Staircase Inclusion Compounds Formed by Tetrahalodiquinoline Hosts

The tetrabromodiquinoline 2, and its tetraiodo counterpart 3, are members of the new tetrahalo aryl
host family. They form lattice inclusion compounds when crystallized from many organic liquids, and the X-ray
crystal structures of five such compounds are reported and analyzed in crystal engineering terms. Host molecules
assemble into parallel staircases by means of aryl offset face−face and halogen−halogen interactions both within,
and between, the staircases. The guests are situated in parallel interstitial channels. Variation of the type of included
guest can result in significant changes to the construction and symmetry of the host staircase assemblies.