Solvent and temperature effects on the deactivation pathways of excited ion pairs produced via photoinduced proton transfert

L. Biczók, Pierre Valat, Véronique Wintgens

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The kinetics of the energy dissipation pathways of the excited ion pairs formed upon light absorption of the hydrogen bonded complex between N-methyl-3-hydroxynaphthalimide (3HONI) and 1-methyl-imidazole (MIm) has been studied in a wide temperature range in solvents of various polarities. In polar media such as butyronitrile, three emitting species are found which are assigned as hydrogen bonded, solvent separated and free ion pairs. In contrast, less polar solvents do not favour free ion pair formation, and reversible transition occurs between the excited hydrogen bonded (HBIP) and solvent separated (SSIP) ion pairs around room temperature. Systematic steady-state and time-resolved fluorescence measurements combined with computer modelling enabled the deduction of the kinetic parameters for all excited state deactivation processes in solvents of moderate polarity. The Arrhenius parameters of the interconversion between the ion pairs, the A-factor for the radiationless deactivation of SSIP and the radiative rate constant of HBIP diminish with the increasing dielectric constant of the media. The enthalpy and the entropy change in the SSIP formation from HBIP become less negative in more polar solvents. Going from ethyl acetate to CH2Cl2 the most profound decrease (more than three orders of magnitude) is observed for the A-factor of SSIP → HBIP reaction.

Original languageEnglish
Pages (from-to)230-235
Number of pages6
JournalPhotochemical and Photobiological Sciences
Volume2
Issue number3
DOIs
Publication statusPublished - Mar 2003

Fingerprint

deactivation
Thermal effects
temperature effects
Protons
Ions
Temperature
protons
Hydrogen
ions
polarity
hydrogen
deduction
kinetics
Entropy
electromagnetic absorption
imidazoles
Kinetic parameters
Excited states
Light absorption
acetates

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Cell Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics

Cite this

Solvent and temperature effects on the deactivation pathways of excited ion pairs produced via photoinduced proton transfert. / Biczók, L.; Valat, Pierre; Wintgens, Véronique.

In: Photochemical and Photobiological Sciences, Vol. 2, No. 3, 03.2003, p. 230-235.

Research output: Contribution to journalArticle

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