Syntheses, Structures, and Solution Behavior of Organic-Functionalized Uranyl Peroxide Nanoclusters

Uranyl peroxide clusters are mostly cage clusters that consist of U(VI) in the form of the uranyl ion bridged through peroxo or hydroxyl groups. In this thesis, uranyl peroxide clusters are studied in the form of organic-inorganic hybrid complexes. The organic ligand, benzene-1,2-diphosphonate, has been incorporated into uranyl peroxide clusters, resulting in five new structures built from 19-24 uranyl ions. The obtained structures exhibit unique properties in terms of coordination chemistry of the uranyl ion, solid state packing and solution behavior.

Dissolution of uranyl peroxides, such as studtite, leads to the formaton of uranyl peroxide clusters with generally high solubility in water. However, the organic ligand functionalized cluster exhibits a relative low solubility. The incorporation of organic ligands into the cluster impacts the solubility of uranyl peroxide clusters and enables the cluster to dissolve in the organic solvent dimethyl sulfoxide (DMSO). The functionalized cluster is more stable in DMSO than in water where its conversion into other cluster-like species has been identified.

Uranyl peroxide clusters have typically been obtained by one-pot synthesis upon mixing uranyl ions, hydrogen peroxide, and alkali cations under ambient conditions. Given that functionalized-clusters can be converted into other cluster species in water, uranyl peroxide clusters have been used as precursors to obtain other cluster species

through their transformations in water. A new cluster has been obtained through the disassembly and reassembly of a functionalized cluster upon heating.

Disassembly and reassembly of the functionalized cluster has produced the cluster without functional groups. Attempts have to made to achieve the reverse reaction which produces the functionalized cluster from the unfunctionalized cluster precursor.