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I'm using the porphyrin template provided with ConQuest as part of my substructure but the search seems to be missing hits I know are there: what is going on?

Solution

Although the templates provided within ConQuest are intended to represent 2D substructures as stored in the CSD, porphyrin is unfortunately a special case as it is difficult to represent all the resonance forms with a single template. Using the template as given in ConQuest will retrieve the majority of porphyrin hits however it may miss cases where some of the bonds are aromatic. To avoid this issue, the porphyrin template bonds should be re-typed as Any. The template can then be re-saved: full instructions on how to do this can be found in the ConQuest documentation.​