Time-Resolved Assembly of Cluster-in-Cluster {Ag_(12)}-in-{W_(76)} Polyoxometalates under Supramolecular Control

摘要

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))Ag_(18) Cl-(Te3W_(38)O_(134))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 = oo and m~—5 for compound 3 (after 14 days). The reaction is based upon the self-organization of two {Te3W_(38)} units around a single chloride template and the formation of a {Ag_(l2)} cluster, giving a {Ag_(l2)}-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 ESl-MS. Further, control experiments demonstrate the crucial role that TeO_3~(2-) , Cl~- , and Ag~+ play in the self-assembly of compounds 1-3.