Spectroscopy and thermal decay of a photomerocyanine in mixtures of polar and nonpolar solvents

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Absorption and emission spectra of the merocyanine (MC) form of 6- nitrobenzospiropyran (SP), as well as the kinetics of the thermal decay of MC to SP, were measured in solvent mixtures of ethanol-hexane, ethanol-toluene and acetonitrile-toluene. For all these mixtures, the Stokes shift of MC shows...

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Detalles Bibliográficos
Autores principales: Wetzler, D.E., Aramendía, P.F., Japas, M.L., Fernández-Prini, R.
Formato: JOUR
Materias:
acetonitrile
alcohol
benzene derivative
hexane
merocyanine
nitrogen derivative
pyran derivative
solvent
toluene
article
chemical reaction kinetics
chemical structure
controlled study
enthalpy
photochemistry
spectroscopy
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_14639076_v1_n21_p4955_Wetzler
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:Absorption and emission spectra of the merocyanine (MC) form of 6- nitrobenzospiropyran (SP), as well as the kinetics of the thermal decay of MC to SP, were measured in solvent mixtures of ethanol-hexane, ethanol-toluene and acetonitrile-toluene. For all these mixtures, the Stokes shift of MC shows the same linear dependence with the solvent parameter E(T)(30). The thermal decay kinetics is monoexponential in acetonitrile-toluene mixtures and biexponential in those containing ethanol. The activation parameters of the rate constants display very different behaviours with E(T)(30): whereas ΔG≠ is linear in this parameter, E(a) shows abrupt variations with this polarity parameter. This is compensated by changes in ΔS≠, resulting in a linear correlation between E(a) and ΔS≠.

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