Three Single Stranded Helical Coordination Polymers of a Macrocyclic Metalloligand and Mg, Zr and Pb Nodes

Three new coordination polymers, {[Mg(NiL1)(HO)]·CHCHOH·2HO} (1), {[Zr(NiL1)(OH)(HO)]·8HO} (2) and {[Pb(NiL1)(HO)]·3HO} (3), were prepared from a macrocyclic metalloligand NiL1. HL1 denotes 1,4-dihydro-2,3-dioxo-5,6:- 9,10:13,14-tribenzo[1,4,8,11]tetraazacyclotetradeca-7,11-diene-7,12-dicarboxylate. Single crystal X-ray diffraction studies revealed that 1, 2 and 3 have infinite single stranded helical structures. In each of the three compounds, NiL1 plays the role of the bridging ligand by chelating one node via two oxamido carbonyls and binding to another through a carboxylate oxygen atom. 1D helical coordination polymers of macrocyclic metalloligands and those of Mg, Zr and Pb nodes are all not common. The generation of the three complexes manifests further that NiL1 is a bridging ligand unprecedentedly powerful in directing the formation of single stranded helical coordination polymers. It is the combination of multiple features of NiL1 that are responsible for its high powerfulness of inducing these helical structures. The outcome implies that combining multiple features surporting the formation of such helices into one ligand should be an effective strategy for the design and selection of bridging ligands powerful for the production of such structures.