Hybrid inorganic-organic core-shell nanoparticles from surface-functionalized titanium, zirconium, and vanadium oxo clusters

Novel surface-functionalized metal oxo clusters were obtained using an in situ surface-modification method based on the sol-gel process. A reaction of 2-bromoisobutyric acid with Zr(OPr)(4) or Ti((OPr)-Pr-i)(4) resulted in the compounds Zr5O4(BrC(CH3)(2)COO)(10)((OPr)-Pr-n)(2)((PrOH)-Pr-n)(4) and Ti6O4(BrC(CH3)(2)COO)(8)((OPr)-Pr-i)(8). The reaction of 2-bromopropionic acid with VO((OPr)-Pr-i)(3) resulted in the cluster V3O3(BrC(CH3)COO)(6)((HOPr)-Pr-i). All obtained compounds have in common that the organic functionalities are exclusively located on the surface of the well-defined subnanometer metal oxo clusters. The prepared compounds were successfully used as macro-initiators in atom transfer radical polymerizations (ATRP) and produced inorganic-organic core-shell nanoparticles.