Two new Keggin-type polyoxometalate-based entangled coordination networks constructed from metal-organic chains with dangling arms

Highlight
• We report two new Keggin-type POM-based entangled coordination networks.
• Compound 1 exhibits the 2-D → 3-D polythreading networks.
• Compound 2 possesses the 2-D → 3-D zipper-closing networks.
• Compound 1 and 2 show good UV photocatalytic activity for MB degradation.

Two new polyoxometalate(POM)-based entangled coordination networks with chemical formula of [Mn2(H2O)2(BBPTZ)5][SiW12O40] (1) and [Ni2(H2O)2(BBPTZ)5][SiMo12O40]·6H2O (2) (BBPTZ = 4.4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl), were prepared in a hydrothermal reaction system. Compounds 1–2 were characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. In compound 1, dangling arms thread in quadrangular window of the adjacent 2-D layers, thus resulting in a rare 2-D → 3-D polythreading motif. Compound 2 exhibits a rare 2-D → 3-D zipper-closing motif. Using the degradation of methylene blue (MB) as the model, the photocatalytic activities of compounds 1–2 were investigated. Both compounds show efficient catalytic activity for the degradation of MB with the order of 2 > 1. It is found that the POM species of compounds 1–2 play the main role in the photocatalytic degradation process.

Two new entangled coordination networks based on metal-organic chains with dangling arms and Keggin-type polyoxometalates (POMs) were assembled by changing pH and transition metal cations.Figure optionsDownload as PowerPoint slide