In situ co-crystallization of cresols with aniline and fluoroanitines: subtle interplay of strong and weak hydrogen bonds

"In situ crystallization" is a technique, which is used to crystallize the materials, which are liquid at ambient conditions, on the single crystal X-ray diffractometer. This technique has been utilized to study crystal structures of a number of liquids, gases and mixtures of liquids and gases in the past. In this manuscript, we describe the formation of cocrystals of a few cresols with aniline and fluoroanilines using this technique. Different pairs of cresol and aniline/fluoroaniline resulted into various cocrystals, which display different crystalline motifs involving strong O-H center dot center dot center dot N, N-H center dot center dot center dot O hydrogen bonds along with weak C-H center dot center dot center dot O and C-H center dot center dot center dot F hydrogen bonds. The observed differences in crystal packing indicate that the role of weak hydrogen bonds in these systems is significant and need to be considered.