Simplified Molecular Input Line Entry System: Difference between revisions

Revision as of 02:50, 23 May 2020

Revision as of 22:37, 26 May 2020

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Bonds between [[Aliphatic compound|aliphatic]] atoms are assumed to be single unless specified otherwise and are implied by adjacency in the SMILES string. Although single bonds may be written as <code>-</code>, this is usually omitted. For example, the SMILES for [[ethanol]] may be written as <code>C-C-O</code>, <code>CC-O</code> or <code>C-CO</code>, but is usually written <code>CCO</code>.

Double, triple, and quadruple [[chemical bond|bonds]] are represented by the symbols <code>=</code>, <code>#</code>, and <code>$</code> respectively as illustrated by the SMILES <code>O=C=O</code> ([[carbon dioxide]] {{CO2}}), <code>C#N</code> ([[hydrogen cyanide]] HCN) and <code>[Ga-+]$[As+-]</code> ([[gallium arsenide]]).

An additional type of bond is a "non-bond", indicated with <code>.</code>, to indicate that two parts are not bonded together. For example, aqueous [[sodium chloride]] may be written as <code>[Na+].[Cl-]</code> to show the dissociation.