Supramolecular organic salts constructed from 6-hydroxyquinoline and nitrobenzoic acids

The crystal structures of the proton-transfer salts of 6-hydroxyquinoline with 3,5-dinitrobenzoic acid (1) and 4-nitrobenzoic acid (2) have been determined at room temperature. Their comparative structural features and hydrogen- bonding patterns are described here. Compound 1 crystallizes in the monoclinic P2 ₁/c space group, while 2 in the triclinic P-1 space group. Unit cell dimensions and contents are: a = 7.6956(15), b = 26.075(5), c = 7.7233 (15) Å, β = 95.96(3)° for 1; a = 7.7325(15), b = 8.5939 (17), c = 12.394(3) Å, β = 77.63(3)° for 2. Supramolecular architectures are formed by intermolecular hydrogen bonds in the proton-transfer process. The supramolecular structures are stabilized by N-H·O, O-H·O and C-H·O hydrogen bonds between the two components. Extensive hydrogenbonding interactions give two-dimensional network structures. In addition, π-π stacking interactions exist in the salt 1 due to the aromatic rings.