Fig. 8
From: Development of an open-source software for isomer enumeration
Influence of the order of the atoms in the SMILES strings on the notation for the local stereo configuration. The displayed molecule corresponds to e.g. the SMILES string Br[C@](Cl)(I)F. If the order of the first-neighbor atoms of the central carbon in the string is changed by an odd permutation (odd number of swaps), the stereo configuration notation of the carbon changes from ‘@’ to ‘@@’. For example, if the iodine and the chlorine are swapped, this results in the string Br[C@@](I)(Cl)F. For an even permutation (even number of swaps), the stereo configuration notation stays the same. For example, if the bromine and the chlorine are swapped and then the chlorine and the iodine are swapped, this results in the string I[C@](Br)(Cl)F