Cocrystallization of N-donor type compounds with 5-sulfosalicylic acid: The effect of hydrogen-bonding supramolecular architectures

Benzotriazole, N,N′-dimethylpiperazine and N-methylpiperazine were applied to crystallize with 5-sulfosalicylic acid (5-H2SSA), affording three new binary molecular cocrystals [(C6H6N3+)·(C7H5O6S−)]·H2O (1), [(C6H16N22+)1/2·(C7H5O6S−)]·H2O (2) and [(C5H14N22+)·(C7H5O6S−)2]·3H2O (3) under general conditions. Proton-transferring occurs from acid to nitrogen of N-donor compounds in all compounds 1, 2 and 3. Analysis of the hydrogen-bonding synthons and their effects on crystal packing were also presented in the context of crystal engineering and host-guest chemistry. In compound 1, 1-D infinite chains are extended to a 2-D layered architecture via strong O-H…O hydrogen bonds and then to a 3-D network by N-H…O interactions. Compou 2 and 3 both have the 1-D chain which is formed by O-H…O bonds and weak C-H…O hydrogen bonds. A common intramolecular S(6) [synthon I] ring is formed by the hydroxyl with the carboxyl group in all three compounds.