Are gamma amino acids promising tools of crystal engineering? – Multicomponent crystals of baclofen

Abstract

Baclofen, (RS)-4-amino-3-(4-chlorophenyl)butanoic acid, is a slightly water soluble hydrophobic γ-amino acid and primarily used as a muscle relaxant. The crystal structure, thermal analysis and powder X-ray analysis of the multicomponent crystals formed between baclofen and selected monocarboxylic acids (benzoic acid, p-toluic acid and 1-hydroxy-2-naphthoic acid), dicarboxylic acids (oxalic acid and maleic acid) and p-toluene sulfonic acid are presented. Conformation and protonation properties of the baclofen moiety are discussed. Hirshfeld surface analysis is used to analyse the specific intermolecular interactions in the presented structures, and their percentage appearance is correlated with the melting points of the multicomponent crystals.