Polly Arnold talks about Pac-man molecules, f-block chemistry and the countryside. Interview by Nicola Wise. 

	Polly Arnold is chair of synthetic inorganic chemistry at the University of Edinburgh. Her research interests include making unusual and reactive complexes of the lanthanides, actinides and early transition metals. Polly is a member of the DaltonTransactions advisory board.

What inspired you to become a scientist?

Like so many others, it was due to the enthusiasm of a few science teachers, and in particular chemistry teachers. My mother also pointed out that I couldn't do chemistry in my spare time, so I went for it!  

What motivated you to specialise in f-block chemistry? 

There are still a lot of unknowns left to explore in this area of the periodic table. This makes it fascinating and worth investing some time in. Increasingly, technological advances are also making it easier to make and study esoteric molecules that would have been very hard to characterise a decade ago.

Your work on uranium has made quite an impression with regards to the discovery of the 'Pac-Man' like molecule which is able to bind to the uranyl ion. Can you briefly explain how this chemistry works?

Jason Love's group, here in Edinburgh, had been working on Pac-Man shaped ligands for catalysis. In collaboration we bound a single, linear uranyl dication UO22+ into one half of the Pac-Man and found that treatment with a base led, we think, to incorporation of potassium cations bound to the uranyl oxo group inside the Pac-Man's mouth and disrupted the normally very strong O-U-O bonding. This activated the other oxo group to cleave C-Si and N-Si bonds and allowed us to show the first covalent bond forming reactions of the uranyl ion. This ion is ubiquitous, and traditionally very inert, so it was exciting to demonstrate chemistry that reactive transition metal oxo compounds participate in for uranium. It suggests that C-H activation chemistry might be accessible using this reductive functionalisation strategy. 

The compounds are air-sensitive and are not useful for sequestration in their current form. But they do improve our understanding about the behaviour of uranium and uranyl salts, which is at the core of dealing with our nuclear waste legacy.

What other projects are you working on at the moment?

Continuing on the theme of C-H activation, we've been looking at high oxidation state cerium N-heterocyclic carbene complexes and palladium (IV)complexes for catalytic hydrocarbon halogenation. Our carbene ligands are good at stabilising high oxidation states and survive the harsh oxidising conditions, so there's lots of scope to make some nice asymmetric catalysts.

We're also looking at the polymerisation of biorenewables into biodegradable polymers including esters and carbonates. By making enormous chiral, monoanionic ligands for lanthanide cations, we've been getting good control over polymer stereochemistry.

What's hot at the moment in your research area? 

I really like the recent progress that people have made in making terminal oxo and nitride complexes of late transition metals - Hill's and Milstein's palladium and platinum oxos and Burger's iridium nitrido complex. They're so stunningly different to the archetypal soft chemistry you think about for late-metal complexes, but they look so sensible to an early-metal chemist. I'm sure there is a lot of interesting chemistry to come out of these systems in the near future. 

Which part of your career are you most proud of? 

That's easy - my PhD students. It's fantastic to watch each of them blossom over their three years as they first get to grips with their project and become experts. 

Academia is quite male dominated. What do you think about this? 

I would be interested to hear this question answered by a male academic. It's a waste of brainpower if you only ever pick your next scientist from 50 per cent of the talent pool, but I can understand the very sensible attitude that people take towards selecting a career with an easily identifiable support structure. It's a sweeping generalisation, but a good female student usually needs to be told in no uncertain terms that she's good, or brilliant, by a supervisor. This does not come naturally to the British.   And all our students need to be encouraged to look for bits of role models in all those around them, and combine the attributes they admire and aspire to.

Which scientist, current or historic, do you most admire? 

The person who springs to mind is John Bercaw (California Institute of Technology, Pasadena, US). He does beautiful chemistry and is not afraid to work with metals at both ends of the periodic table, which too many chemists regard as a taboo. And more importantly, everyone that knows him says he is one of the nicest people in chemistry. Of course, this will be another reason why his chemistry is so good. 

What do you like to do when you're not doing chemistry? 

We've nearly finished installing the kitchen, which has been a lot of fun but has taken ages as I've travelled a lot recently. The city and the countryside round here are so beautiful, I'm about ready to give up major DIY projects now, and am going to spend more time running, hiking, and climbing.