(2Z)-1-(5-Hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-3-(4-methylanilino)but-2-en-1-one

A twist is evident in the title compound, C21H21N3O2, the dihedral angle between the terminal six-membered rings being 29.46 (10)°; the linked five- and six-membered rings are coplanar [1.30 (11)°]. The carbonyl O atom accepts intramolecular hydrogen bonds from the adjacent hydroxy and amine groups. The three-dimensional crystal packing is achieved through C—H⋯π interactions.

A twist is evident in the title compound, C 21 H 21 N 3 O 2 , the dihedral angle between the terminal six-membered rings being 29.46 (10) ; the linked five-and six-membered rings are coplanar [1.30 (11) ]. The carbonyl O atom accepts intramolecular hydrogen bonds from the adjacent hydroxy and amine groups. The three-dimensional crystal packing is achieved through C-HÁ Á Á interactions.
While in (I), Fig. 1, the linked five-and six-membered rings are co-planar, forming a dihedral angle of 1.30 (11)°, there is a twist about the N3-C15 bond as seen in the value of the C13-N3-C15-C16 torsion angle of 146.9 (2)°; the dihedral angle between the terminal six-membered rings is 29.46 (10)°. The carbonyl-O2 atom accepts hydrogen bonds from the adjacent hydroxyl-and amine-groups, Table 1. These groups do not participate in intermolecular interactions.
Rather, molecules are consolidated in the three-dimensional crystal packing by C-H···π interactions, Fig. 2 and Table 1.

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H = 0.95 to 0.98 Å, U iso (H) = 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation. The N-H and O-H-atoms were located in a difference Fourier map, and were refined with distance restraints of N-H = 0.88±0.01 and O-H = 0.84±0.01 Å, respectively; their U iso values were refined. Owing to poor agreement, the (3 6 3) reflection was omitted from the final cycles of refinement.  The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Figure 2
A view in projection down the a axis of the unit-cell contents of (I). The C-H···π interactions are shown as purple dashed lines.