What determines the rate of excited-state intramolecular electron-transfer reaction of 4-(N,N'-dimethylamino)benzonitrile in room temperature ionic liquids? A study in [bmim][PF6]

Santhosh, Kotni ; Samanta, Anunay (2012) What determines the rate of excited-state intramolecular electron-transfer reaction of 4-(N,N'-dimethylamino)benzonitrile in room temperature ionic liquids? A study in [bmim][PF6] ChemPhysChem . ISSN 1439-4235

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/cphc.20...

Related URL: http://dx.doi.org/10.1002/cphc.201100655

Abstract

The kinetics of excited-state intramolecular electron-transfer reaction and dynamics of solvation of the intramolecular charge transfer (ICT) state of 4-(N,N'-dimethylamino)benzonitrile (DMABN) was studied in 1-butyl-3-methylimidazloium hexafluorophosphate, [bmim][PF6], by monitoring the dual fluorescence of the system. The picosecond time-resolved emission spectra (TRES) of DMABN exhibit decay of the locally excited (LE) emission intensity and shift of the ICT emission peak position with time, thus capturing the kinetics of evolution of the ICT state from the LE state and solvent relaxation of the ICT state. These results show that the LE→ICT transformation rate is determined not by the slow dynamics of solvation in ionic liquid, but is controlled mainly by the rate of structural reorganization of the molecule, which accompanies the electron-transfer process in this polar viscous medium. Even though both solvent reorganization around photo-excited DMABN and structural rearrangement of the molecule are dependent on the viscosity of the medium, it is the latter process that contributes to the viscosity dependence of the LE→ICT transformation.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Excited-state Charge Transfer; Ionic Liquids; Photochemistry; Solvation Dynamics; Time-resolved Emission Spectroscopy
ID Code:86702
Deposited On:12 Mar 2012 16:08
Last Modified:12 Mar 2012 16:08

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