The fluorescence of ion pairs of the fluorenyl carbanion

Brocklehurst, B.; Young, R. N.

doi:10.1039/b103730g

Cited by 1 publication

(2 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The activation energy of this transition is scarcely influenced by the solvent, however, about 5-fold decrease is observed for the A-factor with increasing dielectric constant of the medium. Temperature dependent non-radiative decay has been found also for excited fluorenyl salts 12 and the Arrhenius parameters reported in that case agree with the results shown in Table 3.…”

Section: Solvent Effect On Kinetic and Thermodynamic Parameterssupporting

confidence: 85%

“…Brocklehurst and Young have demonstrated that the interconversion between excited ion pairs is not a universal process, the rate depending on the solvent and cation. 12 To avoid the interference originating from ground state ion pairing we exploit the ultrafast proton transfer within the excited hydrogen bonded complex to selectively produce the excited contact ion pairs. Light absorption of the complex between N-methyl-3-hydroxynaphthalimide (3HONI) and 1-methyl-imidazole (MIm) (Scheme 1) results in strong dual fluorescence in media of moderate polarity and the two bands have been assigned to hydrogen bonded and solvent separated ion pairs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Biczók

Valat

Wintgens

2003

Photochem Photobiol Sci

View full text Add to dashboard Cite

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 CH 2 Cl 2 the most profound decrease (more than three orders of magnitude) is observed for the A-factor of SSIP HBIP reaction.

show abstract

Section: Solvent Effect On Kinetic and Thermodynamic Parameterssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%