Hierarchy and cooperativity between π-type halogen bonds and aromatic carboxylic acid dimers in co-crystal formation

Abstract

Co-crystallization of benzoic and cinnamic acids with the halogen-bond donor 1,4-diiodoperchlorobenzene is reported. In both co-crystals, the carboxylic acid dimer is maintained due to the strength of this supramolecular interaction. As a result, the π-type halogen bond then behaves as an ancillary force that aids in co-crystal formation due to the latent abilities of these aromatic acids to accept this type of halogen bond without disrupting the stronger acid dimer. The hierarchy of these non-covalent interactions, in terms of binding energy, was quantified by a series of density functional theory calculations.