Synthesis, Structural Characterization, and Antitumor Activity of a Ca(II) Coordination Polymer Based on 1,6-Naphthalenedisulfonate and 4,4'-Bipyridyl.

A novel Ca(II) coordination polymer, [CaL(4,4'-bipyridyl)(H₂O)₄] (L = 1,6-naphthalenedisulfonate), was synthesized by reaction of calcium perchlorate with 1,6-naphthalenedisulfonic acid disodium salt and 4,4'-bipyridyl in CH₃CH₂OH/H₂O. It was characterized by elemental analysis, IR, molar conductivity and thermogravimetric analysis. X-ray crystallography reveals that the Ca(II) coordination polymer belongs to the orthorhombic system, with space group 2₁2₁2₁. The geometry of the Ca(II) ion is a distorted CaNO₆ pengonal bipyramid, arising from its coordination by four water molecules, one nitrogen atom of 4,4'-bipyridyl molecule, and two oxygen atoms from two L ligands. The complex molecules form a helical chain by self-assembly. The antitumor activity of 1,6-naphthalenedisulfonic acid disodium salt and the Ca(II) coordination polymer against human hepatoma cell line and human lung adenocarcinoma cell line reveals that the Ca(II) coordination polymer inhibits cell growth of human lung adenocarcinoma cell line with IC50 value of 27 μg/mL, and is more resistive to human lung adenocarcinoma cell line as compared to 1,6-naphthalenedisulfonic acid disodium salt.