Figure Persented: We report the synthesis and characterization of eight new Mo, W, or V-containing polyoxometalate (POM) bisphosphonate complexes with metal nuclearities ranging from 1 to 6. The compounds were synthesized in water by treating MoVI, WVI, VIV, or VV precursors with biologically active bisphosphonates H2O 3PC(R)(OH)PO3H2 (R = C3H 6NH2, Ale; R = CH2S(CH3) 2, Sul and R = C4H5N2, Zol, where Ale = alendronate, Sul = (2-Hydroxy-2,2-bis-phosphono-ethyl)-dimethyl-sulfonium and Zol = zoledronate). Mo6(Sul)2 and Mo 6(Zol)2 contain two trinuclear MoVI cores which can rotate around a central oxo group while Mo(Ale)2 and W(Ale) 2 are mononuclear species. In V5(Ale)2 and V5(Zol)2 a central VIV ion is surrounded by two VV dimers bound to bisphosphonate ligands. V6(Ale) 4 can be viewed as the condensation of one V5(Ale) 2 with one additional VIV ion and two Ale ligands, while V3(Zol)3 is a triangular VIV POM. These new POM bisphosphonates complexes were all characterized by single-crystal X-ray diffraction. The stability of the Mo and W POMs was studied by 31P NMR spectroscopy and showed that all compounds except the mononuclear Mo(Ale)2 and W(Ale)2 were stable in solution. EPR measurements performed on the vanadium derivatives confirmed the oxidation state of the V ions and evidenced their stability in aqueous solution. Electrochemical studies on V5(Ale)2 and V 5(Zol)2 showed reduction of VV to V IV, and magnetic susceptibility investigations on V 3(Zol)3 enabled a detailed analysis of the magnetic interactions. The presence of zoledronate or vanadium correlated with the most potent activity (IC50-1-5 μM) against three human tumor cell lines.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry