MOLECULAR-COMPLEXES OF SULFONAMIDES .2. 1/1 COMPLEXES BETWEEN DRUG MOLECULES - SULFADIMIDINE ACETYLSALICYLIC-ACID AND SULFADIMIDINE-4-AMINOSALICYLIC ACID

The preparation and crystal structures of the 1:1 complexes sulfadimidine-acetylsalicylic acid (I) and sulfadimidine-4-aminosalicylic acid (II) are described. Each complex unit is maintained by two intermolecular hydrogen bonds, namely N-H . . . O=C and N . . . H-O, involving the N atom of the sulfonamide group and one pyrimidine N atom of the sulfonamide and the carboxylic group of the acid. Molecular parameters for protonated complexed aspirin, as found in I, are reported for the first time and reveal a significantly different conformation from that of the uncomplexed aspirin molecule. The structure of the 4-aminosalicylic acid molecule does not change significantly on complexation with sulfadimidine. Variation in the hydrogen bonded N . . . O distances in these complexes and their analogs is discussed.