Synthesis and Disassembly/Reassembly of Giant Ring-Shaped Polyoxotungstate Oligomers

The disassembly and reassembly of giant molecules are essential processes in controlling the structure and function of biological and artificial systems. In this work, the disassembly and reassembly of a giant ring-shaped polyoxometalate (POM) without isomerization of the monomeric units is reported. The reaction of a hexavacant lacunary POM that is soluble in organic solvents, [P2W12O48](14-), with manganese cations gave the giant ring-shaped POM [gamma-P2W12O48Mn4-(C5H7O2)(2)(CH3CO2)}(6)](42-). This POM is a hexamer of manganese-substituted {P2W12O48Mn4} units, and its inner cavity was larger than any of those previously reported for ring-shaped polyoxotungstates. It was disassembled into monomeric units in acetonitrile, and the removal of the capping organic ligands on the manganese cations led to reassembly into a tetrameric ring-shaped POM, [{gamma-P2W12O48Mn4(H2O)(6)}(4)-(H2O)(4)](24-).