Rotational diffusion of a new large non polar dye molecule in alkanes

Goudar, Radha ; Gupta, Ritu ; Kulkarni, Giridhar U. ; Inamdar, Sanjeev R. (2015) Rotational diffusion of a new large non polar dye molecule in alkanes Journal of Fluorescence, 25 (6). pp. 1671-1679. ISSN 1053-0509

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Rotational reorientation times of a newly synthesized 2,5-bis(phenylethynyl)1,4-bis(dodecyloxy) benzene (DDPE) are experimentally determined in series of n-alkanes by employing steady state and time resolved fluorescence depolarization technique with a view to understand rotational dynamics of large non-polar solute molecule in non-polar solvents and few general solvents of different sizes and varying viscosity. It is observed that rotational reorientation times vary linearly as function of viscosity. The hydrodynamic stick condition describes the experimental results at low viscosities while the results tend to deviate significantly from it at higher viscosities. This is attributed to the possibility of long chains in solvents hosting a variety of chain defects (end-gauche, double-gauche, all-trans, kink, etc.) thereby reducing the effective length of the molecule, leading to a slightly reduced friction. The experimental results are compared with the predictions of Stokes-Einstein-Debye (SED) hydrodynamic theory as well as the quasi-hydrodynamic theories of Gierer-Wirtz (GW) and Dote-Kivelson-Shwartz (DKS). The predictions from these theories underestimate τr in the solvents employed in the study.

Item Type:Article
Source:Copyright of this article belongs to Springer-Verlag.
Keywords:Rotational Dynamics; Anisotropy; SED Hydrodynamics; Slip and Stick Behaviour
ID Code:102563
Deposited On:04 Mar 2017 15:19
Last Modified:04 Mar 2017 15:19

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