Preyssler Polyoxometalate Supported Transition Metal Bipyridine Coordination Complexes.

We have synthesized two Preyssler-type polyoxometalate ({NaP5W30O110}14-)-based compounds [{CoII(C10H8N2)3}4{CoIII(C10H8N2)}0.74H4NaP5W30O110]·24H2O (1) and [{CuII(C10H8N2)2}4(C10H10N2)3NaP5W30O110]·6H2O (2) by solvothermal synthesis. The crystal structure of compound 1 consists of Preyssler polyoxometalate (POM) coordinated to {CoIII(2,2'-bpy)} (bpy = 2,2'-bipyridine, C10H8N2) complex and two uncoordinated {CoII(2,2'-bpy)3} complexes. The molecular structure of compound 2 consists of four {CuII(2,2'-bpy)2} complexes coordinated to terminal oxygens of Preyssler polyanion and three 2,2'-bipyridinium cations. Compounds 1 and 2 have been characterized unambiguously by single-crystal X-ray crystallography including PXRD, FT-IR, TGA, and DRS spectroscopy. In this work, compounds 1 and 2 are used as photocatalysts in the degradation of environmentally hazardous methylene blue (MB) dye via UV light irradiation. Compound 2 outperforms compound 1 in catalytic efficiency for the degradation of MB dye, achieving 78.1% efficiency compared to 72.3% for compound 1. The redox activities of compounds 1 and 2 have been investigated by electrochemical studies. Interestingly, compounds 1 and 2 exhibit solid-state fluorescence at room temperature.