Chain relaxation kinetics in the intramolecular charge transfer reaction of 1-(9-anthryl)-3-(4-dimethylaniline)propane in supercritical CO 2: bulk solvent properties characterize reactivity

Abstract

Intramolecular charge transfer rate constants of ADMA (1-(9anthryl)-3-(4- N, N-dimethylaniline)propane) have been determined vs. density in supercritical fluid CO 2 from fluorescence lifetimes of ADMA and APP (1-(9-anthryl)-3-phenylpropane). Comparison with results in mixed liquids indicates that viscosity plays a dominant role in determining the kinetics in supercritical CO 2. The chain relaxation times observed in supercritical CO 2 follow the behavior predicted from the bulk fluid viscosity, demonstrating that local density enhancement has no effect on this diffusion-controlled reaction rate. The results serve to characterize the length scale over which solvent density augmentation in supercritical CO 2 may influence diffusion-controlled reactions.