Ionic Liquids:  Novel Media for Characterization of Radical Ions

Marcinek, Andrzej; Zielonka, Jacek; Gębicki, Jerzy; Gordon, Christopher P.; Dunkin, Ian R.

doi:10.1021/jp0117718

Cited by 101 publications

(109 citation statements)

References 26 publications

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“…were utilized to characterize the properties of RTILs [7][8][9]. Pulse radiolysis and time-resolved fluorescence [10][11][12][13][14][15][16] have also been applied to study the reaction processes occurring in RTILs. These studies have provided some important information on the polarity and biphasic property of RTILs and have thrown light on the dynamics of ionic diffusion and internal motion of the dissolved solutes.…”

Section: Introductionmentioning

confidence: 99%

Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent

Zhu

et al. 2006

IJMS

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Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate [bmim] [PF 6 ] and its binary mixed solutions with organic solvent (DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355 nm, using anthraquinone (AQ) as a probe molecule. It was indicated that the triplet excited state of AQ ( 3 AQ*) can abstract hydrogen from [bmim] [PF 6 ]. Moreover, along with the change of the ratio of RTIL and organic solvent, the reaction rate constant changes regularly. Critical points were observed at volume fraction V RTIL = 0.2 for RTIL/MeCN and V RTIL = 0.05 for RTIL/DMF. For both systems, before the critical point, the rate constant increases rapidly with increasing V RTIL ; however, it decreases obviously with V RTIL after the critical point. We conclude that the concentration dependence is dominant at lower V RTIL , while the viscosity and phase transformation are dominant at higher V RTIL for the effect of ionic liquid on the decay of rate constant.

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Section: Introductionmentioning

confidence: 99%

Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent

Zhu

et al. 2006

IJMS

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“…This suggests that dissociation of the excited complex occurs. In addition to the 320 nm peak, the broad absorption in visible wavelength range can be seen, which is not observed by pulse radiolysis measurements [Marcinek et al, 1999] …”

Section: Introductionmentioning

confidence: 73%

“…As shown in Fig. 4, at 320 nm, the sharp peak was observed, which can be assigned to a neutral radical [bmim] · [Marcinek et al, 1999]. This suggests that dissociation of the excited complex occurs.…”

Section: Introductionmentioning

confidence: 79%

Photo-detrapping of solvated electrons in an ionic liquid

Takahashi

Suda

Seto

et al. 2009

Radiation Physics and Chemistry

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“…. Figure 1a shows the absorption spectrum of ionized indole in a BMIM þ PF 6 À /CH 2 Cl 2 matrix. The intense peak at 330 nm and the double-humped band at 560/605 nm have been previously attributed to the radical cation of indole.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Dimer Radical Cations of Indole and Indole-3-carbinol: Localized and Delocalized Radical Cations of Diindolylmethane

2011

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Extending our previous study on the title species (J. Phys. Chem. A 2010, 114, 6787), we investigated the dimer cations that are formed on oxidation of the glucobrassin derivatives indole-3-carbinol (I3C) and diindolylmethane (DIM) and of parent indole (I). Radiolysis in ionic liquid and Ar matrices shows that, at sufficiently high concentrations and/or on annealing the solid glasses, intense intermolecular charge-resonance (CR) absorption bands in the NIR herald the formation of sandwich-type dimer cations. The molecular and electronic structure of these species is modeled by calculations with the double-hybrid B2-PLYP-D density functional method which yields predictions in good accord with experiment. The radical cation of DIM also shows a CR band, but unlike in the case of I and I3C, its occurrence is not dependent on the concentration but instead on the solvent: in ionic liquid the CR band is initially absent and arises only on annealing, whereas in Ar matrices it is present from the outset and undergoes blue shifting and sharpening on annealing. These puzzling findings are rationalized on the basis of B2-PLYP-D calculations which predict that neutral DIM exists in the form of two conformers, present in different relative amounts in the two experiments, which on vertical ionization form distinct radical cations, a nonsymmetric one where the odd electron is largely localized on one of the two indole moieties and one with C 2 symmetry where charge and spin are completely delocalized over both halves of the molecule, thus giving rise to an intramolecular CR transition. On annealing, the nonsymmetric cation relaxes to a similarly delocalized structure with C s symmetry, thus explaining the observed increase and the shift of the CR band. We believe that DIM •+ represents the first example of a radical cation which can exist under the same conditions as a localized and a delocalized complex cation.

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Ionic Liquids: Novel Media for Characterization of Radical Ions

Cited by 101 publications

References 26 publications

Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent

Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent

Photo-detrapping of solvated electrons in an ionic liquid

Dimer Radical Cations of Indole and Indole-3-carbinol: Localized and Delocalized Radical Cations of Diindolylmethane

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