Crystal structures of three carbazole derivatives: 12-ethyl-7-phenylsulfonyl-7<i>H</i>-benzofuro[2,3-<i>b</i>]carbazole, (1), 2-(4,5-dimethoxy-2-nitrophenyl)-4-hydroxy-9-phenylsulfonyl-9<i>H</i>-carbazole-3-carbaldehyde, (2), and 12-phenyl-7-phenylsulfonyl-7<i>H</i>-benzofuro[2,3-<i>b</i>]carbazole, (3)
Acta crystallographica. Section E, Crystallographic communications