Chain relaxation kinetics in the intramolecular charge transfer reaction of 1-(9-anthryl)-3-(4-dimethylaniline)propane in supercritical CO2: bulk solvent properties characterize reactivity

Intramolecular charge transfer rate constants of ADMA (1-(9anthryl)-3-(4-N,N-dimethylaniline)propane) have been determined vs. density in supercritical fluid CO2 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 CO2. The chain relaxation times observed in supercritical CO2 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 CO2 may influence diffusion-controlled reactions.