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

Abstract

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 H α and H m 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.