The title molecule, C22H19N3O2, is a new polymorphic modification, viz. the β-phase; the α-phase has been previously published [Liang & Wang (2010). Acta Cryst. E66, o1968–o1969]. In the crystal of the β-phase, the molecules pack in helical chains generated by C—H...O hydrogen bonds and offset π–π-stacking interactions. Adjacent chains are associated through C—H...π interactions. In the α-phase, molecules are linked by C—H...O and N—H...O hydrogen bonds, forming layers parallel to the (10-2) plane. In addition, π–π-stacking interactions and C—H...π(ring) interactions consolidate the packing. The packing is compared to that of the α-phase. The title compound was refined as a two-component twin.
