Polymorphic Diversity: N‑Phenylbenzamide as a Possible Polymorphophore

In this work, we identify and describe a moiety that may be capable of encouraging the formation of polymorphs. Four new N-phenylbenzamide-based compounds have been synthesized yielding four pairs of polymorphs upon recrystallization. The structures of these have been discussed and compared with the previously reported polymorphs of N-[2-(hydroxymethyl)­phenyl]­benzamide. The results indicate that the conformation of the N-phenylbenzamide group is generally constant but is sometimes altered by the crystal packing. The N-phenylbenzamide group is capable of intermolecular N–H···O hydrogen bonding but requires a change in conformation which is generally resisted by the molecule. As a consequence, weak forces such as C–H···O, C–H···N, C–H···π, and π···π interactions play significant but varying roles in these structures. One possible reason for the varying nature of the π···π interactions may be due to the variation of the electrostatic potential across the N-phenylbenzamide group in which negative and positive regions alternate across the face of the molecule. It is the combination of all these attributes that possibly leads to polymorphism being observed in the structures reported here.