synthesizing, characterization, and electrochemical behavior of [(b-α-siw9o34)2cd4(h2o)2]12- and evaluating the toxicity of this compound and other sandwich-type polyoxometalates on human cancer cell lines by inducing apoptosis

The dimeric silicotungstate, [(b-α-siw9o34)2cd4(h2o)2]12- (i), has been synthesized in a new and simple method by reaction of a-b-na9hsiw9o34‧23h2o with cadmium nitrate under controlled temperature conditions. i was characterized by elemental analysis, ft-ir, 29si, and 113cd nmr spectroscopy, and this was verified by single-crystal x-ray structural analysis of the combined salts of na+ and nh4+. the (nh4)10na2[(b-α-siw9o34)2cd4(h2o)2]·22h2o salt crystallizes in the monoclinic system (space group p21/n) with a = 16.2706(18) å, b = 13.8262(17) å, c = 20.307(3) å, b= 113.419(2)° and z = 2. two lacunary b-α-[siw9o34]10- keggin moieties are connected by a rhomboid cd4o16 group to form the heteropolyanion, which has a sandwich-like shape. cyclic voltammetry was used to examine the electrochemical and electrocatalytic properties of i in an aqueous solution. the redox processes of wvi and cdii centers are represented by the two sequential cathodic/anodic peaks observed in electrochemical experiments. the redox waves of i are ph-dependent. for this compound, the tungsten and cadmium-centered waves exhibit a classical potential shift at ph values between 1.6 and 4.6 as a function of acidity. i electrocatalysis tendencies toward the reduction of nitrite ions have been thoroughly investigated. additionally, in this study, the cytotoxic and apoptogenic activity of several sandwiched-type polyoxometalates (i, ([(b-α-pw9o34)2cd4(h2o)2]10-(ii), [(b-α-pw9o34)2mn4(h2o)2]10- (iii), [(b-α-pw9o34)2co4(h2o)2]10- (iv), [(b-α-pw9o34)2zn4(h2o)2]10-(v), [(znw9o34)2wzn3(h2o)2]12- (vi), [(znw9o34)2wcd3(h2o)2]12- (vii), and [(b-α-pw9o34)2zn2cd2(h2o)2]10- (viii)) were tested on four types of human cancer cells (mcf-7, b16f10, du-145, and pc3). all tested compounds showed cytotoxic activity which is mediated via apoptosis.