Beyond Clusters: Supramolecular Networks Self-Assembled from Nanosized Silver Clusters and Inorganic Anions

Assembly of small clusters into rigid bodies with precise shape and symmetry has been witnessed by the significant advances in cluster-based metal-organic frameworks (MOFs), however, nanosized silver cluster based MOFs remain largely unexplored. Herein, two anion-templated silver clusters, CO3@Ag-20 and SO4@Ag-22, were ingeniously incorporated into a 2D sql lattice (1, [CO3@Ag-20(iPrS)(10)(NO3)(8)(DMF)(2)](n)) and an unprecedented 3D two-fold interpenetrated dia network (2, [SO4@Ag-22(iPrS)(12)(NO3)(6)2NO(3)](n)), respectively, under mild solvothermal conditions. Their atomically precise structures were confirmed by single-crystal X-ray diffraction analysis and further consolidated by IR spectroscopy, thermogravimetric analysis (TGA), and elemental analysis. Each drum-like CO3@Ag-20 cluster is extended by twelve NO3- ions to form the 2D sql lattice of 1, whereas each ball-shaped SO4@Ag-22 cluster with a twisted truncated tetrahedral geometry is pillared by four [Ag-6(NO3)(3)] triangular prisms to form the 3D interpenetrated dia network of 2. Notably, 2 is the first interpenetrated 3D MOF constructed from silver clusters. These results demonstrate the dual role of the anions, which not only internally act as anion templates to induce the formation of silver thiolate clusters but also externally extend the cluster units into the rigid networks. The photoluminescent and electrochemical properties of 2 are discussed in detail.