Lab and analysis
SMILES
Definition
A line notation that writes a chemical structure as a short text string, such as CCO for ethanol.
SMILES (Simplified Molecular Input Line Entry System) writes atoms by their symbols, bonds as -, =, # or implied single bonds, branches in brackets and rings with matching digits. Aromatic atoms are written in lowercase, so benzene is c1ccccc1 and acetic acid is CC(=O)O.
The same molecule can have many valid SMILES, so software produces a canonical SMILES for comparison. Isomeric SMILES also carry stereochemistry. You can paste a SMILES into structure search to find a chemical.
Related terms
- CAS registry number (CAS RN)A unique numeric identifier assigned by the Chemical Abstracts Service to a chemical substance, such as 7732-18-5 for water.
- InChIKeyA fixed length 27 character hashed form of the InChI, used to search and link chemical records, for example LFQSCWFLJHTTHZ-UHFFFAOYSA-N for ethanol.
- InChIThe IUPAC International Chemical Identifier, an open text string that describes a chemical structure in layers.
- IUPAC nameThe systematic name of a chemical built by the nomenclature rules of the International Union of Pure and Applied Chemistry.