Ground and excited state dipole moments of ortho derivatives of methyl p-dimethylaminobenzoate

Steady-state spectroscopic studies of ortho (-OCH3 and -OH) derivatives of methyl p-dimethylaminobenzoate indicate that molecules under study are capable of simultaneously creating locally excited (LE) and intramolecular charge transfer (ICT) excited states. The electric dipole moments of investigated compounds in the excited S1(LE) and S1(ICT) states were determined using the theory of solvatochromism, based on: (i) the solvent induced red-shifts of electronic absorption bands (in comparison to their positions in the gas phase), (ii) the solvatochromic shifts of absorption and fluorescence spectra as a function of dielectric constant (ε) and refractive index (n). Obtained experimental data were compared with theoretical results of quantum-chemical calculations, using the AM1 method implemented in the CAChe WS 5.04 program. Finally, the influence of polarizability on the determined dipole moment was analyzed.