Abstract:
The kinetics of thermal conversion of a photogenerated merocyanine into its more stable spiropyrane form was studied in mixtures of ethanol with nonpolar solvents, toluene, n-hexane or CO2. For solutions of ethanol concentration higher than ca. 1.5 M two decay rates are observable. Below that concentration, the relative amplitude of the slow mode becomes negligible, compared to the fast, and the observed kinetics is monoexponential. As reported before in toluene-acetonitrile mixtures, the rate constant for the thermal decay in toluene-ethanol passes through a shallow maximum at low-ethanol concentrations. The activation energy and entropy of both processes were determined; the data corresponding to the fast process have a complex alcohol concentration dependence. A three-species reaction scheme proposed previously for neat alcohols, supplemented with an approximation regarding the effect of medium polarity on the assumed species, is able to capture the essential features of all activation thermodynamic functions in the studied mixtures. © 2002 Elsevier Science B.V. All rights reserved.
Registro:
Documento: |
Artículo
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Título: | Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents |
Autor: | Sciaini, G.; Wetzler, D.E.; Alvarez, J.; Fernández-Prini, R.; Japas, M.L. |
Filiación: | INQUIMAE, Facultad de Ciencias Exactas y Naturales, Pabellón 2, 1428-Buenos Aires, Argentina Unidad Actividad Química, Comisión Nacional de Energía Atómica, Av. Libertador 8250, 1429-Buenos Aires, Argentina Dpto. Ingeniería Química, FRBA, Universidad Tecnológica Nacional, Medrano 951, 1179-Buenos Aires, Argentina Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, Alem 3901, 1653-Villa Ballester, Argentina
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Palabras clave: | Kinetics; Photomerocyanine; Thermal decoloration; acetonitrile; alcohol; carbon dioxide; hexane; merocyanine; pyran derivative; solvent; toluene; action potential; article; chemical analysis; chemical reaction kinetics; concentration response; controlled study; data analysis; decolorization; energy; entropy; molecular stability; photochemistry; polarization; thermal analysis; thermodynamics |
Año: | 2002
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Volumen: | 153
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Número: | 1-3
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Página de inicio: | 25
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Página de fin: | 31
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DOI: |
http://dx.doi.org/10.1016/S1010-6030(02)00294-0 |
Título revista: | Journal of Photochemistry and Photobiology A: Chemistry
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Título revista abreviado: | J. Photochem. Photobiol. A Chem.
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ISSN: | 10106030
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CODEN: | JPPCE
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Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10106030_v153_n1-3_p25_Sciaini |
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Citas:
---------- APA ----------
Sciaini, G., Wetzler, D.E., Alvarez, J., Fernández-Prini, R. & Japas, M.L.
(2002)
. Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents. Journal of Photochemistry and Photobiology A: Chemistry, 153(1-3), 25-31.
http://dx.doi.org/10.1016/S1010-6030(02)00294-0---------- CHICAGO ----------
Sciaini, G., Wetzler, D.E., Alvarez, J., Fernández-Prini, R., Japas, M.L.
"Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents"
. Journal of Photochemistry and Photobiology A: Chemistry 153, no. 1-3
(2002) : 25-31.
http://dx.doi.org/10.1016/S1010-6030(02)00294-0---------- MLA ----------
Sciaini, G., Wetzler, D.E., Alvarez, J., Fernández-Prini, R., Japas, M.L.
"Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents"
. Journal of Photochemistry and Photobiology A: Chemistry, vol. 153, no. 1-3, 2002, pp. 25-31.
http://dx.doi.org/10.1016/S1010-6030(02)00294-0---------- VANCOUVER ----------
Sciaini, G., Wetzler, D.E., Alvarez, J., Fernández-Prini, R., Japas, M.L. Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents. J. Photochem. Photobiol. A Chem. 2002;153(1-3):25-31.
http://dx.doi.org/10.1016/S1010-6030(02)00294-0