Enhanced Guest Inclusion by a Sulfur-Containing Diquinoline Host

The sulfur-bridged compound 7α,15α-dibromo-6,7,14,15-tetrahydro-6α,14α-thiacycloocta[1,2-b:5,6-b′]diquinoline (10) yields an apohost crystal form plus a series of six lattice inclusion compounds. The diverse range of their X-ray crystal forms is described, and the structures are compared in crystal engineering terms. Compound 10 exhibits none of the anomalous properties shown earlier by its oxygen-bridged and nor-bromo cousins. Further, it demonstrates inclusion capabilities considerably superior to its methano-bridged analogue. Although the sulfur atom does not appear to be actively driving inclusion host behavior, closer analysis reveals that it is always involved. Multiple sulfur interactions are present in all these clathrate structures, most commonly involving bifurcated H···S···H motifs.