In order to describe the average structure of crystalline materials at the nano-scale, reticular chemistry proposes to classify crystals, and in particular framework materials, in light of their topology. This approach consists in abstractly regrouping the atoms of a crystal into clusters, called vertices, bonded together by an abstract kind of linkers, called edges -the choice of grouping being informed by chemical sense. In simple compounds, such as dense oxides, the mapping can be trivial, with each atom as a separate vertex and each chemical bond as an edge. For zeolites and aluminosilicates, the tetrahedral atoms T are considered the vertices (T = Al, Si, P, . . . ) and the T-O-T linkages are the edges. In the case of metalorganic frameworks (MOFs), the vertices would be chosen among the secondary building units (SBUs) with more than 2 points of extension, and the edges would correspond to bonds between those as well as ditopic SBUs, for example. Any crystal can then be simplified into a topological structure, called a net, consisting of the sets of vertices and edges (see Figure ).