Dynamics of solvation and rotational relaxation of Coumarin 153 in 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6]–water mixtures

Chakrabarty, Debdeep; Chakraborty, Anjan; Seth, Debabrata; Hazra, Partha; Sarkar, Nilmoni

doi:10.1016/j.cplett.2004.08.141

Cited by 70 publications

(87 citation statements)

References 32 publications

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“…C153 is considered to be an ideal probe because the dynamics probed by C153 have been found to be primarily related to nonspecific solute−solvent interactions in many RTIL systems. 17,52,53,58 BPP is a particularly sensitive probe of microviscosity especially in the heterogeneous environment such as ionic liquid systems. 55−57,59−62 As a result, the microviscosity enhancement effects in the [bmim] [PF 6 ] and TEGDME hybrid system were observed by probing the microviscosity through the two complementary experimental methods.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Evidence for Unusual Microviscosity in Imidazolium Ionic Liquid and Tetraethylene Glycol Dimethyl Ether Cosolvent Mixtures

Wang

et al. 2012

J. Phys. Chem. B

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The rotational dynamics of coumarin 153 (C153) in imidazolium-based ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF 6 ]) and tetraethylene glycol dimethyl ether (TEGDME) mixtures across all mole fractions have been investigated to determine the local viscosity of the microenvironment surrounding the probe molecules. The excimer-to-monomer fluorescence emission intensity ratio (I E /I M ) of a well-known microviscosity probe, 1,3-bis(1-pyrenyl)propane (BPP), is also employed to study the microviscosity of the mixtures as a complementary measurement. The rotational dynamics of C153 show that there are incompact and compact domains within the heterogeneous structural [bmim] [PF 6 ], resulting in fast and slow components of C153 rotational dynamics. The microviscosity in different structural domains of [bmim] [PF 6 ] before and after adding cosolvent TEGDME with different mole fractions is further investigated by studying the fluorescence anisotropy decay of probe molecules. The obtained average rotation time constants show that the microviscosity of [bmim] [PF 6 ] is enhanced after mixing with a certain amount of TEGDME, although the bulk viscosity of TEGDME itself is much lower than that of the ionic liquid. This unusual behavior of microviscosity enhancement is further proven by the steady state fluorescence measurement with the microviscosity probe of BPP. The microviscosity enhancement is reasonably demonstrated by the fast time constant of C153 rotational dynamics and the departure between the experimentally observed and calculated ratio of I E /I M of BPP, which shows that this effect is most pronounced at intermediate mole fractions of the [bmim] [PF 6 ] and TEGDME mixtures. The strengthening effects caused by the molecular interactions between TEGDME and structural heterogeneous ionic liquid [bmim] [PF 6 ] are proposed to interpret the unusual microviscosity behaviors.

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Section: Introductionmentioning

confidence: 99%

Spectroscopic Evidence for Unusual Microviscosity in Imidazolium Ionic Liquid and Tetraethylene Glycol Dimethyl Ether Cosolvent Mixtures

Wang

et al. 2012

J. Phys. Chem. B

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“…[14][15][16][17][18][19] The findings of these investigations reveal that solute rotation is sluggish compared to that in conventional solvents and the observed slow reorientation times have been ascribed to the high viscosity of the ionic liquids. Baker et al 14 have measured the reorientation times of a large non-polar solute BTBP (N,N-bis(2,5-di-tert-butylphenyl)-3,4,9,10-perylenedicaboximide) in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim + ][PF -6 ]) as a function of temperature and concluded that a single layer of [bmim + ] or ] associates with the solute.…”

Section: Introductionmentioning

confidence: 89%

“…Rotational diffusion and solvation dynamics has been investigated in mixtures of ionic liquid with polar solvents such as water, methanol and acetonitrile. 18,19,29 These studies reveal that solvation as well as rotational dynamics becomes faster with an increase in the amount of polar solvent which has been attributed to decrease in the viscosity of the ionic liquid. Addition of non-polar solvents such as toluene and 1,4-dioxane has been found to produce a similar effect on the dynamics.…”

Section: Introductionmentioning

confidence: 93%

The role of specific interactions on dynamical processes in a room temperature ionic liquid

Mali

2009

J Chem Sci

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This article describes our ongoing efforts to comprehend the role of specific interactions on the dynamical processes such as rotational diffusion and photoisomerization in a typical room temperature ionic liquid. Rotational diffusion studies carried out with a pair of structurally similar non-dipolar solutes indicate that organic solutes do experience strong specific interactions even with the highly associative ionic liquids such that their rotation is hindered. Similar measurements carried out with a nonpolar and a dipolar solute in an ionic liquid and a conventional solvent reveal that even in ionic liquids, apart from the viscosity of the medium, the important parameters, which govern the solute rotation are the solvent-size and free volume in case of non-polar solutes, whereas for charged and dipolar solutes, it is the solute-solvent interaction strength. Photoisomerization studies dealing with a pair of carbocyanine derivatives have shed light on the influence of solvent viscosity and specific interactions on the rates of photoisomerization. Our results point to the fact that the positively charged as well as the negatively charged cyanine derivatives do not experience specific interactions with the ionic liquid such that the isomerization rates are affected. However, when the isomerization rates are compared with a conventional isoviscous solvent, it has been noticed that the rates of isomerization are solely governed by viscosity of the medium in case of the positively charged cyanine derivative. In contrast, photoisomerization rates of the negatively charged cyanine derivative are significantly faster in a conventional isoviscous solvent compared to the ionic liquid due to the specific interactions between the solute and the former, which lower the barrier height for isomerization.

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“…[27][28][29][30][31][32][33][34][35][36][37][38] Solvation dynamics in RTIL-polar solvent mixtures were also investigated. [39][40][41] Red-edge effect was also established, both experimentally and theoretically in neat RTILs. We know that water from micelles and reverse micelles and other less polar solvents like methanol, acetonitrile, formamide etc.…”

Section: Introductionmentioning

confidence: 93%

Solvent relaxation of a room-temperature ionic liquid [bmim][PF6] confined in a ternary microemulsion

et al. 2007

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In this paper we have reported the solvent and rotational relaxation of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]) confined in tween 20/([bmim][PF 6 ]/water microemulsion using coumarin 153 (C-153) as probe. The most interesting feature of our experiment was that we observed an increase in solvent relaxation time with increase in R (R = tween 20-to-[bmim][PF 6 ] molar ratio). This is due to the fact that with increase in [bmim][PF 6 ] content of the microemulsions, the microviscosity of the pool of the microemulsions increases, and motion of ions of [bmim][PF 6 ] is hindered in the pool of microemulsions. Since motion of ions is responsible for solvation in room-temperature ionic liquids (RTILs), solvent-relaxation time increases with increase in R.

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Dynamics of solvation and rotational relaxation of Coumarin 153 in 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6]–water mixtures

Cited by 70 publications

References 32 publications

Spectroscopic Evidence for Unusual Microviscosity in Imidazolium Ionic Liquid and Tetraethylene Glycol Dimethyl Ether Cosolvent Mixtures

Spectroscopic Evidence for Unusual Microviscosity in Imidazolium Ionic Liquid and Tetraethylene Glycol Dimethyl Ether Cosolvent Mixtures

The role of specific interactions on dynamical processes in a room temperature ionic liquid

Solvent relaxation of a room-temperature ionic liquid [bmim][PF6] confined in a ternary microemulsion

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