A SMILES (Simplified Molecular Input Line Entry System) string is a way to represent a molecule’s structure as a short text string using printable ASCII characters
Atoms:
Standard abbreviation of the chemical elements, in square brackets, such as [Au] for gold
B, C, N, O, P, S, F, Cl, Br, I - do not need brackets
Bonds:
”.” - Non-bond e.g [Na+][Cl-] to show dissociation
”-” - Single (Usually omitted)
”=” - Double
”#” - Triple
”$” - Quadruple
”:” - Aromatic “one and a half” bond
”/” and ”\” - Single bonds adjacent to double bonds
Rings
C1CCCCC1 for cyclohexane
Branching
Branches are described with parentheses