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.