The role of spacers between carboxylate groups in self-assembly process: Syntheses and characterizations of two novel cadmium(II) complexes derived from mixed ligands

Two novel cadmium(II) coordination polymers, [Cd-2(bpda)(2)(dpe)](n) (1) and [Cd-2{(R)-Hdmpa}(2){(S)-Hdmpa}(2)(dpe)(3)](n) (2), [H(2)bpda = 1,1'-biphenyl-3,3'-dicarboxylic acid, H(2)dmpa = 6,6'-dimethyl-1,1'-biphenyl-2,2'-dicarboxylic acid, and dpe = 1, 2 -di(4 -pyridyl) ethylene] have been prepared by hydrothermal reactions of both Cd(NO3)(2).4H(2)O and dpe with H2bpda and H2dmpa, respectively. I is a threefold interpenetrating three-dimensional coordination network composed of paddle-wheel tetracarboxylate dicadmium(II) units bridged by dpe. 2 affords an example of ligand selfdiscrimination in an assembly process, in which dpe connects the [Cd{(R)-Hdmpa}{(S)-Hdmpa}] building units to generate a one-dimensional ladder structure. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).