Supramolecular Architectures Based on trans -Oxamidato-Bridged Copper(II) Synthons and Intramolecular Synergism

The trans-oxamidato dicopper(II) "synthons", [Cu 2 (trans-L)] 2+ (L= oxen, oxpn, oxap, and oxpy) have been used as construction units when further connected by a second bridging ligand L′ (spacer) to fabricate supramolecular architectures via covalent and hydrogen bonding interactions. The structural topologies of the polymeric networks contained by these compounds depend mainly on the coordination modes of the spacers. When the spacers are 2-connectors bridging two synthons, the resulting compounds usually contain 1-D infinite chains, while 3- or 4-connector provides compounds containing 2-D extended coordination networks. The hydrogen bonds, in which the oxamidate, the spacer, and the water molecules are involved, are prevalent and the predominant intermolecular interactions. Compared with the polymeric networks constructed via covalent bonding interactions between synthons and spacers, the structural topologies of the 3-D supramolecular architectures fabricated via hydrogen bonding interactions are more complicated and difficult to predict. The structural parameters of the chelate rings in the compounds have been discussed and found to change in rather small ranges and the skeleton of each synthon is rigid, which embodies the intramolecular synergistic effect in the supramolecular architectures.