Stability of complexes of aromatic-amides with bromide anion: Quantitativestructure-property relationships

Most of the theoretical studies published to-date on the structural and ele ctronic properties of supramolecules have been devoted to the neutral dr ca tionic complexes, while little is known about anionic systems. A detailed t heoretical study of the interaction between simple aromatic amides and the bromide anion has recently been published (Cajan, M.; Stibor, I; Koca, J. J . Phys, Chem. A 1999, 103, 3778). The present work focuses on the structura l and physicochemical parameters of simple aromatic amides related to their ability to form the 1:1 complex with a bromide anion. A quantitative struc ture-property relationships (QSPR) model for the prediction of association constants is proposed. The model based on 22 complexes and nine molecular d escriptors explained 96% (84% cross-validated) of the variance in associati on constants. The descriptors employed in this model included parameters fo r the characterization of conformational behavior and the 3D structure of a mide molecules, distribution of electron density, on-the amidic functional group, and parameters for substitution on aromatic units. The quantitative structure-property relationship approach predicted the association constant s with comparable quality, but significantly lower computational demand, th an molecular modeling or standard quantum chemistry calculations.