Polyoxometalate-Induced New Self-Assemblies Based on Copper Ions and Bichelate-Bridging Ligands

The introduction of polyoxometalates (POMs) into the metal–organic complex synthetic system containing copper ions and bichelate-bridging ligands (bis­(3-(2-pyridyl)­pyrazole-1-ylmethyl)­benzene, bppmb) led to the isolation of three new organic–inorganic hybrid compounds [Cu^IILo]₂H­[BW₁₂O₄₀]·4H₂O (1), [Cu^ILo]₄[SiW₁₂O₄₀]·5H₂O (2), and [CuLp]₃H₂[BW₁₂O₄₀]·5H₂O (3) (Lo = 1,2-bppmb and Lp = 1,4-bppmb). All three compounds were hydrothermally synthesized and characterized by elemental analyses, IR spectra, TG analyses, powder X-ray diffraction, and single-crystal X-ray diffraction analyses. In these compounds, the use of Keggin-type POMs induces the formation of a series of new metal–organic secondary building units based on the copper ions and bppmb ligands such as helical chain and chiral Möbius Strip, which further form interesting supramolecular self-assemblies with the polyoxoanions. The degradation of Rhodamine-B (RhB) under UV irradiation with compounds 1–3 as the heterogeneous photocatalysts was investigated, and these compounds show good photocatalytic properties for RhB degradation.