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Solutions for "Structures Too General"

Solutions for "Structures Too General"

SciFinder allows your scientists to explore by exact structures and substructures and retrieve the maximum amount of relevant substances. This capability allows scientists to draw a chemical structure in the way that is most familiar to them without having to worry about missing important and interesting answers.

In the last issue of SciFinder Solutions you learned how the Analyze by Precision clusters answers into groups of answers based on how closely they match the drawn structure question. In this issue of SciFinder Solutions you will learn the different solutions that are available when structure questions are very general.

SciFinder allows for the maximum relevant retrieval of substances that match a drawing and automatically finds all substances that contain the same arrangement of atoms and bonds as the structure drawn. In substructure searching, most searches run successfully, but occasionally structure questions are too general and the "Get Substances Not Completed" message will display.

In SciFinder 2004 the user has several options for resolving this situation.

• One approach for structure questions that are too general is to add additional structural attributes to the structure question and retry the search.
• A second option is to use the Autofix button - Use the autofix feature to automatically lock both rings and chains. The lock out feature will make the structure question more precise by eliminating answers where:
  • Fragments drawn as chains are found in ring systems.
  • Fragments drawn as ring systems are embedded in larger ring systems.
• A third option is to use the Additional Options button on the "Get Substances Not Completed" screen. Choosing this option provides you with three features to modify the structure question.
  • Including additional components This feature allows you to exclude substances that contain additional components beyond that specified in the structure question.
  • Including substance types This feature allows you to exclude or include classes of substance, for example, alloys and polymers.
  • Limiting by formula weight This feature allows you to restrict the substances retrieved by a formula weight range.

The three features in Additional Options may be used separately or together. View more details for each of the capabilities cited above.