Large polyoxotitanate clusters: well-defined models for pure-phase TiO2 structures and surfaces.

Careful control of the temperature and duration of the reaction between titanium tert-butoxide and acetic acid leads to the formation of new polyoxotitanate clusters with 14, 18, and 28 Ti atoms. They are considered intermediates in the growth of Ti/O nanoclusters of increasing size. The Ti(28) cluster is the largest crystallized to date. UV/vis spectroscopy on this cluster reveals that the optical band gap is blue-shifted with respect to a cluster containing only 17 titanium atoms indicating that the optical properties are more heavily influenced by the internal structure of the particle than its size.