PKU-10: A New 3D Open-Framework Germanate with 13-Ring Channels

PKU-10, a germanate with the formula [(CH3)4N]3Ge11O19(OH)9, is synthesized under hydrothermal conditions, and its structure is determined by single-crystal X-ray diffraction data. PKU-10 possesses 3D intersected 13-ring channels and presents a new 6-connectedness linkage mode of the Ge7 cluster, T3P2O, forming a pcu topological network. Each Ge7 cluster is, in fact, surrounded by eight Ge7 clusters in a nearly perfect cube because the hydrogen bonds between Ge7 clusters are also taken into account. The structure-directing agent tetramethylammonium (TMA+) ions, locating in the channels, can be partially exchanged by Li+ with retention of the germanate framework. The germanate framework collapses with decomposition of the TMA+ ions at temperatures higher than 240 °C.