Synthesis, crystal structure and Hirshfeld surface analysis of 4-[3-(4-hydroxyphenyl)-4,5-dihydro-1H-pyrazol-5-yl]-2-methoxyphenol monohydrate

In the title pyrazoline derivative, the pyrazoline ring makes angles of 86.73 (12) and 13.44 (12)° with the trisubstituted and disubstituted benzene rings, respectively. In the crystal structure, the molecules are connected into chains running in the b-axis direction by O—H⋯N hydrogen bonding. Parallel chains interact through N—H⋯O hydrogen bonds and π–π stacking of the trisubstituted phenyl rings.

In this article, we report the synthesis of a chalcone derivative by condensation of vanillin with p-hydroxyacetophenone and subsequent cyclization of this chalcone by reaction with hydrazine hydrate. Furthermore the molecular and crystal structure of the title compound, 2, are presented together with a Hirshfeld surface analysis and non-covalent interaction plots.

Figure 1
A view of the molecular structure of 2, with atom labels and displacement ellipsoids drawn at the 50% probability level. H atoms are shown as small circles of arbitrary radii and the O-HÁ Á ÁN interaction as a dotted blue line. Cg1 is the centroid of the C6-C11 ring; see Table 1 for symmetry codes).
Based on the Hirshfeld surface analysis, enrichment ratios (ER, Table 2) were calculated by comparing the contacts in the crystal with those computed as if all types of contact have the same probability of forming (Jelsch et al., 2014). A ratio greater than unity for a pair of elements indicates a high likelihood of forming contacts in the crystal. This is the case for NÁ Á ÁH and OÁ Á ÁH contacts, which is consistent with the high propensity for the formation of O-HÁ Á ÁN and O/N/C-HÁ Á ÁO hydrogen bonds. CÁ Á ÁH contacts are enriched because of the presence of aromatic rings, HÁ Á ÁH contacts are found to have the usual enrichment ratios slightly lower than unity.

Figure 4
Two views of the Hirshfeld surface mapped over d norm for 2 in the range À0.7348 to +1.5269 arbitrary units.
The pyrazoline ring has an envelope conformation with the substituted sp 2 C atom on the flap. The dihedral angle between the phenyl rings is 49.37 (8) , that between the pyrazoline ring and the nitrophenyl ring is 9.7 (1) and that between the pyrazoline ring and the methoxyphenol ring is 56. 78 (9) . The second structure, 3-(2 0 -hydroxy-5 0 -methoxy-phenyl)-5-(3methoxy-4-hydroxyphenyl)-4,5-dihydro-1H-pyrazole (RES-JUV; Gupta et al., 2006), crystallizes in Pbca with one molecule in the asymmetric unit. The conformation of the pyrazoline ring is the same as that in UJUDOU. The phenyl rings make an angle of 56.0 (1) , while the dihedral angles between the pyrazoline ring and the phenyl rings at atom C3 and C5 are 12.1 (1) and 68.2 (1) , respectively.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The O-and N-bound H atoms H2, H14, H21, H22A and H22B were found in difference electron density maps and refined freely. The other H atoms were placed in idealized positions and included as riding contributions with U iso (H) values of 1.2U eq or 1.5U eq of the parent atoms, with C-H distances of 0.93 (aromatic), 0.98 (CH), 0.97 (CH 2 ) and 0.96 Å (CH 3 ). In the final cycles of refinement, eight outliers were omitted. Computer programs: CrysAlis PRO (Rigaku OD, 2018), SHELXT2014 (Sheldrick, 2015a), SHELXL2016 (Sheldrick, 2015b) and OLEX2 (Dolomanov et al., 2009).

Figure 6
Reaction scheme for the synthesis of compound 2.

sup-1
Acta Cryst. CrysAlis PRO (Rigaku OD, 2018); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009). 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.