Categories: Front cover chemistry , Guest posts |  Comments
Guest post from Tom Branson
It’s that time of year again, when all things creepy come out to play. Witches, monsters and of course the grinning pumpkins will be out and about. The humble pumpkin has found itself increasingly popular with artists wishing to outdo each other with their carving skills, but pumpkins have also found a home amongst equally competitive chemists shaping their constructions.
If you’re beginning to think I’ve been hit with a confusion spell then never fear, I’m simply referring to the modest cucurbituril. This molecule gets its name from the term for the pumpkin family. There’s apparently a resemblance between the ribs of the pumpkin and the bonds of the macromolecule. But this similarity is nowhere better shown than in the Halloween themed cover of the latest edition of Chemical Science.
This cover brings us into the darkness of a pumpkin-scientist’s den, light spilling through carved features illuminating the creations within. Looming large on the desk is a ghastly pumpkin, smiling whilst xenon bats flitter in and out of its gaping mouth. The desk is also littered with smaller cucurbiturils and a structure half way through its transmogrification into a fully-fledged pumpkin-xenon-bat-exchanger-thing. On the left side stands an old cage and a bat confined within. A dusty spider’s web blocks the exit, which is also being guarded nearby by acryptophaneunwilling to release its hostage.
The scientist’s intriguing plans lie open on the desk stating the diabolical aims of the pumpkin experiments using NMR and saturation transfer spectroscopy. I’m sure we could dive deeper into these intentions if we can get our hands on that USB stick with its 16 cucurBIT memory. For me, it’s these finishing touches that really make the difference, the attention to detail adding to the tongue-in-cheek appeal of this cover. The combination of molecular structures, scientific data and metaphorical bats combine brilliantly to bring this image to life.
Leif Schröder provides the brains behind this creation, with the study being performed in his lab at the Leibniz-Institut fur Molekulare Pharmakologie in Berlin. Schröder told me that after realising that their article would be published around Halloween he couldn’t resist the pumpkin connection. He collaborated with Barth van Rossum, also from the same institute, and it was his visualisation skills that brought the cover to life. The pair has previously combined this year to produce a wealth of other captivating cryptophane covers.
These ‘pumpkin’ molecules are very promising for use in signal amplification of xenon MRI. Xe cucurbituril complexes are poorly soluble in water and so in order to investigate this system Schroder developed the Hyper-CEST technique, combining hyperpolarised Xe with chemical exchange saturation transfer. Cucurbituril offered a 100-fold improvement in sensitivity when compared with the previous favourite, cryptophane.
I can add this timely Halloween cover to the same category as the champagne and fireworks we saw for Angewandte Chemie’s 125th birthday, but I am yet to confirm a scientific sighting of the Easter bunny. So that leaves me with thoughts of what could be next for the chemical holiday celebrations. Will we see an α‑cyclodextrin become a snowflake this winter? Or after the recent buckyball patisseries can we expect a C60 snowman? If any of you out there have spotted other seasonal cover images then please share them here in the comments.