Competing hydrogen-bond and halogen-bond donors in crystal engineering

摘要: In order to study the structure-directing competition between hydrogen- and halogen-bond donors we have synthesized two ligands, 3,3′-azobipyridine 4,4′-azobipyridine, co-crystallized them with a series of bi-functional donor molecules comprising an activated (I or Br) as well hydrogen-bond (acid, phenol oxime) on same backbone. Based subsequent single-crystal analysis, 5 6 co-crystals are assembled using hydrogen bonds primary driving force accompanied by weaker secondary (C–X⋯O) interactions. However, in out both (O–H⋯N) halogen (C–X⋯N) present interactions leading 1-D chains. Since charges acceptor sites 3,3′- 4,4′-azobipyridine very similar, observed difference binding behaviour highlights importance binding-site location (anti-parallel co-linear 4,4′-azobipyridine) direct influence over structural balance donors.