7-arboxylato-8-hydroxy-2-methylquinolinium monohydrate and 7-carboxy-8-hydroxy-2-methylquinolinium chloride monohydrate at 100 K

International audienceBoth 7-carboxylato-8-hydroxy-2-methylquinolinium monohydrate, C11H9NO3.H2O, (1), and 7-carboxy-8-hydroxy-2-methylquinolinium chloride monohydrate, C11H10NO3+.Cl-.H2O, (11), crystallize in the centrosymmetric P (1) over bar space group. Both compounds display an intramolecular O-H ... O hydrogen bond involving the hydroxy group; this hydrogen bond is stronger in (1) due to its zwitterionic character [O ... O = 2.4449 (11) Angstrom in (1) and 2.5881 (12) Angstrom in (11)]. In both crystal structures, the HN+ group participates in the stabilization of the structure via intermolecular hydrogen bonds with water molecules [N ... O = 2.7450 (12) Angstrom in (1) and 2.8025 (14) Angstrom in (11)]. In compound (11), a hydrogen-bond network connects the Cl- anion to the carboxylic acid group [Cl ... O = 2.9641 (11) Angstrom] and to two water molecules [Cl ... O = 3.1485 (10) and 3.2744 (10) Angstrom