Polymorphism of Aromatic Sulfonamides with Fluorine Groups

N-(2-Phenoxyphenyl)­benzenesulfonamide (1) and fluorine-substituted N-(2-phenoxyphenyl)­benzene sulfonamides (2–5) were designed to examine the effect of a fluorine group in the polymorphism of aromatic sulfonamides. Single-crystal X-ray analysis revealed that those with a fluorine (2–5) afforded polymorphs or pseudopolymorphs while the sulfonamide without fluorine (1) did not. From the differential scanning calorimetry measurements, stable (2a–5a) and metastable (2b–5b) crystalline forms were identified. The sulfonamide 1 formed a dimer through hydrogen bonds (H-bonds), which were aligned into two-dimensional (2D) layers via π/π and CH/π interactions. In 2b, 3b, and 4a, the sulfonamide constructed a dimer through H-bonds, which formed 2D layers via CH/F interactions. The sulfonamides 4 formed a one-dimensional (1D) straight chain via H-bonds, which were arranged into 2D layers via CH/F, CH/O, and CH/π interactions in 4b. The sulfonamide 5 either formed a dimer through H-bonds, which formed 2D layers via CH/O and π/π interactions in 5a, or formed a 1D straight chain via CH/O and π/π interactions, which were arranged into 2D layers via F/F and CH/F interactions in 5b. In the pseudopolymorph 5c, the sulfonamide 5 formed a 1D zigzag chain via CH/F interactions and was assembled into 2D layers via π/π interactions.