SMARTS Representation of Molecular Searches

Using canonical SMILES is a very powerful technique for molecular structure storage and lookup. However, it is sometimes necessary to perform 

Another SQL extension is needed that can understand the molecular structural nature of the SMILES string and treat it like more than just a text string. Suppose there is a function matches (A,B) that returns true when structure A contains structure B. Both these structures could be represented as SMILES and the matches function itself would understand the molecular nature properly. Then matches( C( N)S, C N ) would be true as would matchesCSC N, N C ), as intended. The matches function can be used to find all cyano-containing structures in a table using an SQL clause such as where matches (cansmi, C N )- 

Sometimes the desired substructure is not as simple as a cyano group. For example, to search for di-halogen-substituted carbons, one could use an SQL clause where matches (cansmi, FCF ) or matches(cansmi, 

Thematches(A, B) function is properly defined having A represent a structure using SMILES and B represent substructures using SMARTS. Of course, B may also be a SMILES. In this case, matches will be true when B is a substructure of A. All structures in a table for which CC(0)C is a substructure canbe found by using the SQL clause Where matches (cansmi, 

Convince yourself that any valid SMILES is also a valid SMARTS, but not vice versa. 

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