An Open-Framework Germanate with Polycubane-Like Topology

Body-centered Ge₉ parallelepiped building blocks form the basis of the structure of [Ge₉ O₁₈ (OH)₄ ]⋅2 (H₂ ppz)⋅0.5 (H₂ O) (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 Ų , respectively) in which the piperazinium cations and water molecules reside.