Isomorphic supramolecular structures via one-dimensional hydrogen bonding motifs in crystals of chiral difluorolactates, trichlorolactates and trifluorolactates

Abstract

Optically pure difluorolactates and trichlorolactates were prepared and their crystal structures were determined and compared with those of trifluorolactates. One-dimensional hydrogen bonding networks of these compounds involve infinite OH⋯OH, OH⋯OC, and C–H⋯OC hydrogen bonds. The crystal structure of a single-headed difluorolactate showed a weak intermolecular C–H⋯F hydrogen bond between difluoromethyl (CF₂H) groups, leading to a one-dimensional C–H⋯F chain as a hydrogen bonding motif of the CF₂H group. In the case of trichlorolactates, the steric effect of the trichloromethyl group on the hydrogen bonding system was revealed. Two-dimensional hydrogen bonding networks by double-headed trifluorolactates, difluorolactate and trichlorolactate provided isomorphic layered crystal structures.