Three 9-[(E)-2-(4-halogenophenyl)vinyl]-9H-carbazoles.

The crystal structures of 9-[(E)-2-(4-fluorophenyl)vinyl]-9H-carbazole, C20H14FN, (I), 9-[(E)-2-(4-chlorophenyl)vinyl]-9H-carbazole, C20H14ClN, (II), and 9-[(E)-2-(4-bromophenyl)vinyl]-9H-carbazole, C20H14BrN, (III), are determined mainly by van der Waals forces. The chloro and bromo derivatives are highly isomorphous, while the fluoro derivative has a different packing mode. Weak C-H...X interactions are also involved in the crystal packing. The molecular structures of the three compounds are similar, with relatively large twist angles of ca 55 degrees between the carbazole and benzene planes.