Solvation dynamics study of 3-aminophthalimide in n-butanol solution at different temperatures

Abstract

We have studied the solvation dynamics of 3-aminophthalimide (3-AP) in n-butanol. The fluorescence lifetimes and the rotational correlation times of the molecule were measured at several wavelengths over the emission spectrum at six temperatures. Solvation time correlation functions were evaluated from wavelength dependent fluorescence lifetime distributions at four temperatures for 3-AP in n-butanol solution. The solvation dynamics of 3-AP was strongly temperature dependent. The solvation times of 3-AP were compared to the dielectric relaxation times (τL and τD) of n-butanol and to the solvation times of 4-amino-N-methyl-phthalimide (4-ANMP) studied earlier in n-butanol and n-decanol solutions. The solvation time of 3-AP molecule in n-butanol at room temperature was much closer to the longitudinal dielectric relaxation time than to the Debye time. At low temperatures the solvation times of 3-AP and 4-ANMP approach the Debye times of n-butanol. The solvation dynamics of 3-AP occurs on a time scale roughly given by the longitudinal relaxation time as predicted by the simple continuum theory.