Infrared spectra and structure of molecular complexes of aromatic acids

FTIR spectra of pharmacologically active molecules of benzoic acid and its derivatives have been measured in CCl₄ solutions and in microcrystals. Features of the formation of intra-and intermolecular hydrogen bonds have been analyzed. Spectral attributes have been revealed that characterize the participation of a carboxyl group in different types of intermolecular interactions with the formation of cyclic, linear, and criss-cross dimers. Mechanisms of the intermolecular interactions are shown to be defined by the character of the substituents attached to the benzene ring in the para- and meta-positions relative to the carboxylic group.