Competing hydrogen bonding and halogen bonding interactions in crystal engineering: A case study of bi-functional donor molecules

Abstract

Based on the recent determined co-crystals of a set of bi-functional donor molecules with two isomeric symmetric acceptors, the competition between hydrogen bonding and halogen bonding interactions in crystal engineering was investigated in this work using the M06-2x and ωB97XD methods. The preference of the occurrence of secondary weak interactions was observed in hydrogen-bonded complexes. Hydrogen bonding interactions are predicted to be much stronger than corresponding halogen bonding interactions. No obvious difference was found between the systems of the two acceptors under study. The model complexes, in which hydrogen bonds and halogen bonds coexist, show additivity. Finally, a comparison between theoretical results and experimental observations was presented, and the implications of the calculations on the supermolecular assemblies based on the two interactions were also discussed.