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 pi/pi and CH/pi 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/pi interactions in 4b. The sulfonamide 5 either formed a dimer through H-bonds, which formed 2D layers via CH/O and pi/pi interactions in 5a, or formed a 1D straight chain via CH/O and pi/pi 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 pi/pi interactions.