Synthesis, structure, and characterization of two polyoxometalate–photosensitizer hybrid materials

Two hybrid materials based on the tris(bipyridine)ruthenium(II), [Ru(bpy)3]2+ and Keggin-type polyoxometalates, [PW11O39]7− and [PW12O40]3−, namely, [Ru(bpy)3][K5PW11O39] (1) and [Ru(bpy)3][KPW12O40] (2) were synthesized. X-ray crystallographic study of the red-colored complex, 2, shows that it crystallizes in the orthorhombic space group Pbcn and the polyanions are associated with the [Ru(bpy)3]2+ counterions by Coulombic forces and supramolecular interactions. The molecular complex is further connected and forms a three-dimensional framework through C–H⋯OPOM and other weak interactions. These complexes were further characterized by FT-IR, UV–Vis, 1H and 31P NMR, luminescent spectra and computational studies. Significantly, these combined spectroscopic studies show that these polyoxometalate–dye hybrids have strong electronic interactions between the cationic dye and polyanion units.

Graphical abstractTwo complexes involving a [Ru(bpy)3]2+ photosensitizer and a polyoxometalate (POM), [Ru(bpy)3][K5PW11O39] (1) and [Ru(bpy)3][KPW12O40] (2), have been characterized by X-ray crystallography and several spectroscopic techniques. Significantly, the photosensitizer and POM units exhibit strong inter-unit electronic interactions.Figure optionsDownload full-size imageDownload as PowerPoint slide