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, C(26)H(19)NO(3)S, (1), C(27)H(20)N(2)O(8)S, (2), and C(30)H(19)NO(3)S, (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 R (2) (2)(12) inversion dimers for compound (1), and to R (2) (2)(24) inversion dimers and R (4) (4)(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.