The sketcher used to allow structure searching within WebCSD communicates with our CSD search engine via a SMARTS substructure representation. Occasionally, the translation from a SMARTS substructure to the equivalent substructure in the CSD is not completely straightforward. If you would like to learn more about SMARTS or visualise SMARTS patterns, the web application SMARTSviewer by the University of Hamburg is an excellent reference.
If you have any questions or concerns about your search results, please do contact us through CCDC support. We are very happy to help out if you would like some guidance on sketching or defining queries in WebCSD.