NAME

Chemistry::OpenSMILES::Aromaticity - Aromaticity handling routines

DESCRIPTION

Chemistry::OpenSMILES::Aromaticity encodes some aromaticity handling subroutines for aromatisation and kekulisation. Both implementations are experimental, handle only some specific cases and are neither stable nor bug-free, thus should be used with caution.

METHODS

aromatise( $moiety )

Mark electron cycles as aromatic.

kekulise( $moiety, $order_sub )

Find nonfused even-length aromatic cycles consisting only of B, C, N, P, S and mark them with alternating single and double bonds. Subroutine as well accepts an optional subroutine reference $order_sub, providing external order for atoms. This is needed to stabilise the algorithm, as otherwise the outcomes of bond assignment may turn out different. $order_sub is called with an atom as $_[0] and is expected to return a value providing a distinct order indication for every atom. These can be any scalar values, comparable using Perl's "cmp" operator. If $order_sub is not given, initial atom order in input is consulted.

electron_cycles( $moiety )

Find electron cycles according to "Finding Electron Cycles" algorithm from <https://depth-first.com/articles/2021/06/30/writing-aromatic-smiles/>. Use with caution: the implementation is experimental.