Journal of Chemical Physics, Vol.118, No.9, 4127-4133, 2003
Rotational dynamics of nondipolar probes in associative solvents: Modeling of hydrogen bonding interactions using the extended charge distribution theory of dielectric friction
As an exercise in our ongoing efforts to understand the solute-solvent frictional coupling, hydrogen bonding interactions between the probe 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole and associative solvents such as n-alcohols, formamide and N-methylformamide are modeled as dielectric friction using Alavi-Waldeck (AW) extended charge distribution theory. The mechanical friction experienced by the probe is calculated using Stokes-Einstein-Debye hydrodynamic theory with slip boundary condition and also from the measured reorientation times of another structurally similar, but nonhydrogen bonding solute molecule, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole. When the size of the solvent domains is used as an adjustable parameter in the AW analysis, a good agreement between the experimentally measured reorientation times and the calculated ones is obtained. The limitations of the applicability of the AW model to associative solvents are discussed. (C) 2003 American Institute of Physics.