Lanthanide-Connecting and Lone-Electron-Pair Active Trigonal-Pyramidal-AsO 3 Inducing Nanosized Poly(polyoxotungstate) Aggregates and Their Anticancer Activities

Abstract

By virtue of the stereochemical effect of the lone-electron pair located on the trigonal-pyramidal-AsO 3 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-AsO 3 inducing nanosized poly(polyoxotungstate) aggregates [H 2 N(CH3}2]6 Na 24 H 16 {[Ln 10 W 16 (H 2 O) 30 O 2 ](B-α-AsW 9 O 33}897H 2 O [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 {[Ln 10 W 16 (H 2 O) 30 O 50 ](B-α-AsW 9 O 33}846is constructed from eight trivacant Keggin [B-α-AsW 9 O 33}99- ' fragments through ten Ln centers and sixteen bridging W atoms in the participation of fifty extraneous oxygen atoms. Notably, 4 and 8 can be stable in the aqueous solution not only for eight days but also in the range of pH = 3.9-7.5. Moreover, the cytotoxicity tests of 4 and 8 toward human cervical cancer (HeLa) cells, human breast cancer (MCF-7) cells and mouse fibroblast (L929) cells were performed by the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and the cell apoptosis processes were characterized by calcein AM/PI staining experiments, annexin V-FITC/PI staining experiments and morphological changes.