Crystal Structures of Pyridine Sulfonamides and Sulfonic Acids

Despite the widespread occurrence of pyridinesulfonic acid and pyridinesulfonamide functional groups in drugs and pharmaceuticals, and their use as ligands in metal–organic frameworks, a systematic structural study of their hydrogen bonding and molecular packing is lacking. We discuss crystal structures of 2-, 3-, and 4-pyridinesulfonic acids/amides in terms of N⁺–H···O^– hydrogen bonds, N–H···O dimer/catemer synthons, and graph set notations. This model study provides a background for polymorph screening and solid form hunting of pharmacologically active sulfonamides.