Self-assembly of a family of macrocyclic polyoxotungstates with emergent material properties

Using a time-dependent synthetic approach, the construction of a new class of macrocyclic tungstotellurite heteropolyacid cluster-squares, [W28Te8O112]24− (1a), [W28Te9O115]26− (2a) and [W28Te10O118]28− (3a) has been achieved. Isolation of these architectures is facilitated by the tellurite anions, which act as templates within structural building units and linkers between them, as well as pendant ligands which subsequently control inter-cluster aggregation, thereby defining a new architectural principle in the assembly of polyoxotungstate clusters. ESI-MS studies on these assemblies provide insights into the self-assembly process, distinguishing the different structural roles between the templating, linking and pendant tellurium-based anions. Further, cation exchange reactions on the crystalline forms of the macrocyclic POMs cause a morphological transformation resulting in the emergence of microtubular architectures with vast aspect ratios thereby opening the way to fabricate new material architectures capable of exploiting the properties of HPAs in applications such as ion exchange, catalysis and sensing.