The wonders of alkyl chains

Earlier today, my friend and colleague, Professor Dwight Seferos (http://www.chem.utoronto.ca/wp/seferos/), gave the 2014 John Polanyi lecture. The talk showcased the Seferos lab’s command over conjugated materials based on heterocyclic frameworks (mainly seleno- and tellurophenes). One particular structural piece that seems to be central to this kind of research is the alkyl chain-containing repeating unit shown below.

lll

As you might imagine, all of the electronic properties of such polymers are ascribed to the aromatic nucleus, whereas the aliphatic side chain is there to ensure packing, ultimately controlling the interchain interactions and material morphology. I just wanted to comment on this “alkyl chain business” as I think some folks might have a tendency to trivialize the unique structural aspects of straight alkyl chains. Indeed, many practitioners of synthesis view them as fairly boring bystanders that, while central to function, are really not that exciting. All they do is pack parallel to each other, so what’s the big deal, you might say? Well, not so fast… While I was listening to Dwight’s expertly delivered presentation, I remembered one of my favourite old papers by the one and only – K. Barry Sharpless (my mentor). This manuscript hails from 1975 and describes a property that makes you realize that there is nothing remotely boring when it comes to straight alkyl chains. In the graphic below you can see the craziest separation ever performed (in my humble opinion). The two long chain alcohols differ by just two methylene units, yet are separable upon shaking the mixture over calcium chloride. These are the real wonders of chemistry, ladies and gentlemen. I am curious if subtle effects such as this can exert an influence on properties other than alcohol separation.

ttt

http://pubs.acs.org/doi/abs/10.1021/jo00897a015

2 thoughts on “The wonders of alkyl chains

  1. Amazing! The effect of small difference from two methylene units might get amplified once the compounds self assemble. I always wondered if such unique selectivity can be achieved with peptide assemblies.

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