An Open-Framework Germanate with Polycubane-Like Topology

Body-centered Ge9 parallelepiped building blocks form the basis of the structure of [Ge9O18(OH)4]⋅2 (H2ppz)⋅0.5 (H2O) (ASU-14, ppz=piperazine). In this new structure type for an open-framework germanate (see picture for a section of the structure) the building blocks are linked together at each of their eight vertices to give the rare polycubane topology with an intersecting channel system of ten- and eight-membered rings (pore sizes 5×6 and 4×4 Å2, respectively) in which the piperazinium cations and water molecules reside.