The interface between physics, chemistry (and materials science) can be a fascinating one. Here I show a carbon nanotorus, devised by physicists[cite]10.1103/PhysRevLett.88.217206[/cite] a few years ago. It is a theoretical species, and was predicted to have a colossal paramagnetic moment . Carbon nanotorus.

The title of this post paraphrases E. J. Corey’s article in 1997 (DOI: 10.1016/S0040-4039(96)02248-4) which probed the origins of conformation restriction in aldehydes. The proposal was of (then) unusual hydrogen bonding between the O=C-H…F-B groups. Here I explore whether the NCI (non-covalent-interaction) method can be used to cast light on this famous example of how unusual interactions might mediate selectivity in organic reactions.

The Pirkle reagent is a 9-anthranyl derivative (X=OH, Y=CF ₃ ). The previous post on the topic had highlighted DIST1, the separation of the two hydrogen atoms shown below. The next question to ask is how general this feature is. Here we take a look at the distribution of lengths found in the Cambridge data base, and focus on another interesting example. 9-anthranyl derivatives. Click for Pirkle with normalised C-H lengths.

Observation of the slow racemization of isobornyl chloride in a polar solvent in 1923-24 by Meerwein led to the recognition that mechanistic interpretation is the key to understanding chemical reactivity. The hypothesis of ion pairs in which a chloride anion is partnered by a carbocation long ago entered the standard textbooks (see DOI 10.1021/ed800058c and 10.1021/jo100920e for background reading).

Libraries (and librarians) are evolving rapidly. Thus a week or so ago one of our dynamic librarians here, approached some PhD students and academics to ask them how they used “ Web 2.0 ” (thanks Jenny!). The result was edited (thanks John!) and uploaded, where you can see it below (embedded in this post, I might add, using HTML5). No doubt there is more of this genre to come.

This molecule is not leaving me in peace. It and I first met in 1990 (DO: 10.1039/C39910000765), when we spotted the two unusual π-facial bonds formed when it forms a loose dimer.

In earlier posts, I alluded to what might make DNA wind into a left or a right-handed helix. Here I switch the magnification of our structural microscope up a notch to take a look at some more inner secrets. A fragment of a single chain of DNA, taken from a Z-helix.

The previous post set out a problem in conformational analysis. Here is my take, which includes an NCI (non-covalent interaction) display as discussed in another post. The lowest energies of the four diastereomers A-D , each in two conformations ( 1/2 ) were calculated at the ωB97D/6-311G(d,p)/SCRF=ethanol level, and are shown here relative to A1 (kcal/mol) as free energies.

Conformational analysis comes from the classical renaissance of physical organic chemistry in the 1950s and 60s. The following problem is taken from E. D. Hughes and J. Wilby J. Chem. Soc. , 1960, 4094-4101, DOI: 10.1039/JR9600004094, the essence of which is that Hofmann elimination of a neomenthyl derivative (C below) was observed as anomalously faster than its menthyl analogue.

Introductory organic chemistry invariably features the mechanism of haloalkane solvolysis, and introduces both the Sn1 two-step mechanism, and the Sn2 one step mechanism to students. They are taught to balance electronic effects (the stabilization of carbocations) against steric effects in order to predict which mechanism prevails.

At a recent conference, I talked about what books might look like in the near future, with the focus on mobile devices such as the iPad. I ended by asserting that it is a very exciting time to be an aspiring book author, with one’s hands on (what matters), the content . Ways of expressing that content are currently undergoing an explosion of new metaphors, and we might even expect some of them to succeed!