Influence of temperature and viscosity on anthracene rotational diffusion in organic solvents: Molecular dynamics simulations and fluorescence anisotropy study

Jas, Gouri S.; Wang, Yan; Pauls, Steven W.; Johnson, Carey K.; Kuczera, Krzysztof

doi:10.1063/1.475172

Cited by 61 publications

(67 citation statements)

References 70 publications

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“…Numerous studies carried out with dipolar and non-polar solutes in non-polar solvents indicate that the rotation of a medium-sized solute molecule is close to slip behaviour. 50,[58][59][60][61][62][63][64][65][66][67][68][69] Thus, the rotation of both DMDPP and DPP is in accordance with the predictions based on the literature data. However, structurally these two solutes are similar and their van der Waals volumes are almost the same.…”

Section: Do Organic Solutes Experience Specific Interactions With Ionsupporting

confidence: 90%

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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Section: Do Organic Solutes Experience Specific Interactions With Ionsupporting

confidence: 90%

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

Mali

2009

J Chem Sci

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“…Berg and coworkers studied transient dichroism of the anthracene/benzyl alcohol system and found a fast decay with a sub-picosecond time constant which is almost independent of temperature [8]. This fast decay was assigned to inertial rotation by comparison to the computer simulation [9]. The inertial rotation they found is not free-rotor-like, but strongly modified by interaction with the solvent.…”

Section: Discussionmentioning

confidence: 94%

Terahertz spectroscopy of polar solute molecules in non-polar solvents

Oka

Tominaga

2006

Journal of Non-Crystalline Solids

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“…5 If there is a cancellation of errors in the experimental diffusion constant, then the cancellation is quite good under a wide variety of conditions.…”

Section: Anthracene Rotation In Small-molecule Solventsmentioning

confidence: 97%

Friction on Small Objects and the Breakdown of Hydrodynamics in Solution: Rotation of Anthracene in Poly(isobutylene) from the Small-Molecule to Polymer Limits

2002

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The friction on a nanometer-sized object, as measured by the molecular rotation time of dissolved anthracene, is compared to the macroscopic viscosity in poly(isobutylene) (PIB) over a molecular-weight range extending from the small-molecule limit (isooctane, M ) 114 g/mol) to the entangled polymer (M ) 85 000 g/mol). Calibration studies in small-molecule solvents show that anthracene rotation is a near ideal example of StokesEinstein-Debye (SED) behavior with slip boundary conditions. The average rotation time follows SED behavior based on the macroscopic viscosity η ∞ for PIBs up to a moderate length (M ) 615 g/mol, η ∞ ) 2000 cP). Beyond this length, the rotational friction shows a sharp transition to a weak dependence on the polymer length. The transition length is not associated with any standard length scale of the static polymer structure. In particular, SED behavior continues well beyond the point where the solvent length or volume exceeds the solute's dimensions. An additional transition from exponential to nonexponential rotational relaxation occurs at a shorter polymer length. The breakdown of simple hydrodynamics and the SED model is attributed to exceeding a dynamical length scale associated with torsional flexibility and not to exceeding a simple ratio of solvent-to-solute size.

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Influence of temperature and viscosity on anthracene rotational diffusion in organic solvents: Molecular dynamics simulations and fluorescence anisotropy study

Cited by 61 publications

References 70 publications

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

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

Terahertz spectroscopy of polar solute molecules in non-polar solvents

Friction on Small Objects and the Breakdown of Hydrodynamics in Solution: Rotation of Anthracene in Poly(isobutylene) from the Small-Molecule to Polymer Limits

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