An acronym in cheminformatics: SFN for stoichiometric formula notation

SFN stands for stoichiometric formula notation [1-3]. An SFN describes a chemical compound in terms of its composition based on atoms and characteristic groups of atoms (structural subunits). For example, the mineral genthelvite, Zn₄(Be₃Si₃O₁₂)S, can be encoded as Zn4(Be3Si3O12)S. This SFN matches the displayed formula, only excluding its markup. An SFN is a document-neutral linear notation.

The versatility of SFN strings is appreciated when used with the CurlySMILES language, providing a format to specify materials due to phase, nanostructure, doping and other characteristics; for example: {*TiO2}{tfphn=rutile} encodes a titanium dioxide thin film with TiO₂ in the rutile phase, {*Fe3O4}{np}{dp} encodes dispersed magnetite nanoparticles, and {*ZnO}{IMa=F} encodes fluorine-doped zinc oxide.

SFNs also occur in composite and nanocomposite notations such as {/{*WS2}/{*WO3}}{np}, encoding tungsten-based WS₂/WO₃ nanoparticles.

SFNs are further used in combination with SMILES notations to encode functionalized material surfaces, particles and clusters, such as a thiophenolate capped cadmium sulfide nanoparticle: c1ccccc1S{-|c={*CdS}{np}}.

Keywords: chemical materials encoding, empirical formula, molecular formula, structural formula, brutto formula, summary chemical formula, nanostructures, functionalized material surfaces

References
[1] Axel Drefahl: CurlySMILES: a chemical language to customize and annotate encodings of molecular and nanodevice structures. Journal of Cheminformatics 2011, 3:1.
DOI: 10.1186/1758-2946-3-1.
[2] Axel Drefahl: The CurlySMILES Project: Stoichiometric Formula Notation (SFN) [www.axeleratio.com/csm/proj/sfn.htm].
[3] Examples E5, E16, E17, E18 and E20 in additional file of [1] entitle CurlySMILES encoding examples [www.jcheminf.com/content/supplementary/1758-2946-3-1-s1.pdf].