Inclusion crystals of 2,2′,7,7′,9,9′-hexahalo-9,9′-bisfluorenyl derivatives: a new family of polyhalo aryl hosts

The preparation and inclusion properties of the new halo aryl hosts, 2,2′,7,7′,9,9′-hexahalo-9,9′-bisfluorenyl derivatives 5–7, are described. The host compounds 5–7 having four halogen atoms on the aromatic rings form stable inclusion crystals with many guest compounds, whereas the parent compound 4 does not. The X-ray structures of the host 4 and representative inclusion compounds of hosts 5–7 were determined, allowing rationalization of several of the experimental observations.