PROBING SOLUTE-SOLVENT ELECTROSTATIC INTERACTIONS - ROTATIONAL DIFFUSION STUDIES OF 9,10-DISUBSTITUTED ANTHRACENES

The rotational diffusion of 9,10-disubstituted anthracenes is studied in various solvents. By systematic variation of the anthracene functio nalities the influence of the electrostatic properties of the solute o n the solute-solvent frictional coupling is investigated. These studie s explore the range of validity of continuum based dielectric friction models for describing the frictional coupling. It is found that a con tinuum model of the solvent with an extended charge distribution for t he solute is adequate in unassociated solvents, but does not adequatel y describe the friction in the associated solvent, benzyl alcohol. (C) 1997 American Institute of Physics.