This section gives an overview of the following for use in Explore by Chemical Substance or Reaction:

• Retrieval possibilities using substructure searching
• Structure drawing precision tools
• Structure evaluation tools

With substructure searching, you can retrieve structure matches such as:

• Exact matches, including stereoisomers, radiolabeled matches, and charged matches
• Matches of the structural skeleton, with substitution at open positions
• Matches of the structural skeleton, with the skeleton embedded within a larger ring system
• Closely related matches resulting from hydrogen migration and double-bond rearrangement, e.g., tautomers
• Closely related matches resulting from charge migration, e.g., zwitterions

Tools are available to control substructure retrieval.

When you want to control	Use this tool
Substitution	Lock tool
Ring formation	Lock Out Rings tool
Retrieval of: Isotopes Mixtures Polymers Metal-containing substances Incompletely described substances	Preferences (Explore tab)

A decision chart summarizes applications of these drawing tools.