaction intermediates (4) properties of excited states of Cr(III)-polypyridyl complexes; (5) mechanisms of intramolecular electron transfer.

  • This report contains sections entitled: (1) Cage escape yields in the quenching of Ru(II) photosensitizers; (2) Characterization of one-electron reduced Ru(II) complexes; (3) Synthesis and characterization of new Ru(II) photosensitizers; (4) Reductive quenching of Ru(II) and Cr(III) complexes; and (5) Photosensitized initiation of polymerization. 11 refs.

  • During the period covered by this progress report, the examination of intermediates from transition metal excited-state electron-transfer reactions followed certain well-defined themes; the techniques of conventional and time-resolved spectrofluorimetry, continuous and pulsed laser flash photolysis, and continuous and pulse radiolysis were employed. Research involves Ru(II) complexes and Cr(III) complexes. 23 refs., 2 tabs.