Molecular assemblies based on the template-directing effect of anionic polyoxometalate clusters and organic cationic flexibility

Molecular assembly processes by utilizing the template-directing effect of anionic polyoxometalate clusters and the flexible organic cation have achieved three hybrids: (H2bpp)(Hbpp)[PMo12O40]·3DMF (1), (H2bpp)(Hbpp)(bpp)2 [PMo9V3O40(VO)2]2 (2), and (H2bpp)2[β-Mo8O26] (3) (bpp = 1,3-bis(4-pyridyl)propane). Three compounds were characterized using single crystal X-ray crystallography, elemental analysis, IR, XPS, EPR, voltammetric behavior and TGA. Crystal structural analyses revealed that compounds 1–3 were all constructed from protonated organic bpp cations with different POM clusters: isolated α-Keggin P–Mo cluster in 1; dimer of bi-capped α-Keggin P–Mo–V anions linked through a {V2O2} unit in 2; β-octamolybdate isopolyanion in 3, respectively. All three assemblies demonstrated a higher thermal stability. The protonated bpp cations lost at temperature higher than 300 °C that the strong intermolecular interactions may account for the high initial temperature of weight loss. The electrochemistry property of compound 2 modified carbon paste electrode was also studied in 1 M H2SO4 aqueous.

The current work demonstrates an idea to control the molecular assembly processes by using the template-directing effect of anionic polyoxometalate clusters and flexible organic molecules.Figure optionsDownload as PowerPoint slide