Solvation dynamics of room-temperature ionic liquids: evidence for collective solvent motion on sub-picosecond timescales

Kobrak, Mark N.; Znamenskiy, Vasiliy

doi:10.1016/j.cplett.2004.07.049

Cited by 115 publications

(120 citation statements)

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“…Simulations by Kobrak and Znamenskiy 59 have also indicated collective cation-anion motion on subpicosecond time scales, which again argues against a purely anionic subpicosecond solvation response. The existence of collective motion is not inconsistent with our suggestion of the role of the organic cation.…”

Section: Discussionmentioning

confidence: 99%

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Dynamic Solvation in Imidazolium-Based Ionic Liquids on Short Time Scales

et al. 2006

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Steady-state and time-resolved Stokes shift data for the probe coumarin 153 in two imidazoles, six imidazolium-based ionic liquids, and several other solvents are presented. These results are consistent with our original suggestion (J. Phys. Chem. B 2004, 108, 10245−10255) that initial solvation is dominated by the organic moiety of the ionic liquid, and they show that for the imidazole-based liquids initial solvation is in all cases very rapid. Solvation by methylimidazole and butylimidazole is complete in 100 ps, and all of the imidazolium ionic liquids demonstrate similarly rapid initial solvation. Owing to the importance of determining the amount of initial solvation that is missed in a given experiment with finite time resolution, we discuss a method of estimating the intramolecular contribution to the reorganization energy. This method yields 2068 cm-1 and is compared with an alternative method. ReceiVed: February 1, 2006; In Final Form: May 18, 2006 Steady-state and time-resolved Stokes shift data for the probe coumarin 153 in two imidazoles, six imidazoliumbased ionic liquids, and several other solvents are presented. These results are consistent with our original suggestion (J. Phys. Chem. B 2004, 108, 10245-10255) that initial solvation is dominated by the organic moiety of the ionic liquid, and they show that for the imidazole-based liquids initial solvation is in all cases very rapid. Solvation by methylimidazole and butylimidazole is complete in 100 ps, and all of the imidazolium ionic liquids demonstrate similarly rapid initial solvation. Owing to the importance of determining the amount of initial solvation that is missed in a given experiment with finite time resolution, we discuss a method of estimating the intramolecular contribution to the reorganization energy. This method yields 2068 cm -1 and is compared with an alternative method.

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Section: Discussionmentioning

confidence: 99%

“…[56][57][58][59] In a recent computer simulation, Shim et al 57 place a dipolar excitation on a model diatomic solute in a RTIL. They observe a fast initial relaxation and suggest that it arises from translations of the anions.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Solvation in Imidazolium-Based Ionic Liquids on Short Time Scales

et al. 2006

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“…[1][2][3][4] The importance of ionic liquids has consequently stimulated considerable interest in their dynamic solvation properties, both in the experimental and the theoretical arenas. [26][27][28][29][30][31][32] An intriguing aspect of certain ionic liquids, which has only recently become appreciated, is their ability to promote micelle formation or to form micelles themselves. [33][34][35][36] Major questions regarding dynamic solvation by ionic liquids deal with whether the organic cation or the inorganic anion solvate preferentially on different time scales, the role of the correlated motion of the ion pairs and their lifetime, and the importance of translational motion of the ions relative to dipolar relaxation.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Roles of the Constituents of Ionic Liquids in Dynamic Solvation: Comparison of an Ionic Liquid in Micellar and Bulk Form

et al. 2006

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Dynamic solvation of the dye, coumarin 153, is compared in an ionic liquid that forms micelles in water against the bulk solvent. This provides the unprecedented opportunity of investigating the behavior of the ionic liquid in two globally different configurations. It is proposed that the imidazolium moiety is in both cases responsible for the majority of the solvation, which manifests itself in the first 100 ps. Exploiting the use of ionic liquids capable of accommodating specific structures thus provides a deeper insight into how solutes interact with these fascinating and interesting solvents (at least those that are imidazolium based) that are gaining ever increasing interest in the scientific community.

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“…In particular, negligible vapor pressure of RTILs makes them a green alternative of conventional organic solvent. For understanding of RTIL's dynamical behavior at the molecular level, solvation and rotational dynamics have been studied experimentally Cang et al, 2003;Funston et al, 2007;Ingram et al, 2003;Jin et al, 2007;Karmakar & Samanta, 2002a;Lang et al, 2006) and theoretically Kobrak, 2006;2007;Kobrak & Znamenskiy, 2004;Shim et al, 2006;2007;Shim & Kim, 2009). It is found that the ultrafast relaxation in a subpicosecond time regime contributes substantially to solvation dynamics, disproving the diffusion-controlled solvation in RTILs.…”

Section: Introductionmentioning

confidence: 99%