Crystallisation of the tetrahaloaryl host 2,4,10,12-tetrabromo-6,7,14,15-tetrahydro-6,14-thiacycloocta[1,2-b:5,6-b′]diquinoline 7 from benzene, chloroform, 3-methylpyridine, 4-methylpyridine, 2-methylpyridine, or tert-butylcyclohexane, yields a series of closely related inclusion compounds (7)2·(guest) in space group P1̅. Two host molecules surround a single guest to form a penannular repeat unit in each of these crystal structures. Structural variation arises from the differing guest sizes, shapes and interactions. The corners of four molecular pens are linked by utilising novel S/Br clusters as supramolecular synthons: S2Br4 for the first four compounds, and S2Br6 for the latter two cases. The aromatic faces of the repeat units associate through offset π…π interactions. Aromatic edge–edge linkage occurs in the former group of compounds by means of N2Br2 and N2Br4 clusters, but these are absent in the final two structures. Mesitylene (1,3,5-trimethylbenzene) is too wide for penannular inclusion. It yields an alternative layer structure, (7)·(mesitylene), also in P1̅. This compound is stabilised by means of host–guest C–H…π associations, plus host–host aromatic and S…Br…Br…N interactions. [ABSTRACT FROM AUTHOR]