The title compound, C30H25NO2S, crystallizes with two independent molecules (A and B) having similar conformations in the asymmetric unit. Both phenothiazine units have a butterfly structure; the dihedral angles between the planes of the benzene rings are 17.95 (13) and 12.65 (14)° for molecules A and B, respectively. In the crystal, the B molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers with an R22(10) ring motif. The A molecules are linked by C—H...π interactions. Layers of A molecules and layers of B molecules are linked by a second C—H...π interaction, forming A–B–B–A slabs, which stack back-to-back and lie parallel to the bc plane.
