CONTROL ISSUES
Background. Time to re-write organic chemistry textbooks: a catalyst has been developed that recognizes the topology of just one face of a planar reaction intermediate. Remarkably, this enables one mirror-image isomer of the reaction product to be made selectively.
In a nutshell, the research describes a new way to hold a molecule in place at a particular orientation. This work will presumably enable future researchers to explore a vast new āchemical spaceā of all possible molecules. (An accessible summary of the research can be found in thisĀ excellent News & Views piece. Paywall)
Design challenge. Unlike some papers in Nature, this one is not easily understood by those outside the field. When we decided to feature it on the cover, we knew it would be a challenge to visualize. We called for aid -Ā Ā and expert scientific illustrator Ella MarushchenkoĀ answered! Ella has created many striking journal covers in the past, so we knew she would be up for the challenge.Ā
This from Ella about her process:
āIn the article, scientists described a new way to hold a molecule in place at a particular orientation. āDirecting the undirectableā was the working cover line at the start of the project, and helped inform our thinking. One of the ideas which came from the editors was to show a trigonal planar cation being held in place by the catalyst, with the attacking group coming from the other side. We worked with corresponding author Eric Jacobsen to refine this idea. He helpfully sent us ChemDraw files of the molecules, and worked closely together with Kelly and me on the cover image.
Our challenge was to visually convey the idea that a molecule was being controlled. This requires some sort of visual metaphor that people can relate to. The first idea was to show the molecule being held by a hand. Modeling of the hand is always a challenging part for me because the hand should look anatomically correct and elegant. To model a hand holding something I always look at my own hand and try to see it from different angles. I took a 3D printed molecule and started rotating it to find the best perspective.Ā
While I was doing it my cat decided to help me and played a role of the attacking molecule, displaying previously undiscovered acting talent (second image).
Kelly asked me to show the hand in a wireframe style, to make it more symbolic than realistic, and I agreed with her because I really like this style. I decided to show all molecules in 3D with reflective materials. To show the difference between the three substituents on the intermediate, I decided to use not only shape and color, but also different numbers of polygons. In this way the difference between three substituents was obvious.Ā
One of our first drafts shows the wireframe hand holding a molecule in place (third image).Ā While this overall composition works well, the idea of using the hand did not work out. The hand overlapped oddly with the trigonal planar cation, and was too large when rendered from that angle, which distracted from the molecule itself. After some discussion, we decided to try something less prominent than the hand, agreeing to show control by tweezers (final cover, top image).ā
Summary. This cover was an interesting exercise in finding the right metaphor to communicate an esoteric, complex idea to an audience of non-specialists.Ā As Nature is a multidisciplinary journal, we walk a line between getting the essentials of the art right for specialists, while at the same time creating a dynamic and understandable image for scientists outside of the field.
The design solution of the tweezers enables the non-specialist viewer to understand that molecular control is happening, but without having to think too deeply about what is doing the manipulating. Or, for that matter, who owns the hand!
-Kelly Krause


















