Crystal structures of three carbazole derivatives: 12-ethyl-7-phenyl­sulfonyl-7H-benzofuro[2,3-b]carbazole, (1), 2-(4,5-dimeth­­oxy-2-nitro­phen­yl)-4-hy­dr­oxy-9-phenyl­sulfonyl-9H-carbazole-3-carbaldehyde, (2), and 12-phenyl-7-phenyl­sulfonyl-7H-benzofuro[2,3-b]carbazole, (3)

The three title compounds, C26H19NO3S, (1), C27H20N2O8S, (2), and C30H19NO3S, (3), are carbazole derivatives, where (1) and (3) are heterocycle-containing carbazoles with a benzo­furan moiety fused to a carbazole unit. In (2), a di­meth­oxy­nitro­phenyl ring is attached to the carbazole moiety. In the three derivatives, a phenyl­sulfonyl group is attached to the N atom of the carbazole unit. Compound (1) crystallizes with two independent mol­ecules in the asymmetric unit (A and B). The carbazole skeleton in the three compounds is essentially planar. In compound (1), the benzene ring of the phenyl­sulfonyl moiety is almost orthogonal to the carbazole moiety, with dihedral angles of 85.42 (9) and 84.52 (9)° in mol­ecules A and B, respectively. The benzene ring of the phenyl­sulfonyl group in compounds (2) and (3) are inclined to the carbazole moiety, making dihedral angles of 70.73 (13) and 81.73 (12)°, respectively. The S atom has a distorted tetra­hedral configuration in all three compounds. In the crystals, C—H⋯O hydrogen bonds give rise to R22(12) inversion dimers for compound (1), and to R22(24) inversion dimers and R44(40) ring motifs for compound (2). The crystal packing in (1) also features C—H⋯π and π–π inter­actions [shortest inter­centroid distance = 3.684 (1) Å], leading to supra­molecular three-dimensional aggregation. In the crystal of compound (2), the combination of the various C—H⋯O hydrogen bonds leads to the formation of a three-dimensional network. In the crystal of compound (3), mol­ecules are linked by C—H⋯O hydrogen bonds, forming chains running parallel to the a axis, and the chains are linked by C—H⋯π inter­actions, forming corrugated sheets parallel to the ab plane.