SMILES

Simplified molecular input line entry specification 

The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings SMILES strings can be imported by most molecule editor for conversion back into two dimensional drawings or three dimensional models of the molecules.The term Canonical SMILES refers to the version of the SMILES specification that includes rules for ensuring that each distinct chemical molecule has a single unique SMILES representation.A common application of Canonical SMILES is for indexing and ensuring uniqueness of molecules in a database. The term Isomeric SMILES refers to the version of the SMILES specification that includes extensions to support the specification of isotopes, chirality, and configuration about double bonds. A notable feature of these rules is that they allow rigorous partialspecification of chirality. In terms of a graph-based computational procedure, SMILES is a string obtained by printing the symbol nodes encountered in a depth-first tree traversal of a chemical graph.The chemical graph is first trimmed to removehydrogen atoms and cycles are broken to turn it into a spanning tree. Where cycles have been broken, numeric suffix labels are included to indicate the connected nodes.Parentheses are used to indicate points of branching onthe tree.

-Simplified Molecular Input Line Entry System (SMILES)

-Widely used AND computationally efficient

-Uses atomic symbols and a set of intuitive rules

-Uses hydrogen-suppressed molecular graphs (HSMG)

below are some of the examples: