different chemical compositions?

The common theme behind these questions is to illustrate how the methodology developed here allows researchers to identify materials that have similar pore geometries.

MOFs and zeolites {#mofzeol}
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In Figure \[MOFzeo\], we identify the structures in the IZA+ hypothetical zeolite database ([*7,8*]{}) that are most topologically similar to some of the best known MOFs (e.g., MOF-5 and Cu-BTC). The figure shows that we can indeed find hypothetical zeolite structures that look very similar to these MOFs.

-4cm ![\[MOFzeo\]The zeolites most similar to MOF-5 and Cu-BTC with respect to PerH.](MOFzeoU "fig:") -4cm

Hypothetical and experimental MOFs {#hmof}
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For hypothetical MOFs we have a database of over 140,000 materials. ([*9*]{}) An interesting question is whether pore geometries similar to those occurring in hypothetical MOFs have already been synthesized. This question is difficult to answer with traditional methods, since the materials might differ in their chemical composition. We have compared the similarity of structures from the database of hypothetical MOFs (hMOFs) with the experimental structures in the CoRE-MOF database. Figure \[hMOFexMOF\] shows two examples of similar structures. The color coding of the structures shows that the chemical composition of the two structures is very different.

![\[hMOFexMOF\]Finding hypothetical MOFs 