On the dual emission of p-dimethylaminobenzonitrile and its photophysical implications

A solvatochromic analysis of available absorption and LE and TICT emission data in p-dimethylaminobenzonitrile (DMABN) was conducted. Applying the Abe method to the results of a thermochromic analysis of DMABN in 1-chlorobutane (ClB) allowed us to determine the polarizability and dipole moment of the excited electronic states involved in the absorption and emission transitions. As shown herein, the LE → TICT excited state reaction for DMABN is triggered by the solvent polarity but is additionally influenced by the viscosity. The experimental evidence negates the assumption that the radiative constant for the TICT fluorescence of DMABN is temperature-dependent.