Determination of ground and excited state dipole moments of 4,5'-diamino[1,1':3',1''-terphenyl]-4',6'-dicarbonitrile using solvatochromic method and quantum-chemical calculations.

Electronic absorption and fluorescence spectra of 4,5'-diamino[1,1':3',1''-terphenyl]-4',6'-dicarbonitrile (1) were recorded at room temperature in several solvents of different polarity. The results of spectroscopic measurements are analyzed using the theory of solvatochromism, based on a dielectric continuum description of the solvent and the classical Onsager cavity model. The difference in the excited and ground state dipole moments (mu(e)-mu(g)) of the molecule under study was estimated using methods applied by Bayliss, Ooshika, McRae, Lippert, Mataga, Bakhshiev and Kawski. Finally, the influence of polarizability on the determined change of the dipole moment was discussed. Austin model 1 (AM1) semiempirical molecular calculations were carried out to estimate the ground state dipole moment.