Crystal structure and Hirshfeld surface analysis of (E)-6-(4-hydroxy-3-methoxystyryl)-4,5-dihydropyridazin-3(2H)-one

In the title compound, intermolecular C—H⋯O, O—H⋯O and N—H⋯O hydrogen bonds link the molecules into a three-dimensional supramolecular network.

In the title compound, C 13 H 14 N 2 O 3 , the dihydropyridazine ring (r.m.s. deviation = 0.166 Å ) has a screw-boat conformation. The dihedral angle between its mean plane and the benzene ring is 0.77 (12) . In the crystal, intermolecular O-HÁ Á ÁO hydrogen bonds generate C(5) chains and N-HÁ Á ÁO hydrogen bonds produce R 2 2 (8) motifs. These types of interactions lead to the formation of layers parallel to (121). The three-dimensional network is achieved by C-HÁ Á ÁO interactions, including R 2

Structural commentary
In the title molecule ( Fig. 1), the configuration relative to the double bond at C5 and C6 is E. The dihydropyridazine ring has a screw-boat conformation, with an r.m.s. deviation of 0.166 Å for the ring atoms, with the maximum deviation from the ring being 0.178 (3) Å for the C3 atom; the C2 atom lies À0.177 (3) Å out of the plane in the opposite direction relative to the C3 atom. The dihedral angle between the dihydropyridazine ring mean plane and the benzene ring (C7-C12) is 0.77 (12) , indicating an almost planar conformation of the molecule favouring delocalization over the C4-C5 C6-C7 bridge.
[101]. Likewise, N1-H1Á Á ÁO1 ii hydrogen bonds between the N-H function of the dihydropyridazine ring and the carbonyl O atom generate centrosymmetric dimers with an R 2 2 (8) motif. The two types of hydrogen bonding result in the formation of layers parallel to (121). A three-dimensional supramolecular network is eventually formed through intermolecular C13-H13AÁ Á ÁO2 iii and C13-H13CÁ Á ÁO2 iv hydrogen bonds with R 4 2 (8) motifs ( Fig. 2 and Table 1).

Hirshfeld surface analysis
Hirshfeld surface analysis was used to quantify the intermolecular interactions of the title compound, using Crystal-Explorer17.5 (Turner et al., 2017). The Hirshfeld surface analysis was planned using a standard (high) surface resolution with the three-dimensional d norm surfaces plotted over a fixed colour scale of À0.7021 (red) to 2.2382 a.u. (blue). The surfaces mapped over relevant intermolecular contacts are illustrated in Fig. 3

Synthesis and crystallization
To a solution of 6-(4-hydroxy-3-methoxyphenyl)-4-oxohex-5enoic acid (0.25 g, 1 mmol) in 20 ml of ethanol, an equimolar amount of hydrazine hydrate was added. The mixture was maintained under reflux until thin-layer chromatography (TLC) indicated the end of the reaction. After cooling, the precipitate which formed was filtered off, washed with ethanol and recrystallized from ethanol. Slow evaporation at room temperature led to the formation of single crystals of the title compound.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms on C atoms were placed in idealized positions and refined as riding, with C-H = 0.93-0.97 Å and U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) otherwise. The NH and OH hydrogens were located in a difference Fourier map and were constrained with N-H = 0.86 Å and U iso (H) = 1.2U eq (N), and O-H = 0.86 Å and U iso (H) = 1.5U eq (O), using a riding model.  SHELXL2018 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 2012), SHELXL2018 (Sheldrick, 2015b), PLATON (Spek, 2009) and publCIF (Westrip, 2010). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.17 e Å −3 Δρ min = −0.17 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.