Thermochromie Excited - State Dipole Moment Measurements of p-Cyano-N,N-diethylaniline in Ethyl Acetate

Abstract

The effect of temperature on absorption and fluorescence spectra of p-cyano-N,N-diethylaniline (CDEA) in ethyl acetate has been studied for temperatures ranging from 293 K to 418 K. At T = 293 K two fluorescence bands are observed: long wavelength emission (LE) and short wavelength emission (SE) of much lower intensity compared to the first one. With temperature increase (which leads to the decrease of dielectric constant ɜ of the solvent) the intensity of SE band strongly increases, however its hypsochromic shift compared to the shift of LE band is rather slight. The electric dipole moments for CDEA determined based on this thermochromic method are: μLEe = 13.4 D and μSEe = 7.5 D forμg = 5.5 D, and μLEe = 139 D and μSEe = 8.3 D for μg = 6.6 D. The values obtained are compared with those of p-cyano-N,N-dimethylaniline (CDMA) determined using different methods. © 2014, Verlag der Zeitschrift für Naturforschung. All rights reserved.