Polyoxometalate-phosphonate compounds: Synthesis, structure, photocatalytic and antitumor properties

Abstract

Two polyoxometalate-phosphonate compounds with the formular (TBA)2(Hbiz)2 [(C3H5O2P)2Mo5O21]•05H2O (1) and [Ni(2,2′bpy)3]2[(C6H5P)2Mo5O21]•3H2O (2) (TBA=tetrabutylammonium, biz=benzimidazole, bpy=bipyridine) have been synthesized under hydrothermal condition and structurally determined by single-crystal X-ray diffraction. Compound 1 and 2 are Strandberg-type polyoxometalate. The compounds were characterized by various means containing elemental analysis, PXRD, IR and thermal gravimetric analysis. Additionally, their photocatalytic degradation properties toward rhodamine-B are investigated. Compound 2 as catalyst has higher photocatalytic degradation of RhB than 1 due to its larger porosity. Results of the experiment on antitumor activities in vitro showed that two compounds inhibited five different human cancer cells (gastric cancer cells, HGC-27 and SNU668; liver cancer cells, Huh7; and colon cancer cells, HCT116 and SW480) demonstrated dose dependency and selectivity. The relationship between structure and biology activity indicate that inorganic and organic segments may influence the antitumor activity, the introduction of biz and 3-phosphonopropionic acid into P2Mo5 can make compound 1 better antitumor activities.