In conclusion, we have successfully prepared a complete set of
halogen substituted quinolylsalicyaldimines. The packing within
the structures is dominated by p–p, CAH N and CAH O interactions
which form stacks although the angle and type of stacks
formed and the individual interactions which hold these stacks together
vary depending on the halogen. The results clearly demonstrate
that both the steric and electronic effects of the halogens
need to be considered when attempting to predict what structure
will be obtained, although computational studies are able to predict
conformational preferences of the individual molecules. Moreover,
it is evident that introduction of a halogen into a molecule
does not guarantee the presence of halogen bonding in the resulting
structure and further emphasizes the challenge of trying to predict
crystal structures based purely on the molecular structure