Spectroscopic properties of ethyl 5-(4-aminophenyl)-3-amino-2,4-dicyanobenzoate

The luminescence properties of ethyl 5-(4-aminophenyl)-3-amino-2,4-dicyanobenzoate (EAADCy) have been studied using steady-state, time-resolved spectroscopic techniques, electrochemical measurements and semiempirical calculations. A series of photophysical measurements and quantum-chemical calculations were carried out with EAADCy in search of an evidence of the occurrence of the aniline group rotation. Studies in different solvents, as well as semiempirical calculations, indicate that conformations with donor and acceptor groups coplanar absorb and emit at wavelengths that are longer than those observed for donor-acceptor groups oriented orthogonally. The values of the dipole moments of planar and perpendicular form of molecule under study were estimated from solvatochromic shifts of absorption and fluorescence spectra as a function of the solvent dielectric constant and refractive index. Experimentally calculated changes of the dipole moment values are in fair agreement with semiempirical computational predictions.