SMILES is an acronym for Simplified Molecular Input Line Entry System. It is a one-dimensional string of character code that describes the 3D structure of a chemical species. SMILES code can be obtained from database search from databases such as PubChem, or it can be generated from a 2D ChemDraw sketch of the molecule.
The original SMILES code was developed by David Weininger at the US EPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s, with contributions from Gilman Veith, Rose Russo (US EPA), Albert Leo and Corwin Hansch (Pomona College). It has been modified and extended several times since its initial inception, most notably by Daylight Chemical Information Systems. The International Union of Pure and Applied Chemistry (IUPAC), introduced InChl (International Chemistry Modifier) as a standard in July 2006, although SMILES remains more commonly used today. OpenSMILES, and open source version of SMILES, was released in 2007.
In this tutorial, I go over the process of generating SMILES code for a small molecule in ChemDraw, obtaining SMILES code from the PubChem database, and importing it into 3D modeling software, Chimera X and Molecular Operating Environment (MOE).