Syntheses, crystal structures, Hirshfeld surface analyses and energy frameworks of two 4-aminoantipyrine Schiff base compounds: (E)-4-{[4-(diethylamino)benzylidene]amino}-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one and (E)-4-[(4-fluorobenzylidene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

The title Schiff base compounds, C22H26N4O (I) and C18H16FN3O (II), were each synthesized by a single-step condensation reaction. The substituted benzylidene ring is inclined to the pyrazole ring mean planes by 22.92 (7)° in I and 12.70 (9)° in II. The phenyl ring of the 4-aminoantipyrine unit is inclined to the pyrazole ring mean plane by 54.87 (7)° in I and by 60.44 (8)° in II. In the crystal of I, the molecules are linked by C—H...O hydrogen bonds and C—H...π interactions to form layers lying parallel to (001). In the crystal of II, the molecules are linked by C—H...O and C—H...F hydrogen bonds and C—H...π interactions, thereby forming layers lying parallel to (010). Hirshfeld surface analysis was employed to further quantify the interatomic interactions in the crystals of both compounds.