N′-(2-Hy­droxy-3-meth­oxy­benzyl­idene)pyrazine-2-carbohydrazide monohydrate

In the title hydrated Schiff base, C(13)H(12)N(4)O(3)·H(2)O, the dihedral angle between the aromatic rings is 5.06 (11)° and an intra­molecular O—H⋯N hydrogen bond closes an S(6) ring. In the crystal, O(w)—H⋯O and O(w)—H⋯N (w = water) hydrogen bonds link the components into centrosymmetric tetra­mers (two Schiff bases and two water mol­ecules). Longer N—H⋯O hydrogen bonds link the tetra­mers into [010] chains. A weak C—H⋯O hydrogen bond and aromatic π–π stacking between the pyrazine and phenyl rings [centroid–centroid separations = 3.604 (2) and 3.715 (2) Å] are also observed. [Image: see text]