Modeling substituent dependence of the twist and shielding in a series of N-[4-(nitro)benzylidene]anilines with an inclusion of solvent effects

For a series of 15 N-[4-(nitro)benzylidene]anilines experimentally characterized previously in dimethylsulfoxide solution the geometries were optimized using several density functional theory-based approaches which included, either explicitly or implicitly, dimethylsufoxide as a solvent. Using these geometries the nucleus independent chemical shifts were calculated for model systems and served as estimates of the diamagnetic anisotropy contributions to the Hα and Hm chemical shifts. The experimental chemical shifts corrected for the diamagnetic anisotropy contributions were successfully correlated with the corresponding chemical shift increments. The approach based on the Integral Equation Formalism-Polarized Continuum Model geometries showed the best overall performance and can be used for reliable predictions of the structural and spectroscopical properties of azomethine-containing moieties in different solvents.