Drawing Query Structures

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What Are Query Structures?

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Using a query structure to specify properties for atoms and bonds provides an efficient way to search chemical databases such as ChemFinder, DARC, RS³, or ISIS/Base. You can use a query structure to narrow or broaden your search.

For example, creating a query structure indicating a bond as either double or single might broaden your search. Indicating atom properties where a particular atom must have a charge of +3 might narrow your search.

Because ChemDraw is not a chemical database application, the interpretation of query structures involves other programs. Not all databases support the same query properties. If you use a query structure containing properties not understood by a given database, one of the following may happen:

• An error message appears
• The unsupported properties are ignored

To use query structures for searching you may do either of the following:

• Paste the query structure into a database search window and initiate a search.
• Save the structure in an appropriate file format and open the file in the database application.

For more information on query properties see "Query Properties", or consult the documentation for your chemical database.

NOTE: You can assign conflicting or nonsensical properties. For example, you can require that one of the atoms in benzene is not part of any ring, which is inherently impossible. The results of the search depend on the query system used, but usually no matches are found.