Crystal structure of (E)-4-hy­droxy-6-methyl-3-{1-[2-(4-nitro­phen­yl)hydrazinyl­idene]eth­yl}-2H-pyran-2-one

The title compound, C(14)H(13)N(3)O(5) (HMNP), was synthesized by the simple condensation of p-nitro­phenyl­hydrazine with de­hydro­acetic acid (DHA) in a 1:1 molar ratio in ethanol. HMNP has been characterized by using FT–IR, (1)H and (13)C NMR and UV–Vis spectroscopic and single-crystal X-ray diffraction techniques. The crystal packing reveals strong hydrogen bonds between the NH group and the carbonyl O atom of di­hydro­pyran­one moiety, forming chains along [101]. The thermal stability of the synthesized compound was confirmed by thermogravimetric analysis and it was found to be stable up to 513 K. The UV–Vis spectrum shows the presence of a strong band at λ(max) 394 nm. (1)H NMR and single-crystal X-ray analyses confirmed the presence of the enol form of the ligand and dominance over the keto form. The crystal studied was a non-merohedral twin with the refined ratio of the twin components being 0.3720 (19):0.6280 (19).