Anomalous Inclusion Behavior Shown by a Thia-Bridged Diquinoline Derivative

The sulfur-bridged compound 6,7,14,15-tetrahydro-6,14-thiacycloocta[1,2-b:5,6-b′]diquinoline (11) yields a solvent-free crystal form but also produces lattice inclusion compounds containing chloroform, water, and methanol. This latter behavior is in marked contrast to the noninclusion characteristics shown by its corresponding oxygen- and methano-bridged analogues. X-ray structures of the three different crystal types formed by 11 reveal that all contain a two-molecule repeat unit in which the S atom of the first is located within the V-shaped cleft of the second. This assembly is reminiscent of a ball and socket joint, and the adoption of this motif is the root cause of the unexpected solid-state inclusion properties shown by 11.