Lanthanide-Connecting and Lone-Electron-Pair Active Trigonal-Pyramidal-AsO3Inducing Nanosized Poly(polyoxotungstate) Aggregates and Their AnticancerActivities

摘要

By virtue of the stereochemical effect of the lone-electron pair located on the trigonal-pyramidal-AsO3 groups and the one-pot self-assembly strategy in the conventional aqueous solution, a series of novel lanthanide-bridging and lone-electron-pair active trigonal-pyramidal-AsO3 inducing nanosized poly(polyoxotungstate) aggregates [H2N(CH3)2]6 Na24H16{[Ln10W16(H2O)30O50](B-α-AsW9O33)8}·97H₂O [Ln = Eu^III (>1), Sm^III (>2), Gd^III (>3), Tb^III (>4), Dy^III (>5), Ho^III (>6), Er^III (>7), Tm^III (>8)] were prepared and further characterized by elemental analyses, IR spectra, UV spectra, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. The most remarkable structural feature is that the polyanionic skeleton of {[Ln₁₀W₁₆(H₂O)₃₀O₅₀](B-α-AsW₉O₃₃)₈}⁴⁶⁻ is constructed from eight trivacant Keggin[B-α-AsW₉O₃₃]⁹⁻fragments through ten Ln centers and sixteen bridging W atoms in the participationof fifty extraneous oxygen atoms. Notably, >4 and >8 can be stable inthe aqueous solution not only for eight days but also in the range ofpH = 3.9–7.5. Moreover, the cytotoxicity testsof >4 and >8 toward human cervical cancer (HeLa) cells, human breastcancer (MCF–7) cells and mouse fibroblast (L929) cells were performed bythe 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay andthe cell apoptosis processes were characterized by calcein AM/PI stainingexperiments, annexin V-FITC/PI staining experiments and morphological changes.