A STUDY OF THE PHOTOPHYSICAL AND PHOTOREDOX PROPERTIES OF RUTHENIUM(II) COMPLEXES WITH PI-ACCEPTOR LIGANDS.
Item
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Title
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A STUDY OF THE PHOTOPHYSICAL AND PHOTOREDOX PROPERTIES OF RUTHENIUM(II) COMPLEXES WITH PI-ACCEPTOR LIGANDS.
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Identifier
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AAI8401911
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identifier
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8401911
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Creator
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WOLFGANG, STEVEN MARC.
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Contributor
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Harry D. Gafney
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Date
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1984
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Inorganic
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Abstract
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The photophysical and photoredox properties of Ru(bpy)(,3)('2+) ionically bound to Corning code #7930 porous Vycor glass, PVG, are investigated. The complex is adsorbed from aqueous solution to the glass. The latter is transparent and, therefore, amenable to spectroscopic techniques. Absorption, emission and resonance Raman spectra of Ru(bpy)(,3)('2+) adsorbed to PVG, Ru(bpy)(,3)('2+) ads, resemble spectra of the complex in aqueous or alcoholic solutions, and when excited with a low intensity pulse, the luminescence of the adsorbed complex decays exponentially with a lifetime of 740 (+OR-) 20 nsec. Coadsorbed gases, N(,2)O, SO(,2), and O(,2), quench both the intensity and lifetime of the luminescence of Ru(bpy)(,3)('2+) ads. Quenching by N(,2)O and SO(,2) occurs by electron transfer, although formation of the redox pair proceeds via different pathways. N(,2)O is weakly adsorbed and quenches by a dynamic process, suggesting that adsorbed N(,2)O migrates along the PVG surface. O(,2) and SO(,2) are more strongly adsorbed and therefore, quench predominately by a static process. Adsorption of these gases is random and analysis of the static quenching data yields a quenching distance, r, of 11 (+OR-) 1 (LESSTHEQ) r (LESSTHEQ) 17 (+OR-) 2 (ANGSTROM) for O(,2). Since SO(,2) quenches by an electron transfer mechanism, similar analysis suggests the occurrence of long range, 27 (+OR-) 2 (ANGSTROM), electron transfer in PVG.;Resonance Raman and emission spectra are reported for a series of complexes, Ru(azpy)(,2)L('n+), where azpy represents 2-(phenylazo)pyridine and L various monodentate or a bidentate ligand. The resonance Raman spectra reveal a relatively localized MLCT excited state with large distortions of the azo N=N bond. Emission maxima for the luminescent complexes are significantly red-shifted relative to other Ru(II) diimine complexes. These data along with previously measured electrohemical data suggest an energy level ordering in which the luminescent LMCT state is an exergonic oxidant and endergonic reductant. Quenching by a series of related oxidative and reductive quenchers is consistent with the calculated energetics of the photoinduced redox processes.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
