Structure, photochemistry and applications of metal-doped polyoxotitanium alkoxide cages

Metal-doped polyoxotitanium cages (M-POTs) of the type [TixOy(OR)zMnXm] (M = a main group, transition metal or lanthanide; X = an anion such as a halide) can be regarded as molecular fragments of metal-doped TiO2. As such M-POTs can be used as structural models for the inclusion of metal ions into the TiO2 lattice and the ways in which well-defined microstructural changes affect photo-induced hole-electron separation. They are also potential organically-soluble redox-catalysts for a range of organic transformations and have been shown to be useful single-source precursors for the deposition of metal-doped TiO2. The applications of M-POTs as molecular precursors to metal-doped TiO2 offers a high degree of atomic control in the low temperature fabrication of photocatalytic thin films, which have applications in pollution control and water splitting. This perspective highlights the structural trends in M-POTs, their electronic behaviour and their applications as single-source precursors, looking at current and future trends in the development of inorganic precursors for device applications.