Synthesis, crystal structure and antitumor activities of the dimeric silicotungstate containing cobalt: Na5K7[{β-SiCo2W10O36(OH)2(H2O)}2] ·39.5H2O

The dimeric polyoxometalate Na5K7[{β-SiCo2W10O36(OH)2(H2O)}2] ·39.5H2O (1) was synthesized and characterized by elemental analysis, IR spectroscopy and thermal gravimetric analysis. A single-crystal X-ray analysis was carried out on the crystal (1) which crystallizes in the triclinic system, space group p ī, with a = 13.231 Å, b = 20.170 Å, c = 21.513 Å, α = 62.964°, β = 89.866°, γ = 78.325° and Z = 1. The polyanion (1) consists of two {β-SiCo2W10O36(OH)2(H2O)}6− Keggin moieties linked via two OH bridging groups, leading to a dimeric silicotungstate containing four cobalt ions. The experiment of antitumor activities in vitro shows that the title compound (1) exhibits remarkable inhibitory actions on liver cancer cells (SMMC-7721) and ovarian cancer cells (SK-OV-3).