Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents

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 concen...

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Autores principales:	Sciaini, Alberto Germán, Wetzler, Diana E., Fernandez Prini, Roberto, Japas, María Laura
Publicado:	2002
Materias:	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
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10106030_v153_n1-3_p25_Sciaini http://hdl.handle.net/20.500.12110/paper_10106030_v153_n1-3_p25_Sciaini
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_10106030_v153_n1-3_p25_Sciaini
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spelling	paper:paper_10106030_v153_n1-3_p25_Sciaini2023-06-08T15:59:35Z Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents Sciaini, Alberto Germán Wetzler, Diana E. Fernandez Prini, Roberto Japas, María Laura 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 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. Fil:Sciaini, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Wetzler, D.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Fernández-Prini, R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Japas, M.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10106030_v153_n1-3_p25_Sciaini http://hdl.handle.net/20.500.12110/paper_10106030_v153_n1-3_p25_Sciaini
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	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
spellingShingle	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 Sciaini, Alberto Germán Wetzler, Diana E. Fernandez Prini, Roberto Japas, María Laura Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
topic_facet	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
description	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.
author	Sciaini, Alberto Germán Wetzler, Diana E. Fernandez Prini, Roberto Japas, María Laura
author_facet	Sciaini, Alberto Germán Wetzler, Diana E. Fernandez Prini, Roberto Japas, María Laura
author_sort	Sciaini, Alberto Germán
title	Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
title_short	Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
title_full	Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
title_fullStr	Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
title_full_unstemmed	Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
title_sort	kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents
publishDate	2002
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10106030_v153_n1-3_p25_Sciaini http://hdl.handle.net/20.500.12110/paper_10106030_v153_n1-3_p25_Sciaini
work_keys_str_mv	AT sciainialbertogerman kineticsofthermaldecolorationofaphotomerocyanineinmixturesofproticandnonpolarsolvents AT wetzlerdianae kineticsofthermaldecolorationofaphotomerocyanineinmixturesofproticandnonpolarsolvents AT fernandezpriniroberto kineticsofthermaldecolorationofaphotomerocyanineinmixturesofproticandnonpolarsolvents AT japasmarialaura kineticsofthermaldecolorationofaphotomerocyanineinmixturesofproticandnonpolarsolvents
_version_	1768542950507151360

Kinetics of thermal decoloration of a photomerocyanine in mixtures of protic and nonpolar solvents

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