Time-Resolved Assembly of Cluster-in-Cluster {Ag12}-in-{W76} Polyoxometalates under Supramolecular Control

We report the time-resolved supramolecular assembly of a series of nanoscale polyoxometalate clusters (from the same one-pot reaction) of the form: [H(10+m)Ag18Cl-(Te3W38O134)(2)](n), where n=1 and m=0 for compound 1 (after 4 days), n=2 and m=3 for compound 2 (after 10 days), and n-infinity and m-5 for compound 3 (after 14 days). The reaction is based upon the self-organization of two {Te3W38} units around a single chloride template and the formation of a {Ag-12} cluster, giving a {Ag-12}-in-{W-76} cluster-in-cluster in compound 1, which further aggregates to cluster compounds 2 and 3 by supramolecular Ag-POM interactions. The proposed mechanism for the formation of the clusters has been studied by ESI-MS. Further, control experiments demonstrate the crucial role that TeO32-, Cl-, and Ag+ play in the self-assembly of compounds 1-3.