Many InChIs and quite some feat—that is the greeting offered to all interested in the IUPAC International Chemical Identifier, InChI, in a review published by Wendy Warr in J Comput Aided Mol Des (August 2015, 29:8, pp. 681-694; http://dx.doi.org/10.1007/s10822-015-9854-3). The article details not only the history of the project, but also its recent and current development, and celebrates 15 years of work since the project was first launched in 2000. The 14-page paper includes 275 references.
Warr recalls that, back in 2000, the increasing complexity of molecular structures made conventional naming procedures inconvenient, and there was no suitable, openly available electronic format for linking chemical structures over the Internet. InChI was developed as a freely available, non-proprietary identifier for chemical substances that can be used in printed and electronic data sources, thus enabling easier linking of data compilations and unambiguous identification of chemical substances. InChI was developed under the auspices of IUPAC, with principal contributions from the US National Institute of Standards and Technology (NIST), and more recently, the InChI Trust. While the IUPAC InChI SubCommittee has the responsibility for continued authentication of the InChI standard, the InChI Trust, in turn, develops and supports the non-proprietary InChI standard and promotes its use to the scientific community. Version 1 was launched in 2005 and the current version (1.04) was released in September 2011. CI readers have been regularly updated on InChI, its developments and applications (A. McNaught, Chem Int 28(6):12-14 (2006); J. Frey, Chem Int 28(6):14-15 (2006); S. Heller and A. McNaught, Chem Int 31(1):7-9 (2009); A. Yerin, et al, Chem Int 35(6):12-15 (2013)).
A second article released slightly earlier, in May 2015, by the core project task group, documents the design, layout, and algorithms of InChI, and was published in Journal of Cheminformatics (Heller et al. (2015) 7:23; http://dx.doi.org/10.1186/s13321-015-0068-4). This 34-page article is intended to provide a reasonably detailed description without being overlong for a journal article. For a more technical description, the reader is referred to the InChI Technical Manual and the free source code of the InChI software, available from the InChI Trust website at www.inchi-trust.org .
In her conclusion, Warr reminds us that establishing a standard is not a quick process; and that we should be impressed with what InChI has achieved over 15 years. She also declares that the InChI Trust does not intend to stop there. A new application programming interface (API) is being tested. Currently, the InChI algorithm can handle neutral and ionic organic molecules, radicals, and some inorganic, organometallic, and coordination compounds. Steps to expand it to handle more complex chemical structures are underway. Work continues on polymers and mixtures. Efforts on generic (‘‘Markush’’) structures are planned once funding is secured. In the longer term, consideration will be given to the InChI resolver, QR codes for InChI, macromolecules, positional isomers, crystal structures, and to extending the coverage of inorganic, organometallic and coordination compounds.
Volunteers willing to join the team will define the InChIs of the future. IUPAC and the InChI Trust continue to seek new members and people willing to help maintain and enhance the InChI standard.
For more information, contact Steven Heller <firstname.lastname@example.org>
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