phenyl–perfluorophenyl interaction to regulate molecular alignment and arrangement for crystal engineering, we examined and compared in detail the crystalstructures of N,N′-diphenylurea compounds 1–6. We found that phenyl–perfluorophenyl interaction greatly influenced the intermolecular arrangement in the crystal, and we were able to prepare a cocrystal of 1 and 2, in which the molecules were alternately