High-pressure studies of solvent viscosity effects on large-amplitude isomerization rates

Abstract
The solvent viscosity effects on the intramolecular excimer (IE) formation of 1,3-di-l-pyrenylpropane (DPP) and the ground-state isomerization of 3.3′-diethyloxadicarbocyanine iodide (DODCI) were studied by means of a high-pressure technique. Kramers equation is well applied to the former while it is not to the latter, in which the approach of frequency dependent friction was applied. The activation volume due to solvent dynamical effects (αΔV¦ η) and the intrinsic activation volume (ΔV i) are also determined.