Chemistry’s symbolic language has evolved since the mid-nineteenth century.Credit: Sigrid Gombert/SPL
Think back to those organic-chemistry classes at school. Did you draw a benzene ring as a hexagon that contained a circle, to represent its delocalized clouds of electrons? If so, you are showing your age. Convention these days is a depiction containing three double bonds.
How molecules are represented is important. It is a worry when the literature contains ugly or inconsistent versions. So this week, the Nature journals launch two tools to help both expert and casual chemists (see go.nature.com/2zvoeza). An updated chemical structure guide details how authors should draw molecules. And an associated template enables them to do so in the program ChemDraw. (Both can be found in each journal’s guide to authors.) Our goal is to make the creation of figures much simpler, especially for those working outside their core discipline.
Appearance and aesthetics play a significant part in chemistry. Organic chemists often describe their strategies to make natural products or pharmaceuticals as ‘elegant’ or ‘attractive’. Robert Burns Woodward, winner of the Nobel Prize in Chemistry in 1965, noted that the creative challenge that synthesis offers would see it endure as long as people “write books, paint pictures, and fashion things which are beautiful, or practical, or both”. And as French chemist Marcellin Berthelot put it in the nineteenth century, “chemistry creates its own object” — conjuring an image of a molecular artist.
This attitude goes hand in hand with a science that is primarily drawn, not written. Take benzene. In 1858, chemists August Kekulé and Archibald Scott Couper independently suggested the concept of a chemical structure that links carbon atoms. The invention thereafter of a symbolic language showing how the various atoms are connected gave chemists a way to show what was going on in their flasks. Famously, Kekulé had a vision in which he saw the ouroboros — a snake biting its own tail — giving him the idea for benzene’s ring structure. Since then, there have been many modifications to how structures are represented, as our understanding of electrons, covalent bonding, quantum mechanics and molecular shape have evolved.
Equally important is presentation. And as the molecules that can be made become ever more complex, we need updated design principles. Fraser Stoddart at Northwestern University in Evanston, Illinois, who won a share of the Nobel Prize in Chemistry last year for his role in creating molecular-sized machines, is noted for his use of colour in his papers to represent different parts of a molecule. These illustrate the various atomic-scale pumps, switches and knots with cartoons that link to the chemistry involved. Some chemists are more creative artists than are others.
So, more than simply standardizing how chemical structures look in Nature journals, we hope that our guide and template will help researchers to depict the complexity of life’s molecules clearly. For those unfamiliar with the drawing software, this template will do the work, as well as avoiding chemical impossibilities such as ‘Texas’ carbons (named for their resemblance to the emblem of the Lone Star State). Everything is already in Nature style and to scale, so the tools mean less work for authors and editors alike. We offer them, not to dampen flair, but to make it easier for all to draw chemical structures with minimal fuss. Now go create!
