(E)-N'-(5-Chloro-2-hydroxy-benzyl-idene)-4-(8-quinol-yloxy)butanohydrazide monohydrate.

The crystal of the title Schiff base compound, C(20)H(18)ClN(3)O(3)·H(2)O, was twinned by a twofold rotation about (100). The asymmetric unit contains two crystallographically independent mol-ecules with similar conformations, and two water mol-ecules. The C=N-N angles of 115.7 (6) and 116.2 (6)° are significantly smaller than the ideal value of 120° expected for sp(2)-hybridized N atoms and the dihedral angles between the benzene ring and quinoline ring system in the two mol-ecules are 52.5 (7) and 53.9 (7)°. The mol-ecules aggregate via C-Cl⋯π and π-π inter-actions [centroid-centroid distances = 3.696 (5)-3.892 (5) Å] and weak C-H⋯O inter-actions as parallel sheets, which are further linked by water mol-ecules through N-H⋯O and O-H⋯O hydrogen bonds into a supra-molecular two-dimensional network.