“Captured and put in chains” – new article in Angewandte Chemie

“Captured and put in chains” – new article in Angewandte Chemie

I recently finished working in Trinity College Dublin after five and a half productive years. My final project was completed in the weeks before I left and submitted to the prestigious journal Angewandte Chemie on the 1st April, the day I started in my new position at Universität Bern.

This article has just come out, and I’m rather proud of it, and happy that it is a fitting ending to my time in Dublin. My original goal in Thorri Gunnlaugsson’s research groupwas to form interlocked molecules, such as “catenanes”, but this challenging goal kept moving further down the queue as we discovered new and interesting ways to exploit the “btp” motif (which has been the topic of all my research to date). But finally, and somewhat unexpectedly, we achieved this goal.

Creating these new structures built upon interesting behaviour we reported in our Chemistry – A European Journal article early this year – where we saw that btp molecules could interact with each other, forming pairs through weak hydrogen bonding. We wondered if this could be used to pre-organise molecules together in such a way that they could be ‘clipped’ together into interlocked rings (by “RCM”, as outlined in the Scheme above). This approach has occasionally been reported before for amides,but not for molecules like the ones we describe.

A representation of the formation of catenanes from btp ligands

In fact, this reaction was more successful than expected – and in the first case I tried, we were surprised to find the majority product (50% yield) was the interlocked “catenane”, with independent non-interlocked rings also observed. We were able to fully identify and characterise these molecules using X-ray crystallographic analysis, giving the clear pictures below (thanks to Dr Salvador Blasco).

These were nice structures, but I wanted them to do something more than look pretty! Discussions with my friend Anna Aletti opened up the idea that the cavity in the middle of the structures might be a perfect fit for some negatively charged ion guest, such as chloride, nitrate or sulfate – none of these ions did very much, but phosphate (the tetrahedral H2PO4- ion), on the other hand, caused changes in the “catenane” host, indicating specific interactions between these two molecules. This was exciting. It makes these the first catenanes in the literature to have such interactions with tetrahedral anions.

The catenane acts as a selective host for phosphate, as can be seen from changes in the NMR spectrum

Detailed analysis of the formation of these interesting compounds, as well as their adducts with phosphate was important to strengthening these results and making sure we understood what we were seeing. Working closely with Dr Gary Hessman, Technical Officer at TCD, allowed further insight into the systems and their composition.

If any of this sounds interesting, then you should read the article (http://dx.doi.org/10.1002/anie.201603213) or at least look at the pictures! One fun advantage of publishing in Angewandte Chemie is that they translate your abstract into German (which I am currently learning), which means I now know the useful everyday term “Triazolylwasserstoffbrüken“, which – of course – means “triazolyl hydrogen-bonding interactions”. I now use that in the pubs of Bern almost daily!

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TG Group travel to Southampton for Supramolecular Symposium

It was nice to catch up with some old colleagues in Southampton and chat molecular logic with my “academic grandfather” AP de Silva, as well as why he enjoyed being educated by Buddhist monks and Catholic nuns at the same time in Sri Lanka!

Gunnlaugsson Group, Trinity College Dublin

Anna Aletti, Samuel Bradberry and Dr. Oxana Kotova of the TG group attended Southampton Supramolecular Chemistry Symposium on the 24th of June 2016.

delegates Southamption Supramolecular Symposium 2016 Delegates

All of them presented posters and, in addition, Samuel gave an excellent talk on “Lanthanide Luminescent Logic – functional organic scaffolds and soft polymers gels as logic gate mimics”.

DSC_0048 Sam giving his talk

DSC_0036 Sam and A P at the poster session

DSC_0043 Oxana with her poster

DSC_0035 Anna presenting her poster

2016-06-24 18.02.36 A P de Silva, Oxana, Anna, Joe and Sam at the drinks reception

Our former group member Dr. Joseph Byrne who is currently a postdoctoral researcher in the University of Bern attended the conference as well and presented a poster on his recent work published in Angew. Chem. Int. Ed. on self-templated btp [2]Catenane.

The meeting included speakers and posters from UK Universities and beyond, including an outstanding lecture from the…

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Surprisin’ horizon 

Now that summer is here, something keeps happening to me on my cycle to work, and it keeps on surprising me. The cloudy sky of spring has lifted, more or less permanently, and so as I round  one particular corner on my route, I see the alpine vista over the train lines. I can’t help but smile stupidly every time. The horizon is beautiful when the sky is blue in contrast to the snow capped peaks. And I consistently forget that I will see this view almost every day. It’s nice to smile on the way to work!