Molecular substructure and pattern search. ZINC-22 allows molecules containing a given substructure or molecular pattern expressed as SMILES or SMARTS to be found rapidly using Arthor (Figure ). The interface allows up to 20,000 molecules containing the substructure or pattern to be found and displayed interactively, often in seconds. Molecules that are found may be put in the shopping cart or downloaded using the menu in the top right. Up to 100,000 molecules may be downloaded using the download menu. If more than 100,000 molecules are desired, the user should use the Arthor tool in the TDLR interface (tldr.docking.org). Smallworld (above) provides an alternative and faster approach to substructure search.