Pi-halogen dimers and V-shaped tetrahalo aryl inclusion hosts

Abstract

1,4,8,11-Tetrabromo-5bα,6,12bα,13-tetrahydropentaleno[1,2-b:4,5-b′]diquinoline 6 has been synthesised and found to be an efficient lattice inclusion host for a range of small solvent molecules. The compound is a new example of the tetrahalo aryl host family, a group of molecules characterised by having a combination of inclined aromatic planes and halogen substitution at their extremities. The X-ray structures of (6)·(carbon tetrachloride) and (6)₂·(allyl cyanide) are presented and discussed in crystal engineering terms. Both structures contain a common motif (the pi-halogen dimer) where two inversion-related host molecules pack such that one bromine atom from each is situated in the cleft of its V-shaped partner. This efficient packing motif provides a combination of π⋯Br and OFF (offset face–face) interactions within one supramolecular building block.