Abstract

Single crystal X-ray structures of the oxygenated diquinoline derivatives 3 and 4 show that, in both cases, the ether oxygen atom interacts very effectively with two 1,3-peri aromatic hydrogens of an adjacent molecule. A six-membered cycle involving two C–H⋯O weak hydrogen bonds results and in structure 4 this plays a key role in preventing inclusion host behaviour. The occurrence of this motif has been investigated using the Cambridge Structural Database and is compared with the behaviour more commonly observed between ethers and aromatic hydrogens.