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.