Germanate frameworks constructed from oxo germanium cluster building units

This article describes the recent research progress in the field of crystalline germanate frameworks with oxo germanium clusters as building units. By using different amine molecules or transition-metal complexes as the structure-directing agents, new oxo germanium clusters, such as Ge₇, Ge₈, Ge₉, Ge₁₀, and Ni@Ge₁₄ units, have been prepared and organized into extended frameworks with chain-like, tubular, layered, slab-like, and three-dimensional structures. The combination of different types of oxo germanium clusters in the same crystalline framework provides an additional way to tune the framework structures. Besides their rich structural chemistry, the germanate frameworks exhibit interesting properties including ion-exchange, microporosity, and thermal stability, suggesting their potential application in molecular sieving and catalysis.