Double-stranded helices and molecular zippers assembled from single-stranded coordination polymers directed by supramolecular interactions

Using three nonlinear dicarboxylates, isophthalate (ipa), 4,4'-oxybis(benzoate) (oba), and ethylenedi(4-oxybenzoate) (eoba), we have prepared five neutral infinite copper(H) dicarboxylate coordination polymers containing lateral aromatic chelate ligands, namely [Cu(ipa)(2,2'-bpy)](n)-2nH(2)O (1), [Cu-2(ipa)(2)(phen)(2)H2O](n) (2), [Cu(oba)(phen)](n) (3), [Cu(oba)(2,2'-bpy)](n) (4), and [Cu(eoba)(phen)](n) (5; 2,2'-bpy= 2,2'-bipyridine, phen = 1,10-phenanthroline) by hydrothermal synthesis. X-ray single-crystal structural analyses of these complexes reveal that the nonlinear flexible or V-shaped dicarboxylates can induce the helicity or flexuousity of the polymeric chains and aromatic chelate ligands are important in providing potential supramolecular recognition sites for pi-pi aromatic stacking interactions. An appropriate combination of the bridging dicarboxylate and aromatic chelate can induce a pair of single-stranded helical or flexuous chains to generate a double-stranded helix or molecular zipper through supramolecular interactions, respectively.