A single-helix coordination polymer with mixed ligands [Zn2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (phen=1,10-phenanthroline;: chdc = cyclohexanedicarboxylate)

A coordination polymer with mixed ligands [Zn-2(phen)(2)(e,a-cis-1,4-chdc)(2)(H2O)(2)](n) (chdc=cyclohexanedicarboxylic acid; phen=1,10-phenanthroline) was prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, TG analysis, and single-crystal X-ray diffraction analysis. X-ray crystal structural analyses reveal that 1 and 2 are isomorphic and belong to the monoclinic system. C40H36Zn2N4O10, P2(1)/c, a=10.084(2) angstrom, b=8.9072(18) angstrom, c=20.276(4) angstrom, beta=99.92(3)degrees, V=1793.9(6) angstrom(3), Z=1. In the structures of 1, the 1,4-chdc ligand possesses only one kind of e,a-cis-conformation although there are both cis- and trans-conformations in the raw material. Two oxygen atoms of one carboxyl in 1,4-chdc ligand and another oxygen atom of contraposition carboxyl link adjacent Zn atoms into an infinite I D zigzag chain. The most attractive structural feature of I is that it exhibits an infinite chiral chain-like structure with 2(1) helices along the b-axis. In addition, the right- and left-handed chains are alternate. Meanwhile, the adjacent chains of 1 is linked via hydrogen bonds into 2D network structures, which further form 3D frameworks via pi-pi interactions of 1,10-phen. (c) 2004 Elsevier B.V. All rights reserved.