organic chemistry. It does not look like much, but this small little molecule brought us ferrocene, fluxional NMR, aromatic anions and valley-ridge inflexion points. You might not have heard of this last one, but in fact I mentioned the phenomenon in my post on nitrosobenzene. As for being at a crossroads, more like a Y-junction. Let me explain why.
Posts Tagged ‘iPad’
A month or so ago at a workshop I was attending, a speaker included in his introductory slide a QR (Quick Response) Code. It is a feature of most digital eco-systems that there is probably already “an app for it”. So I thought I would jump on the band wagon by coding an InChI string. Here it is below:
I have for perhaps the last 25 years been urging publishers to recognise how science publishing could and should change. My latest thoughts are published in an article entitled “The past, present and future of Scientific discourse” (DOI: 10.1186/1758-2946-3-46). Here I take two articles, one published 58 years ago and one published last year, and attempt to reinvent some aspects. You can see the result for yourself (since this journal is laudably open access, and you will not need a subscription). The article is part of a special issue, arising from a one day symposium held in January 2011 entitled “Visions of a Semantic Molecular Future” in celebration of Peter Murray-Rust’s contributions over that period (go read all 15 articles on that theme in fact!).
Most representational chemistry generated on a computer requires the viewer to achieve a remarkably subtle transformation in their mind from two to three dimensions (we are not quite yet in the era of the 3D iPad!). The Cahn-Ingold-Prelog convention was a masterwork (which won the Nobel prize). It is shown in action for the molecule on the left below. The CIP notation was actually generated by Chemdraw, and required a fair sprinkling of wedged and hashed bonds to (try to) remove stereoambiguity and generate the labels (try it for yourself). As part of a lecture course on pericyclic reactions, I tell the students that the reaction involves a [1,3] sigmatropic migration of the red carbon and that this migration proceeds with inversion of configuration at this migrating carbon (as the selection rules require). Perceiving what the correct CIP product label should be (with inferred stereochemical labels, resolving ? into either R or S) is IMHO one of the most difficult conceptual experiences in all of organic chemistry. I have over the years struggled to find a way of revealing this in lecture notes (these struggles with the “lecture notes” will be the topic of a future post here). However, I think I may have finally cracked it; my solution is set out below!
For those of us who were around in 1985, an important chemical IT innovation occurred. We could acquire a computer which could be used to draw chemical structures in one application, and via a mysterious and mostly invisible entity called the clipboard, paste it into a word processor (it was called a Macintosh). Perchance even print the result on a laserprinter. Most students of the present age have no idea what we used to do before this innovation! Perhaps not in 1985, but at some stage shortly thereafter, and in effect without most people noticing, the return journey also started working, the so-called round trip. It seemed natural that a chemical structure diagram subjected to this treatment could still be chemically edited, and that it could make the round trip repeatedly. Little did we realise how fragile this round trip might be. Years later, the computer and its clipboard, the chemistry software, and the word processor had all moved on many generations (it is important to flag that three different vendors were involved, all using proprietary formats to weave their magic). And (on a Mac at least) the round-tripping no longer worked. Upon its return to (Chemdraw in this instance), it had been rendered inert, un-editable, and devoid of semantic meaning unless a human intervened. By the way, this process of data-loss is easily demonstrated even on this blog. The chemical diagrams you see here are similarly devoid of data, being merely bit-mapped JPG images. Which is why, on many of these posts, I put in the caption Click for 3D, which gives you access to the chemical data proper (in CML or other formats). And I throw in a digital repository identifier for good measure should you want a full dataset.